Mycotic Pseudoaneurysms of the Superior Mesenteric and Splenic Artery: A Case Report

Visceral artery aneurysms and pseudoaneurysms are defined as aneurysms of the splenic, superior mesenteric, or inferior mesenteric arteries and their respective branches. Mycotic aneurysms, defined as aneurysms of the arterial wall caused by bacterial or fungal embolization, are a rapidly progressive and often fatal form of arterial aneurysms that can form in the visceral arteries. Aneurysms and pseudoaneurysms of the visceral arteries most commonly present as abdominal pain. The ambiguity with which they often present, paired with their high risk of rupture and hemorrhage, creates a highly precarious situation for clinicians. Failure to identify an aneurysm or pseudoaneurysm of the visceral arteries in time can be a fatal mistake. We present a case of mycotic pseudoaneurysms of the superior mesenteric artery and splenic artery secondary to infective endocarditis managed with open surgical resection, coil embolization, and splenectomy in a 36-year-old male with a history of intravenous drug use. The patient presented with a chief complaint of abdominal pain and confusion. He was admitted for sepsis and work-up of suspected bacteremia and endocarditis. MRI revealed multiple cortical infarcts suggestive of an embolic shower, and transesophageal echocardiogram showed mitral valve vegetations. CT imaging showed an aneurysm of the superior mesenteric artery, later determined to be a pseudoaneurysm. The patient underwent emergent open superior mesenteric artery pseudoaneurysm resection as well as splenectomy due to intraparenchymal pseudoaneurysms and associated necrosis and intraparenchymal hemorrhage. Our case highlights the importance of considering visceral artery aneurysms when formulating a list of differential diagnoses for patients presenting with abdominal pain due to their vague presenting symptoms in conjunction with their potential to rapidly progress to aneurysmal rupture and catastrophic hemorrhage.