Semi-automated analysis of color M-mode echocardiographic images for determining transmitral pressure gradients using a simplified Euler equation

We hypothesize that a simplified version of the Euler equation (SEE) utilizing differences in velocity over a distance and time as obtained by color Doppler M-mode (CMM) echocardiography can approximate actual peak transmitral pressure gradients (ΔP_TM). In 14 patients undergoing open-heart surgery, ΔP_TM was measured under various hemodynamic conditions using 2 high fidelity transducers, 5 cm apart. Transesophageal CMM images were simultaneously acquired and a customized image analysis application was wed to abstract spatiotemporal velocity characteristics. Using both the SEE and a simplified Bernoulli equations, ΔP_TM were determined and compared to the actual ΔP_TM. While the simplified Bernoulli equation resulted in a poor estimate (y=0.075x+0.71, r=0.45), the ΔP_TM obtained using the SEE correlated strongly (y=0.79x+0.48, r=0.91) with the actual measurements. Semi-automated analysis of CMM images using a SEE can accurately estimate actual ΔP_TM