[Flow characteristics in 3 kinds of heart valve prosthesis]

Transvalvular turbulence caused by the blood flow in implanted cardiac valvular prosthesis is the cause of thrombosis at the post-valvular region. The literature in this connection indicates that thromboembolic complications are more common with the tilting disc mechanical valves. In order to study the turbulence caused by porcine biological prosthetic valves, by a caged-ball Biomed mechanical valve and by a tilting disc Björk-Shiley valve, a device was developed which permits to visualize and to photograph flow characteristics in the three types of valves with the purpose of determining the degree of turbulence generated in each case. An additional accessory equipment was devised for the purpose of measuring static and dynamic pressures at various levels of the test tube containing the prosthetic valve wherein the variations in pressure reflect the degree of turbulence. The data obtained from 500 pressure registrations were analyzed in a computer. The data indicate that the porcine biological valve causes the least turbulence, whereas the mechanical valves create greater turbulence. Of the mechanical valves, the tilting disc prosthetic valve causes considerably greater turbulence, in particular in the vicinity of the smaller orifice.