Fetal Bradyarrhythmia Associated With Congenital Heart Defects

to AVB and myocarditis, respectively, resulting in a poor prognosis. We previously reported that fetal hydrops is associated with a poor prognosis in fetuses without CHD7 and we suggested that myocardial dysfunction, rather than the severity of bradyarrhythmia, was associated with fetal hydrops. In contrast, in fetuses with CHD, congenital bradyarrhythmia is thought to result from the structural defect itself.8,9 An embryological insult in the early gestational phase has been proposed to be the pathogenic mechanism of conduction system defects. Hetetal bradyarrhythmia is an uncommon but life-threatening disease, especially in cases of complete atrioventricular block (AVB), which has a poor prognosis even in the postnatal period because of fetal hydrops and severe heart failure.1–4 Fetal bradyarrhythmia may occur with and without associated congenital heart defects (CHD). In fetuses without CHD, the association of AVB with maternal anti-Ro/Sjögren’s syndrome A antibodies is well established.5,6 These antibodies damage the conduction system and the myocardium, and lead F