Fetal Arrhythmia: Bradycardia and Tachycardia

Fetal arrhythmia is a common observation during an obstetrical fetal assessment. Most abnormal heart rhythms detected in utero are benign and resolve spontaneously. However, sustained and extreme tachycardia or bradycardia can result in fetal hydrops or even in utero fetal demise. Therefore, prompt evaluation and appropriate prenatal management are crucial when fetal arrhythmia is observed. The determination of the nature of arrhythmia, however, may be challenging. In this chapter, we review the various abnormal heart rhythms encountered during fetal life and the fetal echocardiographic evaluation methods used to determine the nature of arrhythmia, both bradycardias and tachycardias, as well as the approach in perinatal management.