Simplified method for estimating true aortic valve mean gradient from simultaneous left ventricular and peripheral arterial pressure recordings. Estimation of the aortic valve gradient by simultaneous recording of left ventricular and peripheral arterial pressures is subject to error due to delay and modulation of the arterial pressure contour as it propagates from the ascending aorta. This error can be corrected by averaging the mean gradients derived from unaltered and temporally aligned simultaneous left ventricular-peripheral arterial pressure tracings. In 26 patients with aortic stenosis and simultaneous recordings of ascending aortic and femoral arterial pressure we compared this method with a simplified approach in which the peripheral arterial pressure is partially aligned by advancing it against the left ventricular pressure by 50% of the time delay of the simultaneously recorded upstrokes. Gradients measured this way predicted the true aortic valve gradients (left ventricular-ascending aortic) with a mean difference of +1.1 mm Hg (range = +10 to -5 mm Hg). We recommend use of this simplified method of correction because it predicts true aortic valve gradient equally well as the averaging technique (r = 0.977 vs. 0.979) and requires half the time and effort. 