Fetal Arrhythmia and Related Fetal and Neonatal Outcome

The evolution of fetal echocardiography (Motion and pulsed Doppler modes) has made possible the antenatal diagnosis of cardiac rhythm anomalies. Fetal cardiac arrhythmias are common anomalies, 20% of which are potentially dangerous. M-mode (motion-mode) echocardiography recording of the fetal heart cannot identify electrical events in the heart, but does depict the mechanical events that succeed them. Pulsed Doppler echocardiography identifies possible arrhythmias over a period of time, allowing for the measurement of these time intervals, a parameter absolutely necessary for the classification of various types of cardiac arrhythmias. Irregular cardiac rhythm (premature atrial contraction, premature ventricular contractions) is the most common disorder seen in practice in specialized fetal echography. These anomalies are usually benign and resolve spontaneously until delivery, thus do not require treatment. Fetal tachyarrhythmia (increased heart rate of 160-189 bpm) is detected by echocardiography, with a wide range of rhythm disorders. It is imperative to understand the mechanism of tachyarrhythmia, so that an accurate and rational management strategy can be formulated in each case. Fetal bradyarrhythmia is characterized by frequent irregular rhythm, low sustained heart rate (10 seconds-few minutes), below 110 bpm, or a combination of both. The diagnosis of the specific bradycardia depends on the echocardiogram findings and the atrioventricular conduction pattern.Once fetal bradycardia is noted, a quick fetal ultrasonographic examination should be performed to assess the normal fetal movements, fetal tone, thus contributing to the diagnosis of fetuses in distress, who require emergency delivery by cesarean section. This paper is an update of the diagnostic approaches in the current practice for different types of fetal heart rhythm disorders, the impact on the fetus and the newborn and their management.