Exploration of the cause of the low intensity aortic component of the second sound in nonhypotensive patients with poor ventricular performance.

This investigation was undertaken to explore the cause of the diminished second sound (S2) that may occur in normotensive patients with poorly performing ventricles. Intra-aortic sound and pressure were measured in 16 patients with angina; eight had normal ventricular performance (ejection fraction greater than or equal to 60%) and eight had poor performance (ejection fraction less than 50%). The amplitude of S2 was lower in patients with poor ventricular performance as was negative d/dt. Aortic pressure was conparable in both groups. The ampitude of S2 was linearly related to the rate of change of the pressure gradient that developed across the aortic valve during diastole (r = 0.82). The latter also correlated with negative dp/dt (r = 0.82). These observations indicate that in patients with poor ventricular performance, isovolumic relaxation may be compromised. This would cause a reduction of the rate of development of the diastolic pressure gradient, which would result in a diminished S2.