Preconditioning causes improved wall motion as well as smaller infarcts after transient coronary occlusion in rabbits.

BACKGROUNDA brief coronary occlusion before a more prolonged occlusion results in less myocardial infarction than the longer occlusion alone. However, the effects of this preconditioning on recovery of systolic function after coronary occlusion have not been determined.METHODS AND RESULTSUltrasonic crystals implanted in rabbit myocardium measured segment length in the distribution of a branch of the left coronary artery that was fitted with a snare occluder. Rabbits were randomly allocated to either nonpreconditioned or preconditioned groups. Rabbits in the latter group underwent preconditioning with a 5-minute coronary occlusion followed by 10 minutes of reperfusion. Then the coronary artery was occluded for 20 minutes in all rabbits, after which it was allowed to reperfuse for 90 minutes. The hearts were then excised, and infarct size was measured by staining with triphenyltetrazolium chloride. During coronary occlusion, all hearts except one demonstrated either akinesis or paradoxical bulging. Five min...