Prenatal diagnosis of fetal complete atrioventricular block with QT prolongation and alternating ventricular pacemakers using multi-channel magnetocardiography and current-arrow maps

We report a case of fetal complete atrioventricular block (CAVB) with QT prolongation and alternating ventricular pacemakers diagnosed by magentocardiography (MCG). Fetal bradyarrhythmia of around 60 bpm was detected at 30 weeks of gestation. Ultrasonography revealed fetal CAVB without structural cardiac anomalies. MCG was recorded at 30 weeks of gestation using a 64-channel superconducting quantum interference device (MC-6400, Hitachi, Japan). The averaged MCG revealed QT prolongation, and the current-arrow maps generated by MCG revealed alternating ventricular pacemakers. The diagnosis was confirmed by electrocardiogram after birth. A permanent pacemaker was implanted during the early neonatal period, and the infant was healthy at 6 months of follow-up. MCG may be a useful diagnostic tool for fetal CAVB with QT prolongation and alternating ventricular pacemakers.