Electrophysiologic effects of epinephrine in humans

Division of Cardiology, University of Michigan Medical Center, Ann Arbor.

The electrophysiologic effects of circulating epinephrine in humans were examined in four study groups of 10 subjects each. In 10 subjects without structural heart disease (Group 1) and in 10 patients with coronary disease or dilated cardiomyopathy (Group 2) epinephrine infusion at 25 and 50 ng/kg body weight per min for 14 min resulted in an elevation of the plasma epinephrine concentration in the physiologic range. In both groups it produced a dose-dependent decrease in the effective refractory period of the atrium, atrioventricular (AV) node and ventricle and improvement in AV node conduction. Epinephrine facilitated the induction of sustained ventricular tachycardia in 3 of the 20 subjects. In Group 3, a beta-adrenergic blocking dose of propranolol was added to the infusion of 50 ng/kg per min of epinephrine. Propranolol not only reversed the effects of epinephrine, but also lengthened these variables compared with baseline values. In Group 4, propranolol was administered first, followed by 50 ng/kg per min of epinephrine. Propranolol alone slowed AV node conduction and mildly prolonged the refractory periods. In the presence of beta-blockade, epinephrine had no effect on AV node properties but resulted in a lengthening of the atrial and ventricular effective refractory periods. In conclusion, epinephrine in physiologic doses shortens the effective refractory period of the atrium, AV node and ventricle, improves AV node conduction and may facilitate the induction of sustained ventricular tachycardia. The overall electrophysiologic effects of epinephrine result from stimulation of beta-receptors. Stimulation of alpha-receptors by epinephrine has no effect on the AV node but prolongs the effective refractory period of the atrium and ventricle, partially offsetting the shortening of refractory periods mediated by beta-receptor stimulation.

This article has been cited by other articles:

				J. Kolarova, Z. Yi, I. M. Ayoub, and R. J. Gazmuri Cariporide Potentiates the Effects of Epinephrine and Vasopressin by Nonvascular Mechanisms During Closed-Chest Resuscitation Chest, April 1, 2005; 127(4): 1327 - 1334. [Abstract] [Full Text] [PDF]

				D. W. Rodenbaugh, H. L. Collins, D. G. Nowacek, and S. E. DiCarlo Increased susceptibility to ventricular arrhythmias is associated with changes in Ca2+ regulatory proteins in paraplegic rats Am J Physiol Heart Circ Physiol, December 1, 2003; 285(6): H2605 - H2613. [Abstract] [Full Text] [PDF]

				C.-W. Chiou, S.-A. Chen, M.-H. Kung, M.-S. Chang, and E. N. Prystowsky Effects of Continuous Enhanced Vagal Tone on Dual Atrioventricular Node and Accessory Pathways Circulation, May 27, 2003; 107(20): 2583 - 2588. [Abstract] [Full Text] [PDF]

				M D Lowe, E Rowland, M J Brown, and A A Grace {beta}2 Adrenergic receptors mediate important electrophysiological effects in human ventricular myocardium Heart, July 1, 2001; 86(1): 45 - 51. [Abstract] [Full Text] [PDF]

				A A J Adgey and P W Johnston Approaches to modern management of cardiac arrest Heart, October 1, 1998; 80(4): 397 - 401. [Full Text]

				T. Q. Kong Jr, J. J. Goldberger, M. Parker, T. Wang, and A. H. Kadish Circadian Variation in Human Ventricular Refractoriness Circulation, September 15, 1995; 92(6): 1507 - 1516. [Abstract] [Full Text]