On the mechanism of accentuation of the first heart sound in mitral stenosis.

In 10 patients with mitral stenosis, catheterization of the left ventricle and the left atrium has revealed a considerable increase in dp/dt at the moment of closure of the mitral valve in comparison with 10 healthy controls. Systolic and diastolic pressure and the contractility indicators (dp/dtmax and dp/dtmax/P) did not differ from the values found in the controls, and Vmax was even reduced. Simultaneously with the change in the dp/dt ratio at the moment of the mitral valve closure there occurred also a proportional change in the Ist heart sound amplitude. The authors therefore suggest that besides anatomical changes, a role in the accentuation of the Ist heart sound in mitral stenosis is played also by the haemodynamic factor - the dp/dt ratio at the moment of the mitral valve closure.