Mesenteric, Hepatic, & Splenic Artery Aneurysms
Historically, mesenteric aneurysms had a high mortality rate because of delay in diagnosis. High-resolution CT scanning has increased the capability to detect incidental mesenteric aneurysms and has broadened our understanding of the disease. In the last decade, hepatic artery aneurysms have become the most common of the visceral artery aneurysms, superseding splenic artery aneurysms, which now comprise less than 40% of the total. Superior mesenteric, celiac, gastric, and gastroepiploic artery aneurysms each represents about 5% of visceral aneurysms. Aneurysms of mesenteric branch vessels are rare and often associated with connective tissue disease or vasculitis.

Medial degeneration is the most commonly cited cause of hepatic aneurysms. Increasingly, however, injury during cholangiography, hepatic biopsy, or blunt abdominal trauma is implicated -  particularly in intrahepatic aneurysms, which account for about half of all hepatic aneurysms. Splenic artery aneurysms are most commonly related to medial fibroplasia, though portal hypertension, splenomegaly, pregnancy, and local inflammation (eg, pancreatitis) have all been implicated as possible risk factors.

These aneurysms occur four times more frequently in women than in men, underscoring possible hormonal influences. Most superior mesenteric artery aneurysms are associated with infective endocarditis and suspected septic emboli. Atherosclerosis may play a role in the pathogenesis of celiac artery aneurysms -  and a secondary role in development of other mesenteric aneurysms.

Surgical (aneurysmectomy or aneurysmorrhaphy with ligation of branches) or endovascular (embolization) management is warranted for symptomatic aneurysms and aneurysms over 2 cm in circumference. Asymptomatic splenic aneurysms less than 2 cm in diameter rarely rupture, and treatment is not generally advised unless the patient is pregnant or anticipates becoming pregnant since the highest risk of rupture is in young women during pregnancy.

Abbas MA et al: Hepatic artery aneurysm: factors that predict complications. J Vasc Surg 2003;38:41.

Grego FG et al: Visceral artery aneurysms: a single center experience. Cardiovasc Surg 2003;11:19.

Renal Artery Aneurysms
Renal artery aneurysms have a reported incidence of about 1% in the adult population. Many are asymptomatic and diagnosed as an incidental finding on CT scan or angiography performed for another purpose. Others are found during evaluation for hematuria, renal infarct, flank pain, or suspected renovascular hypertension. Five percent present with rupture. Fibromuscular dysplasia is present in about 40% of patients; another 25% have atherosclerosis. Medial degeneration, trauma, and injury after renal biopsy or percutaneous nephrolithostomy are other potential causes. Indications for treatment include size greater than 2 cm, local symptoms, renovascular hypertension, distal embolization, growth on serial imaging, or aneurysms in women of childbearing age.

The standard surgical approach for renal artery aneurysms is excision with interposition grafting; infrequently, the aneurysm extends into the branch vessels, and ex vivo reconstruction may be required. Autologous and prosthetic materials have been equally effective for interposition grafting of main renal arteries greater than 5 mm in diameter, with a 5-year primary patency rate approaching 70%. Recently, polytetrafluoroethylene-covered stent grafts have been used for treatment of saccular aneurysms of the main renal artery. Interlobar aneurysms can be treated by endovascular embolization with microcoils.

Pfeiffer T et al: Reconstruction for renal artery aneurysm: operative techniques and long-term results. J Vasc Surg 2003; 37:293.

Schneidereit NP et al: Endovascular repair of a ruptured renal artery aneurysm. J Endovasc Ther 2003;10:71.