Mechanisms of postoperative junctional ectopic tachycardia: Chronotropic and inotropic regulation in the neonate heart

Junctional ectopic tachycardia (JET) is a common arrhythmia in postoperative pediatric patients after open-heart surgery for congenital heart defects. This arrhythmia is life-threatening and mechanisms of this arrhythmia are not yet clear. Isolated working hearts from neonate rabbits were administered P-adrenergic agonists alone or with antagonists under normal or ischemia-reperfusion stunned conditions. The effect of the sodium hydrogen exchanger inhibitor HOE642 on the recovery of ischemia-reperfusion stunned leA ventricle was tested, the potential for P-adrenergic agonist-induced arrhythmogenesis on the stunned neonate hearts was examined as well. We found that dopamine has a positive chronotropic, and a negative inotropic effect on the isolated neonate rabbit heart. Furthermore, dopamine has an arrhythmogenic effect on the ischemia-reperfusion stunned neonate myocardium. Finally, it was shown that HOE642 has a significant protective effect on contractile function in the neonate myocardium on recovery from ischemia-reperfusion stunning, but was not robust in its antiarrhythmic effect.