Effects of unilateral stellate ganglion blockade on the arrhythmias associated with coronary occlusion.

In anesthetized dogs the circumflex and/or the anterior descending coronary artery were briefly occluded (10 to 90 seconds) and ectopic beats occurring during the occlusion or for 60 seconds following release were counted. Control occlusions were alternated with occlusions performed during complete, reversible, unilateral blockade of either the right or the left stellate ganglion. This was achieved with thermodes through which coolant was circulated. In this way the shortcomings associated with stellectomy, which is irreversible, are avoided. Blockade of the right stellate ganglion increased the number of ectopic beats associated with coronary occlusion. The occurrence of episodes of ventricular tachycardia and fibrillation was also greater. By contrast, blockade of the left stellate ganglion reduced or abolished occlusion-induced arrhythmias. These effects are independent of changes in heart rate or vegal activity; they depend solely upon unilateral alteration in sympathetic tone, and are not demonstrable when such tone is low. We suggest that the right and left cardiac sympathetic nerves have a different influence upon cardiac excitability.