Embolization: Selected Procedures

Number: 0856

Table Of Contents

Policy
Applicable CPT / HCPCS / ICD-10 Codes
Background
References

Policy

Scope of Policy

This Clinical Policy Bulletin addresses selected embolization procedures.

  1. Medical Necessity

    Aetna considers the following procedures medically necessary:

    1. Alcohol embolization or sclerotherapy and/or surgery for symptomatic venous malformations as evidenced by pain, swelling, ulceration, or hemorrhage
    2. Coil embolization in the treatment of arterio-venous malformations (AVMs)/aneurysm and splenic artery aneurysm
    3. Coil embolization of gastric varices
    4. Endovascular embolization for an extracranial AVM or fistula
    5. Geniculate artery embolization for knee hemarthrosis following total knee arthroplasty if member has failed conservative therapies (e.g., ice, immobilization, compression, saline lavage, corticosteroid instillation, and selective COX-2 inhibitors); and demonstrated synovial hyper-vascularity on angiography
    6. Portal vein embolization before surgical resection of cholangiocarcinoma
    7. Pre-operative embolization of skull base meningiomas
    8. Renal artery embolization/angioinfarction, as a pre-operative adjunct to nephrectomy, in the treatment of persons with large, hypervascular renal cell carcinomas
    9. Selective arterial embolization for the treatment of giant cell tumor
    10. Splenic artery embolization for the treatment of hyper-splenism secondary to hepatic cirrhosis as an alternative to splenectomy
    11. Transcatheter arterial embolization for non-variceal upper gastro-intestinal bleeding
    12. Transcatheter embolization (embolotherapy) in the treatment of intractable or recurrent severe posterior epistaxis when conservative measures have failed
    13. Tumor embolization or pre-operative tumor embolization to reduce intra-operative bleeding prior to surgical resection in the treatment of hypervascular tumors or metastases from hypervascular tumors
    14. Vascular embolization for the treatment of type I/type II endovascular leak.

  2. Experimental and Investigational

    Aetna considers the following procedures experimental and investigational (not an all-inclusive list) because the effectiveness of these approaches has not been established:

    1. Coil embolization and occlusion of the hypogastric veins for the prevention or treatment of deep vein thrombosis (DVT)
    2. Embolization for locoregional treatment of metastatic pancreatic cancer
    3. Endovascular embolization in the treatment of spinal dural arterio-venous fistula
    4. Genicular artery embolization for the treatment of osteoarthritis-related knee pain
    5. Hemorrhoidal embolization (HydroPearl microspheres)
    6. HydroPearl microspheres for the treatment of AVMs in the lower extremity
    7. Left gastric artery embolization for the treatment of obesity
    8. Middle meningeal artery embolization for chronic subdural hematoma
    9. Paraumbilical vein coil embolization for the treatment of hepatic encephalopathy
    10. Pre-operative embolization for carotid body tumor resection
    11. Prostate artery embolization for the treatment of benign prostatic hyperplasia/obstruction (see CPB 0079 - Benign Prostatic Hypertrophy (BPH) Treatments).

  3. Related Policies

Table:

CPT Codes / HCPCS Codes / ICD-10 Codes
Code Code Description

CPT codes covered if selection criteria are met:
37241 Vascular embolization or occlusion, inclusive of all radiological supervision and interpretation, intraprocedural roadmapping, and imaging guidance necessary to complete the intervention; venous, other than hemorrhage (eg, congenital or acquired venous malformations, venous and capillary hemangiomas, varices, varicoceles)
37242     arterial, other than hemorrhage or tumor (eg, congenital or acquired arterial malformations, arteriovenous malformations, arteriovenous fistulas, aneurysms, pseudoaneurysms) [not covered for prostate artery embolization]
37243     for tumors, organ ischemia, or infarction
37244     for arterial or venous hemorrhage or lymphatic extravasation
61624 Transcatheter permanent occlusion or embolization (eg, for tumor destruction, to achieve hemostasis, to occlude a vascular malformation), percutaneous, any method; central nervous system (intracranial, spinal cord)
61626 Transcatheter permanent occlusion or embolization (eg, for tumor destruction, to achieve hemostasis, to occlude a vascular malformation), percutaneous, any method; non-central nervous system, head or neck (extracranial, brachiocephalic branch)
75894 Transcatheter therapy, embolization, any method, radiological supervision and interpretation

CPT codes not covered for indications listed in the CPB:
Hemorrhoidal embolization -no specific code

HCPCS codes not covered for indications listed in the CPB:
HydroPearl microspheres –no specific code

ICD-10 codes covered if selection criteria are met:
C22.0 Liver cell carcinoma [hepatocellular carcinoma]
C22.1 Intrahepatic bile duct carcinoma
C64.1 - C64.9 Malignant neoplasm of kidney, except pelvis [renal cell carcinoma]
D16.00 - D16.9 Benign neoplasm bones [localized giant cell tumor]
D32.0 Benign neoplasm of cerebral meninges
D49.2 Neoplasm of unspecified behavior of bone, soft tissue, and skin [localized giant cell tumor]
D73.1 Hypersplenism [secondary to hepatic cirrhosis]
I67.1 Cerebral aneurysm, nonruptured
I72.8 Aneurysm of other specified arteries [splenic artery]
I86.4 Gastric varices
K92.2 Gastrointestinal hemorrhage, unspecified [upper gastrointestinal bleeding]
M25.061 - M25.069 Hemarthrosis, knee
Q27.0 - Q27.9 Other congenital malformations of peripheral vascular system
Q28.0 - Q28.9 Other congenital malformations of circulatory system
R04.0 Epistaxis [intractable or recurrent severe posterior]

ICD-10 codes not covered for indications listed in the CPB:
C75.4 Malignant neoplasm of carotid body
E66.01 – E66.9 Obesity
G93.49 Other encephalopathy [hepatic encephalopathy
I62.03 Nontraumatic chronic subdural hemorrhage
K64.0 – K64.9 Hemorrhoids and perianal venous thrombosis
M17.0 – M17.9 Osteoarthritis of knee
N40.0 - N40.3 Benign prostatic hyperplasia

Background

Splenic artery aneurysms account for 60 % of all visceral arterial aneurysms.  They are the only aneurysms that are more common in women, with a female-to-male ratio of 4:1.  The development of aneurysms in the splenic artery has been attributed to systemic arterial fibrodysplasia, portal hypertension, and increased splenic arterio-venous shunting that occurs in pregnancy.  Splenic artery aneurysms are most often asymptomatic.  Symptomatic patients exhibit vague left upper quadrant or epigastric discomfort and occasional radiation of pain to the left shoulder or subscapular area.  Only 2 % of splenic artery aneurysms result in life-threatening rupture. 

Coil embolization is a catheter-based procedure that allows precise closure of abnormal blood flow in a blood vessel.  A catheter with a metallic occluding coil is inserted into an artery, usually in the groin (the femoral artery).  It is then advanced to the abnormal blood vessel.  Once properly positioned, the metal coil is released, springing into position within the vessel.  It remains firmly in place by the expansion of the metal coils.  A blood clot will form on the coil, completely obstructing the abnormal blood flow beyond the coil.  Eventually a scar will form, creating a permanent seal.

Although the individual study numbers are small, the total studied over several years is significant and the evidence has demonstrated that coil embolization in the treatment of splenic artery aneurysms is safe and effective and may induce less morbidity than open surgery, in particular by preserving the spleen.

Leffroy et al (2008) evaluated the outcomes of endovascular treatment of splenic artery aneurysms and pseudoaneurysms.  From April 2002 to May 2007, 17 patients (mean age of 55.2 years, range of 17 to 82) with splenic artery aneurysms (n = 7) or pseudoaneurysms (n = 10) underwent endovascular treatment.  Six patients were asymptomatic, 3 had symptomatic nonruptured aneurysms, and 8 had ruptured aneurysms.  Lesions were in the proximal splenic artery (n = 5), intermediate splenic artery (n = 3), splenic hilum (n = 6), or parenchyma (n = 3).  Embolization was with microcoils by sac packing (n = 8), sandwich occlusion of the main splenic artery (n = 4), or cyanoacrylate glue into the feeding artery (n = 4).  Computed angiotomography was done within the first month and magnetic resonance angiography (MRA) after 6 and 12 months, then yearly.  Mean follow-up was 29 months (range of 1 to 62).  Exclusion of the aneurysm was achieved in 16 (94.1 %) patients.  One patient with an intra-parenchymal pseudoaneurysm underwent splenectomy after failed distal catheterization.  No major complications occurred.  Post-embolization syndrome developed in 4 patients, who had radiographic evidence of splenic microinfarcts.  The authors concluded that transcatheter embolization of splenic artery aneurysms/pseudoaneurysms is safe and effective and may induce less morbidity than open surgery, in particular by preserving the spleen.  Coil artifacts may make MRA preferable over computed tomography for follow-up.

Ikeda and colleagues (2008) described their experiences with the treatment of visceral artery aneurysms (VAA) by transcatheter coil embolization and proposed indications for treating VAA by this method.  A total of 22 patients with VAA were treated by coil embolization; 9 had splenic-, 7 renal-, 4 pancreaticoduodenal arcade-, and 2 proper hepatic artery-aneurysms.  The transcatheter coil embolization procedure included coil embolization and coil-packing of the aneurysmal sac, preserving the native arterial circulation.  Transcatheter coil embolization with aneurysm packing was technically successful in 16 (72.7 %) of the 22 patients and the native arterial circulation was preserved.  Post-procedure angiograms confirmed complete disappearance of the VAA.  In 4 of the 9 splenic artery aneurysm patients, the native arterial circulation was not preserved.  In 1 renal artery aneurysm patient, stenosis at the aneurysmal neck necessitated placement of a stent before transcatheter coil embolization.  Magnetic resonance angiographs obtained during the follow-up period (mean of 27 months) demonstrated complete thrombosis of the VAA in all 22 patients.  Infarction occurred in 1 splenic- and 2 renal artery-aneurysms patients; the latter developed flank pain and fever after the procedure.

Yamamoto et al (2008) published the findings of a small study evaluating the clinical results and technical problems of transcatheter coil embolization for splenic artery aneurysm.  Subjects were 16 patients (8 men, 8 women; age range of 40 to 80 years) who underwent transcatheter embolization for splenic artery aneurysm (14 true aneurysms, 2 false aneurysms) during the period January 1997 through July 2005.  Embolic materials were fibered coils and interlocking detachable coils.  Embolization was performed by the isolation technique, the packing technique, or both.  Technically, all aneurysms were devascularized without severe complications.  Embolized aneurysms were 6 to 40 mm in diameter (mean of 25 mm).  Overall, the primary technical success rate was 88 % (14 of 16 patients).  In the remaining 2 patients (12.5 %), partial re-canalization occurred, and re-embolization was performed.  The secondary technical success rate was 100 %; 7 (44 %) of the 16 study patients suffered partial splenic infarction.  Intra-splenic branching originating from the aneurysm was observed in 5 patients.  According to the authors, transcatheter coil embolization should be the initial treatment of choice for splenic artery aneurysm.

Piffaretti and associates (2007) assessed the endovascular embolization of splenic artery aneurysms and false aneurysms with special consideration given to post-operative complications in 15 patients (11 women; mean age of 56 years; range of 39 to 80 years) with splenic artery aneurysm (n = 13) or false aneurysm (n = 2) treated with coil embolization.  The lesion was asymptomatic in 9 patients, symptomatic in 5 patients, and ruptured in 1 patient.  The mean aneurysm diameter was 33 +/- 23 mm (range of 15 to 80 mm).  Post-operative follow-up evaluation included a clinical visit and spiral computed tomography at 1, 4, and 12 months, and yearly thereafter.  Endovascular treatment was possible in 14 patients (93 %) (1 failure: neck cannulation).  Peri-operative mortality was not observed.  Morbidity included post-embolization syndrome in 5 patients (30 %).  Neither pancreatitis nor spleen abscess occurred.  The mean follow-up period was 36 months (range of 3 to 60 months).  During follow-up evaluation 1 sac reperfusion was detected that was sealed successfully with additional coils.  Surgical conversion or open repair was never required.

Tulsyan et al (2007) studied the outcomes of the management of VAA with catheter-based techniques.  Between 1997 and 2005, 90 patients were identified with a diagnosis of VAA.  This was inclusive of aneurysmal disease of the celiac axis, superior mesenteric artery (SMA), inferior mesenteric artery, and their branches.  Surveillance without intervention occurred in 23 patients, and 19 patients underwent open aneurysm repair (4 ruptures).  The endovascular treatment of 48 consecutive patients (mean age of 58, 60 % men) with 20 VAA and 28 visceral artery pseudoaneurysms (VAPA) was the basis for this study.  Electronic and hardcopy medical records were reviewed for demographic data and clinical variables.  Original computed tomography (CT) scans and fluoroscopic imaging were evaluated.  The endovascular treatment of VAA was technically successful in 98 % of 48 procedures, consisting of 3 celiac axis repairs, 2 left gastric arteries, 1 SMA, 12 hepatic arteries, 20 splenic arteries, 7 gastroduodenal arteries, 1 middle colic artery, and 2 pancreaticoduodenal arteries.  Of these, 29 (60 %) were performed for symptomatic disease (5 ruptured aneurysms).  Coil embolization was used for aneurysm exclusion in 96 %.  N-butyl-2-cyanoacrylate (glue) was used selectively (19 %) using a tri-axial system with a 3-F microcatheter for persistent flow or multiple branches.  The 30-day mortality was 8.3 % (n = 4).  All peri-operative deaths occurred in patients requiring urgent or emergent intervention in the setting of hemodynamic instability.  No patients undergoing elective intervention died in the peri-procedural period.  Post-procedural imaging was performed after 77 % of interventions at a mean of 16 months.  Complete exclusion of flow within the aneurysm sac occurred in 97 % interventions with follow-up imaging, but coil and glue artifact complicated CT evaluation.  Post-embolization syndrome developed in 3 patients (6 %) after splenic artery embolization.  There was no evidence of hepatic insufficiency or bowel ischemia after either hepatic or mesenteric artery aneurysm treatment.  Three patients required secondary interventions for persistent flow (n = 1) and recurrent bleeding from previously embolized aneurysms (n = 2).

Gabelmann et al (2002) conducted a review of their 10-year experience with endovascular embolization of VAA.  A total of 25 patients (13 men; mean age of 52.1 years, range of 31 to 80) presented with VAAs of varying locations and etiologies: 10 splenic, 3 gastroduodenal, 2 pancreaticoduodenal, 3 hepatic, 3 superior mesenteric, 2 celiac, 1 left gastric, and 1 jejunoileal.  Ten patients were asymptomatic; 7 aneurysms were ruptured.  Transcatheter coil embolization was the treatment of choice in all patients.  Coil placement was initially (less than 7 days) successful in 23 (92 %) patients.  One superior mesenteric artery aneurysm remained perfused, and recurrent bleeding occurred 2 days after intervention in 1 case, but repeated embolization excluded the aneurysm.  One patient with necrotizing pancreatitis died from sepsis 10 days after endovascular treatment and surgery (4 % 30-day mortality).  Long-term follow-up revealed excellent results after an average 48.7 months (range of 14 to 75) with only 1 recurrence after 12 months.

Guillon et al (2003) assessed the endovascular treatment of 12 patients (mean age of 59 years, range of 47 to 75 years) with splenic artery aneurysm (n = 10) or false aneurysm (n = 2).   The lesion was asymptomatic in 11 patients; hemobilia was observed in 1 patient.  The lesion was juxta-ostial in 1 case, located on the intermediate segment of the splenic artery in 4, near the splenic hilus in 6, and affected the whole length of the artery in 1 patient.  In 10 cases, the maximum lesion diameter was greater than 2 cm; in 1 case 30 % growth of an aneurysm 18 mm in diameter had occurred in 6 months; in the last case, 2 distal aneurysms were associated (17 and 18 mm in diameter).  In 1 case, stent-grafting was attempted; 1 detachable balloon occlusion was performed; the 10 other patients were treated with coils.  Endovascular treatment was possible in 11 patients (92 %) (1 failure: stenting attempt).  In 4 cases among 11, the initial treatment was not successful (residual perfusion of aneurysm); surgical treatment was carried out in 1 case, and a second embolization in 2.  Thus, in 9 cases (75 %) endovascular treatment was successful: complete and persistent exclusion of the aneurysm but with spleen perfusion persisting at the end of follow-up on CT scans (mean of 13 months).  An early and transient elevation of pancreatic enzymes was observed in 4 cases.

Arterio-venous malformation (AVM) is a disorder of the blood vessels that is characterized by a complex, tangled web of abnormal arteries and veins connected by 1 or more AV fistulas (abnormal communications); AVMs of the hemangioma type are congenital.  While they can occur anywhere in the body and have been found in the arms, hands, legs, feet, lungs, heart, liver, and kidneys; 50 % of these malformations occur in the brain, brainstem, and spinal cord.  Arterio-venous malformations of the intestine, also referred to as angiodysplasias, are distinct from hemangiomas and true congenital AVMs.  They are thought to be acquired degenerative lesions secondary to progressive dilation of normal blood vessels within the submucosa of the intestine.  An arteriovenous malformation may hemorrhage, or bleed, leading to serious complications that can be life threatening. 

Endovascular embolization is the therapeutic introduction of various substances or other materials, into the circulation, to occlude blood vessels.  This is intended to either arrest or prevent bleeding, or devitalize a structure, tumor or organ by occluding it’s blood supply. 

Various embolization devices and several types of embolic agents have been approved by the U.S. Food and Drug Administration (FDA).  The currently available embolic agents include liquid embolitics, particulate materials, metallic coils, and detachable balloons.  There are numerous liquid embolic agents, the most commonly used being absolute alcohol (100 % ethanol) and various tissue adhesives, including the cyanoacrylates and Onyx (EV3 Neurovascular).  Two commonly used particulate materials are Gelfoam and polyvinyl alcohol (PVA).

There are 2 broad categories of metallic coils: coils that are pushed from a catheter with a metal coil pusher or guidewire, and coils that are released by breaking a bond between the coil and the pushing wire.

Based on the clinical evidence, endovascular embolization is an acceptable treatment modality for an extra-cranial AVM or fistula.

Renal cell cancer accounts for 90 to 95 % of malignant neoplasms arising from the kidney.  Gross or microscopic hematuria is the most common presenting sign, followed by abdominal pain and a flank or abdominal mass.

Renal artery embolization is a non-surgical technique.  Using x-rays (angiography), a catheter is directed into the renal artery by a specially trained radiologist (Interventional Radiologist).  Material is injected through the catheter into the artery causing the blood to clot and block blood flow to the kidney.  Nephrectomy is the surgical procedure to remove a kidney.

Based on the clinical evidence, renal artery embolization/angioinfarction, as a pre-operative adjunct to nephrectomy, is an acceptable alternative in the treatment of patients with large, hypervascular renal cell carcinomas.

Epistaxis is bleeding from the nose or nasal hemorrhage and is classified as anterior or posterior.  Approximately 90 % of epistaxis events are idiopathic.  Transcatheter embolization (embolotherapy) is the intentional occlusion of a vessel by deposition of thrombogenic materials directly into the vessel via an angiographic catheter.  Based on the clinical evidence, transcatheter embolization (embolotherapy) is an acceptable alternative in the treatment of intractable or recurrent severe posterior epistaxis when conservative measures have failed.

A hypervascular tumor is a tumor characterized by an abnormal increase in blood vessel growth in the area.  These vessels feed the tumor cells, and may be characterized by abnormal connections between veins and arteries.  Hypervascular tumors may be benign (meningiomas, osteoblastomas, chondromas), malignant (renal cell carcinoma, thyroid carcinoma, hepatocellular carcinoma, glomus tumor) or metastatic tumors from these primary sites (list is not all-inclusive). 

Tumor embolization is defined as the blockage of the vascular supply to a tumor.  Embolization is the therapeutic introduction of various substances into the circulation to occlude vessels, either to arrest or prevent hemorrhaging, to devitalize a structure tumor or organ by occluding it’s blood supply or to reduce blood flow an arteriovenous malformation.  The occlusion is usually performed via an endovascular approach, transcatheter embolization (embolotherapy) by deposition of thrombogenic materials directly into the vessel via an angiographic catheter or by direct percutaneous injection of embolic agents into the tumor.  The goals of embolization may be adjunctive, curative, or palliative.  The procedure is usually performed in a single session, simultaneously with diagnostic arteriography, but may also be performed in multiple staged sessions.  Pre-operative embolization is also performed.

Tumor embolization or pre-operative tumor embolization to reduce intra-operative bleeding prior to surgical resection may be considered medically necessary in the treatment of hypervascular tumors or metastases from hypervascular tumors.

