[Evaluation of Hancock mitral valve by M-mode echocardiography. Clinical significance of the timing of closing and opening of the valve].

: The valve function of a Hancock xenograft in the mitral position was evaluated by M-mode echocardiograms guided by the two-dimensional echocardiogram. From M-mode echocardiograms, the intervals from the second heart sound to mitral valve opening (II-MVo) and from the Q wave to mitral valve closure (Q-MVc) were measured in 24 patients with a Hancock xenograft, 16 with mitral stenosis (MS) and 20 normal controls. Twenty-four patients with a Hancock xenograft were divided into four groups according to the echocardiographic pattern of the xenograft. Fourteen with normal echocardiograms (I: N.P.), five with delayed opening of cusps from 20 to 90 msec (II: D.O.), three with a coarse fluttering of cusps in diastole (III: D.F.), and two with an obstructed prosthesis (IV: O.P.). The valve function of groups II and III was clinically normal. This suggests that a coarse fluttering of cusps and delayed opening of cusps do not always indicate malfunction of the Hancock xenograft. M-mode echocardiograms of group IV showed an increased thickening of cusps, multiple dense echoes between valve stents and a lack of a clear E point. The beat-to-beat variations of Q-MVc and II-MVo intervals showed no significant differences among patients with the Hancock xenograft, MS and normal controls. A small time-dependent variation of Q-MVc and II-MVo intervals observed in patients with the Hancock xenograft did not seem to interfere the reliable reproducibility of these intervals. In group I, II-MVo interval was 104 +/- 8 msec (mean +/- S.E.), which was significantly longer than that of normal controls (54.5 +/- 2.5 msec) (p less than 0.005). In groups II and III, II-MVo interval was almost equal to that of group I, but in two of group IV, this interval was 20 and 30 msec, respectively which was markedly shortened. Q-MVc intervals did not show significant differences among groups I, II, III and IV. There were significant differences in Q-MVc interval among patients with MS and the Hancock xenograft and normal controls. II-MVo interval of group I was inversely correlated with mean diastolic posterior wall velocity (MDPWV), stroke index (SI) and delta ejection time (ET), but significantly correlated with delta preejection period (PEP) and PEP/ET. However, there was no significant relationship between II-MVo interval and pulmonary capillary wedge pressure. This suggested that prolonged II-MVo interval reflects postoperative left ventricular dysfunction. In conclusion, to evaluate the function of a Hancock xenograft, echocardiograms of valve cusps and measurement of II-MVo interval have useful clinical significance.