Atrioventricular pressures and their relationships during stellate stimulation

Abstract

Pressures were recorded simultaneously from the four cardiac chambers in anesthetized, open-chest dogs during electrical stimulation of the stellate ganglion before and after bilateral vagotomy. Augmentation of atrial contraction was shown to accompany that in the ventricles by increased atrial pressures, as well as by the direct recording of atrial force. Fast-speed records revealed the augmentation was primarily in the a-wave. In some experiments mean atrial pressures increased slightly, in others they remained essentially unchanged, and, in still others, declined during stimulation. The particular response in any given animal was not predictable. There was no consistent relationship between the change in right and left mean atrial pressures, although they showed simultaneous augmentation in amplitude of the a-wave. The augmented a-wave resulted in a significant increment in the atrioventricular pressure gradient during late diastole, and thus contributed to increased ventricular filling. Mean pressures consistently increased in both right and left ventricles during stellate stimulation.