Coil Embolization for the Treatment of Arterio-Venous Malformations (AVMs) / Aneurysm

Koebbe and colleagues (2006) reviewed the clinical and angiographic outcomes for 1,307 patients undergoing endovascular treatment of intracranial aneurysms. This analysis focused on posterior circulation and middle cerebral artery aneurysms, as well as cases of stent-assisted coil embolization. They reviewed their procedural protocol and patient selection criteria for endovascular management. Several large clinical trials have demonstrated the safety and effectiveness of endovascular treatment of intracranial aneurysms. The International Subarachnoid Aneurysm Trial provides Level I evidence demonstrating a significant reduction in disability or death with endovascular treatment compared with surgical clipping. The most common procedural complications include intra-procedural rupture and thromboembolic events; avoidance strategies were also discussed. Vasospasm after subarachnoid hemorrhage causes neurological morbidity and mortality and can be successfully managed by early recognition and interventional treatment with angioplasty, pharmacologic agents, or both. The authors concluded that long-term studies evaluating experience with aneurysm coil embolization during the past decade indicated that this is a safe and durable treatment method. The introduction of stent-assist techniques has improved the management of wide-neck aneurysms. Future technology developments will likely improve the durability of endovascular treatment further by delivering bioactive agents that promote aneurysm thrombosis beyond the coil mass alone. It is clear that endovascular therapy of both ruptured and un-ruptured aneurysms is becoming a mainstay of practice in this patient population. Although not replacing open surgery, the continued improvements have allowed aneurysms that previously were amenable only to open clip ligation to be treated safely with durable long-term outcomes.

Bruno and Meyers (2013) stated that arterio-venous malformations (AVMs) of the brain are rare, complex, vascular lesions that can result in significant morbidity and mortality. Modern treatment of brain AVMs is a multi-modality endeavor, requiring a multi-disciplinary team with expertise in cerebrovascular neurosurgery, endovascular intervention, and radiation therapy in order to provide all therapeutic options and determine the most appropriate treatment regimen depending on patient characteristics and AVM morphology. Current therapeutic options include microsurgical resection, radiosurgery (focused radiation), and endovascular embolization. Endovascular embolization is primarily used as a pre-operative adjuvant before microsurgery or radiosurgery. Palliative embolization has been used successfully to reduce the risk of hemorrhage, alleviate clinical symptoms, and preserve or improve neurological function in inoperable or non-radiosurgical AVMs. Less frequently, embolization is used as “primary therapy” particularly for smaller, surgically difficult lesions. Current embolic agents used to treat brain AVMs include both solid and liquid agents. Liquid agents including N-butyl cyanoacrylate and Onyx are the most commonly used agents. As newer embolic agents become available and as micro-catheter technology improves, the role of endovascular treatment for brain AVMs will likely expand. The authors noted that embolization under these circumstances should be used to treat specific high-risk AVM angio-architectural features such as aneurysms.

Lanzino et al (2013) performed a meta-analysis of prospective controlled trials of clipping versus coil embolization for ruptured aneurysms. These researchers performed a search of the English literature for published prospective controlled trials comparing surgical clipping with endovascular coil embolization for ruptured intracranial aneurysms. Data were abstracted from the identified references. Outcomes of interest were the proportion of patients with a poor outcome at 1 year and episodes of re-bleeding from the index treated aneurysm after the allocated treatment. There were 3 prospective controlled trials eligible for inclusion. These studies enrolled 2,723 patients. Meta-analysis of these studies showed that the rate of poor outcome at 1 year was significantly lower in patients allocated to coil embolization (risk ratio, 0.75; 95 % confidence interval [CI]: 0.65 to 0.87). This relative effect is consistent with an absolute risk reduction of 7.8 % and a number needed to treat of 13. The effect on mortality was not statistically different across the 2 treatments. Re-bleeding rates within the first month were higher in patients allocated to endovascular coil embolization. The authors concluded that on the basis of the analysis of the 3 high-quality prospective controlled trials available, there is strong evidence to indicate that endovascular coil embolization is associated with better outcomes compared with surgical clipping in patients amenable to either therapeutic strategy.

Morales-Valero et al (2014) performed a comprehensive literature search for reports on contemporary endovascular treatment of internal carotid artery (ICA) bifurcation aneurysms from 2000 to 2013, and these investigators reviewed their experience. They extracted information regarding peri-procedural complications, procedure-related morbidity and mortality, immediate angiographic outcome, long-term clinical and angiographic outcome, and re-treatment rate. Event rates were pooled across studies by using random-effects meta-analysis. Including their series of 37 patients, 6 studies with 158 patients were analyzed. Approximately 60 % of the aneurysms presented as un-ruptured; 88.0 % (95 % CI: 68.0 % to 96.0 %) of aneurysms showed complete or near-complete occlusion at immediate post-operative angiography compared with 82.0 % (95 % CI: 73.0 % to 88.0 %) at last follow-up. The procedure-related morbidity and mortality were 3.0 % (95 % CI: 1.0 % to 7.0 %) and 3.0 % (95 % CI: 1.0 % to 8.0 %), respectively. The re-treatment rate was 14.0 % (95 % CI: 8.0 % to 25.0 %). Good neurologic outcome was achieved in 93.0 % (95 % CI: 86.0 % to 97.0 %) of patients. The authors concluded that endovascular treatment of ICA bifurcation aneurysms is feasible and effective and is associated with high immediate angiographic occlusion rates. However, re-treatment rates and procedure-related morbidity and mortality were non-negligible.

Turfe et al (2015) stated that endosaccular coil embolization and parent artery occlusion (PAO) are established endovascular techniques for treatment of cavernous carotid aneurysms. These researchers performed a systematic review of published series on endovascular treatment of cavernous carotid aneurysms to determine outcomes and complications associated with endovascular coiling and PAO of cavernous carotid artery aneurysms. In September 2013, these investigators conducted a computerized search of MEDLINE and EMBASE for reports on endovascular treatment of intracranial cavernous carotid aneurysms from January 1990 to August 2013. Comparisons were made in peri-procedural complications and outcomes between coiling and PAO patients who did not receive bypass. Event rates were pooled across studies using random effects meta-analysis. A total of 20 studies with 509 patients and 515 aneurysms were included in this systematic review. Aneurysm occlusion rates at greater than 3 months after operation were significantly higher in the PAO without bypass group (93.0 %, 95 % CI: 86.0 to 97.0) compared with the coiling group (67.0 %, 95 % CI: 55.0 to 77.0) (p < 0.01). Re-treatment rates were significantly lower in the PAO without bypass group (6.0 %, 95 % CI: 2.0 to 12.0) compared with the coiling group (18.0 %, 95 % CI: 12.0 to 26.0) (p = 0.01). Coiling patients had a similar morbidity rate (3.0 %, 95 % CI: 2.0 to 6.0) compared with PAO without bypass patients (7.0 %, 95 % CI: 3.0 to 12.0) (p = 0.13). Coiling patients had a similar mortality rate (0.0 %, 95 % CI: 0.0 to 6.0) compared with PAO without bypass patients (4.0 %, 95 % CI: 1.0 to 9.0) (p = 0.68). the authors concluded that evidence from non-comparative studies suggested that traditional endovascular options are highly effective in treating cavernous sinus aneurysms. PAO is associated with a higher rate of complete occlusion. Peri-procedural morbidity and mortality rates were not negligible, especially in patients receiving PAO.

Jiang and colleagues (2021) stated that whether the use of endovascular embolization could provide additional benefits in patients treated with stereotactic radiosurgery (SRS) for intracranial arterio-venous malformations (IAVMs) remains controversial.  In a meta-analysis, these researchers examined the safety and efficacy of SRS with and without prior endovascular embolization in patients with IAVMs.  The electronic databases of PubMed, Embase, and Cochrane Library were searched for eligible studies published from inception to August 12, 2020.  The pooled results for obliteration rate, re-hemorrhage rate, and permanent neurological deficits were calculated by ORs with 95 % CIs using the random-effects model.  The sensitivity analysis, subgroup analysis, and publication bias for investigated outcomes were also evaluated.  A total of 19 studies (2 prospective and 17 retrospective studies) involving a total of 3,454 patients with IAVMs were selected for the final meta-analysis.  These investigators noted that prior embolization and SRS were associated with a lower obliteration rate compared with SRS alone (OR, 0.57; 95 % CI: 0.44 to 0.74; P < 0.001).  However, prior embolization and SRS were not associated with the risk of re-hemorrhage (OR, 1.05; 95 % CI: 0.81 to 1.34; p = 0.729) and permanent neurological deficits (OR, 0.80; 95 % CI: 0.48 to 1.33; p = 0.385) compared with SRS alone.  The sensitivity analysis suggested that prior embolization might reduce the risk of permanent neurological deficits in patients with IAVMs treated with SRS.  The treatment effects of prior embolization in patients with IAVMs could be affected by nidus volume, margin dose, intervention, and follow-up duration.  The authors concluded that this meta-analysis found that prior embolization was associated with a reduced risk of obliteration in patients with IAVMs treated with SRS; and prior embolization might reduce the risk of permanent neurological deficits in patients with IAVMs.  Moreover, these researchers stated that these conclusions should be verified in further large-scale RCTs.

The authors stated that this study had several drawbacks.  First, most included studies (17/19) had a retrospective, observational design, and the conclusions of this study were based on lower evidence level, which should be interpreted cautiously.  Second, the disease status and experience of the clinician were different across included studies, which could affect the prognosis of IAVMs.  Third, the heterogeneity across included studies was not fully explained using sensitivity and subgroup analyses, which restricted the reliability of pooled conclusions.  Fourth, the background therapeutic options and rehabilitation strategies were not addressed, which could affect the treatment effects between groups for the mid-term and long-term outcomes.  Finally, the inherent limitations of the meta-analysis based on published articles included publication bias and analysis based on pooled data.

An UpToDate review on “Extracranial carotid artery aneurysm” (Kirkwood, 2015) states that “Options for endovascular repair include bare metal stent placement with or without trans-stent coil embolization of the aneurysm sac, exclusion of the aneurysm using a stent-graft, or endovascular occlusion of the carotid artery. Features favoring an endovascular approach include pseudoaneurysm related to trauma, aneurysm of the distal internal carotid artery, and hostile neck anatomy”.

Furthermore, guidelines on “The management of patients with unruptured intracranial aneurysms” from the American Heart Association/American Stroke Association (Thompson et al, 2015) support treatment of intra-cranial aneurysms if they are enlarging. The guidelines note that endovascular coiling is an effective treatment for select unruptured intracranial aneurysms (UIAs) that are considered for treatment (Class IIa; Level of Evidence B); endovascular coiling is associated with a reduction in procedural morbidity and mortality over surgical clipping in selected cases but has an overall higher risk of recurrence (Class IIb; Level of Evidence B).

Vascular Embolization for the Treatment of Endovascular Leak

Lu and colleagues (2010) analyzed a single-center experience of fibrin glue sac embolization to eliminate type I endoleaks after endovascular aneurysm repair (EVAR), assessing the feasibility and effectiveness of the technique in long-term follow-up. A retrospective study was conducted involving 783 EVAR patients treated between August 2002 and February 2009. Under a standardized protocol, 42 (5.4 %) patients (37 men; mean age of 73 ± 8 years) underwent intra-operative transcatheter fibrin glue sac embolization to resolve type I endoleak persisting after initial intra-operative maneuvers to close the leak or in necks too short or angulated for cuff placement. Intra-sac pressure was measured before and after glue injection. Computed tomographic angiography was performed to assess the outcome after 3, 6, and 12 months and annually thereafter. In this type I endoleak cohort, 16 (38.1 %) patients had proximal necks less than 10 mm long, and 5 (11.9 %) patients had proximal neck angulation greater than 60°; 22 additional devices (8 stents, 14 cuffs) had been placed in the initial attempts to resolve the endoleaks. After fibrin glue injection, 41 (97.6 %) of the 42 endoleaks were resolved using a mean 15 ± 10 ml of glue. Intra-sac pressure decreased significantly in successfully treated cases. The patient who failed embolotherapy was converted to open surgery (2.4 %); he died 2 months later from multi-organ failure. Two (4.8 %) patients died in the peri-operative period from myocardial infarction. One (2.4 %) patient developed right lower extremity ischemia unrelated to the fibrin glue treatment. There were no allergic reactions. Over a median follow-up of 39.9 months (range of 10 to 88), 3 (7.1 %) patients died (1 aneurysm-related). Cumulative survival was 90.5 % at 1 year, 87.0 % at 3 years, and 82.6 % at 5 years. The mean maximal aneurysm diameter fell from the baseline 59.5 ± 14.7 mm to 49.0 ± 11.6 mm (p < 0.001). Of the 4 patients with increased aneurysm diameter during follow-up, 1 was converted, 2 are being observed due to advanced age, and 1 died of renal failure. No recurrent type I endoleak or glue-related complications were observed in follow-up. The authors concluded that fibrin glue sac embolization to eliminate type I endoleak after EVAR yielded excellent results in their experience, effectively and durably resolving the leaks. Balloon occlusion of the proximal aorta must be done during glue injection to block proximal flow and facilitate formation of a structured fibrin clot.

Sidloff et al (2013) assessed the risk of rupture, and determined the benefits of intervention for the treatment of type II endoleak after EVAR. This systematic review was done according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Outcome data included incidence, spontaneous resolution, sac expansion, interventions, clinical success, and complications including conversion to open repair, and rupture. A total of 32 non-randomized retrospective studies were included, totaling 21,744 patients who underwent EVAR. There were 1,515 type II endoleaks and 393 interventions. Type II endoleak was seen in 10.2 % of patients after EVAR; 35.4 % resolved spontaneously. Fourteen patients (0.9 %) with isolated type II endoleak had ruptured abdominal aortic aneurysm; 6 of these did not have known aneurysm sac expansion. Of 393 interventions for type II endoleak, 28.5 % were unsuccessful. Translumbar embolization had a higher clinical success rate than transarterial embolization (81 versus 62.5 % respectively; p = 0.024) and fewer recurrent endoleaks were reported (19 versus 35.8 %; p = 0·036). Transarterial embolization also had a higher rate of complications (9.2 % versus none; p = 0.043). The authors concluded that aortic aneurysm rupture after EVAR secondary to an isolated type II endoleak is rare (less than 1 %), but over 1/3 occur in the absence of sac expansion. Translumbar embolization had a higher success rate with a lower risk of complications.

Khaja et al (2014) reported their experience with the use of an ethylene vinyl alcohol copolymer (Onyx) in an off-label fashion for the treatment of type II endoleak after endovascular repair of the thoracic (TEVAR) and abdominal (EVAR) aorta. A retrospective review of patients with type I and/or II endoleak treated with Onyx was performed. Data regarding the technical, clinical, and imaging outcomes were collected. Technical success was defined as decreased or eliminated endoleak on the first imaging follow-up. Clinical success was defined as unchanged or decreased aneurysm sac size on subsequent follow-up. A total of 18 patients (15 males, 3 females) with a mean age of 79 years (range of 69 to 92) met inclusion criteria (16 abdominal aortic aneurysm, 2 thoracic aortic aneurysm). Sixteen patients had type II endoleak, and 2 had complex type II endoleak with a type I component. The interval between endograft placement and treatment was a mean of 30 months. Direct sac treatment approach was used in 13 patients; transarterial approach was used in 3 patients. Seven patients required the use of coils, N-butyl cyanoacrylate glue, or Amplatzer vascular plugs. The average volume of Onyx used per treatment was 5.6 ml (range of 2.5 to 13). Duration of imaging follow-up was 0.75 to 72.5 months (mean of 32.8). Sixteen of 18 (88.9 %) patients had initial technical and clinical success; 2 of 18 patients (11.1 %) were initial technical failures, and 1 remained a failure despite a second treatment and attempted surgical ligation. Eight of 18 (44.4 %) of patients eventually required a second intervention, 5 (27.8 %) of them due to delayed clinical failure. Complications included 1 psoas hematoma, 1 transient L2 nerve paresis, and 1 intraperitoneal Onyx leak; all of these were without clinical sequelae. The authors concluded that Onyx with or without coil/glue/Amplatzer plug embolization is safe and useful in the treatment of type II endoleak after TEVAR and EVAR. However, long-term clinical and imaging follow-up is needed for early detection and management of recurrence of the primary endoleak or the development of new, secondary endoleaks or enlargement of the aneurysm sac.

Eberhardt et al (2014) reported a single-center experience with transcatheter embolization of type I endoleaks using the liquid embolic agent Onyx. A total of 8 patients (4 men; mean age of 74.8 years, range of 63 to 86) with 10 type I endoleaks (6 abdominal and 4 thoracic) diagnosed 2 days to 9 years after endovascular repair were treated with Onyx embolization because cuff extension was precluded by an insufficient landing zone in 6 cases and an unsuitable aortic diameter in 2. Endoleaks were accessed with a 4-F diagnostic catheter and a coaxially introduced dimethylsulfoxide-compatible microcatheter. Onyx-34 was predominantly applied due to its high viscosity; patent side branches were coil embolized prior to Onyx delivery in 3 cases. Technical success of the procedure was achieved in all cases. The mean volume of Onyx used for abdominal endoleaks was 11.8 ml (range of 3.0 to 25.5) and 19.4 ml (range 4.5 to 31.5) for thoracic endoleaks. The average duration of the procedure was 76.7 minutes (range of 34.5 to 110.6), and the average radiation dose area product was 18.8 cGy*cm (2) (range of 10.6 to 55.8). Re-perfusion of the endoleak was detected in 1 case 2 days after the procedure. A second case showed an occluded endoleak but a small trace of contrast between the aortic wall and the stent-graft. Non-target embolization was not found in any case. Mean follow-up was 13.2 months (range of 8 to 24). The mean reduction in diameters for thoracic aneurysms after 6 and 12 months was 0.4 and 0.9 cm, respectively, and 0.6 and 1.2 cm, respectively, for abdominal aneurysms. The authors concluded that transcatheter embolization of type I endoleaks using Onyx is a simple, safe, and sustainable treatment option with a high primary success rate for cases in which stent-graft extension is not possible. Moreover, they stated that the benefit of additional coil embolization remains uncertain.

Ishibashi et al (2014) evaluated the late events and mid-term results after EVAR. Between December 2006 and May 2012, a total of 175 abdominal aortic aneurysms were treated by EVAR. Aneurysm-related events were analyzed. The complications that occurred during the EVAR procedure were renal artery occlusion in 2 patients, access artery injury in 2, delivery failure in 1, retrograde aortic dissection in 1, and death from hepatic failure in 1 patient. Five adverse endoleaks (4 type I, 1 type III) remained at discharge, and the technical success rate was 97 %. On follow-up, limb occlusion had occurred in 5 patients. Unilateral renal atrophy was found in 3 patients, but none of the patients required new hemodialysis. Sac enlargement (greater than or equal to 5 mm) developed in 10 patients. Their culprit endoleaks were type Ia in 1, II in 8, and V in 1 patient. Transarterial embolization was performed for 3 out of the eight type II endoleaks. The rate of freedom from secondary re-intervention was 93 % at 3 and 5 years, respectively. The survival and freedom from aneurysm-related events rates were 74 % at 3 years and 47 % at 5 years. The authors concluded the mid-term results of EVAR were excellent with a low rate of aneurysm-related deaths, although there were relatively high aneurysm-related event rates. Sac re-enlargement from type II endoleaks was the most common major issue at the mid-term follow-up.

In a systematic review and meta-analysis, Zhang and colleagues (2022) examined the effect of preventive collateral arteries embolization before endovascular aneurysm repair (EVAR) to reduce type II endoleaks (T2EL), aneurysm enlargement, and re-interventions.  These researchers carried out a comprehensive search of PubMed, Medline, Web of Science, and Embase to identify articles in English, related to preventive collateral arteries embolization before EVAR, published until October 2020.  A total of 12 relevant studies, including 11 retrospective studies and 1 RCT, were identified and fulfilled the specified inclusion criteria.  A total of 1,706 patients in 11 studies were involved in the meta-analysis.  The overall incidence of T2EL was 17.3 % in the embolization group versus 34.5 % in the control group (OR 0.36, p < 0.01).  The incidence of persistent T2EL was 15.3 % versus 30.0 % (OR 0.37, p < 0.01); 5 studies reported the incidence of sac enlargement, with the rate 10.2 % versus 24.9 % (OR 0.25, p < 0.01); 9 studies reported T2EL related re-interventions, and it was 1.3 % in the embolization group and 10.4 % in control (OR 0.14, p < 0.01).  The technical success of collateral arteries embolization was 92.1 % (455/494) in the 12 studies; 1.2 % (10/829) patients suffered a mild complication of collateral arteries embolization, and 2/829 patients died because of the embolization.  The authors concluded that collateral arteries embolization is a promising approach to prevent the occurrence of T2EL, sac enlargement, and re-intervention.  Moreover, these researchers stated that high-quality studies are needed to provide stronger evidence-based medical suggestions regarding the effectiveness of this approach.

