Balloon dilation of mitral stenosis in adult patients: Postmortem and percutaneous mitral valvuloplasty studies

Preliminary reports have documented the utility of percutaneous balloon valvuloplasty of the mitral valve in adult patients with mitral stenosis, but the mechanism of successful valve dilation and the effect of mitral valvuloplasty on cardiac performance have not been studied in detail. Accordingly, mitral valvuloplasty was performed in five postmortem specimens and in 18 adult patients with rheumatic mitral stenosis, using either one (25 mm) or two (18 and 20 mm) dilation balloons. Postmortem balloon dilation resulted in increased valve orifice area in all five postmortem specimens, secondary to separation of fused commissures and fracture of nodular calcium within the mitral leaflets. In no case did balloon dilation result in tearing of valve leaflets, disruption of the mitral ring or liberation of potentially embolic debris. Percutaneous mitral valvuloplasty in 18 patients with severe mitral stenosis (including 9 with a heavily calcified valve) resulted in an increase in cardiac output (4.3 ± 1.1 to 5.1 ± 1.5 liters/min, p < 0.01) and mitral valve area (0.9 ± 0.2 to 1.6 ± 0.4 cm², p < 0.0001), and a decrease in mean mitral pressure gradient (15 ± 5 to 9 ± 4 mm Hg, p < 0.0001), pulmonary capillary wedge pressure (23 ± 7 to 18 ± 7 mm Hg, p < 0.0001) and mean pulmonary artery pressure (36 ± 12 to 33 ± 12 mm Hg, p < 0.01). Left ventriculography before and after valvuloplasty in 14 of the 18 patients showed a mild (≤1 +) increase in mitral regurgitation in five patients and no change in the remainder. Embolic phenomena were not observed in any patient. Serial radionuclide ventriculography showed an increase in left ventricular peak filling rate (2.20 ± 1.20 to 2.50 ± 1.20 end-diastolic volumes per second [EDV/s], p < 0.05). Serial echocardiography/phonocardiography showed improvement in mitral valve excursion (11 ± 6 to 14 ± 6 mm, p < 0.001), mitral EF slope (7 ± 4 to 13 ± 5, p < 0.001), left atrial diameter (5.7 ± 0.9 to 5.3 ± 0.8 cm, p < 0.001), S₂-opening snap interval (0.07 ± 0.03 to 0.08 ± 0.02 second, p < 0.02) and mitral valve area (0.9 ± 0.2 to 1.5 ± 0.4 cm², p < 0.0001). All patients were discharged from the hospital with de- creased symptoms after valvuloplasty. It is concluded that percutaneous mitral valvuloplasty can be performed in adult patients with mitral stenosis, including patients with calcific disease, and can result in significant improvement in valvular function. The mechanisms of successful dilation include commissural separation and fracture of nodular calcium.