Haemodynamic and sound events preceding first heart sound in mitral stenosis.

Phonocardiograms showed crescendo vibrations preceding Ml in 23 patients with mitral stenosis and atrial fibrillation. In the I5 patients subjected to cardiac catheterization, simultaneous left atrial and left ventricular pressure tracings revealed that the vibrations occurred during the preisovolumic phase of left ventricular systole and that there was a synchronous rise in the left atrial pressure during this period.