An UpToDate review on “Complications of endovascular abdominal aortic repair” (Chaer, 2015) states that “Endoleak is defined as persistent flow of blood into the aneurysm sac after device placement and indicates a failure to completely exclude the aneurysm. Five types of endoleak are described and are discussed below. Endoleak is associated with a continued risk for aneurysm expansion or rupture. The most common types of endoleak (I and II) are usually managed successfully with the placement of additional stents or embolization techniques, but sometimes surgery is needed …. For distal type I endoleaks that persist after balloon angioplasty of the distal attachment site, iliac limb extensions are used. If the iliac limb has been undersized, a flared iliac extension limb can be placed to exclude the endoleak. If the distal common iliac artery does not have an adequate length to provide a proper seal, coil embolization of the origin of the hypogastric artery and placement of a limb extension into the external iliac artery may be needed …. The approach to the repair of type II endoleaks is most commonly endovascular, consisting of transarterial embolization of the feeding vessels or translumbar embolization of the aneurysm sac. In the systematic review, there were 393 interventions for 1515 type II endoleaks, of which 71.5 percent were technically successful. Among studies that reported outcomes of intervention, translumbar embolization (n = 57) had a higher initial success rate (81 versus 63 per cent) and fewer recurrent endoleaks (19 versus 36 percent) compared with transarterial embolization (n = 120)”.

Coil Embolization and Occlusion of the Hypogastric Veins for the Prevention or Treatment of Deep Vein Thrombosis

UpToDate reviews on “Primary (spontaneous) upper extremity deep vein thrombosis” (Goshima, 2015) and “Approach to the diagnosis and therapy of lower extremity deep vein thrombosis” (Bauer, 2015) do not mention coil embolization as a therapeutic option.

In addition to UpToDate, American College of Chest Physicians’ guidelines have no recommendations for coil embolization and occlusion of the hypogastric veins for the prevention or treatment of DVT.

Prostate Artery Embolization

Schreuder and colleagues (2014) summarized the evidence on clinical outcomes and complications of prostatic arterial embolization (PAE) in patients with benign prostatic hyperplasia (BPH). These investigators searched Medline and Embase for PAE trials of patients with BPH up to November 2013.  Two reviewers independently checked the inclusion and exclusion criteria and performed data extraction of study characteristics, quantitative and qualitative outcomes, and complications.  The search yielded 562 studies, of which 9 articles with 706 patients were included.  In these 9 articles, there was a possible overlap of data and the quality of 8 studies was assessed as poor.  All patients had moderate-to-severe, lower urinary tract symptoms (LUTS).  The mean age ranged from 63.4 to 74.1 years.  After embolization, a decrease of the prostate volume (PV) and post void residual (PVR) was seen mainly in the 1st month with a further decrease up to 12 months, increasing afterwards.  The prostate specific antigen (PSA) decreased up to 3 months after PAE, increasing afterwards.  The peak urinary flow (Qmax) increased mainly the 1st month and decreased after 30 months.  The international prostate symptom score (IPSS) and quality of life (QOL)-related symptoms improved mainly during the 1st month, with a further improvement up to 30 months.  No deterioration of the international index of erectile function (IIEF) was seen after PAE; the PAE procedure appeared safe.  The authors concluded that although the number of studies was small, qualitatively poor, and with overlap of patients, the initial clinical outcomes as reported up to 12 months appeared positive and safe.

Li and associates (2015) reported the results of PAE with combined polyvinyl alcohol particles 50-μm and 100-μm in size as a primary treatment in 24 patients with severe LUTS secondary to large BPH. From July 2012 to June 2014, these researchers performed PAE in 24 patients (65 to 85 years, mean of 74.5) with severe LUTS due to large BPH (greater than or equal to 80 cm3) and refractory to medical therapy.  Embolization was performed using combination of 50-μm and 100-μm in particles size.  Clinical follow-up was performed using the IPSS, QOL, Qmax, PVR volume, the IIEF, PSA, and PV measured by magnetic resonance imaging at 1, 3, 6, and every 6-month thereafter.  Technical success was defined when PAE was completed in at least 1 pelvic side.  Clinical success was defined as the improvement of both symptoms and QOL.  A Student's t-test for paired samples was used.  Prostate artery embolization was technically successful in 22 patients (92 %); bilateral PAE was performed in 19 (86 %) patients and unilateral in 3 (14 %) patients.  Follow-up data were available for 22 patients observed for mean of 14 months.  The clinical improvement at 1, 3, 6, and 12-month was 91 %, 91 %, 88 %, and 83 %, respectively.  At 6-month follow-up, the mean IPSS, QOL, PVR, and Qmax were from 27 to 8 (p = 0.001), from 4.5 to 2.0 (p = 0.002), from 140.0 ml to 55.0 ml (p = 0.002), and from 6.0 ml/s to 13.0 ml/s (p = 0.001), respectively.  The mean PV decreased from 110 cm 3 to 67.0 cm 3 (mean reduction of 39.1 %; p = 0.001).  The PSA and IIEF improvements after PAE did not differ from pre-PAE significantly.  No major adverse events were noted.  The authors concluded that the combination of 50-μm and 100-μm particles for PAE was a safe and effective treatment for patients with severe LUTS due to large BPH, which further improves the clinical results of PAE.  These preliminary findings need to be validated by well-designed studies.

Russo and co-workers (2015) evaluated 1-year surgical and functional results and morbidities of PAE versus open prostatectomy (OP). These investigators undertook 1:1 matched-pair analysis (IPSS, peak flow [PF], PVR, and PV) of 287 consecutive patients treated for BPO, including 80 OP and 80 PAE.  Inclusion criteria were as follows: LUTS or BPO, IPSS greater than or equal to 12, PSA less than 4 ng/ml, or PSA between 4 and 10 ng/ml but negative prostate biopsy, total PV greater than 80 cm(3), and PF less than 15 ml/s.  Follow-up was performed at 1 month, 6 months, and 1 year at clinic.  Primary end-points of the study were the comparison regarding IPSS, IIEF-5, PF, PVR, and IPSS-QOL after 1 year of follow-up.  Regarding primary end-points, OP group had lower IPSS (4.31 versus 10.40; p < 0.05), 1-year PVR (6.15 versus 18.38; p < 0.05), 1-year PSA (1.33 versus 2.12; p < 0.05), IPSS-QOL (0.73 versus 2.78; p < 0.05), IIEF-5 (10.88 versus 15.13; p < 0.05), and greater PF (23.82 versus 16.89; p < 0.01).  The matched-pair comparison showed higher value of post-operative hemoglobin level (mg/dL) and shorter hospitalization (days) and catheterization (days) for PAE group.  At the multi-variate logistic regression, PAE was associated with persistent symptoms (IPSS greater than or equal to 8; odds ratio [OR], 2.67; 95 % CI: 0.96 to 7.4; p < 0.01) and persistent PF less than or equal to 15 ml/s (OR, 4.95; 95 % CI: 1.73 to 14.15; p < 0.05) after 1 year.  The authors concluded that PAE could be considered a feasible minimally invasive technique but failed to demonstrate superiority to OP because of the increased risk of persistent symptoms and low PF after 1 year.

Jones and colleagues (2015) stated that PAE has emerged as a promising treatment for LUTS secondary to BPH. However, although it has gained increasing attention in radiology literature, it remains under-reported from a urologic perspective.  These investigators provided an up-to-date review of this minimally invasive technique.  The authors concluded that evidence suggested PAE is a promising option for patients with large PV, multiple co-morbidities, and suboptimal results from pharmacotherapy.  Moreover, they stated that larger, randomized studies with longer follow-up periods are needed for PAE to be formally established in the urology community.

Nejmark et al (2015) examined the use of PAE as a preparatory step before TURP in the treatment of BPH in patients with large prostates. The study included 59 patients with BPH and high risk of anesthesia who underwent super-selective embolization of prostatic arteries.  The examination included a survey on the IPSS, assessment of QOL, estimation of prostate and node size with trans-rectal ultrasound (TRUS), determination of PSA level; in doubtful cases a needle prostate biopsy was performed.  To analyze the quality of urination, uro-flowmetry was conducted.  The effectiveness of the treatment was evaluated after 6, 12 and 24 months follow-up.  By the 6th month of observation IPSS score significantly decreased, while the Qmax increased.  This trend persisted during the subsequent 6-month follow-up.  The results of 24 months follow-up after PAE showed stable effect.  Prostate and node volumes reduced an average of 53 % and 47 %, respectively; the maximal reduction of PV was 82 %; 17 (28.8 %) patients with prostate size reduction to less than 80 cm3 underwent TURP.  The authors concluded that PAE may be considered as a method of pre-operative treatment of BPH patients with large prostates and multiple co-morbidities, providing them with the possibility of endoscopic treatment.  They stated that further study will aid in sorting out the methodology of embolization, and determining the indications and contraindications for this treatment modality before it is introduced to clinical practice.

Nair and associates (2015) discussed upcoming new surgical techniques in management of BPH. These researchers performed a systematic search of Scopus, Medline, Embase and Cochrane databases using relevant key words.  Intra-prostatic injections with a variety of agents have been explored as these can be readily performed under local anesthesia.  Alcohol injections into the prostate have been abandoned due to potential side effects but there has been ongoing development of 2 alternative agents, NX-1207 and PRX-302.  Both have shown good safety profiles and early effectiveness in phase II studies.  Thermal treatment with the Rezum device performed as an out-patient procedure has shown both safety and effectiveness in phase I and II studies.  Aquablation shows promise in phase II studies with few side effects and is a relatively automated procedure, albeit requiring general anesthesia.  Prostate artery embolization has been reported in a number of studies, but clinical outcomes have been unpredictable.  Histotripsy has had a number of complications in animal models and despite technical improvement has not yet progressed beyond feasibility studies in humans.  The authors concluded that some of the new techniques and technologies available for BPH have been shown to be relatively safe and effective and await validation with phase III clinical trials.

Cizman and co-workers (2016) reviewed the available safety and effectiveness data for PAE in the treatment of BPH. PubMed was searched for publications that included PAE for the treatment of BPH through May 2015.  Two independent reviewers determined the appropriateness for inclusion of each article and compiled data by using pooled weighted means and standard deviations.  The literature search identified 161 articles, of which 7 studies, with a total of 562 patients, met all inclusion/exclusion criteria.  Prostatic artery embolization was performed bilaterally in 85 % of patients, unilaterally in 12 %, and unsuccessfully in 3 %; IPSS decreased from 24.51 ± 6.12 at baseline to 10.42 ± 5.39 at 6 months; QOL score decreased from 4.76 ± 0.98 at baseline to 2.51 ± 1.13 at 6 months; Qmax increased from 8.41 ml/s ± 2.63 at baseline to 15.44 ml/s ± 5.64 at 6 months; PVR measurement decreased from 105.94 ml ± 76.77 at baseline to 39.57 ml ± 15 at 6 months; PSA level decreased from 4.79 ng/ml ± 5.42 at baseline to 3.16 ng/ml ± 1.5 at 6 months.  None of these parameters showed clinically significant changes from 6 months to 12 months.  Total PV decreased from 96.56 cm3 ± 35.47 at baseline to 46.73 cm3 ± 20.51 at 12 months.  There were 200 minor complications and 1 major complication.  The authors concluded that PAE improved LUTS caused by BPH, with a favorable short- to mid-term safety profile.  Long-term outcomes are need to ascertain the effectiveness of PAE for the treatment of BPH.

Pisco et al (2016) confirmed that PAE has a positive medium- and long-term effect in symptomatic BPH. Between March 2009 and October 2014, a total of 630 consecutive patients with BPH and moderate-to-severe LUTS refractory to medical therapy for at least 6 months or who refused any medical therapy underwent PAE.  Outcome parameters were evaluated at baseline; 1, 3, and 6 months; every 6 months between 1 and 3 years; and yearly thereafter up to 6.5 years.  Mean patient age was 65.1 ± 8.0 years (range of 40 to 89).  There were 12 (1.9 %) technical failures.  Bilateral PAE was performed in 572 (92.6 %) patients and unilateral PAE was performed in 46 (7.4 %) patients.  The cumulative clinical success rates at medium- and long-term follow-up were 81.9 % (95 % CI: 78.3 % to 84.9 %) and 76.3 % (95 % CI: 68.6 % to 82.4 %).  There was a statistically significant (p < o.0001) change from baseline to last observed value in all clinical parameters: IPSS, QOL, PV, PSA, Qmax, PVR, and IIEF.  There were 2 major complications without sequelae.  The authors concluded that PAE had a positive effect on IPSS, QOL, and all objective outcomes in symptomatic BPH.  The medium-term (1 to 3 years) and long-term (greater than 3 to 6.5 years) clinical success rates were 81.9 % and 76.3%, with no urinary incontinence or sexual dysfunction reported.

Jones and associates (2016) noted that prostate urethral lift and PAE represent 2 evolving techniques with contrasting mechanisms of action (mechanical decompression versus angiographic embolization). Both approaches yield relief of LUTS over a period of several weeks.  They display similar safety profiles with self-limiting pelvic discomfort characterizing the commonest minor adverse event.  Both procedures have the potential to be carried out under local anesthesia and in the out-patient setting with suitability for patients with cardiovascular co-morbidities.  Neither has been found to cause degradation of sexual function.  The authors concluded that further randomized trials are needed to delineate the formal position of these techniques in the surgical management of BPH.

Lebdai and co-workers (2016) reviewed current knowledge on clinical outcomes and peri-operative complications of PAE in patients treated for LUTS related to benign prostatic obstruction (BPO). These researchers performed a systematic review of the literature published from January 2008 to January 2015 on PubMed/Medline.  A total of 57 articles were identified, and 4 were selected for inclusion in this review.  Only 1 randomized clinical trial compared transurethral resection of the prostate (TURP) to PAE.  At 3 months after the procedure, mean IPSS reduction from baseline ranged from 7.2 to 15.6 points.  Mean Qmax improvement ranged from +3.21 ml/s to +9.5 ml/s.  When compared to TURP, PAE was associated with a significantly lower IPSS reduction 1 and 3 months after the procedure.  A trend toward similar symptoms improvement was however reported without statistical significance from 6 to 24 months.  Major complications were rare with 1 bladder partial necrosis due to non-selective embolization.  Mild adverse events occurred in 10 % of the patients and included transient hyperthermia, hematuria, rectal bleeding, painful urination or acute urinary retention.  These investigators stated that further comparative studies are mandatory to assess post-operative rates of complications, especially acute urinary retention, after PAE and standard procedures.  The authors concluded that early reports suggested that PAE may be a promising procedure for the treatment of patients with LUTS due to BPO.  However, the low level of evidence and short follow-up of published reports precluded any firm conclusion on its mid-term effectiveness.  They stated that further clinical trials are needed before any use in clinical practice.

Roberts (2016) noted that there has been a recent resurgence in development of new BPH technologies driven by enhanced understanding of prostate pathophysiology, development of new ablative technologies, and the need for less morbid alternatives as the mean age and complexity of the treatment population continues to increase. The author highlighted new BPH technologies and reviewed the available clinical data with specific emphasis on unique features of the technology, procedural effectiveness and safety, and potential impact on current treatment paradigms.  New technologies have emerged that change the shape of the prostate to decrease urinary obstruction and enhance delivery of a lethal thermal dose by steam injection into the transition zone of the prostate.  Energy can be delivered to the prostate via a beam of high-pressure saline or focused acoustic energy to mechanically disintegrate prostate tissue.  Methods of cell death are being targeted with selectivity by PAE and specific to prostate cells via injectable biological therapies.  The author concluded that a number of new technologies are at various stages of development and improve on the transurethral resection of the prostate paradigm by moving closer to the ideal BPH therapy that is definitive, can be performed in minutes, in the office setting, with only local anesthesia and oral sedation.

Teon and colleagues (2017) systemically reviewed the current evidence on PAE in treating men with BPH.  These investigators performed a systemic literature search in PubMed, Embase and Web of Science on May 1, 2016 without time constraints.  Outcomes of interest included the changes in the IPSS, QOL score, Qmax, PVR, IIEF score, PV and PSA level.  A total of 987 records were identified through database searching.  After removing duplicates, screening and reviewing full-length texts, a total of 5 records remained, with 2 randomized controlled trials (RCTs) and 3 non-randomized cohort studies.  Transurethral resection of prostate resulted in better IPSS than PAE.  Open prostatectomy had better IPSS, QOL score, Qmax and PVR, but worse IIEF score than PAE at 1 year.  Unilateral PAE had higher rate of poor clinical outcome than bilateral PAE, but the difference became statistically insignificant after adjusting for age; IPSS, QOL score, Qmax, PVR, IIEF score, PV and PSA did not differ between the 2 groups.  PAE with 100-μm PVA particles resulted in greater reduction in PSA level, but worse IIEF score than PAE with 200-μm PVA particles; IPSS, QOL score, Qmax, PVR, PV and poor clinical outcome did not differ between the 2 groups.  The authors concluded that available evidence on different aspects of PAE was limited; further studies are needed to examine the role of PAE as compared to other forms of medical and surgical treatment.

Zumstein and colleagues (2018) performed a systematic review and meta-analysis of clinical trials comparing the safety and efficacy of PAE versus established surgical therapies.  Medline, Embase, and York CRD were searched up to June 23, 2018.  Only comparative studies were included.  The risk of bias was assessed by the Cochrane Collaboration tool.  Meta-analyses were performed using RevMan 5.3.  A total of 5 studies including 708 patients met the selection criteria.  Risk of bias was rated high for most of the studies.  Mean reduction in the IPSS was lower after PAE compared with standard surgical therapies (mean difference [MD] of 3.80 points [95 % CI: 2.77 to 4.83]; p < 0.001).  PAE was less efficient regarding improvements in all functional parameters assessed including maximum urinary flow, PVR, and reduction of PV.  In contrast, patient-reported erectile function (IIEF of 5) was better after PAE and significantly fewer adverse events occurred after PAE.  The authors concluded that the findings of this study suggested that PAE is not as effective as established surgical therapies but has fewer side effects.  These researchers stated that large-scale RCTs including longer follow-up periods are needed to determine whether PAE is the best treatment for certain types of patients; thus, PAE should not yet be considered a standard treatment.

In a Cochrane review, Jung et al (2022) examined the effects of PAE compared to other procedures for treatment of LUTS in men with BPH.  The authors concluded that compared to TURP, PAE may provide similar improvement in urologic symptom scores and QOL.  While these investigators are very uncertain regarding major AEs, PAE likely increases re-treatment rates.  While erectile function may be similar, PAE may reduce ejaculatory disorders.  These researchers stated that certainty of evidence for the outcomes of this review was low or very low except for re-treatment (moderate-certainty evidence), signaling that the confidence in the reported effect size is limited or very limited, and that this topic should be better informed by future research.

In a systematic review and network meta-analysis, Lucas-Cava et al (2023) compared the safety and effectiveness of prostatic urethral lift (PUL) versus PAE for the treatment of BPH.  The authors concluded that available evidence suggested that PUL and PAE exhibited similar clinical safety and effectiveness profiles in the management of LUTS associated with BPH.  However, the quality of evidence was relatively low because of the paucity of RCTs available, and results should be interpreted with caution.

Partial Splenic Artery Embolization for the Treatment of Hyper-Splenism Secondary to Hepatic Cirrhosis

In a meta-analysis, Wang and colleagues (2017) examined the effectiveness of partial spleen arterial embolization (PSAE) in the treatment of hyper-splenism due to hepatic cirrhosis.  PubMed, Embase, Cochrane Library, Wan Fang, CNKI, Vip, and CBM databases were searched for RCTs, cohort studies, and case-control studies that compared PSAE with splenectomy in the treatment of hyper-splenism secondary to hepatic cirrhosis from their inception to July 25, 2015.  Statistical analysis was conducted in Cochrane Network RevMan v5.3.  Primary outcomes included the pre- and post-operative platelet and leukocyte counts and hemoglobin levels.  Secondary outcomes were operative time, intra-operative volume of bleeding, and length of hospital stay.  Mean and standard deviation were obtained from each study and then pooled using fixed- or random-effects models to calculate the mean difference.  A total of 10 original studies investigating 737 patients were included.  Both the PSAE group and the splenectomy group yielded higher post-operative platelet and leukocyte counts and hemoglobin levels than the pre-operative.  The difference of platelet and leukocyte counts and hemoglobin levels between post-operative and pre-operative levels in the PSAE group was smaller than that in the splenectomy group.  Furthermore, compared with the splenectomy group, the PSAE group exhibited shorter operative time, less intra-operative bleeding, and shorter length of stay.  The authors concluded that PSAE is a mini-invasive therapy, which can be applied to treat hyper-splenism secondary to hepatic cirrhosis effectively, particularly for patients with a poor overall condition.  However, they stated that further high-quality studies are needed because this meta-analysis was limited by the quality of studies and the large statistical heterogeneity.

