Effect of myocardial oxygen consumption on infarct size in experimental coronary artery occlusion

The influence of myocardial oxygen consumption (MVO2) at the moment of coronary occlusion on the size of the ensuing necrosis was investigated in 12 anaesthetised dogs. A two-infarction model was used with a sequential occlusion of two distant coronary branches in the same heart, however under different levels of MVO2. One group of occlusions was produced at a high MVO2 of 21.6 +/- 3.0 ml O2 . min-1 . 100 g-1. This group was compared with a second in which necrosis proceeded at a low MVO2 estimated to be 5.9 +/- 1.5 ml O2 . min-1 . 100 g-1 averaged over a 90-min occlusion period. Infarct size expressed as percentage of perfusion area was 43 +/- 28% in group 1 and 11 +/- 11% in group 2 (p less than 0.005). The mass of the perfusion area was equal in both groups (17 +/- 4 g, 19 +/- 6 g). The amount of myocardial necrosis, which after a 90-min occlusion depends on the acute collateral blood flow, was in every case greater under high MVO2. Thus a low MVO2 at the moment of occlusion can postpone myocardial necrosis.