Postconditioning markedly attenuates ventricular arrhythmias after ischemia-reperfusion.
BACKGROUND
Brief periods of reocclusion (postconditioning) during early reperfusion reduce myocardial infarct size. Whether postconditioning has an effect on lethal ventricular arrhythmias independent of infarction in an in-vivo regional ischemia model is unknown. The purpose of this study was to determine if postconditioning limited reperfusion arrhythmias in a necrosis-free model.


METHODS
Anesthetized rats were subjected to 5 minutes of proximal coronary artery occlusion; they were randomized to a control group (n = 15) that underwent reperfusion alone or a postconditioning group (n = 15) that received four cycles of 20 seconds reperfusion, 20 seconds reocclusion before final reperfusion.


RESULTS
During the final reperfusion phase, ventricular arrhythmias occurred in 14 of 15 control rats and 8 of 15 postconditioning rats (P = .017). Ventricular tachycardia occurred in 10 of 15 control rats vs 4 of 15 postconditioning rats (P = .028). Control rats demonstrated 1.3 runs of ventricular tachycardia per minute vs 0.4 runs in postconditioning rats (P = .026). The average duration of ventricular tachycardia runs was 8.8 +/- 3.2 seconds in the control group vs 5.0 +/- 3.9 seconds in postconditioning rats (P = NS).


CONCLUSIONS
This in-vivo study showed that postconditioning markedly attenuates ventricular arrhythmia after regional ischemia in a noninfarct model.
Kloner
Robert A
RA
Heart Institute, Good Samaritan Hospital and Division of Cardiovascular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90017, USA. rkloner@goodsam.org
Dow
Joan
J
Bhandari
Anil
A
D000818:Animals; D005260:Female; D006801:Humans; D019157:Ischemic Preconditioning, Myocardial; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D010865:Pilot Projects; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D017180:Tachycardia, Ventricular / Q000517:prevention & control*; D018879:Ventricular Premature Complexes / Q000517:prevention & control*