Prediction of Intracardiac Pressures and Assessment of Ventricular Function with Doppler Echocardiography

Doppler echocardiography provides a noninvasive technique by which blood flow in cardiac chambers and vessels can be characterized, and the timing and direction of flow can be determined. Transvalvular pressure gradients can be quantified noninvasively by Doppler echocardiography. Combined imaging and Doppler allow quantification of volume flow rates. Intracardiac pressures and cardiac function can be evaluated by combining such measurements with observations from the physical examination. One of the most important concepts used in noninvasive estimation of intracardiac pressures is that transvalvular pressure gradients can be calculated in the presence of valvular regurgitation as well as in the presence of valvular stenosis. In both instances, the Doppler equation is used to calculate blood velocity (V) from the Doppler frequency shift (Fd) and the cosine of the Doppler angle (COS 6):