Dissociation between left ventricular untwisting and filling. Accentuation by catecholamines.

Abstract

Untwisting occurs principally during isovolumic relaxation before filling and is markedly enhanced in speed and magnitude by catecholamines. This partial return of the left ventricle to its preejection configuration before mitral valve opening could represent an important mechanism for the release of potential energy stored in elastic elements during the systolic deformation. These myocardial restoring forces would be markedly enhanced by physiological changes consequent to catecholamines such as during exercise, offsetting the concomitant shortening of the filling period.