Despite many years of study, certain aspects of @entity741 remain incompletely understood. One observation that motivated this study is that acute, complete occlusion produces elevations but never @entity308 of the ST-segment potentials in electrocardiographic leads over the @entity63 zone. Limited flow, on the other hand, leads to @entity308 , both in in situ experiments and during clinical stress tests. The prevailing biophysical theory of @entity63 suggests that complete occlusion should produce at least transient @entity308 , a finding we have neither observed in our own studies nor uncovered in the literature. Our goal with these experiments was to understand the difference between complete occlusion and reduced coronary flow, specifically the behavior at the transition between the two. We have performed experiments by using isolated @entity235 hearts with a cannulated left anterior descending artery suspended in a @entity1 shaped electrolytic @entity3368 . To create a range of @entity63 conditions, we changed coronary flow rates both suddenly and in controlled sequences and varied the heart rate of the isolated heart. The main finding was that in the isolated heart preparation, @entity308 over the @entity63 zone arose only under conditions of combined restricted flow and elevated heart rate. Reduced coronary flow alone never produced @entity308 . These findings suggest that heart rate and probably metabolic work create the conditions necessary for @entity63 that reduced flow alone cannot provoke. They furthermore suggest that the degree of @entity308 for a given restriction in coronary flow may depend on heart rate, which supports the notion of rate correction for clinical stress electrocardiogram testing.

The role of heart rate in XXXX from restricted coronary perfusion.

@entity1 :: ('9606', 'Species') :: ['human'] @entity308 :: ('MESH:D003866', 'Disease') :: ['ST-segment depression', 'depression', 'epicardial ST-segment depression'] @entity63 :: ('MESH:D007511', 'Disease') :: ['subendocardial ischemia', 'ischemia', 'ischemic'] @entity235 :: ('9615', 'Species') :: ['dog'] @entity3368 :: ('10010', 'Gene') :: ['tank'] @entity741 :: ('MESH:D017202', 'Disease') :: ['myocardial ischemia']
@entity741 :: (MESH:D017202,Disease) :: ['myocardial ischemia']
