Heart block is when signals that control the heartbeat are partly or fully blocked. This leads to slow or skipped heartbeats. It also makes it hard for the heart to pump blood. Heart block can range from mild to serious and life-threatening.
There are 3 types of heart block:
Anatomy of the Heart
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Heart block is caused by:
The risk of heart block increases with age. Other things that may raise the risk are:
Your doctor will ask about symptoms and past health. A physical exam will be done. A heart doctor may make the diagnosis.
Diagnosis is based on tests, such as:
Treatment depends on the type of heart block. In general, treatment may not be needed for first-degree heart block.
If medicines are causing heart block, they will be stopped or changed.
Some second degree—and all third degree heart block—will need a pacemaker. A pacemaker is an implanted device to help the heart beat at a normal pace.
Underlying conditions will also need to be treated.
Some heart block cannot be prevented. For others, the risk may be lowered by:
American Heart Association
Heart Rhythm Society
Canadian Heart Rhythm Society
Heart and Stroke Foundation of Canada
Atrioventricular (AV) conduction disorders. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/atrioventricular-av-conduction-disorders. Accessed September 14, 2021.
Atrioventricular block. Merck Manual Professional Version website. Available at: https://www.merckmanuals.com/professional/cardiovascular-disorders/arrhythmias-and-conduction-disorders/atrioventricular-block. Accessed September 14, 2021.
Bolourchi M, Silver ES, et al. Advanced heart block in children with Lyme disease. Pediatr Cardiol. 2019;40(3):513-517.
Heart block. Heart Rhythm Society website. Available at: https://upbeat.org/heart-rhythm-disorders/heart-block#axzz2OHs4EXZq. Accessed September 14, 2021.
Heart conduction disorders. American Heart Association website. Available at: https://www.heart.org/en/health-topics/arrhythmia/about-arrhythmia/conduction-disorders. Accessed September 14, 2021.
Last reviewed July 2021 by
EBSCO Medical Review Board
Nicole Meregian, PA
Last Updated: 9/14/2021