Intrauterine therapy of fetal tachyarrhythmias: intraperitoneal administration of antiarrhythmic drugs to the fetus in fetal tachyarrhythmias with severe hydrops fetalis.

In cases of fetal tachyarrhythmia with congestive heart failure accompanied by signs of non-immune hydrops fetalis, the transplacental treatment of the fetus with antiarrhythmic agents by administration of drugs to the mother is only rarely successful. In the two cases reported, the cardioversion of a supraventricular tachycardia to a sinus rhythm or a constant 2:1 AV conduction block to a 1:1 AV conduction with atrial flutter could only be achieved after additional antiarrhythmic treatment directly administered to the fetus using ultrasound guidance. Drugs used include: beta-methyldigoxin, verapamil, propafenon, and they were administered according to the dosing amounts for intravascular injections. This was carried out 12 times in case 1 by the intraperitoneal route into the fetal ascites and twice in case 2. This led in both cases to varying durations of a sustained sinus rhythm after 5-15 minutes. This technically relatively simple procedure affords the option of rapidly achieving high concentrations, even when antiarrhythmic agents are administered which do not adequately cross the placenta. This direct treatment is indicated in cases of tachyarrhythmia with advanced signs of non-immune hydrops fetalis as a supplement to the high-dose transplacental therapy using antiarrhythmic agents.