Partial Splenic Embolization for the Treatment of Gastro-Esophageal Variceal Hemorrhage

Wang and associates (2016) noted that partial splenic embolization (PSE) is used in the management of gastro-esophageal variceal hemorrhage (GEVH).  However, it is uncertain whether it has beneficial effects for GEVH patients in preventing variceal recurrence and variceal hemorrhage, as well as promoting overall survival (OS), when it is combined with conventional therapies.  In this study, the databases including PubMed, Embase, Web of Science, Google scholar, and Cochrane Central Register of Controlled Trials were searched up to November 11, 2015.  Meta-analyses were performed by using Review Manager 5.3 software for analyzing the risk of bias, Newcastle-Ottawa Scale for assessing the bias of cohort studies, and GRADEprofiler software for assessing outcomes obtained from the meta-analyses.  A total of 1,505 articles were reviewed, and 1 RCT and 5 cohort studies with 244 participants were eligible for inclusion.  The pooled hazard ratio (HR) of variceal recurrence is 0.50 (95 % CI: 0.37 to 0.68; p < 0.00001; I2 = 0 %).  The pooled HR of variceal hemorrhage is 0.24 (95 % CI: 0.15 to 0.39; p < 0.00001; I2 = 0 %).  The pooled HR of OS is 0.50 (95 % CI: 0.33 to 0.67; p < 0.00001; I2 = 0 %).  Meta-analyses demonstrated statistically significant superiority of combinational therapies over conventional therapies in preventing variceal recurrence and variceal hemorrhage and prolonging OS.  The complications related to PSE were mild or moderate and non-fatal.  The authors concluded that the results indicated that PSE had beneficial effects for GEVH patients, however, future investigation with a larger number of subjects in multi-center clinical trials is needed.  The authors stated that the relatively small size of samples (1 RCT and 5 cohort studies with 244 participants) may be the biggest drawback of this study.  If the findings reported in this study could be verified by future studies, the application of PSE, particularly when it is combined with conventional therapies, may be included in the clinical guidelines of GEVH treatment.

Selective Arterial Embolization for the Treatment of Giant Cell Tumor

He and colleagues (2017) noted that giant cell tumor of the bone (GCTB) is a locally aggressive tumor with a certain distant metastatic rate.  For sacral GCT (SGCT) and pelvic GCT (PGCT), surgery has its limitations, especially for unresectable or recurrent tumors.  Selective arterial embolization (SAE) has been reported to be a therapeutic  option in several cases, but there are few systematic reviews on the effects of SAE on SGCT and/or PGCT.  In a systematic review, these investigators searched Medline and Embase databases for eligible English articles.  Inclusion and exclusion criteria were conducted before searching.  All the clinical factors were measured by SPSS software, with p-values less than or equal to 0.05 considered statistically significant.  A total of 9 articles were retrieved, including 44 patients receiving SAE ranging from 1 to 10 times.  During the mean follow-up period of 85.8 months, the radiographic response rate was 81.8 %, with a local control and OS rate of 75 % and 81.8 %, respectively.  No bowel, bladder, or sexual dysfunction was observed; 3 patients developed distant metastases and finally died.  Patients with primary tumors tended to have better prognosis than those with recurrence (p = 0.039).  The authors concluded that the favorable outcomes of SAE suggested that it may be an alternative treatment for SGCT and PGCT patients for whom surgery is not appropriate.

In a case-series study, Ji and associates (2017) examined the effectiveness of a new treatment strategy of combination of SAE and denosumab as neoadjuvant or stand-alone treatment for large sacro-pelvic GCT.  All 3 cases were proved to be GCT by core-needle biopsy.  Post-treatment pathological change was confirmed by further biopsy.  The patient in case 1 was diagnosed with large recurrent sacral GCT and received 6 times of endovascular embolization with 2-month interval and started on denosumab simultaneously after 1st session of embolization.  The 2nd case was a 22-year old female presented with a massive ilio-sacral tumor; SAE was performed for 3 sessions and denosumab was started simultaneously.  The patients was on treatment for 6 months.  Both patients experienced a dramatic decrease in symptoms and concomitant improvement in function after the 1st embolization and weekly injection of denosumab.  Tumor removal was performed in case 2.  The last case was a pelvic GCT and the patient received SAE and denosumab for 6 months; tumor was then removed with purpose of complete cure.  The 1st patient was still on denosumab with stable tumor; the other 2 patients were both free of recurrence after surgical removal of the tumors.  No denosumab was used post-operatively.  The authors reported the first 3 cases treated by combination of SAE and denosumab in the literature and aimed to raise an alternative method for large GCT at challenging anatomical locations, for which surgery would carry significant risk.  They stated that SAE and denosumab can synergisticacally promote sclerosis and result in significant decrease in pain.  They stated that it is reasonable to consider using SAE combined with denosumab neoadjuvantly to reduce the extensiveness and morbidity of surgery, however further investigation is needed.  This was a small study (n = 3) and its findings were confounded by the combined use of SAE and denosumab.

An UpToDate review on “Giant cell tumor of bone” (Thomas and Desai, 2017) states that “For sacral tumors, another option is arterial embolization, although published experience is limited”. Guidelines on giant cell tumor of the bone from the National Comprehensive Cancer Network (2018) state that "[s]erial arterial embolizations have been shown to be effective in the management of patients with giant cell tumors of the extremities, especially for tumors with large cortical defects and joint involvement and for those with large giant cell tumors of the sacrum."

Geniculate Artery Embolization for Knee Hemarthrosis Following Total Knee Arthroplasty

Kalsi and colleagues (2007) described the case of a 79-year old woman who presented with recurrent hemarthrosis 8 years after primary total knee arthroplasty (TKA).  An arterio-venous fistula of the superior lateral geniculate artery was diagnosed by arteriography after arthroscopy of the knee revealed multiple organized hematomata with minimal synovitis.  The arterio-venous fistula was treated by percutaneous coil embolization and the symptoms resolved.

Given and associates (2008) noted that spontaneous non-hemophiliac hemarthrosis is an unusual entity, which has been little described.  These researchers presented 3 cases of spontaneous recurrent hemarthrosis post-TKA and successful management with embolization.  Three male patients were referred to the authors’ service for angiography and treatment of recurrent hemarthrosis post-TKA.  In all 3 patients antegrade ipsilateral common femoral artery punctures and selective angiography of the geniculate branches were performed with a micro-catheter.  Abnormal vasculature was noted in all cases.  Subsequent embolization was performed with Contour (Boston Scientific, Target Vascular, Cork, Ireland) embolization particles (150 to 250 and 250 to 355 μm) in 2 patients and micro-coils in the 3rd (TornadoR; Cook Inc., Bloomington, IN).  Technical success was 100 % -- 1 patient had a recurrence of symptoms requiring a repeat procedure 6 months later.  No complications were encountered.  The authors concluded that selective angiography and particle embolization is an effective technique for management of this unusual but problematic post-operative sequelae.

In a case-series study, Bagla and co-workers (2013) noted that spontaneous recurrent hemarthrosis after TKA was reported to occur in 0.3 % to 1 % of patients, likely secondary to hypertrophic vascular synovium.  In this case-series study, a total of 5 patients who underwent previous TKA presented with spontaneous hemarthrosis received selective arterial embolization with spherical embolic particles (diameter range of 100 to 700 μm).  Angiography demonstrated synovial hyper-vascularity with geniculate artery "tumor blush" appearance in all patients.  Average time to resolution of effusion was 2.6 weeks, with no recurrences reported during follow-up (mean of 25.4 months; range of 16 to 48 months); 2 patients experienced transient cutaneous ischemia.  The authors concluded that selective geniculate artery embolization with spherical embolic particles was an effective treatment for spontaneous recurrent hemarthrosis of the knee.

Weidner and colleagues (2015) stated that recurrent hemarthrosis is an uncommon but troublesome complication following TKA.  These investigators reported the results for 13 patients with spontaneous recurrent hemarthrosis after TKA treated with arterial embolization.  The average interval between TKA and embolization was 47 months (range of 2 to 103 months), and the average time from onset of hemarthrosis to embolization was 4.1 months (range of 1 to 11 months).  Geniculate arterial embolization led to resolution of hemarthrosis in 12 of 13 patients (92.3 %).  The 1 clinical failure likely represented a case of misdiagnosed peri-prosthetic joint infection; 2 patients experienced transient cutaneous ischemia related to distal particulate embolization that resolved spontaneously.  The authors concluded that selective geniculate arterial embolization was a safe and effective treatment for recurrent hemarthrosis after TKA.

Azubuike and associates (2016) stated that hemarthrosis after TKA is an uncommon condition.  These researchers presented a unique case of recurrent hemarthrosis in a 93-year old woman 2 years after an uneventful TKA and described how they successfully treated her with selective angiographic embolization of the geniculate arteries.  Moreover, they stated that although long-term follow-up results were not yet available for this patient, the short-term clinical success achieved was promising.  They stated that transcatheter embolization was a safe therapeutic option for recurrent hemarthrosis for patients who have failed conservative therapy and demonstrated synovial hyper-vascularity on angiography.

Guevara and co-workers (2016) evaluated technical details, clinical outcomes, and complications in patients undergoing geniculate artery embolization for treatment of spontaneous hemarthrosis after knee surgery.  During 2009 to 2014, a total of 10 consecutive patients (7 women; mean age of 57.4 years) underwent geniculate artery embolization at a single tertiary care center.  All patients except 1 had hemarthrosis after TKA; 1 patient presented with hemarthrosis after cartilage surgery; 2 patients in the TKA group had a history of TKA revisions before the embolization.  Embolization was performed with polyvinyl alcohol particles (range of 300 to 700 µm).  In 1 patient requiring repeat embolization, N-butyl cyanoacrylate/ethiodized oil was used.  The end-point for embolization was stasis in the target artery and elimination of the hyperemic blush.  In 10 patients, 14 embolizations were performed with 100 % technical success.  Hemarthrosis resolved in 6 patients; 4 patients required repeat embolization for recurrent hemarthrosis, which subsequently resolved in 2 of 4 patients; 3 of the 4 patients who required repeat embolization had serious co-morbidities, either blood dyscrasias or therapeutic anti-coagulation.  There were 2 minor skin complications that resolved with conservative management.  The average length of follow-up after embolization was 545 days (range of 50 to 1,655 days); 1 patient was lost to follow-up.  The authors concluded that geniculate artery embolization was a safe, minimally invasive therapeutic option for spontaneous and refractory knee hemarthrosis after knee surgery with 100 % technical success.  However, limited clinical success and higher repeat embolization rates were noted in patients with serious co-morbidities.

Cefalu and associates (2017) stated that pseudo-aneurysms are uncommon in patients with trauma, but can cause diagnostic difficulty and result in significant morbidity.  Etiologies range from penetrating and non-penetrating trauma to operative injury during fracture fixation, arthroscopy, total joint arthroplasty, and hardware loosening and removal.  Pseudo-aneurysms can conspicuously present as a pulsatile mass with an audible bruit, or as a subtly expanding hematoma.  In either case, the complications can be serious if diagnosed late.  The authors reported a case of a pseudo-aneurysm arising from the descending geniculate artery following a tibial plateau fracture.  This was suspected following a slowly expanding hematoma and persistent anemia refractory to transfusion.  Computed tomography (CT) angiography was used for confirmation.  Successful treatment was accomplished with embolization, surgical evacuation of the hematoma, delayed skin grafting, and fracture fixation.  The post-operative outcome was satisfactory, with complete wound healing, functional but decreased range of motion (ROM), normal perfusion distal to the injury, and the sole report of mild intermittent knee pain.

van Baardewijk et al (2018) noted that recurrent hemarthrosis is a late complication in up to 1.6 % of patients following TKA.  In the absence of intrinsic coagulopathy, one etiology is bleeding of hypertrophic vascular synovium.  These investigators evaluated the clinical outcome of patients referred to the authors’ center for angiographic embolization of geniculate arteries for recurrent hemarthrosis following TKA.  They retrospectively studied a cohort of patients who were referred for geniculate artery embolization following TKA between August 2011 and September 2016.  A total of 24 embolization procedures were performed on 14 patients; 7 (50 %) of these 14 patients underwent 1 embolization procedure.  Due to symptom recurrence, 4 patients underwent a repeated procedure and 3 patients a 3rd procedure.  All embolization procedures were technically successful at the time of the procedure; 2 patients reported an inguinal hematoma that healed without further treatment.  At a mean follow-up of 26.8 months, clinical success was achieved in 12 of the 14 patients (86 %).  The authors concluded that embolization of the geniculate arteries in this study was a safe and effective treatment of recurrent spontaneous hemarthrosis following TKA.  Although these researchers had performed a substantial number of re-interventions, results of this study showed that this procedure could be safely repeated without adverse events.  They stated that these findings indicated that embolization could possibly be the treatment of choice when conservative measures failed and can be repeated in the event of recurrent or persistent symptoms.

Genicular Artery Embolization for the Treatment of Osteoarthritis-Related Knee Pain

Torkian and colleagues (2021) noted that genicular artery embolization (GAE) is an innovative technique that has been examined as a supplementary therapy for chronic pain secondary to knee osteoarthritis (OA).  In a systematic review and meta-analysis, thee researchers examined the available evidence on the safety and effectiveness of GAE for OA-related knee pain.  They carried out a systematic literature search in PubMed, Web of Science, Embase, and Scopus databases to identify studies related to knee OA treated with GAE.  Therapeutic agents were categorized as embozene, imipenem/cilastatin, resorbable microspheres, and polyvinyl alcohol.  The main outcomes were the mean difference (MD) in pre- and post-embolization pain based on the visual analog scale (VAS) or the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores as well as changes in the need for pain medication; random- and fixed-effects models were employed for data analysis.  Of 379 initially inspected studies, 11 (n = 225 patients; 268 knees) were included in the final review.  The quality of the studies was fair in 8 and poor in 3-categorized according to the National Institutes of Health quality assessment tool.  Overall, 119, 72, 13, and 21 patients were treated with imipenem/cilastatin, embozene, resorbable microspheres, and polyvinyl alcohol, respectively.  Symptomatic improvement was reported in all studies.  The pooled effect size, characterized by MD, showed a significant improvement in the VAS and WOMAC pain scores, with better functional status after GAE.  Pre- versus post-embolization MDs in VAS scores ranged from 32 within the 1st week to 58 after a 2-year follow-up (equivalent to 54 % and 80 % improvement, respectively).  There was a similar trend in the overall WOMAC scores, with MDs ranging from 28.4 to 36.8 (about 58 % and 85 % improvement, respectively).  GAE resulted in a decreased need for pain medication for knee OA, with a 27 %, 65 %, and 73 % decline in the number of patients who used opioids, non-steroidal anti-inflammatory drugs (NSAIDs), and intra-articular hyaluronic acid (HA) injection, respectively (p < 0.00001 for all).  No significant difference between embolic agents was observed with regard to post-GAE pain reduction.  No severe or life-threatening complications were reported.  The authors concluded that this systematic review revealed that mild-to-moderate OA treated by GAE using different embolic particles could generally be considered safe, with no reported serious complications.  The procedure resulted in significant and sustained pain improvement as well as better functional status in the studies reviewed.  However, because of the paucity of high-quality trials, further investigation is needed to examine GAE’s long-term outcomes, its comparative efficacy with other treatment modalities, and its role in the therapeutic approach.  Level of Evidence = IV.

These researchers stated that as far as the general drawbacks of the study were concerned, available studies lacked a control group (other treatment modalities).  Furthermore, the studies had been reported from a limited number of geographical regions; therefore, further patient-centered investigations of the GAE safety and effectiveness in other geographical regions, with a larger sample size from different ethnic groups and longer duration of follow-up, is needed to improve the quality of evidence in terms of safety, durability, and efficacy of this treatment.

In a systematic review, Casadaban and associates (2021) examined the available evidence on GAE for OA-related knee pain.  Using 3 databases, these researchers carried out a systematic review following PRISMA guidelines.  Outcome measures included the VAS and WOMAC.  A total of 3 single-arm studies were included from an initial search yielding 305 results; 186 knees in 133 patients with either mild-to-moderate (174/186, 94 %) or severe (12/186, 6 %) OA underwent embolization with either imipenem/cilastatin sodium (159/186, 85 %) or embozene (27/186, 15 %); technical success was 100 %.  Average VAS improved from baseline at 1 day, 1 week, 1 month, 3 months, 4 months, 6 months, 1 year and 2 years (66.5 at baseline versus 33.5, 32.7, 33.8, 28.9, 29.0, 22.3, 14.8 and 14.0, respectively).  Average WOMAC scores improved from baseline at 1, 3, 4, 6, 12 and 24 months (45.7 at baseline versus 24.0, 31.0, 14.8, 14.6, 8.2 and 6.2).  Severe OA in 12 cases showed initially improved VAS; but was not sustained.  Minor adverse events (AEs) such as erythema in the region of embolization (21/186, 11 %), puncture-site hematoma (18/186, 10 %), paresthesia (2/186, 1 %) and fever (1/186, 0.5 %) were reported.  The authors concluded that limited single-arm studies reported that GAE is promising for treating OA-related pain.  Most treatments performed for mild-to-moderate OA demonstrated durable clinical responses from 6 months to 4 years; and limited data for severe OA suggested a non-durable response.  These researchers stated that future studies should be standardized to facilitate comparison and control for placebo effect.

Middle Meningeal Artery Embolization for Chronic Subdural Hematoma

Srivatsan and colleagues (2019) stated that chronic subdural hematoma is a very common neurosurgical condition.  Although conventional surgical methods, such as burr hole irrigation, have been the mainstay of treatment, middle meningeal artery (MMA) embolization has emerged as a promising adjunctive or alternative treatment.  These investigators performed a meta-analysis and systematic review of this topic.  They carried out a literature search using keywords "chronic subdural hematoma", "chronic subdural hemorrhage", "refractory subdural hematoma", "refractory subdural hemorrhage" and "middle meningeal artery embolization" through October 2018.  Outcome variables of hematoma recurrence, surgical complications, and modified Rankin Scale (mRS) score were analyzed and compared between MMA embolization and conventional surgery cohorts.  A total of 3 double-arm studies comparing embolization and conventional surgery groups and 6 single-arm case series were identified and analyzed.  Hematoma recurrence rate was significantly lower in the embolization group compared with conventional treatment group (2.1 % versus 27.7 %; OR = 0.087; 95 % CI: 0.026 to 0.292; p < 0.001; I2 = 0 %); surgical complication rates were similar between groups (2.1 % versus 4.4 %; OR = 0.563; 95 % CI: 0.107 to 2.96; p = 0.497; I2 = 27.5 %). Number of patients with mRS score  of greater rthan 2 in the embolization (12.5 %) versus conventional treatment (9.1 %) group showed no statistical difference (p = 0.689).  A composite hematoma recurrence rate of 3.6 % was found after summing the 6 case series.  Composite recurrence and complication rates in the embolization cohorts of the double-arm studies and the case series were lower than literature values for conventional surgical treatments.  The authors concluded that MMA embolization is a promising treatment for chronic subdural hematoma; they stated that future randomized clinical trials are needed.

Ironside and colleagues (2021) noted that mMMA embolization has been proposed as a minimally invasive treatment for chronic sub-dural hematoma (cSDH).  In a systematic review and meta-analysis, these researchers compared outcomes after MMA embolization versus conventional management for cSDH.  They carried out a systematic review of PubMed, Embase, Oxford Journal, Cochrane, and Google Scholar databases from April 1987 to October 2020 in accordance with PRISMA guidelines.  Studies reporting outcomes after MMA embolization for greater than or equal to 3 patients with cSDH were included.  A meta-analysis comparing MMA embolization with conventional management was performed.  The analysis comprised 20 studies with 1,416 patients, including 718 and 698 patients in the MMA embolization and conventional management cohorts, respectively.  The pooled recurrence, surgical rescue, and in-hospital complication rates in the MMA embolization cohort were 4.8 % (95 % CI: 3.2 % to 6.5 %), 4.4 % (2.8 % to 5.9 %), and 1.7 % (0.8 % to 2.6 %), respectively.  The pooled recurrence, surgical rescue, and in-hospital complication rates in the conventional management cohort were 21.5 % (0.6 % to 42.4 %), 16.4 % (5.9 % to 27.0 %), and 4.9 % (2.8 % to 7.1 %), respectively.  Compared with conservative management, MMA embolization was associated with lower rates of cSDH recurrence (OR = 0.15 (95 % CI: 0.03 to 0.75), p = 0.02) and surgical rescue (OR = 0.21 (0.07 to 0.58), p = 0.003).  In-hospital complication rates were comparable between the 2 cohorts (OR = 0.78 (0.34 to 1.76), p =0.55).  The authors concluded that MMA embolization is a promising minimally invasive therapy that may reduce the need for surgical intervention in appropriately selected patients with cSDH.  Moreover, these researchers stated that additional prospective studies are needed to examine the long-term durability of MMA embolization, refine eligibility criteria, and establish this endovascular approach as a viable definitive treatment for cSDH.

