Sequence of electrophysiological property and metabolic disorder in ischemic myocardium

The relationships of electrical changes to the time course of reduction in adenosine triphosphate (ATP) content were examined in 41 dogs with coronary artery ligation and 14 control dogs. Twenty dogs with malignant ventricular arrhythmias within 10 min of ischemia (VA dogs) were characterized by widening of the composite electrogram duration (147 +/- 47 msec at 5 min). In contrast, the composite electrogram duration was narrower (71 +/- 12 msec at 5 min, p less than 0.001) in 21 dogs without malignant arrhythmias (non-VA dogs). The degree of ATP reduction in VA dogs was significantly less at 3 min (3.11 +/- 0.28 mumol X g-1, p less than 0.05) and at 5 min (2.93 +/- 0.28 mumol X g-1, p less than 0.05) than in non-VA dogs (2.76 +/- 0.22 mumol X g-1, 2.39 +/- 0.44 mumol X g-1, respectively). The width of the electrograms in VA dogs decreased gradually after 10 min of ischemia, and it was not significantly different from non-VA dogs by 13 min, which coincided with disappearance of a difference in ATP content (2.10 +/- 0.34 mumol X g-1 and 2.35 +/- 0.23 mumol X g-1 in VA dogs and non-VA dogs biopsied at 10-20 min of ischemia). It was concluded that the metabolic deterioration in VA dogs advanced more slowly than that in non-VA dogs within 5 min of ischemia and the decrease in the width of the electrogram after 10 min did not result from a partial recovery of ischemia.