Congenital complete heart block in the fetus: hemodynamic features, antenatal treatment, and outcome in six cases

Congenital heart block (CHB) can result in intrauterine cardiac failure leading to fetal or neonatal loss. To establish perinatal hemodynamic factors which might predict adverse outcome, six fetuses with CHB diagnosed between 20 and 30 gestational weeks were examined by echocardiography at 2-week intervals. Neonatal morbidity and outcome in infancy are detailed. The fetuses showed a significant decrease in ventricular rate (VR) with advancing gestation (60 ± 7 vs 51 ± 4 beats/min, p= 0.03). Cardiac decompensation defined as hydrops or pericardial effusion was associated with VR of lower than 55 beats/min in two fetuses. Three mothers had a therapeutic trial with a sympathomimetic and digoxin. Salbutamol increased VR 10% in one of three fetuses treated. Digoxin decreased pericardial effusion in one hydropic fetus with autoimmune myocarditis. In this fetus, poor left ventricular fractional shortening (LVFS) was accompanied with high umbilical artery resistance index (RI). High amniotic fluid erythropoietin indicated severe hypoxia preceding death. Pacemaker was indicated in all the newborns. At the age of 2 weeks all the surviving infants had tricuspid regurgitation and a shunt through foramen ovale due to asynchronized atrioventricular contraction. During the 12-month follow-up two of five surviving infants had no symptoms. One had symptomatic neonatal lupus. Two infants had patent ductus arteriosus, one with dilated cardiomyopathy. In conclusion, poor fetal outcome was associated with low VR, low LVFS, and high RI. Despite early pacing, morbidity was high in infancy due to cardiomyopathy and associated heart defects. Regular echocardiographic monitoring during pregnancy and after delivery is required in order to optimize care and timing of any interventions.