Surgical Treatment of True Superior Mesenteric Artery Aneurysms.

Background: Superior mesenteric artery aneurysms (SMAAs) are a rare clinical problem that can be associated with significant morbidity and mortality. The optimal surgical approach for both mycotic and degenerative SMAAs remains poorly defined. The study was designed to review our institutional experience and develop a treatment algorithm.

Methods: A single-institution, retrospective review was performed to document presentation, treatment, and outcomes of patients undergoing surgical repair of SMAAs from 2003 to 2020. The primary end-point was 30-day mortality, and secondary end-points included complications, patency, freedom from reinfection, freedom from reintervention, and survival.

Results: Eighteen patients (mean age: 46 ± 16 yrs; 50% male; mean diameter 2.4 ± 2.0 cm) underwent treatment of mycotic (50%) or degenerative (50%) SMAAs. Abdominal pain (66%) was the most common presenting symptom, and the diagnosis was confirmed with CT arteriography. Endocarditis secondary to intravenous drug abuse was responsible for most (88%) of the mycotic SMAAs, with a majority (66%) having positive cultures and Streptococcus being the most common organism. The majority (61%) of patients underwent urgent or emergent repair with aneurysmectomy and interposition saphenous vein bypass being the most common treatment of mycotic SMAAs while aneurysmectomy and prosthetic bypass were used most frequently for degenerative aneurysms. The operative mortality rate was 6% with a major complication rate of 17% (n = 3 patients: respiratory failure/reintubation-1, pulmonary embolism-1, necrotizing pancreatitis/graft disruption and death-1). The single death occurred in a patient with a degenerative aneurysm that developed postoperative pancreatitis and multiple organ dysfunction. The mean clinical follow-up time was 25 ± 48 (95% CI 1-48) months. The estimated primary patency, freedom from reinfection, and freedom from reintervention were 93 ± 7 %, 94 ± 5%, and 94 ± 5%, respectively, at 1 year. The overall mean survival was 55 ± 51 (95% CI 30-80) months with an estimated survival at 3 years of 77 ± 10%.

Conclusions: SMAAs associated with both degenerative and mycotic etiologies can be treated using a variety of surgical approaches with acceptable morbidity and mortality. Mycotic SMAAs should likely be repaired, regardless of size, while the indications for asymptomatic, degenerative aneurysms remain to be defined by further natural history studies.