AJP - Heart and Circulatory Physiology, Vol 244, Issue 1 23-H31, Copyright © 1983 by American Physiological Society
Analysis of coronary collateral structure, function, and ischemic border zones in pigs
R. E. Patterson and E. S. Kirk
The purpose of this study was to compare coronary collateral structure and
function in pigs with those in dogs and to analyze the distribution of
collateral blood flow across the lateral and transmural border zones in the
pig. After acute occlusion of the left anterior descending coronary artery
(LAD) in 26 anesthetized open-chest pigs, minimal collateral blood flow was
indicated by retrograde flow (0.2 +/- 0.1 ml/min) and
microsphere-myocardial blood flow (0.005 +/- 0.001 ml X min-1g-1).
Postmortem injection of the distal LAD followed by clearance of the heart
demonstrated few tiny collateral structures and negligible collateral
filling of other arteries. In contrast to dogs, pigs showed no measurable
gradient of collateral blood flow across the transmural border zone, and
pigs showed no change in collateral blood flow or its transmural
distribution during retrograde drainage of collateral blood flow or
elevated left ventricular filling pressures. Pigs showed higher myocardial
blood flow in the lateral border than in the center of the ischemic zone.
As in the dog, however, this gradient of blood flow across the lateral
border zone was accounted for by overlap between occluded LAD branches and
unoccluded coronary arterial branches rather than by preferential
collateral perfusion of the lateral border of the ischemic zone. We
conclude that the pig has a homogeneous distribution of collateral blood
flow across the transmural and lateral border zones after acute coronary
occlusion but that the minimal collateral circulation limits the usefulness
of the pig as a model of ischemic heart disease.
