[Doppler study of porcine bioprosthesis at the mitral site]

Twenty-nine asymptomatic patients with porcine (9 Liotta, 8 Carpentier, 8 Hancock and 4 Xenomedica) mitral prosthesis without clinical findings of prosthetic dysfunction and with normal M-mode and two-dimensional echocardiography were studied with pulsed and continuous wave Doppler. The following parameters of prosthetic function were evaluated: 1) maximum velocity (Vmax); 2) mean pressure gradient; 3) pressure half-time (P 1/2 t); 4) functional prosthetic area or Doppler orifice area (DOA); 5) mitral prosthetic regurgitation (MR); 6) tricuspid regurgitation (TR), if associated. P 1/2 t reproducibility was tested. For the study of the bioprosthetic function the transducer was located in apical position with the best alignment between ultrasonic beam and flow direction in the apical four-chamber view. The best acoustic signal was the guide to an optimal Doppler recording, analyzed for calculations. In 26 patients without MR at Doppler examination Doppler data were as follows: Vmax 1.6 +/- 0.2 m/sec (1.2-2 m/sec); mean pressure gradient: 4.4 +/- 2.7 mmHg (1.4-13 mmHg); P 1/2 t = 94.2 +/- 19.8 msec (55-140 msec); DOA = 2.4 +/- 0.6 cm2 (1.5-4 cm2). Mild unsuspected MR was detected in 3 patients, but the other parameters did not differ from those of the other 26 patients. TR was found in 10 patients. The degree of reproducibility of P 1/2 t was 0.92. Only the P 1/2 t value was longer among Hancock and Liotta or Xenomedica bioprosthesis (p = 0.005). Furthermore P 1/2 t was longer in the patients with longer follow-up periods than in the others (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)