Author's reply: A novel mechanism of sudden infant death syndrome during atrioventricular reentrant tachycardia: a case report.

We thank Belhassen[1] for the insightful comments on our paper presenting ventricular fibrillation during an atrioventricular reentrant tachycardia in an infant case.[2] This event occurred before the insertion of the catheter. Therefore, the intracardiac electrocardiogram was not recorded during that event. However, a tachycardia with the same morphology and similar cycle length of 225 ms was induced after the catheter insertion. Because of the fatal arrhythmia following the tachycardia, a detailed electrophysiological study was not performed during the tachycardia. However, the earliest atrial activation recording site of the intracardiac electrocardiogram was located on the lateral wall of the left atrium, which was the same as the retrograde conduction of the accessory pathway. We diagnosed that tachycardia as an atrioventricular reentrant tachycardia via the accessory pathway on the lateral wall.

The anesthesia was performed using sevoflurane. The non-invasive blood pressure did not exhibit any significant changes during the 12 min tachycardia just before the event. The coronary artery was assessed by an echocardiogram, which showed a normal origin of the coronary artery. A 12-lead electrocardiogram after the catheter ablation did not exhibit any Brugada type ST-T changes, J waves, or premature ventricular contractions, and the QTc interval was within normal range. Therefore, we considered that an inherited arrhythmia was not suspected and did not perform any genetic testing to assess the possibility of catecholaminergic polymorphic ventricular tachycardia, Brugada syndrome, long QT syndrome, or short QT syndrome. Once again, we appreciate the thoughtful comments regarding our publication.

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