Tachycardia in the Neonate

Atrial flutter (AFL) is the second most common type of tachyarrhythmia in the fetus and neonate. An atrial rate of 240 to 360 beats per minute, 2:1 atrioventricular conduction, and a "saw tooth" appearance on electrocardiogram (ECG) are characteristic. On echocardiogram, bilateral atrial dilatation is the most common finding. Treatment is dependent on the severity of symptoms; delivery is usually indicated in the case of fetal heart failure or hydrops fetalis, whereas postnatal AFL is most commonly treated with direct current cardioversion (DCC). This article presents an illustrative case in which the patient presented antenatally via abnormal nonstress testing and subsequent fetal echocardiogram that was concerning for AFL. Postnatal ECG confirmed this diagnosis and the patient received DCC on the day of birth, followed by digoxin and propranolol as maintenance therapy.