Fetus with heart failure due to congenital atrioventricular block treated by maternally administered ritodrine

The efficacy of maternal administration of ritodrine in cases of congenital atrioventricular block (CAVB), especially with fetal heart failure, is not yet determined.

At 21 2/7 weeks of gestation, isolated CAVB with a ventricular/atrial rate of 55-70/130-140 bpm was found in a fetus from a 30-year-old Japanese nulliparous woman with anti-SSA antibody. Cardiothoracic area ratio (CTAR) was 40% and no fetal hydrops was observed. At 30 2/7 weeks, the ventricular rate decreased to 49 bpm with an atrial rate of 125 bpm. CTAR increased to 53.8% and ascites appeared. Maternal continuous ritodrine infusion was started with rapid improvement of fetal cardiac function; increment in the ventricular rate to 57 bpm and atrial rate to 137 bpm, with a decrement in CTAR to 44.6%. Ascites also gradually decreased and by the fourth day, it had completely disappeared with CTAR of 40.2%. On the 12th day after ritodrine treatment (32 1/7), amniotic fluid volume decreased and fetal weight gain stopped, which led us to assume a worsening intrauterine environment, and cesarean section was performed. A 1,178 g male infant was born with a 5-min Apgar score of 8. Continuous isoproterenol infusion was started, increasing the ventricular rate from 71 to 80 bpm. Pacemaker implantation is under consideration to treat this infant.

Maternal administration of ritodrine not only increased the fetal heart rate but also ameliorated the signs of fetal heart failure, and thus is considered one treatment of choice in CAVB.