Abstract
To evaluate in vivo performance of prosthetic valves in the aortic position, we measured intraoperative hemodynamic variables related to the valves and analyzed the valve function using a computer. After terminating cardiopulmonary bypass in 10 patients (7 Carpentier-Edwards bovine pericardial valves and 3 St. Jude Medical valves), left ventricular and ascending aortic pressures were measured by micromanometers and instantaneous ascending aortic flow was also measured by an electromagnetic flowmeter. Cycle length, mean pressure gradient, stroke volume and effective orifice area for each cardiac cycle were calculated using a computer. The change of the hemodynamics was induced by rapid atrial pacing or inflow occlusion. This computer analysis of each cardiac cycle enabled us to construct the prosthetic valve function curves which were useful for evaluating the performance under the changing hemodynamic conditions.
