Rupture of Anterolateral Papillary Muscle Resulting From Small Artery Occlusion.

A 69-year-old man was admitted to our hospital for dyspnea and fever. Echocardiography showed a mobile mass on the anterolateral papillary muscle and severe mitral regurgitation. Coronary artery angiography showed no stenotic lesion. Infective endocarditis or cardiac tumor was suspected, and a mitral valve operation was performed. Intraoperative observation revealed a partially ruptured anterolateral papillary muscle and no evidence of infection or tumor. Pathologic examination of the resected papillary muscle showed atherosclerotic changes in small arteries and infarcted areas in different postinfarct time phases along the ruptured edge. It could be speculated that microvascular stenosis caused the repeated localized subendocardial infarction over time.