Cardiac arrhythmias in the fetus and newborn.

Arrhythmias are potentially life-threatening problems in the fetus and newborn. Appropriate management depends on accurate diagnosis. Atrioventricular re-entry is the most common type of supraventricular tachycardia in both the fetus and newborn. It should be distinguished from other types of tachycardia - such as atrial flutter, atrial ectopic tachycardia, permanent junctional re-entry tachycardia, and ventricular tachycardia. Neonatal and fetal bradycardias are less common clinical problems. Sustained bradycardia is most often caused by complete atrioventricular block. It can be mimicked by the more common but benign occurrence of non-conducted atrial premature beats.