Pre-Operative Embolization for Carotid Body Tumor Resection

Abu-Ghanem and co-workers (2016) stated that there is no consensus on the impact of pre-operative embolization (EMB) on the surgical outcomes of carotid body tumor (CBT) resections.  These researchers carried out a systematic review and a meta-analysis to examine the role of pre-operative EMB in patients undergoing surgical removal of CBTs.  A total of 15 studies with a total number of 470 patients met the inclusion criteria.  The results of the meta-analysis showed that there was no significant difference in estimated blood loss (EBL), operative time, length of hospital stay (LOS), or risks of cranial nerve injury, vascular injury, and stroke between the EMB and non-EMB (NEMB) groups.  The authors concluded that this systemic review and meta-analysis demonstrated that pre-operative EMB did not confer any operative or post-operative advantage in patients scheduled for CBT surgery.

Cobb and colleagues (2018) noted that CBTs are rare entities for which surgical resection remains the gold standard.  Given their hyper-vascularity, pre-operative EMB is often used; however, controversy exists over whether a benefit is associated.  Proponents of EMB argue that it minimizes blood loss and complications.  Critics argue that cost and stroke out-weigh benefits.  These investigators examined the impact of EMB on outcomes following CBT resection.  Patients undergoing CBT resection were identified using the Healthcare Cost and Utilization Project State Inpatient Database for 5 states between 2006 and 2013.  Patients were divided into 2 groups: CBT resection alone (CBTR) and CBT resection with pre-operative arterial EMB (CBETR).  Descriptive statistics were calculated using arithmetic means with standard deviations (SDs) for continuous variables and proportions for categorical variables.  Patients were propensity score matched on the basis of sex, age, race, insurance, and co-morbidity prior to analysis.  Risk-adjusted odds of mortality, stroke, nerve injury, blood loss, and LOS were calculated using mixed-effects regression models with fixed effects for age, race, sex, and co-morbidities.  A total of 547 patients were identified.  Of these, 472 patients underwent CBTR and 75 underwent CBETR; mean age was 54.7 ± 16 years.  Mean number of days between EMB and resection was 0.65 ± 0.72 days (range of 0 to 3).  When compared with CBTR, there were no significant differences in mortality for CBETR (1.35 % versus 0 %, p = 0.316), cranial nerve injury (2.7 % versus 0 %, p = 0.48), and blood loss (2.7 % versus 6.8 %, p = 0.245).  Following risk adjustment, CBETR increased the odds of prolonged LOS (OR 5.3, 95 % CI: 2.1 to 13.3).  The authors concluded that CBT resection was a relatively rare procedure.  The utility of pre-operative tumor EMB has been questioned; the findings of this study demonstrated no benefit of pre-operative tumor EMB.

Texakalidis and associates (2019) stated that CBTs are highly vascularized tumors that could render tumor resection surgery challenging.  There is evidence suggesting that pre-operative selective EMB could reduce blood loss during surgery and decrease the risk of peri-operative complications; however, recent reports have questioned the benefits that pre-operative EMB provides.  These investigators examined the impact of pre-operative EMB on CBT surgical resection.  This study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.  Eligible studies were identified through a search of PubMed, Scopus, and Cochrane Central Register of Controlled Trials until March 2019.  A random effects model meta-analysis was conducted, and the I2 statistic was used to assess for heterogeneity.  A total of 25 studies comprising 1,326 patients were included.  Patients who received pre-operative EMB had statistically significant lower intra-operative blood loss (weighted mean difference [WMD], -135.32; 95 % CI: -224.58 to -46.06; I2 = 78.6 %).  Duration of the procedure was statistically significantly shorter in the pre-EMB group than the non-EMB group (WMD, -38.61; 95 % CI: -65.61 to -11.62; I2 = 71.9 %).  There were no differences in the rates of cranial nerve (CN) injuries (OR, 1.13; 95 % CI: 0.68 to 1.86; I2 = 12.9 %), stroke (OR, 1.75; 95 % CI: 0.70 to 4.36; I2 = 0 %), transient ischemic attacks (TIAs) (OR, 0.55; 95 % CI: 0.11 to 2.65; I2 = 0 %), or LOS (WMD, 0.32; 95 % CI: -1.35 to 1.98; I2 = 96.4 %) between the 2 groups.  The authors concluded that patients who received EMB prior to CBT resection had statistically significant lower blood loss and shorter duration of operation; the clinical significance of these differences were unclear.  Furthermore, the rates of CN palsy, stroke, TIA, and LOS were similar between patients who had pre-operative EMB and those who did not.

Pre-Operative Embolization of Skull Base Meningiomas

Ilyas and colleagues (2019) stated that neoadjuvant endovascular EMB of skull base meningiomas may facilitate surgical resection, thus, potentially decreasing operative morbidity.  However, due to variation in the reported efficacy and complication rates, the utility of EMB remains incompletely defined.  In a systematic review, these investigators examined the outcomes of pre-operative EMB for skull base meningiomas.  They carried out a literature review to identify studies reporting outcomes of patients with skull base meningiomas who underwent pre-operative EMB.  Baseline, treatment, and outcomes data were analyzed.  Major complications included death, new cranial neuropathy, retinal artery ischemia, permanent neurologic deficit, or intra-cerebral hemorrhage.  The pooled analysis consisted of 15 studies, comprising a total of 403 patients with skull base meningiomas treated with pre-operative EMB.  The most common locations were the sphenoid wing (34% , 87/256 cases), petroclival region (31 %, 80/256 cases), and cavernous sinus (12 %, 31/256 cases).  The median tumor size ranged from 5.0 to 8.0 cm.  Based on pooled data, angiographic absence of tumor blush was achieved in 17 % (13/79 cases).  The median EBL ranged from 225 to 580 ml.  Simpson grade I to III resection was achieved in 74 % (40/54) of patients.  The overall complication, major complication, and mortality rates were 12 % (47/403 patients), 6 % (21/328 patients), and 0.2 % (1/403 patients), respectively.  Pre-operative EMB was a reasonable adjunct to resection for appropriately selected skull base meningiomas.  The authors concluded that future comparative analyses are needed to determine the benefits of pre-operative EMB of skull base meningiomas with respect to extent of resection, operative duration, operative blood loss, and surgical morbidity.

Transcatheter Arterial Embolization for Non-Variceal Upper Gastro-Intestinal Bleeding

Tarasconi and colleagues (2019) noted that very few patients with non-variceal upper gastro-intestinal (GI) bleeding fail endoscopic hemostasis (refractory NVUGIB).  This subset of patients poses a clinical dilemma: should they be operated on or referred to transcatheter arterial embolization (TAE)?  These researchers performed a systematic review of the literature and carried out a meta-analysis of studies that directly compared TAE and surgery in patients with refractory NVUGIB.  They searched PubMed, Ovid Medline, and Embase.  A combination of the MeSH terms "gastrointestinal bleeding"; "gastrointestinal hemorrhage"; "embolization"; "embolization, therapeutic"; and "surgery" were used (("gastrointestinal bleeding" or "gastrointestinal hemorrhage") and ("embolization" or "embolization, therapeutic") and "surgery")).  The search was performed in June 2018.  Studies were retrieved and relevant studies were identified after reading the study title and abstract.  Bibliographies of the selected studies were also examined.  Statistical analysis was performed using RevMan software.  Outcomes considered were all-cause mortality, rebleeding rate, complication rate, and the need for further intervention.  A total of 856 abstracts were found; only 13 studies were included for a total of 1,077 patients (TAE group 427, surgery group 650).  All selected papers were non-randomized studies: 10 were single-center and 2 were double-center retrospective comparative studies, while only 1 was a multi-center prospective cohort study.  No comparative randomized clinical trial was reported in the literature.  Pooled data (1,077 patients) showed a tendency toward improved mortality rates after TAE, but this trend was not statistically significant (OD = 0.77; 95 % CI: 0.50 to 1.18; p = 0.05; I2 = 43 % [random effects]).  Significant heterogeneity was found among the studies.  Pooled data (865 patients, 211 events) showed that the incidence of re-bleeding was significantly higher for patients undergoing TAE (OD = 2.44; 95 % CI: 1.77 to 3.36; p = 0.41; I2 = 4 % [fixed effects]).  Pooling of the data (487 patients, 206 events) showed a sharp reduction of complications after TAE when compared with surgery (OD = 0.45; 95 % CI: 0.30 to 0.47; p = 0.24; I2 = 26 % [fixed effects]).  Pooled data (698 patients, 165 events) revealed a significant reduction of further intervention in the surgery group (OD = 2.13; 95 % CI: 1.21 to 3.77; p = 0.02; I2 = 56 % [random effects]).  A great degree of heterogeneity was found among the studies.  The authors concluded that the findings of this study showed that TAE was a safe and effective procedure; when compared to surgery; TAE exhibited a higher re-bleeding rate, but this tendency did not affect the clinical outcome as shown by the comparison of mortality rates (slight drift toward lower mortality for patients undergoing TAE).  The present study suggested that TAE could be a viable option for the 1st-line therapy of refractory NVUGIB and set the foundation for the design of future randomized clinical trials.  Another issue that needs to be addressed in the future is the best therapeutic option for refractory NVUGIB in hemodynamically unstable patients.

The authors stated that this study had several drawbacks.  First, the retrospective nature of the majority of included studies led to an inevitable selection bias.  Furthermore, the decision between TAE and surgery was made on an individual case-by-case basis by the attending surgeon, making group allocation and randomization difficult to achieve.  This may lead to low external validity.  Furthermore, although the most common cause of refractory bleeding was a peptic ulcer, there remain a variety of etiologies.  TAE and surgical techniques also varied among the included studies.  Regarding complications, only a few studies reported a complication rate for the analyzed procedures and some studies reported re-intervention rates only in case of re-bleeding following the index procedure; thus, the analysis of the re-intervention and complication rates may not represent everyday reality.  Lastly, the modality of mortality detection differed between the studies (in-hospital mortality, 30-day mortality, overall mortality, etc.).  These drawbacks did not impair the power of the present study that represented the largest and most recent meta-analysis available.

Embolization for Locoregional Treatment of Metastatic Pancreatic Cancer

Timmer and colleagues (2021) stated that the prognosis of metastatic pancreatic ductal adenocarcinoma (mPDAC) remains universally poor, requiring new and innovative therapeutic approaches.  In a subset of oligometastatic PDAC patients, locoregional therapy, in addition to systemic chemotherapy, may improve survival.  In a systematic review, these researchers examined available evidence on locoregional treatments for mPDAC.  They carried out a systematic literature search on locoregional techniques, including resection, ablation and embolization, for mPDAC with a focus on hepatic and pulmonary metastases.  A total of 59 studies were identified, including 63,453 patients.  Although subject to significant bias, radical-intent local therapy for both the primary and metastatic sites was associated with a superior median OS from metastatic diagnosis or treatment (hepatic mPDAC 7.8 to 19 months; pulmonary mPDAC 22.8 to 47 months) compared to control groups receiving chemotherapy or best supportive care (hepatic mPDAC 4.3 to 7.6 months; pulmonary mPDAC 11.8 months).  To recruit patients that may benefit from these local treatments, selection appeared essential.  Most significant was the upfront possibility of local radical pancreatic and metastatic treatment.  Furthermore, a patient's response to neoadjuvant systemic chemotherapy, performance status, metastatic disease load and, to a lesser degree, histological differentiation grade and tumor marker CA19-9 serum levels, were powerful prognostic factors that aided in identifying eligible subjects.  The authors concluded that although the exact additive value of locoregional treatments for mPDAC patients could not be distillated from the results, locoregional primary pancreatic and metastatic treatment appeared beneficial for a highly selected group of oligometastatic PDAC patients.  Moreover, these researchers stated that for definite recommendations, large, prospective, well-designed RCTs with strict inclusion and exclusion criteria are needed to validate these findings; locoregional treatment for mPDAC should not be provided outside the context of an experimental trial.

Gastric Variceal Embolization

Iwamoto and Shigemoto (1985) stated that partial splenic artery embolization was performed in 1 patient with cirrhosis during acute variceal bleeding when other direct hemostatic procedures could not be applied.  It clearly assisted in controlling the acute bleeding; and led to subsequent endoscopic sclerosis.  The authors concluded that although its effect was indirect, partial splenic embolization may prove useful in certain clinical situations with acute bleeding where other hemostatic means had failed or were not applicable.

Durham et al (1990) reported that mini-laparotomy and direct catheterization of the mesenteric vein for variceal embolization was attempted in 15 patients in whom medical and endoscopic treatment of variceal hemorrhage had failed.  Hemorrhage was controlled immediately after the procedure in 11 patients.  The 30-day survival rate was 60 % (n = 9).  The cause of death in 6 patients was variceal bleeding (n = 2), liver failure (n = 3), and respiratory failure (n = 1).  The 6-month survival rate was 33 % (n = 5), and the 1-year survival rate was 27 % (n = 4).  Bleeding recurred in 67 % of surviving patients; however, fatal variceal bleeding occurred in only 22 % (n = 2).  Direct mesenteric vein catheterization allowed simplified entry into the portal vein for embolization of bleeding esophageal or gastric varices.  The authors concluded that early experience suggested that these findings were similar to those of percutaneous transhepatic embolization, without the complications and technical demands of a trans-hepatic approach.

Chen et al (2013) examined the efficacy of a transjugular intrahepatic portosystemic shunt (TIPS) alone and TIPS in association with embolotherapy (TIPS+E) in the variceal coronary vein to prevent recurrent variceal bleeding and stent dysfunction after TIPS creation.  Institutional review board (IRB) approval was obtained; all subjects provided informed consent.  A total of 106 patients (66 men, 40 women; age range of 18 to 70 years) with recurrent variceal bleeding due to hepatic cirrhosis were assigned randomly to the TIPS+E (n = 54) or TIPS (n = 52) group from May 2007 to July 2011.  The TIPS was created by using covered stents.  Patients in the TIPS+E group underwent embolotherapy via the jugular vein before TIPS implantation.  Rates of recurrent variceal bleeding, stent patency, and survival were evaluated.  Scores for liver function and quality of life (QOL) were calculated.  TIPS placement was successful in all patients.  Recurrent variceal bleeding ranked 2nd among causes of death after TIPS placement.  Although the 3-year cumulative rates of shunt patency, recurrent variceal bleeding, and survival in the 2 groups were not significantly different (p > 0.05), the 6-month overall rate of shunt patency in the TIPS+E group was significantly higher than that in the TIPS group (96.2 % versus 82.0 %, p = 0.019), and the 6-month overall rate of recurrent variceal bleeding was also significantly lower than that in the TIPS group (5.7 % versus 20.0 %, p = 0.029).  The authors concluded that TIPS+E regimen may reduce the risk of recurrent variceal bleeding during the first 6 months after the TIPS procedure by preventing shunt dysfunction, which may improve liver function and QOL.

These researchers stated that even with lower recurrent variceal bleeding rates, the TIPS+E group did not show a survival advantage over the TIPS group within 6 months after TIPS placement.  When these investigators designed this study, the sample size was estimated on the basis of reducing the recurrent bleeding rate but not the survival rate.  Thus, the sample size was insufficient to demonstrate the smaller difference in survival rates between the 2 groups.  However, they believed it was still valuable to note that the reduction of recurrent variceal bleeding with the TIPS+E regimen was beneficial for increasing hemoglobin (Hb) level, improving liver function, and enhancing QOL in patients with cirrhosis during the first 6 months after the procedure.  Another limitation of this study was that the Viatorr stent, an ePTFE-covered device specially designed for TIPS, was not used in this study because it was not available in China.  However, the cumulative recurrent variceal bleeding rates of the TIPS group with ePTFE-covered Fluency stents in this study were similar to those reported with Viatorr stents (24.3 % versus 26 % at 1 year and 30.7 % versus 32 % at 2 years).  The cumulative shunt patency rates in this study are also almost the same as those of TIPS created with Viatorr stents.  Although there were some differences between the 2 ePTFE-covered devices in their structures and diameters, the changes observed in this study with Fluency stents also were observed in TIPS created with Viatorr stents.

Bazarbashi et al (2020) noted that gastric variceal (GV) bleeding is a feared complication of cirrhosis.  Traditional endoscopic treatment with cyanoacrylate (CYA) injection can be challenging.  Alternatively, endoscopic ultrasound (EUS)-guided delivery of hemostatic coils has shown high therapeutic success without the complications profile of CYA alone.  These researchers compared the clinical outcomes of EUS-guided coil embolization with endoscopic CYA injection for the treatment of GV.  They carried out a matched cohort study using a prospective registry involving 2 tertiary centers.  A total of 10 patients undergoing EUS-based coil therapy were matched in 1:3 fashion to 30 patients who underwent CYA injection.  The matching criteria included type of GV, Charlson co-morbidity index, and bleeding severity.  Primary outcomes were technical success and complications; secondary outcomes were re-bleeding rates, re-interventions rates, total transfusion requirements, and time-to-event analysis (re-bleeding, re-intervention, and transfusion).  Technical success was 100 % for EUS coil therapy versus 96.7 % for CYA injection (p = 1.0).  Complication rates were 10 % in the EUS coil group versus 20 % in the CYA group (p = 0.65).  At 9 months, no EUS coil patient had re-bled compared with 38 % of the CYA group.  No EUS coil patient required blood transfusion for GV re-bleed, whereas over 50 % of CYA patients did; 10 % of EUS coil patients needed re-intervention compared with 60 % of CYA patients.  The EUS coil group had superior time to re-intervention, GV re-bleed, and transfusions (all p < 0.05).  The authors concluded that compared with CYA, EUS-guided coil injection appeared superior for the treatment of GV and should be considered initial endoscopic treatment of choice in centers with interventional EUS expertise.

The authors stated that there are several limitations of the technique and of the study at large.  Limitations of the procedure included the need for fluoroscopy and the use of intravenous contrast, which requires consideration in patients with contrast allergies or renal insufficiency.  However, these researchers felt that varicealography is critically important for anatomic delineation, as described by Robeles-Miranda et al and previous adjunctive injection (e.g., AGS or CYA) to mitigate against embolic complications.  Limitations of the study included but are not limited to the objective small number of cases involved (n = 10; despite being one of the largest comparative studies to-date), the heterogeneity of the endoscopists performing the CYA injection versus experienced endo-sonographer performing coil and AGS injection (limiting generalizability), and the retrospective nature of the study.  It is important to note that the rate of re-bleeding in the CYA arm was 38 % and was higher than that mentioned in the recent literature of 20 % to 30 %, these investigators hypothesized that this was most likely related to the following factors: (i) non-algorithmic approach to CYA injection by more than 1 provider (EUS versus non-EUS use, volume of CYA, technique of injection, etc.), (ii) less rigorous post-procedure protocol of serial evaluation with endoscopy and EUS for varicealography, and (iii) extended follow-up time of up to 9 months.  These researchers wanted to also highlight that 1 patient in the EUS coil group and 4 patients in the CYA group had no evidence of active or recent bleeding.  Finally, the authors wanted to acknowledge that the cohort of EUS coil + AGS patients in this study have been included in a recent step-by-step procedural technique publication highlighting the use of AGS as an alternative agent for adjunctive hemostasis

Furthermore, an UpToDate review on “Methods to achieve hemostasis in patients with acute variceal hemorrhage” (Bajaj and Sanyal, 2021) states that “Alternative treatments that have been studied include variceal band ligation, early TIPS, thrombin injection, use of bands and snares, balloon occluded retrograde transvenous obliteration (BRTO), vascular plug and gelatin sponge-assisted retrograde transvenous obliteration, and coil embolization with gelatin sponge injection”.  

A review on the management of gastrointestinal varices (Boregowda et al, 2019) reported that "the recent emergence of endoscopic ultrasound guided glue and coil injection in treating gastric varices has shown a lower bleeding rate, transfusion requirements, and mortality when compared to glue injection. When EUS guided coil embolization alone was compared with EUS guided glue injection, both had similar hemostasis rates, but coil embolization had fewer adverse events and required a fewer number of endoscopies [citing Romero-Castro, et al., 2013]. When these two techniques were combined (glue + coil), the mean number of coils used, mean volume of glue used, and the recurrence rate was lower compared to either of them alone [citing Bhat, et al., 2016]."

Left Gastric Artery Embolization for the Treatment of Obesity

In a systematic review and meta-analysis, Hafezi-Nejad and colleagues (2019) examined the safety and efficacy of left gastric artery (LGA) embolization as a bariatric procedure.  The Methodological Index for Nonrandomized Studies (MINORS) instrument was used for quality assessment.  Patient characteristics, weight loss after embolization, and complications were reviewed.  Meta-regression was carried out to evaluate associations of age, sex, body mass index (BMI), and ghrelin and leptin levels with weight change after LGA embolization.  The final meta-analysis included 6 prospective, non-randomized trials.  Findings of 3 additional studies reporting weight changes following LGA embolization for control of gastro-intestinal (GI) bleeding were also reviewed.  Pooled analysis of 47 subjects with overweight/obesity showed mean ± SD weight loss after embolization of 8.1 % ± 1.5 % and 8.85 kg ± 1.24 kg (both p < 0.001) after a mean 12-month follow-up.  Male sex (β = 11.36 ± 5.79, p = 0.049) was associated with greater weight loss.  Transient superficial mucosal ulcers were common following LGA embolization.  One major adverse event (AE) comprising severe pancreatitis, splenic infarct, and gastric perforation was reported; treatment was supportive care.  The authors concluded that LGA embolization was associated with statistically significant weight loss and limited complications during short-term follow-up.  Moreover, these researchers stated given that LGA embolization is an investigative method, it is important for researchers to follow standardized protocols and techniques to avoid complications.

