Work

Fetal Supraventricular Tachycardia Complicated by Hydrops Fetalis: A Case Report of Complete Reversal With Transplacental Flecainide Therapy

Year: 2026

Type: article

Abstract: Fetal supraventricular tachycardia (SVT) is the predominant sustained fetal tachyarrhythmia and, when persistent, can progress to tachycardia-induced myocardial dysfunction and nonimmune hydrops fetalis (NIHF), a condition associated with substantial perinatal morbidity and mortality. Although digoxin has historically served as first-line therapy, flecainide demonstrates superior transplacental bioavailability and higher cardioversion rates in hydropic fetuses, in whom placental edema may impair digoxin transfer. We report a case of fetal SVT complicated by hydrops fetalis at 30 weeks' gestation that achieved complete intrauterine reversal following maternal flecainide therapy. A 31-year-old woman was referred after fetal echocardiography demonstrated SVT with a ventricular rate of approximately 300 beats per minute and 1:1 atrioventricular conduction, alongside fetal ascites and pericardial effusion consistent with NIHF. Oral flecainide was initiated and subsequently up-titrated because of persistent fetal tachycardia. Sinus rhythm was restored on treatment day 10, followed by complete sonographic resolution of hydrops by 32+6 weeks' gestation. Labor was induced at 38 weeks, resulting in vaginal delivery of a clinically stable male infant. Postnatally, prophylactic propranolol was started, but recurrent SVT on days 4 and 13 of life required escalation to flecainide and adenosine cardioversion before discharge in sinus rhythm. This case illustrates that regression of hydrops, rather than restoration of sinus rhythm alone, represents a more clinically meaningful marker of fetal cardiovascular recovery and underscores the importance of timely transplacental antiarrhythmic therapy and structured postnatal surveillance, given the well-documented risk of arrhythmia recurrence in infants with a history of fetal SVT complicated by hydrops.

Source: Cureus

DOI: 10.7759/cureus.117572

Authors: Eleni Papaioannou, Aikaterini Martinopoulou, Ariadni Papadopoulou, Christos Kartsiounis, Magdalini Sterpi

Institution: Ippokrateio General Hospital of Thessaloniki

Language: English

Topic: Cardiac Arrhythmias and Treatments

Subfield: Cardiology and Cardiovascular Medicine

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: diamond

OpenAlex ID: W7220854763