Drug therapy for fetal arrhythmias

Diagnosis of specific types of fetal arrhythmias, especially tachyarrhythmias, is still difficult, often making semi-blind treatment inevitable. Published reports of many experienced clinicians show that digoxin remains a mainstream drug for therapy for fetal SVT and AF; digoxin is used as an initial monotherapy or in combination with other drugs if unresponsive to digoxin alone. It remains to be evaluated whether this treatment strategy offers overall better clinical outcomes than other approaches. Verapamil and propranolol are used in combination with digoxin, although successful control by propranolol seems rare. Quinidine and procainamide reportedly are effective in some cases. Reports on successful outcomes of flecainide therapy have emerged recently, although possible negative inotropic actions are of concern. Amiodarone is effective in some cases with incessant tachycardias, but risks of fetal thyroid dysfunction preclude its use as a firstline drug in uncomplicated fetal SVT cases. Empiric findings still prevail in the area of fetal drug therapy for arrhythmias, especially tachycardias. Heterogeniety of the conditions, lack of comparative studies, and difficulty in monitoring fetal drug level, let alone unbound drug concentrations, further complicate assessment of efficacy of different modes of treatment. Problems identified throughout this review have yet to be solved. Despite all these uncertain factors, however, it is clear that no one can undermine never-ending efforts of many clinicians in this exciting field of medicine.