Simultaneous Doppler and catheter transvalvular pressure gradients across St Jude bileaflet mitral valve prosthesis: In vivo study in a chronic animal model with pediatric valve sizes

A mixture of valve types has been used in previous in vivo studies to asses s the accuracy of Doppler echocardiography compared with catheter-measured pressure gradients across prosthetic mitral valves. However, limited data e xist regarding the most commonly used bileaflet mechanical valve. We studie d 14 sheep with St Jude Medical mechanical mitral valves. Continuous wave D oppler data were obtained across each of the 3 valve orifices. Hemodynamic data were obtained simultaneously by direct measurements with catheters. Va lve sizes commonly used in the pediatric population in the mitral position (23 mm, 25 mm, and 27 mm) were studied. Linear regression analyses of Doppl er-predicted versus catheter-measured gradients provided correlation coeffi cients ranging from 0.75 to 0.91. Agreement analysis demonstrated a scatter of Doppler data about the regression line. Although a reasonably good corr elation of Doppler-predicted peak and mean pressure gradients across bileaf let mechanical valves exists in the mitral position, caution Is needed when this method is applied to patients. Doppler overestimation was greatest ac ross the 23-mm valves. Analyses of the specific orifice interrogated demons trated higher estimated pressure gradients across the central orifice compa red with the side orifices.