Traumatic superior mesenteric artery pseudoaneurysm complicated by high-output arteriovenous fistula.

Mesenteric pseudoaneurysms are uncommon vascular lesions most often resulting from trauma, iatrogenic injury, or local inflammation. Arteriovenous fistula formation following pseudoaneurysm development is a reported but exceedingly rare complication. Herein presented is the case of a 57-year-old male who sustained multiple injuries in a high-speed motor vehicle collision and was found to have a pseudoaneurysm of the superior mesenteric artery, further complicated by arteriovenous fistula formation. This presented clinically as persistent atrial fibrillation with rapid ventricular response, high output heart failure, and hemodynamic instability. This was repaired in an open fashion, resulting in immediate cardiac stabilization and an overall favorable outcome for the patient.