Ischemia – reperfusion destabilizes rhythmicity in immature atrio-ventricular pacemakers: a predisposing factor for postoperative arrhythmias

Post-operative arrhythmias, such as Junctional Ectopic Tachycardia (JET) and atrioventricular (AV) block, are serious post-operative complications for children with congenital heart disease 1. We hypothesize that these arrhythmias arise within the AV node because of an ischemia-reperfusion (I/R) insult in the setting of immature myocytes, exacerbated by post-operative inotropy. Rabbit whole heart models of post-operative arrhythmias were generated, focusing on three primary risk factors: age, I/R exposure and the application of dopamine, an inotropic agent. Using optical mapping technology, neonatal rabbit hearts were found to experience persistent post-ischemia arrhythmias of differing severity while mature hearts exhibited no arrhythmias or transient ones, when the three risk factors were varied.Compared to rabbit mature hearts, rabbit neonatal whole hearts demonstrated a susceptibility to I/R insults resulting in alterations in automaticity. An analogous susceptibility may predispose human neonates to post-operative arrhythmias such as JET and AV block.