Advanced Atrioventricular Block after Postnatal Cardioversion for Fetal Ventricular Tachycardia: A Case Report

Abstract

We present a neonatal girl who developed complete atrioventricular block after postnatal cardioversion for fetal ventricular tachyarrhythmia. A pregnant women was referred at 39 gestational weeks due to fetal tachyarrhythmia of 180 bpm and without atrioventricular (AV) dissociation. Subsequently, a baby girl was delivered weighing 3,130 g. Electrocardiography revealed wide QRS tachycardia with left axis deviation, and the esophageal leads revealed a short RP′ duration without AV dissociation. However, AV dissociation was overt after injecting adenosine triphosphate, which suggested ventricular tachycardia. Cardioversion stopped the ventricular tachycardia but led to atrioventricular block with fascicular block (P rate 138 bpm, QRS rate 75 bpm), and the resulting hypotension (32/15 mmHg) was improved by dopamine administration. Echocardiography revealed a left ventricular end-diastolic diameter of 16.8 mm and an ejection fraction of 30％. Serial electrocardiography revealed a second-degree atrioventricular block at 15 hours after birth that reverted to sinus rhythm at day 2 after birth. She was discharged on day 48 after birth. Holter electrocardiographic monitoring did not shown recurrence of either the ventricular tachycardia or the atrioventricular block. The present case was unique because advanced atrioventricular block due to overdrive suppression in the His–Purkinje conduction system followed ventricular tachycardia with ventriculoarterial conduction.