Cardiac sympathetic nerve stimulation and electrocardiographic changes in the closed-chest dog

Electrocardiographic and vectorcardiographic changes in Frank's corrected orthogonal lead system were studied stimulating electrically the right stellate ganglion (RSG), the left stellate ganglion (LSG) and both stellate ganglia (LSG+RSG) in anesthetized closed-chest dogs. The effects of propranolol on arrhythmias induced by the stimulation of the cardiac sympathetic nerve were also investigated. The following results were obtained: (1) The amplitude of T wave increased in Y lead with simultaneous stimulation of both right and left stellate ganglia. The spatial maximum T vector was displaced inferiorly and increased in the magnitude in all cases. These electrocardiographic changes were similar to those which occurred with LSG stimulation alone. (2) The rotation of the T loop, in the left sagital plane, was clockwise in more than 80% with RSG stimulation, while the T loop following the stimulation of LSG alone and LSG+RSG rotated counterclockwise in more than 75% of all cases. (3) In more than 40% of cases with stimulation of left cardiac sympathetic nerves (LSG, left ventrolateral cervical cardiac nerve), arrhythmias such as A-V dissociation and A-V junctional rhythm were recognized. Stimulation of right cardiac sympathetic nerve (RSG, right recurrent cardiac nerve) markedly increased the rate of sinus rhythm in more than 90% of cases. These arrhythmias resulted from the stimulation of nerves decreased or disappeared after the intravenous injection of propranolol.