Nonuniform cardiac sympathetic nerve discharge: mechanism for coronary occlusion and digitalis-induced arrhythmia

Abstract

This study examined nonuniform postganglionic cardiac sympathetic neural discharge as a possible mechanism involved in the production of coronary occlusion or ouabain-induced arrhythmias. After acute occlusion of the left anterior descending coronary artery in 12 cats, anesthetized with alpha-chloralose and pretreated with atropine, arrhythmia occurred within 3 min in eight animals; three of these died in ventricular fibrillation. In recordings from 15 nerves in the eight animals with arrhythmia, spontaneous discharge increased in nine nerves, decreased in five nerves, and showed no change in one nerve. This nonuniform neural discharge was associated with the development of arrhythmia after occlusion. In four of the cats, neural discharge did not change within the first 3 min after coronary artery occlusion and arrhythmia did not occur. Development of ouabain-induced arrhythmia was accompanied by a nonuniform pattern in the neural discharge (13 cats). This discharge may alter ventricular excitation and conduction to produce arrhythmia.