Effects of unilateral stellectomy upon cardiac performance during exercise in dogs.

Abstract

The role of the right and left stellate ganglion (RSG, LSG) in the cardiac response to exercise was determined in 34 chronically instrumented dogs. The dogs were divided into 3 groups: control, left stellectomized (LSGx) and right stellectomized (RSGx). Heart rate (HR), left circumflex coronary flow velocity (CF) and left ventricular pressure were measured during a graded submaximal exercise program on a motor-driven treadmill. At the greatest work load, 6.4 kph (km per h) and 16% grade, HR in the control group was 235 .+-. 5 beats/min, after LSGx was 258 .+-. 6 beats/min (P < 0.05) and after RSGx was 157 .+-. 7 beats/min (P < 0.01). The maximal derivative of left ventricular pressure increased to 7373 .+-. 501 mm Hg/s in the control group; after LSGx it reached 8233 .+-. 759 mm Hg/s [not significant (NS)] and after RSGx, 5524 .+-. 305 mm Hg/s (NS). Control CF increased to 48 .+-. 3 cm/s after LSGx it increased to 57 .+-. 3 cm/s (P < 0.05) and after RSGx to 42 .+-. 5 cm/s (NS). After RSGx most dogs did not reach the greatest work load and the comparison was made at the level attained. Arrhythmias during exercise appeared in 8% of control dogs, in 11% after LSGx and in 86% after RSGx. Apparently sympathetic control of HR is mediated primarily by the RSG; LSGx does not impair myocardial contractility due to compensatory mechanisms exerted by the RSG and RSGx increases the likelihood of arrhythmias during exercise.