Ischemia- and reperfusion-induced ventricular arrhythmias in dogs: Effects of estrogen

N. A. McHugh, S. M. Cook, J. L. Schairer, M. M. Bidgoli, G. F. Merrill

Research output: Contribution to journalArticlepeer-review

65 Scopus citations

Abstract

The purpose of this investigation was to determine if exogenous estrogen could attenuate the ventricular arrhythmias caused by myocardial ischemia and reperfusion. Conjugated equine estrogen, administered as an intravenous bolus injection (100 μg) to anesthetized, instrumented beagles of both genders, significantly attenuated the incidence of ventricular arrhythmias during a 20-min period of ischemia (2 ± 1 vs. 19 ± 16% ectopy) and in the first 5 min of reperfusion (15 ± 9 vs. 69 ± 20% ectopy). By 15-20 min of ischemia, ventricular salvos and nonsustained ventricular tachycardia were frequently observed in nontreated dogs. One dog in this group fibrillated during ischemia. In contrast, estrogen-treated dogs exhibited only an occasional ventricular premature beat during the same period of ischemia. When compared with baseline values, the percent ectopy during ischemia in estrogen-treated dogs was insignificant. During reperfusion, nontreated dogs displayed severe, life-threatening arrhythmias such as sustained ventricular tachycardia. In two of these dogs ventricular tachycardia deteriorated to ventricular fibrillation. In comparison, estrogen-treated dogs displayed only innocuous ventricular arrhythmias during reperfusion, i.e., ventricular premature beats, ventricular salvos, and ventricular bigeminy. In addition to the effect of estrogen on arrhythmias, there was a gradual increase in coronary blood flow on reperfusion in estrogen-treated dogs. This effect of estrogen was preceded by a significantly higher coronary perfusion pressure during ischemia (31 ± 2 vs. 18 ± 4 mmHg, P < 0.05). In conclusion, our findings suggest that antiarrhythmic effects of estrogen treatment might stabilize ventricular rhythmicity during ischemia and reperfusion.

Original languageEnglish (US)
Pages (from-to)H2569-H2573
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume268
Issue number6 37-6
DOIs
StatePublished - 1995

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Keywords

  • conjugated equine estrogen
  • coronary blood flow
  • electrocardiogram
  • myocardial ischemia
  • stunned myocardium

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