Mycotic superior mesenteric artery aneurysm with impending rupture due to infective endocarditis.

A 49-year-old woman with tachycardia was referred to our institution. Transthoracic echocardiography revealed severe mitral regurgitation, and surgery was planned. While awaiting surgery, she developed a fever. Transthoracic echocardiography and transesophageal echocardiography revealed vegetation on the mitral valve leaflet. Blood cultures were positive for Streptococcus anginosus. She was diagnosed with infective endocarditis, and antibiotics were administered. She experienced sudden abdominal pain 26 days after hospitalization. Contrast-enhanced computed tomography scan revealed a mycotic superior mesenteric artery aneurysm with impending rupture without intestinal ischemia, and aneurysm resection was performed. Mitral valve replacement was performed on postoperative day 10, with uneventful postoperative healing.