Pathology of mitral commissurotomy performed with the Inoue catheter: implications for mechanisms and complications.

Pathologic findings were analyzed in 11 patients who had undergone percutaneous transvenous mitral commissurotomy (PTMC) from 1986 to 1992. Nine valves were obtained at mitral valve replacement and two were obtained at necropsy. These 11 specimens represented all cases studied pathologically among 96 patients undergoing PTMC at a single institution (St. Elizabeth's Medical Center) over this time period. Valvuloplasty was performed using a single balloon in three patients, double balloons in three patients, and the Inoue balloon in five patients. Regardless of the balloon used, fracture of commissural fusion was found to be the fundamental mechanism of success for PTMC. Conditions leading to failure of PTMC included inability to cross the valve, incomplete fracture of commissures, and severe subvalvular disease. Complications included hemodynamically significant atrial septal defect (ASD) and mitral regurgitation (MR). Etiology of MR included failure of leaflet coaptation, ruptured leaflet, and torn chordae, commissure, or papillary muscle. In this selected group of patients, no cases of left ventricular perforation were observed regardless of the technique employed. Hemodynamically significant ASD was observed only with standard single- and double-balloon techniques. MR, restenosis, and failed PTMC were observed with both standard and Inoue techniques.