Dissection of the left main coronary artery: diagnosis by angioscopy.

A 58-year-old woman with mitral valve disease was investigated with cardiac catheterization. At catheterization, a suspected dissection of the left main coronary artery occurred. This diagnosis was confirmed at urgent operation by intraoperative angioscopy. The patient underwent mitral valve replacement and coronary artery bypass grafting and made a good postoperative recovery. Coronary angioscopy at operation provides a useful means of diagnosing pathology in the left main coronary artery.