A functional study of distribution of cardiac sympathetic nerves

In dogs with unilaterally sympathectomized hearts, the remaining intact stellate ganglion was electrically stimulated 14–58 days following sympathectomy. Pressures were simultaneously recorded from all four chambers of the heart and the resulting responses compared with those observed in similarly stimulated but nonsympathectomized animals. Augmentor responses were markedly decreased in some animals but relatively unchanged in others, and it is evident that considerable variation exists in the distribution of sympathetic fibers in different animals. A common finding was markedly delayed augmentation in which responses were practically absent during the initial periods of stimulation. Chronotropic responses appeared to be largely dependent upon intact connections via the right sympathetic nerves. It may be concluded that the sympathetic cardiac nerves from the right side go primarily to the atria and nodal tissue, with a variable supply to the ventricles. In some animals the latter supply is very large while in others it is minimal. The left sympathetic cardiac nerves furnish the major supply to the ventricles, with variable but generally lesser distribution to the atria.