Accuracy of the Phonocardiogram in Assessing Severity of Aortic and Pulmonic Stenosis

Abstract

A critical evaluation was made of the reliability of three easily obtainable phonocardiographic criteria in the estimation of ventricular peak pressure in congenital pulmonic and aortic valvular stenosis. In 50 patients with pulmonic stenosis the Q-ejection click interval showed a significant inverse relationship to peak pressure (r=–0.77, p <0.001), while no significant relationship existed in aortic stenosis (r = 0.40, p <0.5). The timing of the peak magnitude of the murmur again related significantly to the right ventricular pressure (r = 0.72, p < 0.001) and with the log of pulmonary valve area (r=–0.72, p <0.001). In contrast no significant relationships existed in aortic stenosis. The degree of splitting also reflected the severity of right ventricular hypertension (r = 0.84, p <0.001), while this measurement in aortic stenosis proved quite variable and did not reflect ventricular peak pressure. The significance of a combination of these criteria in predicting the severity of right ventricular hypertension and in obviating the need for cardiac catheterization is stressed. An explanation for the mechanism underlying the observed changes is given. Q-ejection click interval in particular constitutes an indirect but sensitive way (r =–0.90, p < 0.001) of estimating the rate of pressure development (dp/dt) in the hypertrophied right ventricle.