Effects of left stellate ganglion stimulation on left ventricular synchrony in dogs

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Abstract
The cardiac response to excitation via the sympathetics has led to the inference that improved synchrony of contraction in the ventricular musculature is important to augmented performance. Pin electrodes and strain-gauge arches were fixed to several segments of the left ventricle, and the precise sequence of electrical excitation and mechanical shortening of the septum and epicardial segments of the apex and base compared during control periods and during electrical stimulation of the left stellate ganglion. During stimulation, augmentation in force of contraction was recorded from all segments, including the interventricular septum. In controls, one-half showed initial shortening at the apex and one-half at the base. During stimulation of the stellate, the base contracted first, and the electromechanical coupling time decreased significantly. The septum shortened last in all circumstances. The time interval between the first and the last segment to shorten decreased during stimulation, indicating increased synchrony of contraction. This undoubtedly contributes to the more rapid rise phase of the ventricular pressure pulse during sympathetic stimulation.