Electrocardiographic estimate of peak systolic pressure gradient in children with aortic stenosis.

In children with congenital aortic stenosis a modified mapping system was created to explore the electrocardiographic potentials on the chest surface from the left sternal edge (direct anterior), left axillary line (direct lateral) and midchest (45 degrees anterior to the lateral lead) in the third through the seventh intercostal spaces. Potentials were normalized according to chest size based on elliptical and cylindrical models of the chest with the heart at the center. The unadjusted and adjusted potentials were correlated with the peak systolic gradients across the left ventricular outflow tract and equations to predict the gradients were derived by stepwise multiple regression analysis. The best equation was: Gradient = -15.0 +(3.845 X MCT 4) +(0.474 X CD X LSS 3) + (0.138 X CD X MCS 3) where MCT 4 = T wave amplitude in the lead in the fourth interspace in the midclavicular line CD = AP chest diameter in cm LSS 3 = S wave amplitude in the lead in the third interspace at the left sternal border MCS 3 = S wave amplitude in the lead in the third interspace in the midclavicular line (R = 0.84, SEE = 24.3) There are areas on the chest surface that are unexplored by standard electrocardiography. The electrocardiographic potentials from these areas, when normalized for chest size, yield better estimates of transaortic gradients than previous estimates from the routine electrocardiogram.