Fetal Supraventricular Tachycardia Complicated by Hydrops Fetalis: A Case Report of Complete Reversal With Transplacental Flecainide Therapy.
- 1Department of Neonatology, Neonatal Intensive Care Unit, Hippokration General Hospital of Thessaloniki, Thessaloniki, GRC.
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.
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BibTeX
@article{papaioannou2026fetal,
title = {{Fetal Supraventricular Tachycardia Complicated by Hydrops Fetalis: A Case Report of Complete Reversal With Transplacental Flecainide Therapy.}},
author = {Eleni Papaioannou and Aikaterini Martinopoulou and Ariadni Papadopoulou and Christos Kartsiounis and Magdalini Sterpi},
journal = {Cureus},
year = {2026},
month = oct,
doi = {10.7759/cureus.117572},
url = {https://europepmc.org/article/MED/42997248},
note = {CC BY},
}
RIS
TY - JOUR
TI - Fetal Supraventricular Tachycardia Complicated by Hydrops Fetalis: A Case Report of Complete Reversal With Transplacental Flecainide Therapy.
AU - Eleni Papaioannou
AU - Aikaterini Martinopoulou
AU - Ariadni Papadopoulou
AU - Christos Kartsiounis
AU - Magdalini Sterpi
PY - 2026
DA - 2026/10/07
JO - Cureus
DO - 10.7759/cureus.117572
UR - https://europepmc.org/article/MED/42997248
AB - 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.
SN - 2168-8184
ER -