Treatment of intrauterine supraventricular tachycardia with digoxin and verapamil.

Intrauterine fetal supraventricular tachycardia (ISVT) is a rare condition which is connected with organic heart disease in only 4-10 per cent. However, neonatally these children develop heart failure in a high frequency (62 per cent). Intrauterine digitalization has been suggested as treatment, especially if the fetus is preterm. Fetal therapeutic concentrations might demand doses inconvenient to the mother. We hereby report one case of intrauterine SVT in the 26th gestational week treated with a standard dose of digoxin resulting in subtherapeutic umbilical digoxin levels. When no consistent influence on fetal heart rate could be seen, verapamil (80 mg x 3) was added to the treatment. A reversion of the tachycardia and the fetal ECG changes was achieved within two days. The verapamil treatment could be withdrawn after ten days, while the digoxin treatment was continued. An initial discrete heart enlargement also was reversed by the treatment. The delivery in gestational week 38 was uneventful and the child did well. A neonatal ECG showed a sinus rythm interfoliated with supraventricular extrasystoles. No signs of organic heart disease have appeared. When last seen at nine months of age, the ECG was normal and digoxin had been discontinued without recurrence of tachycardia.