Fetal Arrhythmia

Arrhythmias, abnormal or irregular heartbeats, can happen to babies still in the womb. Some types of irregular and abnormal heartbeats are relatively benign and will not affect the baby at all; others can be life-threatening.

There are many types of Fetal Arrhythmia:

• Tachycardia: The heartbeat is too fast.
• Supraventricular Tachycardia: A rapid heart rhythm that begins in the upper chambers of the heart.
• Bradycardia: The heartbeat is too slow.
• Complete Heart Block: The heartbeat that starts in the atrium does not travel to the ventricle. A person with complete heart block may require a pacemaker. This may happen in fetuses whose mothers have lupus.
• Premature Atrial Contractions: The heartbeat originates in a different part of the atrium than it normally would. These often occur in healthy people, have no symptoms, and typically do not cause problems. In rare cases they can cause supraventricular tachycardia.

If your doctor suspects an arrhythmia after reviewing your routine ultrasound, he or she may request a fetal echocardiogram (echo), an ultrasound of the fetal heart. This safe, noninvasive test shows the structure of the heart and helps determine the type of arrhythmia. This can help us confirm the diagnosis and discuss possible options for treatment.

How is it monitored and treated during and after pregnancy?

Premature heartbeats may have no effect on a fetus. Fetal tachycardia or bradycardia can cause heart failure either in the womb or at birth.

Bradycardia related to complete heart block needs to be closely followed in-utero to watch for development of heart failure.

Supraventricular tachycardia may require treatment before birth, because it can result in heart failure. Typically, mothers are hospitalized and started on medications that help control the fetal heart rate. After delivery, these babies are monitored and may require medication. Our Fetal Heart Team at the Cardinal Glennon St. Louis Fetal Care Institute will monitor your baby closely during pregnancy and help coordinate a delivery plan.

What is the long-term prognosis?

Overall, if treated early, the long-term prognosis for most arrhythmias is good. Babies with tachyarrhythmia may require medication to regulate their heart rates. Some children or adolescents require a minimally invasive procedure to control the arrhythmia. In cases of severe bradycardia, the child may require surgical placement of a pacemaker. Follow-up care with a pediatric cardiologist is crucial to ensure long-term health.