Rate-based management of fetal supraventricular tachycardia.

We reviewed the ultrasonographic studies and the clinical course of 22 fetuses with supraventricular tachycardia to determine whether the heart rate alone could serve as a basis for conservative management. Hydrops was not encountered with heart rates under 230 beats per minute. The conditions of all 22 fetuses stabilized without invasive administration of medications. Eighteen were delivered vaginally and only four by cesarean section. No fetal or neonatal losses occurred. Regardless of the type of supraventricular tachycardia, reducing heart rate in these fetuses to levels preventing or resolving hydrops allowed term vaginal delivery, thereby reducing the substantial problems of ventilating an immature or hydropic neonate.