Heart Block—Adult

(Atrioventricular Block—Adult; AV Block—Adult)

by Amy Scholten, MPH

Definition

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:

First-degree (mildest type)—The heart signals move more slowly from one heart node to another.
Second-degree—Signals from the upper to lower heart are blocked, off and on.
Third-degree, or complete (most serious)—The heart signals cannot pass from the upper to the lower heart at all. This needs care right away.

Anatomy of the Heart

Causes

Heart block is caused by:

Underlying heart disease or certain heart defects
Certain medicines

Risk Factors

The risk of heart block increases with age. Other things that may raise the risk are:

History of heart disease, such as a heart attack, heart failure, valve problems, and endocarditis
An inherited heart defect
Conditions that affect the heart such as sarcoidosis, rheumatic fever, or Lyme disease
Medicines such as beta-blockers, calcium channel blockers, or digitalis

Symptoms

Symptoms of heart block may be:

Lightheadedness
Fainting
Chest pain
Problems breathing

Diagnosis

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:

ECG—tests electrical activity of the heart
Echocardiogram—imaging exam of the heart to look for structural heart disease

Treatment

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.

Prevention

Some heart block cannot be prevented. For others, the risk may be lowered by:

Treating heart problems
A heart healthy lifestyle that includes:
- Regular exercise
- A diet low in animal fat and rich in lean proteins, vegetables, and fruit
- Reducing stress
- Not smoking
- Limiting or not using alcohol and caffeine
Not using medicines that can cause heart block

RESOURCES:

American Heart Association
http://www.heart.org/

Heart Rhythm Society
http://www.hrsonline.org/

CANADIAN RESOURCES:

Canadian Heart Rhythm Society
http://www.chrsonline.ca

Heart and Stroke Foundation of Canada
http://www.heartandstroke.ca

References:

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

EBSCO Information Services is fully accredited by URAC. URAC is an independent, nonprofit health care accrediting organization dedicated to promoting health care quality through accreditation, certification and commendation.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

To send comments or feedback to our Editorial Team regarding the content please email us at healthlibrarysupport@ebsco.com. Our Health Library Support team will respond to your email request within 2 business days.