Successful Management of Fetal Supraventricular Tachycardia With Flecainide in a Case Complicated by Early Hydrops Fetalis: A Case Report.

Fetal arrhythmia that can lead to hydrops fetalis and fetal heart failure if untreated. This case report describes the successful treatment of a fetus with SVT at 26 weeks of gestation using flecainide. A 37-year-old gravida 3, para 2 woman was diagnosed with fetal SVT during a routine ultrasound, which also revealed mild pleural effusion, pericardial effusion, and ascites, raising concerns for hydrops fetalis. A fetal echocardiogram confirmed a heart rate of 250-300 beats per minute with preserved cardiac function. The mother was started on oral flecainide at 100 mg twice daily, which was increased to 150 mg twice daily after 3 days due to persistent fetal tachycardia. Within 24 h of the dosage adjustment, the fetal heart rate normalized to 120-130 beats per minute, and the hydrops resolved by the third week of treatment. The mother delivered a healthy baby at 39 weeks, and the infant has remained free of SVT episodes to date. This case demonstrates the efficacy and safety of flecainide in treating fetal SVT, particularly in cases complicated by early hydrops.