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Fetal Arrhythmia 

What is Fetal Arrhythmia?

Arrhythmia and dysrhythmia, which describe abnormal and irregular heartbeats, can happen to babies still in the womb. Some types of irregular and abnormal heartbeats are relatively benign and will not affect your baby at all; others types can cause mild or serious complications.

There are many types of arrhythmia and dysrhythmia, and they vary in severity:

  • 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 connect to the ventricle. A person with complete heart block may require a pacemaker.
  • 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 do not cause problems. In rare cases they can initiate tachy or brady arrhythmias that need intervention or monitoring.  

How is Fetal Arrhythmia diagnosed during pregnancy?

If your doctor suspects an arrhythmia after reviewing your routine ultrasound, he or she may request a fetal echocardiogram (ECHO), or an ultrasound of the fetal heart. The ECHO shows the structure of the heart and evaluates the contractions in different chambers of the heart, which can help us confirm the diagnosis and decide on the best option for treatment.

How is Fetal Arrhythmia monitored and treated during pregnancy?

Premature beats have very little, if any, effect on a fetus. Fetal tachycardia or bradycardia however, can cause heart failure either in the womb or at birth.

Bradycardia, if related to complete heart block needs to be closely followed in-utero to watch for development of heart failure. Mothers with autoimmune disease have specific antibodies which place the fetus at risk. The antibodies can cross the placenta and damage the conduction system of the baby’s heart.

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 Fetal Care Institute will monitor your baby closely during pregnancy and help coordinate a delivery plan.

How does Fetal Arrhythmia affect delivery, and how is it treated after birth?

Most babies with arrhythmia can be delivered vaginally at full-term, unless otherwise indicated by your obstetrician. With some more severe forms of arrhythmia, your baby may need to be delivered early or via C-section. After delivery, your baby will be monitored in the well baby nursery or the neonatal intensive care unit. 

What is the long-term prognosis and treatment after birth?

Overall, if treated early, the long-term prognosis for most arrhythmias is good. Babies with tachyarrhythmia may require medication to regulate their heart rates. In cases of severe bradycardia, your child may require surgical placement of a pacemaker. Your child will require follow-up care with a pediatric cardiologist.