In a systematic review and meta-analysis, Mizandari and associates (2021) examined recent literature on bariatric LGA embolization for the treatment of obesity and compared this new procedure in human and animal studies.  They carried out a systematic search of Scopus, Medline, Web of Science, Embase, and Google Scholar to identify human and animal studies employing bariatric LGA embolization for the treatment of obesity; Cochrane's Q test and the I2 statistic were employed to determine heterogeneity.  A total of 9 human and 4 animal studies recruiting a total of 118 cases (n = 78 patients and n = 40 animals) were included in analysis.  All assessments on BMI, weight, and ghrelin levels had been fulfilled based on before-after (human studies) and intervention-control designs (animal studies) using bariatric LGA embolization.  The findings suggested that bariatric LGA embolization had significantly decreased BMI (mean difference (MD): - 2.66, 95 % CI: - 3.74 to - 1.58, p < 0.001) and weight (MD: - 8.69, 95 % CI: - 10.48 to - 6.89, p < 0.001) in humans.  Although overall pooled estimate showed no significant changes in ghrelin levels following this procedure (Hedges' g statistic: - 0.91, 95 % CI: - 1.83 to 0.01, p = 0.05) in humans, a significant reduction was observed in animal studies (MD: - 756.56, 95 % CI: - 1098.79 to - 414.33, p < 0.001) along with a significant drop in weight (MD: - 7.64, 95 % CI: - 13.73 to - 1.54, p < 0.001).  The authors concluded that that ghrelin levels in humans had not been affected, although bariatric LGA embolization might significantly improve BMI and weight.

Furthermore, an UpToDate review on “Obesity in adults: Overview of management” (Perreault and Apovian, 2021) does not mention left gastric artery (LGA) embolization as a management / therapeutic option.    

Paraumbilical Vein Coil Embolization for the Treatment of Hepatic Encephalopathy

Cho et al (2014) examined the feasibility of percutaneous access via the re-canalized paraumbilical vein for varix embolization.  Between July 2008 and January 2014, percutaneous access via the re-canalized paraumbilical vein for varix embolization was attempted in 7 patients with variceal bleeding.  Paraumbilical vein puncture was performed under ultrasonographic (US) guidance, followed by introduction of a 5-Fr sheath.  These investigators retrospectively evaluated the technical feasibility, procedure-related complications, and clinical outcomes of each patient.  Re-canalized paraumbilical vein catheterization was performed successfully in all patients.  Gastroesophageal varix embolization was performed in 6 patients, and umbilical varix embolization was performed in 1 patient.  Embolic materials used are n-butyl cyanoacrylate (n = 6) and coil with n-butyl cyanoacrylate (n = 1).  There were no procedure-related complications; 1 patient underwent repeated variceal embolization 6 hours after initial procedure via re-canalized paraumbilical vein, due to re-bleeding from gastric varix.  The authors concluded that percutaneous access via the paraumbilical vein for varix embolization was a simple alternative in patients with portal hypertension.

The author stated that this study had 2 main drawbacks.  First, the study population was too small (n = 1 for umbilical varix embolization); further study with a larger population is needed to confirm the safety of percutaneous access via the paraumbilical vein.  Second, the study lacked a comparison with other access methods such as the trans-splenic and trans-hepatic approaches; however, the paraumbilical vein is superficially located in the abdominal wall, and the authors believed that access via the paraumbilical vein is much easier for inexperienced operators.

Furthermore, UpToDate reviews on “Hepatic encephalopathy in adults: Treatment” (Ferenci, 2021), “Acute toxic-metabolic encephalopathy in adults” (Chalela, 2021) and “Cirrhosis in adults: Overview of complications, general management, and prognosis” (Goldberg and Chopra, 2021) do not mention paraumbilical vein coil embolization as a management / therapeutic option.

Portal Vein Embolization Before Surgical Resection of Cholangiocarcinoma

Ebata et al (2012) noted that portal vein embolization (PVE) has been widely applied before extended hepatectomy; however, its clinical utility for patients with biliary cancer has not been fully addressed.  Between 1991 and 2010, a total of 494 patients with cholangiocarcinoma (n = 353) or gallbladder cancer (n = 141) underwent PVE before extended hepatectomy.  PVE was performed by a trans-hepatic ipsilateral approach using fibrin glue or absolute ethanol with steel coils.  Surgical outcomes of this cohort were retrospectively reviewed.  PVE-related complications requiring interventions were found in 3 (0.6 %) of the 494 patients; no patient died of these complications.  Among the 494 patients, 122 (24.7 %) did not undergo subsequent hepatectomy.  The unresectability rate was significantly higher in patients with gallbladder cancer than in those with cholangiocarcinoma [43.2 % (61/141) and 17.3 % (61/353), respectively, p < 0.001].  The remaining 372 patients underwent hepatectomy, and 24 (6.5 %) died of post-operative complications [13 of 80 (16.3 %) with gallbladder cancer versus 11 of 292 (3.8 %) with cholangiocarcinoma, p < 0.05].  The overall survival (OS) for patients with cholangiocarcinoma was significantly better than that for patients with gallbladder cancer, where the 5-year survival rate was 39 % and 23 %, respectively (p < 0.001); 36 patients with cholangiocarcinoma and 10 patients with gallbladder cancer survived more than 5 years after extended surgery.  The authors concluded that PVE can be performed safely in patients with cholestatic liver, and it has a potential benefit for patients with advanced biliary cancer who are to undergo extended, difficult hepatectomy.

Sofue et al (2014) examined the safety and efficacy of pre-operative right PVE with absolute ethanol in patients with hepatobiliary malignancies.  PVE was performed via a percutaneous trans-hepatic ipsilateral approach, and the right portal branch was embolized with absolute ethanol.  Technical success and complications following PVE, and changes in liver enzyme levels were evaluated.  Changes in future liver remnant (FLR) and FLR/total functional liver volume ratio were calculated.  Complications following hepatic resection were assessed.  A total of 83 patients with hepatobiliary malignancies (53 men, 30 women; mean age of 68 years) underwent right PVE. Tumor types were hilar cholangiocarcinoma (n = 37), liver metastases (n = 14), gallbladder cancer (n = 13), intra-hepatic cholangiocellular carcinoma (n = 10) and hepatocellular carcinoma (HCC) (n = 9).  PVE was performed successfully in all patients; 4 patients (5 %) developed complications following PVE (liver abscess 2, left portal vein thrombosis 1, pseudoaneurysm 1), but this did not preclude hepatic resection.  Liver enzyme levels rose transiently after PVE.  The mean FLR and FLR/total functional liver volume increased after PVE (from 366 to 513 cm(3) and from 31 to 43 %, respectively; both p < 0·001).  Changes in the FLR and FLR/total functional liver volume ratio were comparable between patients with HCC and those with other malignancies (42 and 44 %, and 12 and 12 %, respectively); 69 of 83 patients underwent hepatic resection at a median of 25 days after PVE, with no post-operative mortality.  The authors concluded that pre-operative right PVE with absolute ethanol was safe and effective for induction of selective hepatic hypertrophy in patients with hepatobiliary malignancy.

Glantzounis et al (2017) stated that primary liver and biliary cancers are very aggressive tumors.  Surgical treatment is the main option for cure or long-term survival.  In a systematic review, these researchers examined indications for PVE in patients with inadequate FLR and analyzed other parameters such as resection rate, morbidity, mortality, survival after PVE and hepatectomy for primary hepatobiliary tumors.  Furthermore, the role of trans-arterial chemoembolization (TACE) before PVE, was examined.  They carried out a systematic search of the literature in Pub Med and the Cochrane Library from January 1, 1990 to September 30, 2015.  A total of 40 articles were selected, including 2,144 patients with a median age of 61 years.  The median excision rate was 90 % for HCCs and 86 % for hilar cholangiocarcinomas (HCs).  The main indications for PVE in patients with HCC and presence of liver fibrosis or cirrhosis was FLR of less than 40 % when liver function was good (indocyanine green retention test at 15 min [ICGR15] ICGR15 less than 10 %) and FLR of less than 50 % when liver function was affected (ICGR15:10 to 20 %).  The combination of TACE and PVE increased hypertrophy rate and was associated with better OS and disease-free survival (DFS) and should be considered in advanced HCC tumors with inadequate FLR.  In patients with HCs PVE was performed, after pre-operative biliary drainage, when FLR was less than 40 %, in the majority of studies, with very good post-operative outcome; however, indications should be refined.  The authors concluded that PVE before major hepatectomy allowed resection in a patient group with advanced primary hepato-biliary tumors and inadequate FLR, with good long-term survival.

Olthof et al (2020) stated that pre-operative PVE is frequently used to improve FLR volume (FLRV) and to reduce the risk of liver failure after major liver resection.  In an international, multi-centric, cohort study, these researchers examined post-operative outcomes after PVE and resection for suspected perihilar cholangiocarcinoma (PHC).  Patients undergoing resection for suspected PHC across 20 centers worldwide, from the year 2000, were included.  Liver failure, biliary leakage, and hemorrhage were classified according to the respective International Study Group of Liver Surgery criteria.  Using propensity scoring, 2 equal cohorts were generated using matching parameters (i.e., age, sex, American Society of Anesthesiologists [ASA] classification, jaundice, type of biliary drainage, baseline FLRV, resection type, and portal vein resection.  A total of 1,667 patients were treated for suspected PHC during the study period.  In 298 patients who underwent pre-operative PVE, the overall incidence of liver failure and 90-day mortality was 27 % and 18 %, respectively, as opposed to 14 % and 12 %, respectively, in patients without PVE (p < 0.001 and p = 0.005).  After propensity score matching, 98 patients were enrolled in each cohort, resulting in similar baseline and operative characteristics.  Liver failure was lower in the PVE group (8 % versus 36 %, p < 0.001), as was biliary leakage (10 % versus 35 %, p < 0.01), intra-abdominal abscesses (19 % versus 34 %, p = 0.01), and 90-day mortality (7 % versus 18%, p = 0.03).  The authors concluded that PVE before major liver resection for PHC was associated with a lower incidence of liver failure, biliary leakage, abscess formation, and mortality.  These results demonstrated the importance of PVE as an integral component in the surgical treatment of PHC.

Dondossola et al (2020) noted that cholangiocarcinoma (CCC) is the most aggressive malignant tumor of the biliary tract.  PHC is the most common CCC and its anatomical location makes surgical approach burden by poor results.  Pre-operative staging must consider the extent of liver resection to avoid post-surgical hepatic failure.  During staging, magnetic resonance can obtain satisfactory cholangiographic images, while invasive techniques should be used if bile duct samples are needed.  Consistently, to improve diagnostic potential, bile duct drainage is not necessary in jaundice, while it is indicated in refractory cholangitis or when liver hypertrophy is needed.  Once resectability criteria are identified, the extent of liver resection is secondary to the longitudinal spread of CCC.  Once surgical indication is established, biliary decompression is anyway debated.  Wide accordance on drainage is achieved when a 2-step procedure (2-step hepatectomy or PVE followed by hepatectomy) is needed to increase the FLRV. While in the past type-IV PHC was not considered resectable, some authors reported good results after their treatment.  Conversely, in selected unresectable cases, liver transplantation could be a valuable option.  Adjuvant chemotherapy is the standard of care for resected patients, while neoadjuvant approach has growing evidences.  If curative resection is not achieved, radiotherapy can be added to chemotherapy.  This multi-step curative approach must be carried on in specialized centers.

Kawabata et al (2021) stated that PVE is widely used to promote the hypertrophy of a future liver remnant (FLR) and reduce post-hepatectomy liver failure.  The se researchers examined the efficacy of trans-ileocecal portal embolization (TIPE) associated with staging laparoscopy (hybrid lap-TIPE) for a planned hepatectomy in advanced hepatobiliary cancers.  The hybrid lap-TIPE procedure consisted of staging laparoscopy for complete screening of the abdominal cavity with cyto-reductive surgery (CRS) and subsequent TIPE.  Data on hybrid lap-TIPE, performed between March 2013 and February 2020, were collected retrospectively.  Hybrid lap-TIPE was conducted for 52 patients, and a subsequent TIPE was accomplished in 42 patients (80.8 %), since staging laparoscopy detected latent or unresectable factors in 13 patients (25.0 %), among which 2 patients with HCC and 1 with colorectal liver metastasis received laparoscopic CRS for latent lesions in the FLR.  Finally, radical hepatectomy was completed in 36 patients (69.2 %), including 3 patients who underwent CRS.  The most common operation was an extended right hepatectomy (50.0 %), followed by right hepatectomy (30.6 %), including 3 hepato-pancreato-duodenectomies.  The overall morbidity associated with hybrid lap-TIPE and hepatectomy was 7.1 % and 41.7 %, respectively.  The mortality associated with hybrid lap-TIPE and hepatectomy was 0 % and 5.6 %, respectively.  The rates of 2-year OS and 2-year DFS were 64.8 % and 61.9 %, respectively, after hepatectomy.  The authors concluded that hybrid lap-TIPE was safe and could be a useful therapeutic option for patients with advanced hepatobiliary cancer because it can help to identify optimal candidates for PVE followed by a planned hepatectomy.

Bruning et al (2021) noted that PVE is a minimal invasive pre-operative strategy that aims to increase FLR in order to facilitate extended hemi-hepatectomy.  These investigators analyzed their data retrospectively regarding complications and degree of hypertrophy (DH).  A total of 88 patients received PVE either by particles / coils (n = 77) or by glue / oil (n = 11), supported by 7 right hepatic vein embolization (HVE) by coils or occluders.  All complications were categorized by the Clavien- Dindo (CD) and the CIRSE classification.  In 88 patients (median age of 68 years) there was 1 intervention with a biliary leak and subsequent drainage (complication grade 3 CD, CIRSE 3), 2 with prolonged hospital stay (grade 2 CD, grade 3 CIRSE) and 13 complications grade 1 CD, but no complications of grade 4 or higher neither in Clavien- Dindo nor in CIRSE classification.  The median relative increase in FLR was 47 % (SD 35 %).  The mean pre-intervention standardized FLR rose from 23 % (SD 10 %) to a post-intervention standardized FLR of 32 % (SD 12 %).  The degree of hypertrophy (DH) was 9.3 % (SD 5.2 %) and the kinetic growth rate (KGR) per week was 2.06 (SD 1.84).  The authors concluded that PVE and, if necessary, additional sequential HVE were safe procedures with a low rate of complications and facilitated sufficient pre-operative hypertrophy of the future liver remnant.

Furthermore, an UpToDate review on “Preoperative portal vein embolization” (Kumar, 2021) states that “Preoperative PVE is primarily indicated when a marginal FLR precludes an otherwise potentially curative hepatectomy in selected patients with primary or metastatic liver tumors … In properly selected patients, preoperative PVE increases resectability rates and reduces the incidence of post-hepatectomy liver failure.  Approximately 70 to 80 % of patients who undergo preoperative PVE eventually undergo successful liver resection.  Although the timing of hepatic resection varies, hepatic surgeons generally wait 3 to 6 weeks post-PVE before undertaking resection”.

Endovascular Embolization in the Treatment of Spinal Dural Arterio-Venous Fistula

In a meta-analysis, Yuan et al (2022) compared the effectiveness of microsurgery and endovascular embolization in the treatment of spinal dural arteriovenous fistula (SDAVF).  These researchers carried out a systematic review to retrieve all relevant studies regarding surgical treatment or endovascular embolization of SDAVF up to December 2019 through PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials Results, CNKI, Wanfang Data, and SinoMed.  The Chinese and English key words included: "SDAVF", "spinal dural arteriovenous fistula", "spinal AVM", "spinal vascular malformation and treatment".  The included studies were examined using the Newcastle-Ottawa scale . The early failure rate, long-term recurrence, neurological recovery, and complications were evaluated and the clinical effects of the 2 methods in the treatment of SDAVF were compared by using RevMan 5.3 software.  In addition, a subgroup analysis of the therapeutic effect of endovascular embolization with different embolic agents was carried out.  A total of 46 studies involving 1,958 cases of SDAVF were included, in which 935 cases were treated by microsurgery and 1,023 cases were treated by endovascular embolization.  The funnel plot showed that there was no publication bias.  The results of meta-analysis showed that the incidence of early surgical failure was lower than that of endovascular embolization (OR = 0.20, 95 % CI: 0.13 to 0.30, p < 0.05), and the long-term recurrence was also lower than that of endovascular embolization (OR = 0.36, 95 % CI: 0.22 to 0.58, p < 0.05).  The improvement of neurological function in the surgical patients was significantly higher than that in the patients treated with endovascular embolization (OR = 2.86, 95 % CI: 1.36 to 5.99, p < 0.05).  There was no significant difference in the occurrence of complications between the 2 groups (OR = 1.52, 95 % CI: 0.88 to 2.64, p = 0.14).  In the cases of endovascular embolization, the risk of treatment failure or recurrence was higher with Onyx glue than with n-butyl 2-cyanoacrylate (NBCA), and the difference was statistically significant (OR = 4.70, 95 % CI: 1.55 to 14.28, p < 0.05).  The authors concluded that although the treatment of dural arteriovenous fistulas by intra-vascular embolization has been widely used, the clinical effect of microsurgery was still better than that of endovascular embolization.  Moreover, these researchers stated that large scale and high-quality RCTs are needed to validate the safety and effectiveness of endovascular treatment in SDAVF patients.

HydroPearl Microspheres for the Treatment of Arterio-Venous Malformations in the Lower Extremity

An UpToDate review on “Acquired arteriovenous fistula of the lower extremity” (Stone, 2022) states that “For symptomatic AVFs that fail compression-based therapy, we recommend surgical repair (Grade 1B).  Endovascular repair with a covered stent or coil embolization are alternative treatments for patients who may not tolerate trivial bleeding, have a hostile groin (e.g., prior surgery), or have a prohibitive risk for general anesthesia”.  Microsphere is not mentioned as a therapeutic option in this UTD review.

Hemorrhoidal Embolization

The American Society of Colon and Rectal Surgeons’ clinical practice guidelines on “Management of hemorrhoids” (Davis et al, 2018) had no recommendation for hemorrhoidal artery embolization as a treatment for hemorrhoids. Guidance from the National Institute for Health and Care Excellence (2018) had the following recommendation: "Current evidence on the safety and efficacy of superior rectal artery embolisation for haemorrhoids is inadequate in quality and quantity. Therefore, this procedure should only be used in the context of research." 

Wang et al (2021) noted that whether different embolic particles with comparable diameter result in similar beneficial effects in endovascular embolization of hemorrhoidal disease remains to be established.  In a retrospective, multi-center study, these investigators examined the safety and effectiveness of different types of agents for superior rectal arterial embolization (SRAE) in patients with bleeding hemorrhoids.  They examined patients with recurrent episodes of internal hemorrhoidal bleeding and chronic anemia treated by SRAE in 3 tertiary hospitals between March 2017 and June 2020.  Subjects were divided into 2 study groups based on the embolic materials: embolization with coils (2 to 3 mm) + gelfoam particles at 350 to 560 μm (Group A, n = 23), embolization with coils (2 to 3 mm) + microparticles at 300 to 500 μm (Group B, n = 18).  The technical success, preliminary effectiveness (percentage of patients without hematochezia), post-operative complications and short-term follow-up outcomes were analyzed.  A total of 41 patients (27 men) with symptomatic hemorrhoids were included in the study, mean age was 47 ± 12 years (range of 25 to 72); 39 % (n = 16) patients with grade-II hemorrhoids while 61 % (n = 25) patients with grade-III.  The technical success rate of the embolization procedure was 100 %, and the preliminary effectiveness (87.0 % versus 88.9 %) showed no significant difference between the 2 groups (p = 0.098).  No patients reported post-procedural and short-term serious complications, such as infection, intestinal ischemia or massive hemorrhage during the follow-up period (range of 6 to 15 months).  The authors concluded that both gelfoam particles and microparticles with comparable diameter in the endovascular treatment of hemorrhoidal bleeding showed similarly good short-term safety and effectiveness profile. 

The authors stated that this study had several drawbacks.  First, this was a retrospective, multi-center study of prospectively collected data, there were variations in treatment and evaluation among different hospitals and even between doctors.  Second, the sample size was small (n = 41); and the study did not compare the effects of embolic agents with different particle sizes.  Third, it is probably too early to say for sure that hematochezia will recur or not at maximum 15-month follow-up.  These researchers stated that all these issues should be examined in a randomized clinical trial with longer follow-up.

