Cardiac valve area formula for the assessment of aortic stenosis based upon evaluation of left ventricular wall stress in diastole.

We have investigated the application of an hydraulic orifice equation employing aortic valve pressure gradient derived from ventricular diastolic wall stress measurements to estimate obstructive orifice area in aortic stenosis. The expression is given by A = SV square root (D/W)/(750t), where A is the aortic valve area in cm2, SV is the stroke volume in ml, D is the left ventricular minor axis dimension in diastole, W is the left ventricular posterior wall thickness in diastole and t is the systolic ejection period in sec. Valve areas computed by this expression using diastolic wall stress measurements correspond with valve areas derived from the Gorlin formula at a level characterized by a correlation coefficient of r = 0.95 and a standard error of SE = 0.16 cm2, N = 13 for a series of catheterization studies. All the parameters that enter the new expression may be estimated by conventional echocardiographic techniques.