Early ischemia after complete coronary ligation in the rabbit, dog, pig, and monkey.

The character and extent of the myocardial ischemic "borderzone" was assessed in the rabbit, dog, pig, and monkey. A fluorophotographic technique permitting high resolution (+/- 50 micrometers) display of myocardial ischemia has been developed. Reduced intracellular NADH (ischemia) fluoresces and may be photographed while oxidized NAD (perfused tissue) does not. A coronary artery was ligated for 5 min in open-chest rabbits, dogs, pigs, and monkeys. A fluorescent dye was injected into the left atrium as a coronary vascular marker, and the tissue was quick-frozen. The ischemic margin was well seen and was jagged in all species. The distance from anoxic to perfused tissue (borderzone) was less than 50 micrometers in all species. A narrow "oxygen-diffusion zone" of nonperfused non-anoxic tissue is visible in isolated heart perfused with blood-free solution. The width of this zone is inversely related to myocardial oxygen consumption and is less than 50 micrometers in a working blood-perfused heart. We have not yet correlated the oxygen diffusion zone with the clinically defined salvageable borderzone. In dogs, collateral vessels provide a heterogeneous border to the ischemic region so that the canine ischemic pattern differs from that of pigs, rabbits, and monkeys.