In a prospective, non-randomized, non-controlled study, phase I/II clinical trial, Stecca et al (2021) examined the technical and clinical success rates of SRAE in the treatment of symptomatic grades-II and grade-III hemorrhoidal disease.  A total of 43 patients (24 men and 19 women; mean age of 52 years [18 to 77]) with symptomatic hemorrhoidal disease were treated and completed the 6-month follow-up with anamnestic questionnaire and disease scores, including French bleeding score (FBS), Goligher prolapse, VAS for pain, and QOL.  Clinical success was evaluated at 7 days, 1 month, and 6 months of follow-up by updating the clinical scores.  Statistical analysis was carried out using SPSS 25.0.  A total of 25 patients had grade-II prolapse and 18 patients had grade-III prolapse, with 96 % and 77 %, respectively, having bleeding as a symptom.  All patients were discharged within 24 hours.  The reduction in the FBS (global and single entity) in grade-III prolapse was statistically significant (p = 0.001).  Improvement in the QOL was significant in both groups (p < 0.05).  No serious complications were observed.  The authors concluded that hemorrhoidal embolization was a safe and effective technique in the treatment of symptomatic hemorrhoidal disease with minimal hospitalization, pain, and disruption of daily activities.  It can be offered to patients unwilling to undergo a surgical procedure but can also be indicated in the emergency setting for patients on anti-coagulant therapy or those unfit for surgery.  Moreover, these researchers stated that further comparative, multi-center studies with longer follow-up periods and larger cohorts of patients are needed to confirm the clinical success rate and to provide socioeconomic comparisons of cost-effectiveness and lost working days.

The authors stated that this study had several drawbacks.  First, the small number of subjects (n = 43), especially compared to the studies of other surgical techniques.  Second, the mono-centric design of the study.  Third, the short-term follow-up durations (6 months).  In this trial, the clinical scores showed a slight regression within 6 months compared to 1 month; therefore, indicating the requirement for a longer follow-up to evaluate durability.  Fourth, the range of the QOL scoring instrument that these researchers adopted according to previously published experiences.  In future studies, a QOL instrument with an expanded scale, from 1 to 10, and possibly including specific metrics of function, should be adopted to determine its reliability in evaluating the clinical success rate against FBS.

Buso Gil et al (2022) stated that hemorrhoids are blood cushions located in the anus and lower rectum, acknowledged as a common cause of bleeding, which can reduce QOL.  The development of minimally invasive techniques such as endovascular embolization of superior rectal artery, "Emborrhoid technique", is an effective treatment, with no pain or ischemic complications, and allows quick patient recovery. These investigators described the general technique and discussed the findings of the current literature.  These investigators noted that recently, minimally invasive techniques based on the hyper-flow of hemorrhoidal arteries, such as trans-anal hemorrhoidal de-arterialization (THD), Doppler-guided hemorrhoidal artery ligation (DGHAL), or its endovascular version, the “Emborrhoid technique”, have emerged, showing promising results and more patient comfort.  THD and DGHAL are minimally invasive techniques, with the same rationale as hemorrhoid embolization (HE).  The physio-pathologic effect of DGHAL on hemorrhoidal hyper-flow has been examined, with patients showing a significant decrease of main hemodynamic parameters compared with pre-operative values.  There are no major differences in clinical success and recurrence rates when comparing HE and DGHAL or THD.  These researchers stated that further investigations are needed to compare effectiveness and patient comfort between both treatments.

Per limitations of the different published reports, these researchers stated that they found that most of published reports were retrospective observational studies conducted in 1 single-center with a small number of participants.  Studies have heterogeneous patient selection and different follow-up durations.  Thus, these researchers stated that further multi-center comparative studies with longer follow-up times and larger sample sizes are needed to examine the effectiveness, the indications, and the cost-effectiveness compared with the rest of the treatments.

Panneau et al (2022) noted that chronic hemorrhoidal disease is a common anorectal condition that results in hemorrhoidal hyperplasia, which affects millions of people globally; and is a significant medical and socioeconomic issue.  Rectal bleeding is one of the main chronic symptoms.  Recurrent rectal bleeding can alter an individual's QOL and, more rarely, cause anemia.  Pain is less common, occurring only in the event of complications such as congestive exacerbation, external hemorrhoidal thrombosis, or fissures.  The standard treatment entails dietary and hygiene measures, use of phlebotonic drugs, as well as non-surgical treatment such as infra-red (IR) photo-coagulation or elastic band ligation.  Excisional treatments such as hemorrhoidectomy and hemorrhoidopexy are the reference standards for treatment of hemorrhoidal disease.  Embolization of the rectal arteries (i.e., the Emborrhoid technique) has recently emerged as an effective therapeutic option, with few reported adverse effects, minimal blood loss, and a same-day hospital procedure.  Hemorrhoid embolization is carried out via the femoral or radial access.  The inferior mesenteric artery and then the superior rectal arteries are catheterized with a micro-catheter.  Embolization can be carried out by using different agents.  Studies have shown improvement in symptoms and high technical success rates following treatment.  The basic principles of HE that must be understood to achieve effective treatment, including those related to patient evaluation, the arterial anatomy, basic embolization, and published results, were reviewed.

Nguyenhuy et al (2022) stated that hemorrhoidal disease (HD) is a common anorectal disorder that can substantially impair QOL.  Rectal artery embolization is a recently described technique for the management of HD; however, its safety and effectiveness are currently unclear.  In a systematic review and meta-analysis, these investigators examined the clinical outcomes following RAE.  The PubMed, Medline and Embase databases were searched for studies specifying the management of hemorrhoids with RAE from January 2000 to October 2021.  Primary outcomes were: FBS, VAS for pain, general QOL score, and the Goligher prolapse score (GPS).  Secondary outcomes were technical success, clinical success, post-operative complications, and technical outcomes.  A random-effects meta-analysis was carried out.  Study heterogeneity was evaluated, and sensitivity analysis was performed.  A total of 13 eligible studies were identified including 381 patients.  RAE was associated with improvements in the FBS (MD 2.66; 95 % CI: 2.10 to 3.23), VAS (MD 1.92; 95 % CI: 1.58 to 2.27) and QOL (MD 1.41; 95 % CI: 1.20 to 3.80), although the grade of internal hemorrhoids increased with uncertain clinical significance (MD 0.30; 95 % CI: 0.23 to 0.36).  Technical success was achieved in almost all procedures (99 %; 95 % CI: 94 % to 100 %); however, clinical effectiveness was lower (82 %; 95 % CI: 73 % to 89 %).  Procedural duration and radiation exposure were heterogeneous; and no major complications occurred.  The authors concluded that RAE showed early effectiveness with low rates of peri-procedural complications or morbidity.  These researchers stated that RAE is a promising addition to the therapeutic options available for HD and warrants further investigations.

Talaie et al (2022) noted that hemorrhoids are local vascular structure dilations in the lower rectum, associated with morbidity and reduced QOL.  Endovascular coil or particle embolization of the superior rectal arteries, known as the Emborrhoid technique, is a minimally invasive, image-guided therapy that targets the hemorrhoidal plexus and reduces hemorrhage.  These researchers examined the results of published studies to determine the effectiveness, clinical outcomes, and morbidities associated with the endovascular occlusion of hemorrhoidal arteries for the treatment of internal hemorrhoids.  Current evidence suggest that hemorrhoids treated by Emborrhoid technique using micro-coils, embolic particles or a combination is safe with no reported serious complications.  The authors concluded that hemorrhoid embolization can preserve the anal tone without direct anorectal trauma; and maintain the hemorrhoidal tissue in place requiring minimal local wound care on an outpatient basis.  Moreover, these researchers stated that due to the paucity of high-quality trials, further research is needed to assess its long-term outcomes, compare its effectiveness with other therapeutic modalities, and evaluate examine its role in the treatment of hemorrhoid.

Campennì et al (2022) stated that the Emborrhoid technique is an innovative non-surgical approach for the treatment of severe hemorrhoidal bleeding.  Patient selection and the impact on QOL have not been fully examined.  In a prospective, observational study, these investigators examined the clinical outcomes following the Emborrhoid technique in patients with high surgical risk.  All patients with high surgical risk and anemia due to hemorrhoids were enrolled.  Clinical data and previous blood transfusions were collected.  The Hemorrhoidal Disease Symptom Score and Short Health Scala were completed before the procedure and during the follow-up visits at 1, 6 and 12 months.  Transfusions and serum Hb level variations were registered.  Peri-operative complications and the recurrence of bleeding were evaluated.  Trans-radial/trans-femoral embolization of SRA, and/or middle rectal artery was carried out with Interlock and Detachable Embolization Coils.  From September 2020 to February 2022, a total of 21 patients underwent a super-selective embolization of all branches of the SRA.  The trans-radial approach was most frequently carried out compared to trans-femoral access.  After the procedure, no signs of ischemia were identified; 3 minor complications were observed.  The mean follow-up was 18.5 ± 6.0 months.  At the last follow-up, the mean increase of Hb for patients was 1.2 ± 1.6 g/dL; and 3 patients needed transfusions during follow-up for recurrent hemorrhoidal bleeding.  The Hemorrhoidal Disease Symptom Score and Short Health Scala decreased from 11.1 ± 4.2 to 4.7 ± 4.6 (p < 0.0001) and from 18.8 ± 4.8 to 10.2 ± 4.9 (p < 0.0001), respectively.  Patients who had given up on their daily activities due to anemia have returned to their previous lifestyle.  The authors concluded that the Emborrhoid technique appeared to be a safe and effective option for the treatment of bleeding hemorrhoids in frail patients.  The low complication rate and the significant reduction of post-defecation bleeding episodes were related to the improvement of the hemorrhoidal symptoms and patients’ QOL.  Moreover, these researchers stated that the drawbacks of this trial were its single-center design and the small number of participants (n = 21).  They stated that future prospective, large, multi-center studies are needed to examine the effectiveness of the Emborrhoid techniques and to clarify the indication and clinical management.

De Gregorio et al (2023) examined the safety and effectiveness of catheter-directed hemorrhoidal embolization (CDHE) by micro-coil embolization for rectal bleeding due to hemorrhoids classified as Goligher grade-I to grade-III.  A total of 80 patients (62.5 % men, mean age of 48 ± 9 years) were recruited prospectively.  All subjects had symptomatic bleeding hemorrhoids; they were classified according to Goligher classification: grade-I (13.7 %), grade-II (71.1 %), grade-III (15 %), and no grade-IV were recruited in this study.  In all cases, micro-coils were employed to embolize the SRA, and microspheres if recurrence of bleeding occurred.  Follow-up evaluation (1, 3, 6, and 12 months) included clinical examination and anoscopy.  A questionnaire was carried out to determine improvement regarding bleeding, QOL before, and the degree of patient satisfaction of each participant.  Technical success was achieved in 100 % of the cases; 55 (68.7 %) subjects had the absence of rectal bleeding after 12 months of embolization; VAS and QOL improved 4 points and 1.5, respectively, after embolization.  A total of 25/80 (31.3 %) had a recurrence in rectal bleeding; 17 (21.3 %) patients underwent a 2nd embolization, and 4 patients (5 %) were treated with open hemorrhoidectomy.  No major complications were observed; 16 subjects had minor complications.  Subjective post-treatment symptom and QOL surveys showed significant differences from the baseline survey.  Likewise, the degree of satisfaction in the telephone survey at 12 months revealed a high degree of patient satisfaction (8.3 ± 1.1).  The authors concluded that the findings of this study showed that CDHE's safety profile was acceptable.  At 1-year follow-up, no significant complications were observed.  These researchers stated that CDHE has provided encouraging outcomes in patients with hemorrhoids and mild prolapse Goligher grade-I to grade-III with persistent rectal bleeding.  These preliminary findings need to be validated by well-designed studies.

References

The above policy is based on the following references:

Coil Embolization and Occlusion of the Hypogastric Veins for the Prevention or Treatment of Deep Vein Thrombosis

  1. Goshima K. Primary (spontaneous) upper extremity deep vein thrombosis. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed August 2015.
  2. Bauer KA. Approach to the diagnosis and therapy of lower extremity deep vein thrombosis. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed August 2015.

Coil Embolization for the Treatment of Arterio-Venous Malformations (AVMs) / Aneurysm

  1. Koebbe CJ, Veznedaroglu E, Jabbour P, Rosenwasser RH. Endovascular management of intracranial aneurysms: Current experience and future advances. Neurosurgery. 2006;59(5 Suppl 3):S93-S102.
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  3. Lanzino G, Murad MH, d'Urso PI, Rabinstein AA. Coil embolization versus clipping for ruptured intracranial aneurysms: A meta-analysis of prospective controlled published studies. AJNR Am J Neuroradiol. 2013;34(9):1764-1768.
  4. Morales-Valero SF, Brinjikji W, Murad MH, et al. Endovascular treatment of internal carotid artery bifurcation aneurysms: A single-center experience and a systematic review and meta-analysis. AJNR Am J Neuroradiol. 2014;35(10):1948-1953.
  5. Turfe ZA, Brinjikji W, Murad MH, et al. Endovascular coiling versus parent artery occlusion for treatment of cavernous carotid aneurysms: A meta-analysis. J Neurointerv Surg. 2015;7(4):250-255.
  6. Kirkwood ML. Extracranial carotid artery aneurysm. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed August 2015.
  7. Thompson BG, Brown RD Jr, Amin-Hanjani S, et al; American Heart Association Stroke Council, Council on Cardiovascular and Stroke Nursing, and Council on Epidemiology and Prevention. Guidelines for the management of patients with unruptured intracranial aneurysms: A guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2015;46(8):2368-2400.

Epistaxis

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  12. Kliegman: Nelson Textbook of Pediatrics. 18th Edition. 2007. 19th Edition. 2011.
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  14. Marx: Rosen's Emergency Medicine. 7th Edition. 2009.
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Extracranial Embolization for AV Malformations or Fistulae

  1. Adam: Grainger & Allison's Diagnostic Radiology. 5th Edition.  2008.
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  3. Armsby LR, et al. Management of coronary artery fistulae. Patient selection and results of transcatheter closure. J Am Coll Cardiol. 2002;39(6):1026-1032.
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  7. Do YS, et al. Extremity arteriovenous malformations involving the bone: Therapeutic outcomes of ethanol embolotherapy. J Vasc Interv Radiol. 2010;21(6):807-816.
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  14. Gabbe: Obstetrics: Normal and Problem Pregnancies. 5th Edition. 2007.
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  20. Hayes WS, et al. Onyx® Liquid Embolic System (ev3 Inc.) for Treatment of cranial and spinal arteriovenous malformations. Technology Brief. November 2006. November 2007. December 2008. Archived December 17, 2009.
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Geniculate Artery Embolization for Knee Hemarthrosis Following Total Knee Arthroplasty

  1. Kalsi PS, Carrington RJ, Skinner JS. Therapeutic embolization for the treatment of recurrent hemarthrosis after total knee arthroplasty due to an arteriovenous fistula. J Arthroplasty. 2007;22(8):1223-1225.
  2. Given MF, Smith P, Lyon SM, et al. Embolization of spontaneous hemarthrosis post total knee replacement. Cardiovasc Intervent Radiol. 2008;31(5):986-988.
  3. Bagla S, Rholl KS, van Breda A, et al. Geniculate artery embolization in the management of spontaneous recurrent hemarthrosis of the knee: Case series. J Vasc Interv Radiol. 2013;24(3):439-442.
  4. Weidner ZD, Hamilton WG, Smirniotopoulos J, Bagla S. Recurrent hemarthrosis following knee arthroplasty treated with arterial embolization. J Arthroplasty. 2015;30(11):2004-2007.
  5. Azubuike M, Mikus R, Rafiei P. Geniculate artery embolization for recurrent postarthroplasty hemarthrosis of the knee. Radiol Case Rep. 2016;10(2):1105.
  6. Guevara CJ, Lee KA, Barrack R, Darcy MD. Technically successful geniculate artery embolization does not equate clinical success for treatment of recurrent knee hemarthrosis after knee surgery. J Vasc Interv Radiol. 2016;27(3):383-387.
  7. Cefalu CA, Royals TP, Krause PC. Descending geniculate artery pseudoaneurysm following tibial plateau fracture. Orthopedics. 2017;40(1):e188-e191.
  8. van Baardewijk LJ, Hoogeveen YL, van der Geest ICM, Schultze Kool LJ. Embolization of the geniculate arteries is an effective treatment of recurrent hemarthrosis following total knee arthroplasty that can be safely repeated. J Arthroplasty. 2018;33(4):1177-1180.

Other Investigational Indications

  1. Abu-Ghanem S, Yehuda M, Carmel NN, et al. Impact of preoperative embolization on the outcomes of carotid body tumor surgery: A meta-analysis and review of the literature. Head Neck. 2016;38 Suppl 1:E2386-E2394.
  2. Bajaj JS, Sanyal AJ. Methods to achieve hemostasis in patients with acute variceal hemorrhage. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2021.
  3. Bazarbashi AN, Wang TJ, Jirapinyo P, et al. Endoscopic ultrasound-guided coil embolization with absorbable gelatin sponge appears superior to traditional cyanoacrylate injection for the treatment of gastric varices. Clin Transl Gastroenterol. 2020;11(5):e00175.
  4. Buso Gil S, Puchol MDF, Solaz JS, Hernandez EE. Prevalent technique and results of hemorrhoidal embolization. J Clin Med. 2022; 11(22):6631.
  5. Campennì P, Iezzi R, Marra AA, et al. The Emborrhoid technique for treatment of bleeding hemorrhoids in patients with high surgical risk. J Clin Med. 2022;11(19):5533.
  6. Casadaban LC, Mandell JC, Epelboym Y, et al. Genicular artery embolization for osteoarthritis related knee pain: A systematic review and qualitative analysis of clinical outcomes. Cardiovasc Intervent Radiol. 2021;44(1):1-9.
  7. Chalela JA,. Acute toxic-metabolic encephalopathy in adults. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2021.
  8. Chen S, Li X, Wei B, et al. Recurrent variceal bleeding and shunt patency: Prospective randomized controlled trial of transjugular intrahepatic portosystemic shunt alone or combined with coronary vein embolization. Radiology. 2013;268(3):900-906.
  9. Cho YJ, Kim H-C, Kim YW, et al. Percutaneous access via the recanalized paraumbilical vein for varix embolization in seven patients. Korean J Radiol. 2014;15(5):630-636.
  10. Cobb AN, Barkat A, Daungjaiboon W, et al. Carotid body tumor resection: Just as safe without preoperative embolization. Ann Vasc Surg. 2018;46:54-59.
  11. Davis BD, Lee-Kong SA, Migaly J. The American Society of Colon and Rectal Surgeons clinical practice guidelines for the management of hemorrhoids. Dis Colon Rectum 2018;61(3):284-292.
  12. De Gregorio MA, Guirola JA, Serrano-Casorran C, et al. Catheter-directed hemorrhoidal embolization for rectal bleeding due to hemorrhoids (Goligher grade I-III): prospective outcomes from a Spanish emborrhoid registry. Eur Radiol. 2023 Jul 17 [Online ahead of print].
  13. Drazic BO, Zarate BC, Valdes EF, et al. Embolization of insufficient pelvic veins for pelvic congestion syndrome. Analysis of 17 cases. Rev Med Chil. 2019;147(1):41-46.
  14. Durham JD, Kumpe DA, Van Stiegmann G, et al. Direct catheterization of the mesenteric vein: Vombined surgical and radiologic approach to the treatment of variceal hemorrhage. Radiology. 1990;177(1):229-233.
  15. Ferenci P. Hepatic encephalopathy in adults: Treatment. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2021.
  16. Goldberg E, Chopra S. Cirrhosis in adults: Overview of complications, general management, and prognosis. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2021.
  17. Hafezi-Nejad N, Bailey CR, Gunn AJ, Weiss CR. Weight loss after left gastric artery embolization: A systematic review and meta-analysis. J Vasc Interv Radiol. 2019;30(10):1593-1603.
  18. Ilyas A, Przybylowski C, Chen CJ, et al. Preoperative embolization of skull base meningiomas: A systematic review. J Clin Neurosci. 2019;59:259-264.
  19. Ironside N, Nguyen C, Do Q, et al. Middle meningeal artery embolization for chronic subdural hematoma: A systematic review and meta-analysis. J Neurointerv Surg. 2021;13(10):951-957.
  20. Iwamoto S, Shigemoto K. Partial splenic embolization as an emergency treatment for uncontrollable variceal bleeding: A case report. Am J Gastroenterol. 1985;80(5):387-390.
  21. Jiang Z, Zhang X, Wan X, et al. Efficacy and safety of combined endovascular embolization and stereotactic radiosurgery for patients with intracranial arteriovenous malformations: A systematic review and meta-analysis. Biomed Res Int. 2021;2021:6686167.
  22. Mizandari M, Keshavarz P, Azrumelashvili T, et al. Left gastric artery embolization for obesity treatment: A systematic review and meta-analysis of human and animal studies. Abdom Radiol (NY). 2021;46(9):4440-4451.
  23. National Institute for Health and Care Excellence (NICE). Superior rectal artery embolisation for haemorrhoids. Interventional Procedure Guidance IPG 627. London, UK: NICE; August 29, 2018. 
  24. Nguyenhuy M, Xu Y, Kok HK, et al. Clinical outcomes following rectal artery embolisation for the treatment of internal haemorrhoids: A systematic review and meta-analysis. Cardiovasc Intervent Radiol. 2022;45(9):1351-1361.
  25. Panneau J, Mege D, Di Bisceglie M, et al. Rectal artery embolization for hemorrhoidal disease: Anatomy, evaluation, and treatment techniques. Radiographics. 2022;42(6):1829-1844.
  26. Perreault L, Apovian C. Obesity in adults: Overview of management. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2021.
  27. Srivatsan A, Mohanty A, Nascimento FA, et al. Middle meningeal artery embolization for chronic subdural hematoma: Meta-analysis and systematic review. World Neurosurg. 2019;122:613-619.
  28. Stecca T, Farneti F, Balestriero G, et al. Superior rectal artery embolization for symptomatic grades 2 and 3 hemorrhoidal disease: 6-month follow-up among 43 patients. J Vasc Interv Radiol. 2021;32(9):1348-1357.
  29. Stone P. Acquired arteriovenous fistula of the lower extremity. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2022.
  30. Talaie R, Torkian P, Moghadam AD, et al. Hemorrhoid embolization: A review of current evidences. Diagn Interv Imaging. 2022;103(1):3-11.
  31. Tarasconi A, Baiocchi GL, Pattonieri V, et al. Transcatheter arterial embolization versus surgery for refractory non-variceal upper gastrointestinal bleeding: A meta-analysis. World J Emerg Surg. 2019;14:3.
  32. Texakalidis P, Charisis N, Giannopoulos S, et al. Role of preoperative embolization in carotid body tumor surgery: A systematic review and meta-analysis. World Neurosurg. 2019;129:503-513.e2.
  33. Timmer FEF, Geboers B, Nieuwenhuizen S, et al. Locoregional treatment of metastatic pancreatic cancer utilizing resection, ablation and embolization: A systematic review. Cancers (Basel). 2021;13(7):1608.
  34. Torkian P, Golzarian J, Chalian M, et al. Osteoarthritis-related knee pain treated with genicular artery embolization: A systematic review and meta-analysis. Orthop J Sports Med. 2021;9(7):23259671211021356.
  35. Wang X., Sheng Y, Wang Z. et al. Comparison of different embolic particles for superior rectal arterial embolization of chronic hemorrhoidal bleeding: Gelfoam versus microparticle. BMC Gastroenterol. 2021;21:465.
  36. Yuan CW, Wang YJ, Zhang SJ, et al. Clinical outcomes following microsurgery and endovascular embolization in the management of spinal dural arteriovenous fistula: A meta-analysis study. Beijing Da Xue Xue Bao Yi Xue Ban. 2022;54(2):304-314.
  37. Zhang H, Yang Y, Kou L, et al. Effectiveness of collateral arteries embolization before endovascular aneurysm repair to prevent type II endoleaks: A systematic review and meta-analysis. Vascular. 2022;30(5):813-824.

