[Clinical significance of the click intervals for the diagnosis of dysfunction of the Medtronic-Hall prosthetic valve].

To investigate the clinical significance of click interval for evaluation of prosthetic valve dysfunction, 20 patients underwent Medtronic-Hall (MH) valve replacement (14 in the mitral position and 6 in the aortic position) were studied by simultaneous high-speed recordings of phonocardiogram, echocardiogram and/or Doppler echocardiogram. Two of the 20 patients, one in the mitral and the other in the aortic position, showed MH valve dysfunction. Eleven patients with normally functioning Björk-Shiley (BS) valve in the mitral position served as controls. Results were as follows: 1. There were usually 3 opening clicks (OC1, OC2, OC3) in patients with normally functioning MH valve in the mitral position. These 3 clicks coincided in timing with the beginning of opening, maximum opening and the end of sliding motion, respectively. Both OC1 and OC2 of the MH valve occurred in similar timing with those of the BS valve (A2-OC1 interval: MH = 65.4 +/- 11.8 msec vs BS = 72.3 +/- 17.2 msec; OC1-OC2 interval: MH = 31.2 +/- 7.7 msec vs BS = 27.3 +/- 6.1 msec). However, OC3 occurred significantly later in MH valve than in the BS valve (OC2-OC3 interval: MH = 32.3 +/- 7.5 msec vs BS = 16.4 +/- 3.8 msec, p < 0.01). 2. There were 2 closing clicks (CC1, CC2) in normally functioning the MH valve in the aortic position. These 2 clicks coincided in timing with the beginning and the end of the closing motion, respectively. Mean value of CC1-CC2 interval in 5 prosthetic patients with normal function was 31.0 +/- 9.6 msec. 3. A patient with malfunctioning MH valve in the mitral position showed a markedly prolonged OC1-OC2 interval, ranging from 66 to 140 msec, and she had multiple diastolic clicks after the OC2 phase. Prolonged OC1-OC2 interval was mainly caused by the delay of appearance of OC2, and it was thought to be due to temporary limitation of opening motion of the valve by valve thrombosis. 4. A patient with malfunctioning MH valve in the aortic position showed a markedly prolonged CC1-CC2 interval (100 msec), and he had a significant severe aortic regurgitation during this phase. At operation, fibrinoid thrombus was attached to the aortic annulus at the side of minor orifice of the valve. Closing motion of the valve was disturbed by this thrombus, and the completion of valve closure was markedly delayed.(ABSTRACT TRUNCATED AT 400 WORDS)