Circulation. 58(4):670–678, OCTOBER 1978

PMID: 688578

Issn Print: 0009-7322

Publication Date: October 1978


Share this on facebook   Share this on Twitter   Share this on LinkedIn   Email this article  



Print

Electrophysiologic Effects of Partial Coronary Flow Reduction in the Exposed Canine Heart

WERNER DANIEL;ROBERT SVENSON;THOMAS MASTERS;FRANCIS ROBICSEK;

+ Author Information


    loading  Checking for direct PDF access through Ovid

Abstract

SUMMARY In the open-chested dog, coronary flow reduction results in a decrease of regional myocardial temperature (T). We assessed the contribution of T decrease to changes in refractoriness and conduction delay attributed to ischemia. The independent effect of regional hypothermia on effective refractory period (ERP) was a linear function of the temperature (ERP =-b T + a) with a F = 0.97 ± 0.02 in 11 dogs. The effect on conduction time of a ventricular premature beat was a linear function of the log T at both endocardium (f = 0.95 ± 0.02) and epicardium (F = 0.96 ± 0.01). A 75% reduction in coronary flow resulted in a mean T decrease of 1.9 ± 0.30 C. The T decrease was sufficient to mask the effects of ischemia on shortening of the ERP. Furthermore, the conduction delay of ventricular premature beats during 75% coronary flow reduction could be accounted for by the decrease in T alone in five of seven dogs. We conclude that changes in refractoriness and conduction dnring acute coronary flow reduction in the open-chested dog are due to the composite effects of ischemia and the decrease in regional temperature. The open-chested model may have important limitations in understanding the electrophysiologic effects of acute coronary insufficiency. However, it may have important applications in defining the electrophysiologic environment at the time of coronary artery surgery.

Related Topics

    Related Articles

        loading  Loading Related Articles