[Intracardiac flow dynamic alterations with a prosthetic mitral valve studied by pulsed Doppler technique]

Intracardiac flow dynamic alterations in patients (pts) with prosthetic mitral valve (PMV) were studied to assess prosthetic valve functions using pulsed Doppler technique and two-dimensional echocardiography. The study population consisted of 23 pts who underwent mitral valve replacement (11 with the Starr-Edwards disc valve, nine with the Björk-Shiley tilting disc valve, two with the Hancock porcine valve, and one with the homograft valve), 20 pts with mitral stenosis, and 17 control subjects (15 healthy persons and two with lone atrial fibrillation). All pts had a normal functioning PMV by clinical evaluation except for one patient with a dysfunctioning homograft valve, which was angiographically documented. Flow velocity patterns were obtained at various sites in the left ventricle (LV) and the left atrium (LA). Flow dynamic alterations in pts with PMV were evaluated from the half time of transmitral flow velocity descent in diastole, as an index of the atrioventricular pressure gradient, the extent of dispersion of Doppler frequency spectrum of intraventricular flow as an index of the degree of flow disturbances and the Doppler signals with broadening spectra indicating transvalvular regurgitant flow into the LA. The results were as follows: In pts with PMV, the velocity of transmitral flow decreased slowly and linearly throughout diastole. The half time was significantly prolonged for pts with PMV as compared with that for control subjects (272 + 94 ms [mean + SD] vs 79 + 15 ms, p less than .001), though it was shorter than that in pts with mitral stenosis (457 + 145 ms, p less than .001). In pts with PMV, the half time for pts with the Björk-Shiley valve was relatively short as compared with that for pts with other valve. Marked prolongation of the half time (483 ms) was observed in a patient with a dysfunctioning homograft valve. These findings indicate that any PMV is obstructive, even with normal valve function, as compared with healthy mitral valves and that the Björk-Shiley valve is superior to the other PMVs studied in regard to the pressure gradient across PMV. Diastolic flow velocity patterns in the LV were highly dependent on the type of PMV. Apparently, the flow characteristics in the LV were disturbed in every patient with PMV regardless of the type of PMV. The high pressure gradient across the PMV suggested by the prolonged half time in pts with PMV, may be partially caused by flow disturbances produced by PMV.(ABSTRACT TRUNCATED AT 400 WORDS)