VALVE DEFORMITY AND BALLOON MECHANICS IN PERCUTANEOUS TRANSVENOUS MITRAL COMMISSUROTOMY

Percutaneous transvenous mitral commissurotomy (PTMC) using balloon catheters has emerged as an alternative therapeutic modality for patients with mitral stenosis. When used initially in the United States, a single balloon, designed for peripheral arterial angioplasty, was passed across the intraatrial septum for mitral dilatation. The results were less than ideal, with resultant valve areas between 1.0 and 1.5 cm2. Double balloon dilatation was introduced and yielded valve areas between 1.5 and over 2.0 cm2. However, the double balloon technique is substantially more cumbersome, requires passage of two catheters through the atrial septum with an incidence of atrial septal defect, and results in significant hemodynamic sequelae during the procedure. This report describes a novel single balloon for PTMC. In contrast to the more conventionally used peripheral arterial balloons, this device was specifically designed for mitral stenosis. Results in 25 patients (mean age 60 +/- 5 years; range 29 to 87 years) showed an increase in value area from 0.9 +/- 0.2 cm2 to 1.6 +/- 0.5 cm2 (p < 0.001). In contrast to the results reported with conventional balloon dilatation, there was no difference in the resultant valve area or in the incidence of complications among patients with more severely deformed valves compared with patients with more "ideal" valves for commissurotomy. An in vitro comparison of the pressure-volume characteristics of the conventional versus the Inoue balloon showed the latter to be more compliant, reaching nominal inflated diameter at 2.0 +/- 0.4 atm versus 3.3 +/- 0.5 atm for conventional balloons (p < 0.005). The acceptable results of PTMC with this device in patients with severe valve deformity may be related to these balloon compliance characteristics.