In vitro and in vivo flow dynamic studies of the Starr-Edwards mitral ball valve demonstrate that its effective orifice is smaller than the cage orifice, but it functions with negligible regurgitation and its size can be accurately predicted from angiograms.
Flow dynamic studies were performed in a mechanical pulse duplicator with Starr-Edwards ball valves. It was shown that the "effective orifice" of the ball valve is less than the measured orifice of the cage of the valve. The orifice is decreased to 83 per cent of the measured orifice in the smaller and to 89 per cent in the larger valves. These measurements corresponded well with the measurements of the "effective orifice" of the valve implanted in patients who were examined by left and right heart catheterization and left ventricular angiocardiograms several months after placement of the valve. The closing regurgitation found in early systole in the mechanical system appears to be negligible in patients. Left ventricular angiograms did not show reflux of dye into the left atrium through the valve cage. The size of the mitral annulus in patients was measured from left ventricular angiograms. The size of the mitral ball valve prosthesis which the mitral annulus will accommodate could be predicted with good accuracy from these measurements.
Kezdi et al. (1964) studied this question.