AJP - Heart and Circulatory Physiology, Vol 243, Issue 2 340-H345, Copyright © 1982 by American Physiological Society
Effect of myocardium at risk on outcome after coronary artery occlusion and release
M. Austin, T. L. Wenger, F. E. Harrell Jr, F. A. Luzzi and H. C. Strauss
The relationship between the probability of sustaining ventricular
fibrillation during occlusion or release of a canine coronary artery and
the amount of myocardium made ischemic has never been carefully assessed.
We occluded the left anterior descending coronary artery above or below the
septal artery for 20 min and then released the ligation. The amount of left
ventricle perfused by the ligated vessel was determined by injection of
different color monastral dyes above and below the ligation. Despite
careful ligature placement immediately proximal or distal to the septal
artery, there was wide variation in the amount of left ventricle perfused
by the ligated vessel, or myocardium "at risk." Myocardium at risk ranged
between 24 and 51 g for ligations placed above the septal artery and 14 and
27 g for ligations placed below the septal artery. Ventricular fibrillation
during occlusion and after release correlated significantly with the amount
of myocardium at risk. This relationship was well described using the
logistic risk regression model. The model predicts uniformly low and
uniformly high probability of ventricular fibrillation with small and large
amounts of myocardium at risk, respectively, and a direct correlation for
midrange values of myocardium at risk. This relationship can account for a
substantial portion of non-drug related variability in outcome of
antiarrhythmic trials using the canine coronary occlusion or release model.
