Detection of Björk-Shiley Mitral Valve Dysfunction via Doppler Echocardiography

Abstract

Fifty-eight patients with a Björk-Shiley (B-S) mitral valve were examined to study applicability of Doppler echocardiography in diagnosing and predicting the severity of prosthetic valve dysfunction. The effect of valve replacement on the hemodynamic performance at rest and during bicycle exercise was determined from serial echocardiographic data. The high pressure gradient group in which peak pressure gradients were assumed to be more than 15mmHg at rest, showed negative values of percent change in both stroke volume index (%ΔSVI) and left ventricular end-diastolic volume index (%ΔEDVI). All patients with high pressure gradients had poor exercise response of the left ventricle, whereas most patients with low pressure gradients showed good exercise response. The high pressure gradient group had significantly smaller mitral valve area than did the low pressure group. This suggests that impairment of inflow caused by the artificial valve, namely, prosthetic valve stenosis, is possibly a significant factor causing left ventricular dysfunction—notably a decrease in stroke volume during exercise. Reoperation was performed with good results in 5 of 58 patients because of high pressure gradients across the mitral valve prosthesis caused by tissue overgrowth. We conclude the high pressure gradient group is considered to be a reserved cohort of reoperation and periodical measurement of the pressure gradient via Doppler echocardiography can predict prosthetic valve dysfunction before it deteriorates significantly.