Experimental balloon valvuloplasty of fibrotic and calcific mitral valves

This study evaluated the mechanism of valvular area expansion during single- and double-balloon valvuloplasty in fibrotic and calcific mitral valves. Special interest was focused on the morphological features of the valves treated. Mitral valves that appeared unsuitable for commissurotomy were excised in toto at the time of mitral valve replacement in 15 patients. The excised valves were mounted in a fluid-filled chamber with a window for photographic evaluation. The chamber was perfused continuously to ensure maximal valvular opening. The valve was photographed, and the orifice area was measured before and after balloon expansion. In addition, the specimens were examined macroscopically and radiographically with regard to calcium content and degree and localization of fibrosis. These data were correlated with splitting of commissures and with rupture of leaflets. Nine valves were fibrotic, and six were calcific. Dilatation was performed first with a single-balloon catheter (diameter, 2 cm) and then with a double-balloon catheter (diameter, 2 and 1.5 cm). After dilatation with one balloon, the average mitral valve area increased from 0.79 to 1.09 cm2, and with two balloons, average area increased to 1.59 cm2. The single-balloon technique caused commissural splitting in nine valves, stretching in three, partial leaflet rupture in one, and no change in two. After the double-balloon technique, commissural splitting occurred in 12 valves and three leaflets were ruptured where severe fibrosis and calcification were mainly located within the commissures. As a rule, after dilatation with the single-balloon technique, the remaining stenosis was still severe, and after dilatation with the double-balloon technique, the remaining stenosis was moderate.(ABSTRACT TRUNCATED AT 250 WORDS)