Cardiac sympathetic activity in response to acute myocardial
ischemia.
Newton, Gary E., Allan G. Adelman, Valter C. Lima, Peter H. Seidelin,
Eric Schampaert, John D. Parker.
Division of Cardiology, Department of Medicine, Mount Sinai
Hospital, University of Toronto, Toronto, Ontario
APStracts 3:0485H, 1996.
While experimental evidence has demonstrated that brief periods of
myocardial ischemia are not associated with norepinephrine overflow
from the heart, cardiac sympathetic responses to myocardial ischemia
in humans remain unclear. Eleven patients undergoing angioplasty of
the left anterior descending coronary artery had cardiac
norepinephrine spillover measured immediately before, during the
final minute of a 5 minute balloon inflation, and 1 minute after
deflation. Angioplasty caused significant ST segment elevation and a
reduction in the transcardiac lactate extraction ratio. Cardiac
norepinephrine spillover was reduced from a mean value of 58 14
pmol/min at control, to 41 15 pmol/min during balloon inflation, and
38 14 pmol/min following deflation (p<0.05 versus control for
both inflation and deflation values). In contrast, during balloon
inflation there were significant increases in arterial norepinephrine
and epinephrine concentrations. Therefore a brief period of
myocardial ischemia caused by angioplasty of the left anterior
descending coronary artery does not result in cardiac sympathetic
activation, despite evidence of generalized sympathoadrenal
activation.
Received 2 July 1996; accepted in final form 14 October 1996.
APS Manuscript Number H593-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996