Hydrops Fetalis and Fetal Tachycardia without Congenital Heart Disease; Intrauterine Diagnosis and Treatment

Introduction: We present a 24.5 weeks gestation hydropic fetus, secondary to supraventricular tachycardia that was successfully treated with a wide range of antiarrhythmic drugs.

Case History: A 29 years old woman was referred in the second trimester. During a routine ultrasound scan at 24,5 weeks of gestation, fetal tachycardia with heart rate up to 290/min, pleural and pericardial effusion, scalp edema and ascites were detected; there was no other structural abnormality identified. The patient was treated with oral digoxine 0.25mg + flecainide 100mg three times a day with no response despite having therapeutic levels of digoxin. Impregnation dose was started with amiodarone 900mg followed with 200mg every 8 hours + flecainide and digoxine was stopped gradually. By the day 5 since the beginning of treatment, the basal heart rate was normal at 140/min and amiodarone was stopped after 72hrs gradually and flecainide was stopped until the end of pregnancy.

Discussion: The choice of antiarrhythmic drugs is controversial. Digoxine is probably not the drug of choice because it is known the poor effect in such circumstances, amiodarone because the secondary effects in the mother and the fetus and flecainide has a negative inotropic effect. In or case, we observed an effective response in the fetus with the recovery of sinus rhythm, ventricular function and resolution of hydrops and the baby was successfully delivered at term.

Conclusion: Fetal supraventricular tachycardia is a rare cause of hydrops fetalis and mortality is high if it is not diagnosed and treated prenatally. Flecainide and amiodarone is a rapid and effective drug treatment for this condition.