Prosthetic valves 1977: a retrospective analysis and a look to the future

Experimental and clinical studies that we published in 1972 indicated that the ability of man to extend tissue inward from the valve attachment site is limited to few millimeters, and that the cardiovascular wall/valve body spatial relationships are critically important in prevention of thrombotic complications. Since 1972, clinical observations have supported these conclusions. Cloth-covered valve prostheses in man have failed to become completely covered by tissue. The tilting disc valve (Björk-Shiley) has proved to be an advance over the ball design. However, for maximum hydraulic efficiency, the 60 degrees opening of the prosthesis must be augmented by positioning the valve in harmony with the tilt of the annulus into which is implanted. Currently, we are studying the functional significance (gradient and turbulence) of various positional relationships of the opened disc to the tilt of the anatomic valve annulus. Changing the orientation of the Björk-Shiley mitral prosthesis, for instance, can mean a difference in functional opening ranging from 30degrees to 90degrees, and from 45degrees to 75degrees for the aortic valve.