Clinical course of fetal congenital atrioventricular block in the Japanese population: a multicentre experience

Objectives: To elucidate the prenatal and postnatal course of fetal congenital atrioventricular block (CAVB) during the past decade in the Japanese population. Design: Retrospective multicentre study. All fetuses with CAVB in 10 Japanese institutions in the period from January 1990 to August 2001 were included. Patients: Of the 48 fetuses with CAVB, 17 had a congenital heart defect (CHD) ( 14 with left atrial isomerism) and 31 had a structurally normal heart (22 with positive maternal autoantibodies). Gestational age at diagnosis was 15 to 38 (median 26) weeks. Results: Of the 17 fetuses with a CHD, three were aborted, one died before birth, and eight died after birth ( three in the neonatal period and five after the neonatal period). Of the 31 fetuses without a CHD, two died before birth and two died after birth. CHD (p = 0.005) and the presence of fetal hydrops (p = 0.05) were significant risk factors for death. However, fetal ventricular and atrial heart rates, gestational age at delivery, and birth weight were not related to death. Transplacental medication of sympathomimetics increased the fetal heart rate in five of eight fetuses treated. Dexamethasone did not improve the degree of heart block in any of the six fetuses treated. Postnatally, pacemakers were implanted in 30 of 40 babies. Four fetuses with maternal autoantibodies had decreased cardiac function. Conclusions: CHD and fetal hydrops are risk factors for prenatal and postnatal death. The fetal ventricular rate of 55 beats/min did not appear to be a threshold value by which to predict fetal hydrops. Patients with CAVB should be subjected to close long term follow up to check for the need for pacemaker implantation or for late onset cardiac dysfunction.