Resolution of hydrops fetalis despite persistent fetal tachycardia

Digoxin is the most commonly used medication in the treatment of fetal supr aventricular tachycardias (SVTs). Reports have varied with regard to the pe rcent transfer of maternally administered digoxin across the placenta, rang ing from 100%(1) to virtually zero,(1-3) because the extent and severity of hydrops present in the placenta and fetus affect the rate of transfer. The re are, however, numerous reports of successful conversion to a normal feta l heart rate after maternal administration of digoxin with or without the a ddition of other therapeutic agents.(1,2,4) We report a case in which mater nally administered digoxin was successful in reversing fetal hydrops withou t restoration of a normal fetal heart rate. This supports the view by Klein man et al(3) that in this case without rate control, digoxin also works by improving systolic function in a relatively noncompliant fetal ventricle.