Echocardiographic aortic valve area formula for the estimation of obstruction in stenosis.

We have investigated the use of M-mode echocardiography for the quantification of aortic valve stenosis through the application of a hydraulic orifice equation using only noninvasively determined hemodynamic variables. The new equation is A = (2/5)SV/(t3/2 dP1/4HR), where A is the effective aortic valve area in cm2, SV is the stroke volume in ml, t is the systolic ejection period in seconds, dP is the echographically estimated aortic valve gradient and HR is the heart rate. The predicted valve areas correspond with those derived by conventional cardiac catheterization studies at a level of r = 0.84, SE = 0.14 cm2, N = 10. The results suggest that M-mode echocardiography may have application to the quantitative diagnosis of aortic stenosis.