Intrauterine Adenosine Administration for the Treatment of Fetal Supraventricular Tachycardia in a Fetus With Aortic Stenosis

Fetal tachyarrhythmia and aortic stenosis (AS) both disrupt fetal hemodynamics, leading to congestive heart failure, hydrops, and intrauterine demise. Traditional transplacental treatments for fetal supraventricular tachycardia (SVT) include digoxin, flecainide, and sotalol. However, the treatment of fetal SVT in the setting of AS has not been described, particularly in cases of refractory SVT. We present a case of a 27-year-old nulliparous female carrying a fetus with fetal AS diagnosed at 25 weeks of gestational age (GA). The patient was not a candidate for in utero valvuloplasty. During ultrasound monitoring at 32 and 6/7 weeks of gestation, fetal SVT with a heart rate of 230-260 beats per minute (bpm) was diagnosed. Maternal digoxin was initiated, and sotalol was subsequently added. Due to persistent fetal SVT and a worsening cardiac function, the patient was treated with direct adenosine administration via cordocentesis successfully terminating the fetal arrhythmia. Despite continued transplacental treatment with digoxin and sotalol throughout the course of pregnancy, the fetal SVT recurred at 35 and 5/7 weeks of gestation prompting delivery. Our case illustrates the use of direct intrauterine adenosine as a novel treatment for refractory fetal SVT in the setting of congenital aortic stenosis and concern about progression to fetal hydrops and fetal demise.