Effects of experimental XXXX on the ST segment response to @entity591 .

@entity308 @entity235 @entity591 @entity1188 @entity432 @entity583
Prior studies have shown that @entity591 results in @entity308 in @entity235 with chronic, gradual coronary occlusion. This response was compared with that produced by acute, total occlusion of the left anterior descending artery. Ten @entity235 served as controls; in another 10 @entity235 , an ameroid constrictor was implanted about the left anterior descending artery. This artery was acutely ligated in a third set of 10 animals, and in a final set of 10, the distal left anterior descending coronary vasculature was embolized by latex injection. @entity591 was produced by atrial pacing from rates of 90 to 250 beats/min using implanted atrial electrodes. Electrocardiographic signals registered from 84 torso electrodes were used to construct body surface isopotential maps during the ST segment. In normal @entity235 , pacing increased repolarization potentials without shifts in spatial features. New and abnormal anterior negativity, correlating with significant ST @entity308 , appeared at rates of 170 beats/min or faster in @entity235 with ameroid constriction. However, in both groups with @entity432 that produced transmural @entity583 , @entity591 resulted in increases in anterior ST elevation and reciprocal ST @entity308 . Specific findings demonstrated the lead dependency of the response to @entity591 and the greater than normal increase in potential magnitudes after @entity1188 than in control cases. The similarity of the response with @entity432 and with embolization suggested that the response to @entity591 after @entity1188 was not dependent on coronary collateral function but may represent a direct electrophysiologic effect of rate. Thus, these @entity432 models simulate exercise-induced ST segment elevation as it may be seen clinically.
