Epicardial ischemia as delineated with epicardial S-T segment mapping andnicotinamide adenine dinucleotide (NADH) fluorescence photography.

In isolated rabbit hearts with an experimental coronary arterial occlusion, epicardial ischemia was identified by reduced nicotinamide adenine dinucleotide (NADH) fluorescence photography, a technique that detects areas of myocardial anoxia. Epicardial S-T segment mapping was performed to evaluate the S-T segment changes across an ischemic border defined by NADH fluorescence. After S-T segment mapping and perfusion with a fluorescein dye, serial selections of the hearts revealed that the ischemic area was transmural and and the border was nearly perpendicular to the epicardial surface. As the epicardial ischemic border was approached, S-T segment elevation was first detected 3.3 mm outside the ischemic border, and increased over a transition zone 7 mm wide. S-T segment negativity was not detected immediately outside the ischemic border. It is concluded from these studies that S-T segment changes give relatively imprecise definition of an ischemic border, and that S-T segment changes across an ischemic border are not consistent with those predicted by solid angle analysis.