Aneurysms of the superior mesenteric artery (SMA) and its branches are rare and account for only 6-15% of all visceral artery aneurysms. We present our 30-year experience with management of aneurysms of the SMA and its branches at a high-volume referral center.
A retrospective review of all patients diagnosed with an aneurysm of the SMA or one of its branches from 1988 to 2018 was performed. Pseudoaneurysms and mycotic aneurysms were excluded. Clinical presentation, etiology, aneurysm shape and size, treatment modalities and outcomes were analyzed. Growth rate of aneurysms was estimated using linear regression.
131 patients with 144 aneurysms were reviewed. Patients were primarily male (64%) with a median age of 60. There were 57 fusiform, 30 saccular and 57 dissection-associated aneurysms. 41 patients had an isolated SMA branch aneurysm. Degenerative aneurysms were the most common etiology (66%). 35 patients (27%) were symptomatic at presentation. 111 aneurysms had multiple computed tomography angiograms (CTA) with a median follow-up of 43.6 months (IQR 10.6-87.2 months). Only 18 aneurysms (16%) had an estimated growth rate of ≥1.0 mm per year. Initial aneurysm size was significantly associated with growth rate for fusiform aneurysms (OR 1.13 [95% CI 1.0-1.3], P = 0.02) but not saccular (OR 0.91 [95% CI 0.76-1.1], P = 1.1) or dissection-associated aneurysms (OR 1.2 [95% CI 0.91-1.5], P = 0.20). Acute abdominal pain (OR 5.9 [95% CI 1.6-22]; P = 0.01) and chronic abdominal pain (OR 3.7 [95% CI 1.1-13]; P = 0.04) were associated with aneurysm growth. There were only two ruptures, both of whom had diagnoses of fibromuscular dysplasia and systemic lupus erythematosus, respectively, whom presented as rupture with no prior imaging. 46 patients (34%) underwent operative repair with an average aneurysm size of 24.0 ± 8.6 mm, including 36 open revascularizations and 8 endovascular procedures. There was one perioperative death and nine patients had perioperative complications (25%). There were 91 aneurysms <20 mm with an average size of 13.4 ± 3.1 mm followed over a median of 120.8 months (IQR 30.5-232.2 months), and there were no ruptures within this cohort during the follow-up period.
This study represents one of the largest series on aneurysms of the SMA and its branches. Aneurysms of the SMA are relatively stable. Patients with symptomatic and fusiform aneurysms have a higher risk of growth. Aneurysms <20 mm of degenerative etiology may be safely monitored without treatment.

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