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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 arteriovenous 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 55.2 years, range 17-82) with splenic artery aneurysms (n = 7) or pseudoaneurysms (n = 10) underwent endovascular treatment. Six patients were asymptomatic, three had symptomatic nonruptured aneurysms, and eight 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 after 6 and 12 months, then yearly. Mean follow-up was 29 months (range 1-62). Exclusion of the aneurysm was achieved in 16 (94.1%) patients. One patient with an intraparenchymal pseudoaneurysm underwent splenectomy after failed distal catheterization. No major complications occurred. Postembolization syndrome developed in four patients, who had radiographic evidence of splenic microinfarcts. The authors concluded, “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 magnetic resonance angiography preferable over computed tomography for follow-up.”
An article published by Ikeda and colleagues in 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. Twenty-two 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. Postprocedure angiograms confirmed complete disappearance of the VAA. In four of the nine splenic artery aneurysm patients, the native arterial circulation was not preserved. In one 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 27 months) demonstrated complete thrombosis of the VAA in all 22 patients. Infarction occurred in one splenic- and two renal artery aneurysms patients; the latter developed flank pain and fever after the procedure.
In 2008, Yamamoto et al, 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, 40-80 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 6-40 mm in diameter (mean, 25 mm). Overall, the primary technical success rate was 88% (14 of 16 patients). In the remaining 2 patients (12.5%), partial recanalization occurred, and re-embolization was performed. The secondary technical success rate was 100%. Seven (44%) of the 16 study patients suffered partial splenic infarction. Intrasplenic branching originating from the aneurysm was observed in five patients. According to the authors, transcatheter coil embolization should be the initial treatment of choice for splenic artery aneurysm.
In a 2007 article, Piffaretti and associates assessed the endovascular embolization of splenic artery aneurysms and false aneurysms with special consideration given to postoperative complications in 15 patients (11 women; mean age, 56 y; range, 39-80 y) 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, 15-80 mm). Postoperative 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). Perioperative mortality was not observed. Morbidity included postembolization syndrome in 5 patients (30%). Neither pancreatitis nor spleen abscess occurred. The mean follow-up period was 36 months (range, 3-60 mo). During follow-up evaluation 1 sac reperfusion was detected that was sealed successfully with additional coils. Surgical conversion or open repair were never required.
In 2007, Tulsyan et al studied the outcomes of the management of visceral artery aneurysms with catheter-based techniques. Between 1997 and 2005, 90 patients were identified with a diagnosis of visceral artery aneurysm. 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 58, 60% men) with 20 visceral artery aneurysms (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 visceral artery aneurysms 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 triaxial system with a 3F microcatheter for persistent flow or multiple branches. The 30-day mortality was 8.3% (n = 4). All perioperative deaths occurred in patients requiring urgent or emergent intervention in the setting of hemodynamic instability. No patients undergoing elective intervention died in the periprocedural period. Postprocedural 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. Postembolization syndrome developed in three 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).
In 2002, Gabelmann, Gorich and Merkle conducted a review of their 10-year experience with endovascular embolization of visceral artery aneurysms. Twenty-five patients (13 men; mean age 52.1 years, range 31-80) 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 (<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 14-75) with only 1 recurrence after 12 months.
Guillon et al, 2003, assessed the endovascular treatment of 12 patients (mean age 59 years, range 47-75 years) with splenic artery aneurysm (n = 10) or false aneurysm (n = 2). The lesion was asymptomatic in 11 patients; hemobilia was observed in one patient. The lesion was juxta-ostial in one case, located on the intermediate segment of the splenic artery in four, near the splenic hilus in six, and affected the whole length of the artery in one patient. In 10 cases, the maximum lesion diameter was greater than 2 cm; in one case 30% growth of an aneurysm 18 mm in diameter had occurred in 6 months; in the last case, two distal aneurysms were associated (17 and 18 mm in diameter). In one case, stent-grafting was attempted; one detachable balloon occlusion was performed; the 10 other patients were treated with coils. Endovascular treatment was possible in 11 patients (92%) (one failure: stenting attempt). In four cases among 11, the initial treatment was not successful (residual perfusion of aneurysm); surgical treatment was carried out in one case, and a second embolization in two. Thus in nine 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 13 months). An early and transient elevation of pancreatic enzymes was observed in four cases.
Arteriovenous malformation (AVM) is a disorder of the blood vessels that is characterized by a complex, tangled web of abnormal arteries and veins connected by one or more AV (arteriovenous) 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. AVMs 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. 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 two 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 extracranial arteriovenous malformation or fistula.
Renal cell cancer accounts for 90 to 95 percent 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 nonsurgical 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 preoperative 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. Preoperative embolization is also performed.
Tumor embolization or preoperative tumor embolization to reduce intraoperative bleeding prior to surgical resection may be considered medically necessary in the treatment of hypervascular tumors or metastases from hypervascular tumors.
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