A computerized physiologic pulse duplicator for in-vitro hydrodynamic and ultrasonic studies of prosthetic heart valves.

: A physiologic pulse duplicator for the simultaneous in-vitro hydrodynamic and ultrasonic evaluation of aortic prosthetic heart valves is described. The system is interfaced to a personal computer, which provides greater efficiency over manual techniques in system calibration, data acquisition, and analysis. The data analysis program aids selection of start and end systole and calculates pressure difference across the valve, the closing and regurgitant volumes, flow rates, and the Gabbay and Swanson performance indices. The pulse duplicator is designed to accommodate the ultrasonic measurement of fluid velocities, including pressure difference via the Bernoulli equation, and color-flow imaging. In tests of 19-mm, 23-mm, and 27-mm Bjork-Shiley spherical occluder valves, continuous-wave Doppler ultrasound was found to overestimate by about 50% the pressure difference measured directly by pressure transducers, a finding that is clinically important.