Doppler Sonographic Evaluation of the CarboMedics Bileaf let Valve Prosthesis: One-Year Experience

Between April 1989 and March 1991, 237 CarboMedics bileaf let valve prosthesis carriers (165 aortic and 72 mitral valves, mean age 54.4 years) were studied prospectively with pulsed-and continuous-wave Doppler at a mean interval of 11.4 months following surgery in order to establish ranges of normal flow velocities and pressure gradients. Physical examination revealed no signs of prosthetic dysfunction or heart failure. Postoperative left ventricular function as measured by fractional shortening was 37% for aortic valve carriers and 30% for mitral valve carriers (p = N S). Mean peak velocity (± SD) across the aortic valve was 2.6 m/sec (± 0.4) and calculated instantaneous peak pressure gradient ranged from 11 to 58 mmHg (mean 28.1 ± 10.3). It has to be emphasized that occasional patients with normally functioning valve prostheses can show unusual high gradients. Ring diameters between 21 and 27 mm showed no significant difference with regard to flow velocities and pressure gradients, whereas in 19-mm valves, significantly higher values could be demonstrated. The 123 aortic valve carriers with normal left ventricular function (fractional shortening > 25%) showed significantly higher pressure gradients than the 19 patients with reduced left ventricular function (28.6 ± 11.6 mmHg vs 16.2 ± 5.1 mmHg, p < 0.05). In the mitral position, the mean of peak velocity (± SD) was 1.7 ± 0.4 m/sec and pressure half-time was 108 ± 26 msec, representing a calculated valve area between 1.4 to 3.1 cm2 (mean orifice size 2.1 ± 0.5 cm2). No significant difference between valves of different sizes was found. Additionally, left ventricular function had no influence on Doppler-derived hemodynamic measurements. Minimal valvular or paravalvular backflow (extension < 1 cm from the prosthesis ring) as indicated by pulsed-wave or color Doppler was present in 44% of aortic valve and 7% of mitral valve prostheses. Five patients (3%) with aortic valve prostheses and two patients (3%) with mitral valve prostheses demonstrated severe para-valvular regurgitation without clinical abnormalities.