Transient Fetal Non-Immune Second-Degree 2:1 Atrioventricular Block: A Case Report

We present a case of a transient second-degree 2:1 conduction atrioventricular (AV) block in a fetus with a structurally normal heart and fetal heart rate of 74 bpm at 21 weeks of gestation (WG). The maternal medical history was unremarkable and the autoantibody screening was negative. The subsequent follow-up documented complete resolution of the AV block at 25 WG. The fetal heart rate and AV conduction remained normal until delivery. The postnatal electrocardiogram (ECG) demonstrated normal sinus rhythm and duration of corrected QT (QTc)-intervals. These observations remained normal upon follow-up. Although uncommon, second-degree AV block can be one of the underlying causes of fetal bradycardia.