AJP - Heart and Circulatory Physiology, Vol 246, Issue 4 601-H607, Copyright © 1984 by American Physiological Society
Transmural changes in porcine and canine hearts after circumflex artery occlusion
K. H. McDonough, R. B. Dunn and D. M. Griggs Jr
The distribution of the coronary collateral circulation is an important
determinant of the myocardial response to acute coronary artery occlusion.
The dog shows an unequal response across the ventricular wall, whereas the
pig seems to have more uniform transmural changes. This study was
undertaken to compare the metabolic and blood flow response in pigs and
dogs to acute occlusion of the circumflex artery. Microspheres (8-10
micron) were used to determine control blood flow and flow 5 min after
occlusion. A transmural tissue sample from the center of the ischemic zone
was taken at 8 min after occlusion, and inner, middle, and outer layers
were analyzed for high-energy phosphates and lactate. The remainder of the
heart was analyzed for microsphere distribution. The epicardium in the dog
showed less severe damage than the subendocardium. High-energy phosphates
were higher and lactate lower in this region. In the pig high-energy
phosphates and lactate were the same in the subepicardium and
subendocardium. Blood flow to regions surrounding the central ischemic zone
in pigs was generally uniform across the ventricular wall or greater in the
inner wall than in the outer wall. These results verify that dogs as a
group have a greater subepicardial protection during coronary artery
occlusion. Pigs, however, demonstrate uniform ischemia or even slightly
less severe ischemia in the subendocardium in regions of restricted blood
flow.
