USE OF THE CALIBRATED CAROTID PULSE TRACING FOR CALCULATION OF LEFT-VENTRICULAR PRESSURE AND WALL STRESS THROUGHOUT EJECTION

Calibrated carotid pulse tracings were found previously to provide accurate estimates of end-systolic pressure. This study extends this technique to the estimation of arterial pressure throughout ejection. In twenty patients without aortic stenosis (age range 8-67 yr), simultaneous recordings were made of the pressure tracing in the ascending arota, externally recorded carotid pulse tracing, phonocardiogram, left ventricular echocardiogram and peripheral blood pressure. Data were computer digitized and plots of arterial pressure were derived from the aortic pressure tracing (PA) and from the carotid pulse tracing (PC). Left ventricular (LV) wall stress was then calculated throughout ejection using PA or PC. The noninvasive estimation of pressure was excellent, with a maximum difference of 3.4 mm Hg between population means. This occurred within the first 1/3 of ejection. The wall stress calculations were similar, with a maximum mean population error of 3.5 g/cm2 at 20% of ejection. The peak wall stress values had a mean difference of 1.4 g/cm2; mean wall stress over the LV ejection period was 0.5 g/cm2 higher when calculated from PC than from PA. The carotid pulse tracing provides an accurate reproduction of the morphology of the pressure tracing recorded from the ascending aorta, and when calibrated by peripheral blood pressure measurement, it can be used to calculate LV pressure throughout ejection. These pressure estimates can be used to calculate wall stress throughout ejection with a high degree of accuracy.