Subepicardial aneurysm by venting catheter via the right superior pulmonary vein

Subepicardial aneurysm caused by a left ventricular venting catheter inserted from the right superior pulmonary vein is very rare. Generally, this type of aneurysm is a complication of acute myocardial infarction. We report a 76-year-old woman in whom a left ventricular aneurysm was shown by transthoracic echocardiography 3 years after mitral valve replacement. She underwent left ventricular aneurysmectomy via the 4^th left intercostal space. The left ventricular aneurysm was separated from the pericardium completely; therefore, this aneurysm was not thought to be pseudoaneurysm. The postoperative course was uneventful and the aneurysm was diagnosed as a subepicardial aneurysm from a histological examination.