Congenital Heart Block (CHB)

What is congenital heart block?

Congenital heart block (CHB), or atrioventricular block, occurs when there is a problem with the transfer of the electrical nerve impulses that typically regulate heartbeat and actions of the heart. Fortunately, this condition does not affect blood flow or lead to heart attacks. 

There are three degrees of heart block, all varying based on severity. 

What are the symptoms of congenital heart block?

The symptoms vary depending on severity, the age of the patient, and the underlying cause of the block. A newborn affected by this condition may experience signs of congestive heart failure, be very pale, have heart murmurs, and have a very slow heart rate. 

Other common symptoms include: 

• Decreased exercise tolerance
• Fainting
• Fatigue
• Issues with breathing
• Lack of energy
• Breathlessness 
• Chest pain
• Dizziness
• Enlarged heart

What causes congenital heart block?

A large portion (about half) of cases are caused by an autoimmune disorder of the mother, such as Sjogren’s syndrome or systemic lupus erythematosus. Other causes include a structural abnormality of the heart, inherited and idiopathic, and another condition or tumor. 

How is congenital heart block diagnosed?

Cardiac imaging tests are used to diagnose CHB, such as a fetal echocardiography and fetal electrocardiography. A diagnosis can be obtained while the fetus is still within the mother or after being born. In some cases, a diagnosis does not come until childhood. 

What are the treatments for congenital heart block?

If the block has been diagnosed prenatally, then a doctor may prescribe the mother with adrenocorticosteroids. If the block is severe, early delivery may be necessary. 

For babies and children, a pacemaker is the most commonly used therapy. Alongside a pacemaker, a doctor may prescribe atropine. 

Where can I find out more about congenital heart block?

• • • NORD
    • NIH
    • Texas Children’s Hospital