Partial Splenic Artery Embolization for the Treatment of Hyper-Splenism Secondary to Hepatic Cirrhosis

  1. Wang YB, Zhang JY, Zhang F, et al. Partial splenic artery embolization to treat hypersplenism secondary to hepatic cirrhosis: A meta-analysis. Am Surg. 2017;83(3):274-283.

Partial Splenic Embolization for the Treatment of Gastro-Esophageal Variceal Hemorrhage

  1. Wang P, Liu R, Tong L, et al. Partial splenic embolization has beneficial effects for the management of gastroesophageal variceal hemorrhage. Saudi J Gastroenterol. 2016;22(6):399-406.

Portal Vein Embolization Before Surgical Resection of Cholangiocarcinoma

  1. Bruning R, Schneider M, Tiede M, et al. Ipsilateral access portal venous embolization (PVE) for preoperative hypertrophy exhibits low complication rates in Clavien-Dindo and CIRSE scales. CVIR Endovasc. 2021;4(1):41.
  2. Dondossola D, Ghidini M, Grossi F, et al. Practical review for diagnosis and clinical management of perihilar cholangiocarcinoma. World J Gastroenterol. 2020;26(25):3542-3561. 
  3. Ebata T, Yokoyama Y, Igami T, et al. Portal vein embolization before extended hepatectomy for biliary cancer: Current technique and review of 494 consecutive embolizations. Dig Surg. 2012;29(1):23-29.
  4. Glantzounis GK, Tokidis E, Basourakos S-P, et al. The role of portal vein embolization in the surgical management of primary hepatobiliary cancers. A systematic review. Eur J Surg Oncol. 2017;43(1):32-41.
  5. Kawabata Y, Hayashi H, Yoshida R, et al. Hybrid transileocecal portal vein embolization associated with staging laparoscopy for planned major hepatectomy in advanced hepatobiliary cancers. Langenbecks Arch Surg. 2021;406(4):1119-1128.
  6. Kumar S. Preoperative portal vein embolization. UpToDate [online serial]. Waltham, MA.: UpToDate; reviewed July 2021.
  7. Olthof PB, Aldrighetti L, Alikhanov R, et al. Portal vein embolization is associated with reduced liver failure and mortality in high-risk resections for perihilar cholangiocarcinoma. Ann Surg Oncol. 2020;27(7):2311-2318.
  8. Sofue K, Arai Y, Shimada K, et al. Right portal vein embolization with absolute ethanol in major hepatic resection for hepatobiliary malignancy. Br J Surg. 2014;101(9):1122-1128.

Prostate Artery Embolization

  1. Cizman Z, Isaacson A, Burke C. Short- to midterm safety and efficacy of prostatic artery embolization: A systematic review. J Vasc Interv Radiol. 2016;27(10):1487-1493.
  2. Jones P, Rai BP, Aboumarzouk OM, Somani BK. Prostatic urethral lift vs prostate arterial embolization: Novel nonablative strategies in the management of lower urinary tract symptoms secondary to benign prostate hyperplasia. Urology. 2016;87:11-17.
  3. Jones P, Rai BP, Nair R, Somani BK. Current status of prostate artery embolization for lower urinary tract symptoms: Review of world literature. Urology. 2015;86(4):676-681.
  4. Jung JH, McCutcheon KA, Borofsky M, et al. Prostatic arterial embolization for the treatment of lower urinary tract symptoms in men with benign prostatic hyperplasia. Cochrane Database Syst Rev. 2022;3(3):CD012867.
  5. Lucas-Cava V, Sanchez-Margallo FM, Insausti-Gorbea I, Sun F. Comparative efficacy and safety of prostatic urethral lift vs prostatic artery embolization for benign prostatic hyperplasia: A systematic review and network meta-analysis. BJU Int. 2023;131(2):139-152. 
  6. Lebdai S, Delongchamps NB, Sapoval M, et al. Early results and complications of prostatic arterial embolization for benign prostatic hyperplasia. World J Urol. 2016;34(5):625-632.
  7. Li Q, Duan F, Wang MQ, et al. Prostatic arterial embolization with small sized particles for the treatment of lower urinary tract symptoms due to large benign prostatic hyperplasia: Preliminary results. Chin Med J (Engl). 2015;128(15):2072-2077.
  8. Nair SM, Pimentel MA, Gilling PJ. Evolving and investigational therapies for benign prostatic hyperplasia. Can J Urol. 2015;22 Suppl 1:82-87.
  9. Nejmark AI, Nejmark BA, Tachalov MA, et al. Superselective prostatic artery embolization as a preparatory step before TURP in the treatment of benign prostatic hyperplasia in patients with large prostates. Urologiia. 2015;(2):60-62, 64.
  10. Pisco JM, Bilhim T, Pinheiro LC, et al. Medium- and long-term outcome of prostate artery embolization for patients with benign prostatic hyperplasia: Results in 630 patients. J Vasc Interv Radiol. 2016;27(8):1115-1122.
  11. Roberts WW. New technologies in benign prostatic hyperplasia management. Curr Opin Urol. 2016;26(3):254-258.
  12. Russo GI, Kurbatov D, Sansalone S, et al. Prostatic arterial embolization vs open prostatectomy: A 1-year matched-pair analysis of functional outcomes and morbidities. Urology. 2015;86(2):343-348.
  13. Schreuder SM, Scholtens AE, Reekers JA, Bipat S. The role of prostatic arterial embolization in patients with benign prostatic hyperplasia: A systematic review. Cardiovasc Intervent Radiol. 2014;37(5):1198-1219.
  14. Teoh JY, Chiu PK, Yee CH, et al. Prostatic artery embolization in treating benign prostatic hyperplasia: A systematic review. Int Urol Nephrol. 2017;49(2):197-203.
  15. Zumstein V, Betschart P, Vetterlein MW, et al. Prostatic artery embolization versus standard surgical treatment for lower urinary tract symptoms secondary to benign prostatic hyperplasia: A systematic review and meta-analysis. Eur Urol Focus. 2018;5(6):1091-1100.

Renal Artery Embolization

  1. Bakal CW, Cynamon J, Lakritz PS, Sprayregen S. Value of preoperative renal artery embolization in reducing blood transfusion requirements during nephrectomy for renal cell carcinoma. J Vasc Interv Radiol. 1993;4(6):727-731.
  2. Brenner and Rector’s The Kidney. 7th Edition. 2004.
  3. Grainer & Allison’s Diagnostic Radiology: A Textbook of Medical Imaging. 4th Edition. 2001.
  4. Kaisary AV, Williams G, Riddle PR. The role of preoperative embolization in renal cell carcinoma. J Urol. 1984;131(4):641-646.
  5. Klimberg I, Hunter P, Hawkins IF, et al. Preoperative angioinfarction of localized renal cell carcinoma using absolute ethanol. J Urol. 1985;133(1):21-24.
  6. National Cancer Institute. Renal Cell Carcinoma PDQ. June 2003.
  7. Singsaas MW, Chopp RT, Mendez R. Preoperative renal embolization as adjunct to radical nephrectomy. Urology. 1979;4(1):1-4.
  8. Walsh: Campbell’s Urology. 8th Edition. 2002.
  9. Zielinski H, Szmigielski S, Petrovich Z. Comparison of preoperative embolization followed by radical nephrectomy with radical nephrectomy alone for renal cell carcinoma. Am J Clin Oncol. 2000;23(1):6-12.

Selective Arterial Embolization for the Treatment of Sacral and Pelvic Giant Cell Tumor

  1. He SH, Xu W, Sun ZW, et al. Selective arterial embolization for the treatment of sacral and pelvic giant cell tumor: A systematic review. Orthop Surg. 2017;9(2):139-144.
  2. Ji T, Yang Y, Wang Y, et al. Combining of serial embolization and denosumab for large sacropelvic giant cell tumor: Case report of 3 cases. Medicine (Baltimore). 2017;96(33):e7799.
  3. Thomas DM, Desai J. Giant cell tumor of bone. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed July 2017.
  4. National Comprehensive Cancer Network (NCCN). Bone cancer. NCCN Guidelines in Oncology, v.1.2018. Fort Washington, PA: NCCN; 2018.

Splenic Artery Aneurysm

  1. Gabelmann A, Gorich J, Merkle EM. Endovascular treatment of visceral artery aneurysms. J Endovasc Ther. 2002;9:38-47.
  2. Grainger and Allison’s Diagnostic Radiology: A Textbook of Medical Imaging. 4th Edition. 2001.
  3. Guillon R, Garcier JM, Abergel A, et al. Management of splenic artery aneurysms and false aneurysms with endovascular treatment in 12 patients. Cardiovasc Intervent Radiol. 2003;26(3):256-260.
  4. Ikeda O, Tamura Y, Nakasone Y, et al. Nonoperative management of unruptured visceral artery aneurysms: Treatment by transcatheter coil embolization. J Vasc Surg. 2008;47(6):1212-1219.
  5. Liu CF, Kung CT, Liu BM, et al. Splenic artery aneurysms encountered in the ED: 10 years’ experience. Am J Emerg Med. 2007;25(4):430-436.
  6. Loffroy R, Guiu B, Cercueil JP, et al. Transcatheter arterial embolization of splenic artery aneurysms and pseudoaneurysms: Short- and long-term results. Ann Vasc Surg. 2008;22(5):618-626. 
  7. Piffaretti G, Tozzi M, Lomazzi C, et al. Splenic artery aneurysms: Postembolization syndrome and surgical complications. Am J Surg. 2007;193(2):166-170.
  8. Townsend: Sabiston Textbook of Surgery. 19th Edition. 2012.
  9. Tulsyan N, Kashyap VS, Greenberg RK, et al. The endovascular management of visceral artery aneurysms and pseudoaneurysms. J Vasc Surg. 2007;5(2):276-283; discussion 283.
  10. U.S. Food and Drug Administration website.
  11. Yamamoto S, Hirota S, Maeda H, et al. Transcatheter coil embolization of splenic artery aneurysm. Cardiovasc Intervent Radiol. 2008;31(3):527-534.

Tumors

  1. Abdalla EK, et al. Extended hepatectomy in patients with hepatobiliary malignancies with and without preoperative portal vein embolization. Arch Surg. 2002;137(6):675-680.
  2. Abeloff: Clinical Oncology. 2nd Edition. 2000. 3ird Edition. 2004.
  3. Adam: Grainger & Allison's Diagnostic Radiology. 5th Edition. 2008.
  4. Bashore CJ, Temple HT. Management of metastatic lesions of the humerous. Orthop Clin North Am. 2000;31(4).597-609.
  5. Bendszus M, et al. Is there a benefit of preoperative meningioma embolization? Neurosurgery. 2000;47(6):1306-1311.
  6. Bibbo C, Patel DV, Benevenia J. Perioperative considerations in patients with metastatic bone disease. Orthop Clin North Am. 2000;31(4):577-595.
  7. Bishop GB, et al. Paragangliomas of the neck. Arch Surg. 1992;127(12):1441-1445.
  8. Bradley: Neurology in Clinical Practice. 5h Edition. 2008.
  9. Brenner and Rector’s The Kidney. 7th Edition. 2004.
  10. Breslau J, Eskridge JM. Preoperative embolization of spinal tumors. J Vasc Interv Radiol. 1995;6(6):871-875.
  11. Browner: Skeletal Trauma: Basic Science, Management, and Reconstruction. 3rd Edition. 2003.
  12. Carli DF, et al. Complications of particle embolization of meningiomas: Frequency, risk factors, and outcome. Am J Neuroradiol. 2010;31(1):152-154.
  13. Cleveland Clinic: Current Clinical Medicine. 2nd Edition. 2010.
  14. Cummings: Otolaryngology: Head and Neck Surgery. 4th Edition. 2005.
  15. Dean BL, et al. Efficacy of endovascular treatment of meningiomas: Evaluation with matched samples. Am J Neuroradiol. 1994;15:1675-1680.
  16. DeVita: Cancer Principles and Practice of Oncology. 7th Edition. 2005.
  17. Dowd CF, Halbach VV, Higashida RT. Meningiomas: The role of preoperative angiography and embolization. Neurosurg Focus. 2003;15(1):E10.
  18. Elias D, et al. Preoperative selective portal vein embolization before hepatectomy for liver metastases: Long-term results and impact on survival. Surgery. 2002;131(3):294-299.
  19. Engelhard HH. Progress in the diagnosis and treatment of patients with meningiomas. Part I: Diagnostic imaging, preoperative embolization. Surg Neurol. 2001;55(2):89-101.
  20. Eustatia-Rutten CF, et al. Outcome of palliative embolization of bone metastases in differentiated thyroid carcinoma. J Clin Endocrinol Metab. 2003;88(7):3184-3189.
  21. Flint: Cummings Otolaryngology: Head & Neck Surgery. 5h Edition. 2010.
  22. Gellad FF, et al. Vascular metastatic lesions of the spine: Preoperative embolization. Radiology. 1990;176(3):683-686.
  23. Gemmete JJ, et al. Embolization of vascular tumors of the head and neck. Neuroimaging Clin N Am. 2009;19(2):181-198.
  24. Goetz: Textbook of Clinical Neurology. 2nd Edition. 2003. 3rd Edition. 2007.
  25. Goldman: Cecil Medicine. 23rd Edition. 2007.
  26. Hayes WS. Preoperative portal vein embolization prior to hepatectomy for cholangiocarcinoma. Search & Summary. June 21, 2011.
  27. Hemming AW, et al. Preoperative portal vein embolization for extended hepatectomy. Ann Surg. 2003;237(5):686-691.
  28. Jaeck D, Bachellier P, Nakano H, et al. One or two-stage hepatectomy combined with portal vein embolization for initially nonresectable colorectal liver metastases. Am J of Surg. 2003;185(3):221-229.
  29. Karaman E, et al. Management of paragangliomas in otolaryngology practice: Review of a 7-year experience. J Craniofac Surg. 2009;20(4):1294-1297.
  30. Kasper GC, et al. A multidisciplinary approach to carotid paragangliomas. Vasc Endovascular Surg. 2006;40(6):467-474.
  31. Liapis C, et al. Changing trends in management of carotid body tumors. Am Surg. 1995;61(11):989-993.
  32. Madoff DC, et al. Transhepatic portal vein embolization: Anatomy, indications, and technical considerations. Radiographics. 2002;22(5):1063-1076.
  33. Manke C, et al. Spinal metastases from renal cell carcinoma: Effect of preoperative particle embolization on intraoperative blood loss. Am J Neuroradiol. 2001;22(5):997-1003.
  34. Merritt’s Neurology. 10th Edition. 2000. 11th Edition. 2005.
  35. Murphy TP, Brackmann DE. Effects of preoperative embolization on glomus jugulare tumors.  Laryngoscope. 1989;99(12):1244-1247.
  36. National Cancer Institute. Renal Cell Cancer Treatment PDQ. October 2010.
  37. NCCN Clinical Practice Guidelines in Oncology. Hepatobiliary Cancer. V.2.2011. V.2.2012.
  38. NCCN Clinical Practice Guidelines in Oncology. Thyroid Carcinoma. V.1.2011.
  39. Owen RJT. Embolization of musculoskeletal tumors. Radiol Clin North Am. 2008;46:535-543.
  40. Penna C, Nordlinger B. Colorectal metastasis (liver and lung). Surg Clin North Am. 2002;82(5):1075-1090.
  41. Persky MS, Setton A, Niimi Y, et al. Combined endovascular and surgical treatment of head and neck paragangliomas -- a team approach. Head Neck. 2002;24(5):423-431.
  42. Sabharwal T, Salter R, Adam A, Gangi A. Image-guided therapies in orthopedic oncology. Orthop Clin North Am. 2006;37(1):105-112.
  43. Schuster JM, Grady MS. Medical management and adjuvant therapies in spinal metastatic disease. NeuroSurg Focus. 2001;11(6):e3.
  44. Sun S, Lang EV. Bone metastases from renal cell carcinoma: Preoperative embolization. J Vasc Interv Radiol,. 1998;9(2):263-269.
  45. Tikkakoski T, et al. Preoperative embolization in the management of neck paragangliomas. Laryngoscope. 1997;107(6):821-826.
  46. Townsend: Sabiston Textbook of Surgery. 18th Edition. 2007. 19th Edition. 2012.
  47. Vogel TR, et al. Carotid body tumor surgery: Management and outcomes in the nation. Vasc Endovascular Surg. 2009;43(5):457-461.
  48. Walsh: Palliative Medicine. 1st Edition. 2008.
  49. Zielinski H, et al. Comparison of preoperative embolization followed by radical nephrectomy with radical nephrectomy alone for renal cell carcinoma. Am J Clin Oncol. 2000;23(1):6-12.

Vascular Embolization for the Treatment of Endovascular Leak

  1. Lu Q, Feng J, Yang Y, et al. Treatment of type I endoleak after endovascular repair of infrarenal abdominal aortic aneurysm: Success of fibrin glue sac embolization. J Endovasc Ther. 2010;17(6):687-693.
  2. Sidloff DA, Stather PW, Choke E, et al. Type II endoleak after endovascular aneurysm repair. Br J Surg. 2013;100(10):1262-1270.
  3. Khaja MS, Park AW, Swee W, et al. Treatment of type II endoleak using Onyx with long-term imaging follow-up. Cardiovasc Intervent Radiol. 2014;37(3):613-622.
  4. Eberhardt KM, Sadeghi-Azandaryani M, Worlicek S, et al. Treatment of type I endoleaks using transcatheter embolization with onyx. J Endovasc Ther. 2014;21(1):162-171.
  5. Ishibashi H, Ishiguchi T, Ohta T, et al. Late events and mid-term results after endovascular aneurysm repair. Surg Today. 2014;44(1):50-54.
  6. Chaer RA. Complications of endovascular abdominal aortic repair. UpToDate [online serial]. Waltham, MA: UpToDate; reviewed August 2015.