Iatrogenic perforation of the posterior mitral valve leaflet: a rare complication of pacemaker lead placement.

An inadvertently placed pacing lead in the left ventricle (LV) is a rare and often underdiagnosed complication of pacemaker implantation. We present a case of a 73-year-old woman who was evaluated for dyspnea, 10 years after transvenous pacemaker implantation. Transthoracic and transesophageal echocardiography revealed a secundum atrial septal defect through which the ventricular pacing lead was placed into the LV. Whereas percutaneous extraction of the lead seemed too full of risk, the patient was referred for surgical removal of the wire and closure of the defect. Intraoperatively it was found that the lead had perforated the posterior mitral valve leaflet before it was positioned into the LV apex. Therefore, the wire could only be partially removed during surgery and two lead fragments remained in the LV for which anticoagulation therapy was initiated. This case demonstrates the pre-eminent role of echocardiography in the diagnosis of cardiac structural abnormalities.