Doppler echocardiographic evaluation of Björk-Shiley and St. Jude Medical prostheses in the mitral position.

The left ventricular studies by Doppler echocardiography were performed in 50 patients with a Bjork-Shiley (B-S) mitral valve and 50 patients after implantation of a St. Jude Medical (SJM) mitral valve; the effect of valve replacement on the hemodynamic performance at rest and during bicycle exercise was determined from serial echocardiographic data. Twenty-eight patients (56%) of the B-S group and 42 patients (84%) of the SJM group showed a good response to the exercise. There was no significant difference in the effective orifice area at rest among each sizes of the B-S valve. In the SJM valve, on the contrary, the effective valve orifice area increases in parallel to the size of the SJM valve. There was a clear relation between the valve size and pressure gradient. The pressure gradient directly depends on the valve size and the effective orifice area in the SJM valve. High pressure gradient group in both prostheses had a tendency to take negative values of percent increase in stroke volume. Further, there were no cases showing positive values of percent increase in end-diastolic volume among the patients whose pressure gradients were assumed to be more than 10 mmHg at rest. It is suggested that impairment of inflow caused by the artificial valve, prosthetic valve stenosis, is possibly a significant factor causing left ventricular dysfunction, notably a decrease in stroke volume during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)