[Doppler evaluation of porcine mitral valve dysfunction].

Abstract

Seventy patients with bioprosthetic mitral valve were examined to study the applicability of the Doppler techniques including pulsed, continuous wave and color Doppler echocardiography in diagnosing and evaluating the severity of prosthetic valve dysfunction. The study population consisted of 70 patients who underwent mitral valve replacement (45 patients with Hancock valve, 13 with Angell-Shiley valve, 10 with Carpentier-Edwards valve). The dysfunctions were transvalvular regurgitation in 20 instances and paravalvular regurgitation in three, all of which were confirmed at surgery. A control group of 47 patients with the normally functioning porcine prosthetic mitral valve were also studied. Diastolic transmitral flow patterns were recorded from parasternal and apical approaches using color Doppler echocardiography, and the direction of the flow was definitely identified on the flow image. Transmitral flow signals spread from the mitral orifice to the mid-portion of the interventricular septum, and its direction was perpendicular toward the mitral ring in all cases. Flow velocity patterns in the left ventricle and atrium were recorded in the apical long-axis view of the left ventricle or apical four-chamber view using pulsed (high pulse repetition frequency) and continuous wave Doppler techniques. Two dynamic alterations in patients with the porcine mitral valve were evaluated from 1) the peak velocity and pressure half time (PHT) of transmitral flow in early diastole, and 2) the regurgitant jet in the left atrium indicating transvalvular or paravalvular regurgitation. The results were as follows: 1. Normally functioning porcine mitral valves were characterized by peak velocities (PV) less than or equal to 1.82 (mean +/- SD 1.44 +/- 0.27) m/sec and PHT less than or equal to 180 (mean +/- SD: 135 +/- 30) msec. In 23 patients with prosthetic valve dysfunction documented at surgery, peak velocity (mean +/- SD 2.23 +/- 0.19 m/sec) was significantly greater (p less than .001) than that of patients in the normally functioning prosthetic valves, and PHT ranged from 135 to 340 msec (mean +/- SD: 226 +/- 81 msec). 2. Among the 23 patients with porcine valve dysfunction, a harmonic striped pattern were recorded at the mitral valve levels in eight patients. All these patients had a musical murmur, and their peak velocity was more than 2.0 m/sec, but the PHT was less than 180 msec in seven patients. In these patients, valvular tears without calcification were confirmed at surgery.(ABSTRACT TRUNCATED AT 400 WORDS)