Mitral prosthesis malfunction. Comparative Doppler echocardiographic studies of mitral prostheses before and after replacement.

Publisher Website
Google Scholar
Abstract
To assess the influence of mitral prosthesis malfunction on various Doppler echocardiographic indexes, we studied the changes in the peak mitral flow velocity during early diastolic filling phase (Vmax), the mean transprosthesis pressure drop from the simplified Bernoulii equation, the mitral valve area by the pressure half-time method, and the left ventricular isovolumic relaxation time in 15 patients before and after replacement of the malfunctioning mitral prosthesis using continuous wave Doppler echocardiography. Examination of the 15 replaced prostheses revealed a torn or perforated leaflet in 12 valves and a sewing ring dehiscence in one valve. Additional restricted leaflet motion (classified as mild obstruction) was seen in three of these 13 valves. In the remaining two valves, severe prosthesis obstruction with noted. Changes in the Doppler indexes between the preoperative and postoperative study were present in all patients regarding Vmax (mean, 2.2 .+-. 0.3 vs 1.6 .+-. 0.2 m/sec; p < 0.001), mean gradient (mean, 9 .+-. 5 vs 5 .+-. 0.8 mmHg; p < 0.001), and isovolumic relaxation time (mean, 47 .+-. 12 msec vs 80 .+-. 13 msec; p < 0.001). The mean mitral valve area remained virtually unchanged (2.3 .+-. 0.9 vs 2.6 .+-. 0.3 cm2; p = NS) but increased postoperatively in each patient with preoperative mild or severe prosthesis obstruction without concomitant aortic regurgitation. Our conclusion is that the peak mitral flow velocity, the mean gradient, and the isovolumic relaxation time are useful parameters in the differentiation of normal and abnormal mitral prosthesis function but may not define the underlying lesion. The determination of the mitral valve area facilitates detection of even mild mitral prosthesis obstruction, but, contrary to theoretical considerations, these data suggest this parameter is not significantly influenced by mitral regurgitation.