by EBSCO Medical Review Board
(Atrioventricular [AV] Block—Child)


The heart has two upper chambers called atria and two lower chambers called ventricles. Electrical signals move through nerve bundles to the atria then to the ventricle. The heart pumps rhythmically when the electrical signals pass through as they should.

Heart block happens when the electrical activity of the heart does not travel in the normal way. The heart can still pump blood, but it beats much slower and less efficiently.

There are three types that range from mild to severe:

  • First-degree heart block—Electrical signals reach all parts of the heart but move more slowly than normal. There are usually no symptoms and heartbeat is normal.
  • Second-degree heart block—Some of the electrical signals do not reach the ventricles. This means that sometimes the ventricles do not pump when they should.
  • Third-degree (complete) heart block—No electrical signals are able to reach the ventricles. Cells in the ventricles act as a backup and create their own electrical signals. This allows the ventricles to keep pumping, but it is slower and out of rhythm with the rest of the heart.
Anatomy of the Heart
Copyright © 2002 Nucleus Communications, Inc. All rights reserved.


This problem may be caused by:

  • A heart defect caused by genetics
  • Certain medicines
  • Damage from surgery
  • Infections, such as Lyme disease
  • Lupus in the mother
  • Electrolyte problems
  • An autoimmune disorder

Risk Factors

Things that may raise the risk of this problem are:

  • Prior heart problems like heart failure or valve problems
  • Certain medicines
  • Exposure to toxins


Some children do not have symptoms. Others may have:

  • Lightheadedness
  • Fainting
  • Chest pain
  • Shortness of breath
  • Rapid or slow heartbeat
  • Weakness or lack of energy


The doctor will ask about your child’s symptoms and health history. A physical exam will be done.

The electrical activity of your child's heart may be tested. This can be done with an electrocardiogram (EKG) .


Treatment will depend on the type of heart block your child has. A first-degree heart block may not need treatment.

A pacemaker may be needed for some children with second-degree heart block and all children with third-degree heart block. The pacemaker will send regular electrical signals to the heart. It will keep the heart beating in a more efficient rhythm.


There are no known guidelines to prevent this health problem.


CardioSource—American College of Cardiology 

Heart Rhythm Society 


Canadian Cardiovascular Society 

Heart and Stroke Foundation of Canada 


Atrioventricular (AV) conduction disorders. EBSCO DynaMed website. Available at: Accessed March 9, 2021.

Conduction disorders. National Heart, Lung and Blood Institute website. Available at: Accessed March 9, 2021.

Heart block. Heart Rhythm Society website. Available at: Accessed March 9, 2021.

Heart block. UCSF Benioff Childrens’ Hospital website. Available at: Accessed March 9, 2021.

Kusumoto FM, Schoenfeld MH, et al. 2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay. Circulation. 2019 Aug 20;140(8):e382-e482.

Revision Information

  • Reviewer: EBSCO Medical Review Board Kari Kassir, MD
  • Review Date: 12/2020
  • Update Date: 03/09/2021