Complete resolution of arrhythmia-induced hydrops fetalis in utero.

A 21-year-old G3P2011 Caucasian woman at 27 weeks' gestation presented with fetal tachyarrhythmia between 240 and 270 beats per minute. Fetal supraventricular tachycardia, abdominal ascites, pleural effusion and pericardial effusion indicated hydrops fetalis. Management with digoxin and flecainide converted the fetus to sinus rhythm and resolved the ascites and pleural effusion within 4 days of treatment. Flecainide was discontinued at 31 weeks' gestation due to elevated liver enzymes. Intrahepatic cholestasis was treated with ursodiol. Caesarean section was performed at 37 weeks' gestation. Neonatal echocardiogram revealed a bicuspid aortic valve with mild regurgitation and a patent foramen ovale, and the infant showed no subsequent evidence of tachyarrhythmia or hydrops after delivery. Treatment of hydrops fetalis in the antenatal period is complex, and early diagnosis and treatment can quickly resolve supraventricular tachycardia-induced hydrops fetalis.