Significance of color Doppler M-mode scanline orientation in the non-invasive assessment of intraventricular pressure gradients

The one dimensional Euler equation has been applied to estimate diastolic transvalvular and intraventricular pressure differences from color Doppler M-mode echocardiographic spatiotemporal velocity distributions in an animal model. An assumption made in applying this fluid dynamics principle is that the ultrasound scanline closely approximates an inflow streamline. The purpose of this study was to examine the importance of scanline alignment for pressure gradient estimation using computational models derived from cross-sectional echocardiographic geometry. Pressure gradients computed from M-mode scanlines velocity distributions using the Euler equation were compared with the results of the simulations and demonstrated a strong correlation with the simulated pressure gradients within the central 60% of the mitral valve (r = 0.95, MSE = 0.2 mmHg). Clinical investigations utilizing this noninvasive approach should not be effected by the precise alignment of the scanline with an inflow streamline.