Abstract
Fetal tachyarrhythmias are infrequently encountered in utero. They are divided into subgroups including: atrial flutter/fibrillation, supraventricular tachycardia (SVT), sinus tachycardia, and atrial extrasystoles. Tachyarrhythmias can lead to fetal hydrops, congestive heart failure, and possibly fetal demise. Atrial flutter in a fetus is defined by an atrial rate of 300 to 600 beats per minute (bpm), with or without a 1:1 conduction rate to the ventricles. Atrioventricular reentrant tachycardia (AVRT) is the most common cause of supraventricular tachycardia and should be considered in cases of atrial tachycardia. Recognition of cardiac dysrhythmias is essential in early intervention. Cardiac antiarrthymic agents are frequently used with success to convert fetal dysrhythmias to a normal sinus rhythm. Digoxin is typically first-line therapy, and in more advanced or severe cases, additional drugs are often used.