Unravelling early sinus node dysfunction after pediatric cardiac surgery: a pre-existing arrhythmogenic substrate.

Early post-operative sinus node dysfunction (SND) is common in paediatric patients undergoing surgical correction of congenital heart defects (CHD). At present, the pathophysiology of these arrhythmias is incompletely understood. In this case series, we present three paediatric patients in whom we performed intraoperative epicardial mapping and who developed early post-operative SND. All patients had either an inferior or multiple sinoatrial node (SAN) exit sites, in addition to extensive conduction disorders at superior and inferior right atrium. Our findings contribute to the hypothesis that pre-existing alterations in SAN exit sites in combination with atrial conduction disorders may predispose paediatric patients with CHD for early post-operative SND. Such insights in the development of arrhythmias are crucial as it may be the first step in identifying high-risk patients.