Familial idiopathic atrial fibrillation with fetal bradyarrhythmia.
A woman presented at 28 wk gestation with fetal bradycardia 50 bpm, which persisted until 42 wk when an asymptomatic male baby was delivered. Electrocardiograph at 3 wk of age documented an incessant atrial fibrillation with slow ventricular response. He continued to be asymptomatic, but on follow-up at 16 y of age, 24-h Holter monitor showed a heart rate of 23 bpm and pauses of up to 6 s when a V