Cardiac valve replacement (mechanical) has proven of value as a means of treating serious valvular disease. However, this surgical procedure may be associated with thromboembolism or hemolycis. Despite their current use the biological valves, notably tissue valves, are reported to be associated more frequently with regurgitation immediately after operation or during the late postoperative period than mechanical valves. In a study undertaken to clarify the pathogenetic mechanism of this complication a dura mater cardiac valve of high x-ray absorption was placed in a pulsating flow circuit and the movements of individual leaflets were recorded roentgenophotographically. The momentary pressure on individual leaflets at the the time of their opening and closure was measured simultaneously at 3 different points and compared with roentgenophotographic measurements.
