Heart Block—Adult

(Atrioventricular [AV] Block—Adult)


The heart is made up of 4 chambers. The 2 upper chambers are the atria and the 2 lower chambers are the ventricles. The sinoatrial (SA) node, located near the top of the right atrium, produces electrical signals that are sent to the atrioventricular (AV) node. The AV node then sends the signals to the ventricles, which are the primary pumping chambers of the heart. The electrical signals are transmitted smoothly from the atria to the ventricles, causing rhythmic muscle contractions that pump blood to the rest of the body.
There are 3 types of heart block, ranging from mild to serious:
Third-degree heart block is very serious and requires immediate care from your doctor. First- and second-degree heart block should be diagnosed by your physician, who will help you determine the best course of treatment, if any.
Anatomy of the Heart
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Heart block often occurs when there is underlying heart disease. The causes of heart block include:

Risk Factors

Factors that may increase your chance of heart block include:


If you experience any of these symptoms, do not assume it is due to heart block. These symptoms may be caused by other, less serious health conditions:


Your doctor will ask about your symptoms and medical history. A physical exam will be done. You may be referred to a cardiologist or arrhythmia specialist.
Tests to evaluate the heart can be done with:


The course of treatment will depend on the type of heart block you have. Generally, treatment is not necessary for first-degree heart block.
Talk with your doctor about the best treatment plan for you. A pacemaker may be inserted for some cases of second-degree heart block, and all cases of third-degree heart block. A pacemaker is a device that generates electrical signals to stimulate heart muscle contractions.


To help reduce your chance of heart block:


American Heart Association

Heart Rhythm Society


Canadian Cardiovascular Society

Heart and Stroke Foundation of Canada


Conduction disorders. American Heart Association website. Available at: Updated October 25, 2012. Accessed March 22, 2013.

Gregoratos G. Indications and recommendations for pacemaker therapy. Am Fam Physician. 2005;71(8):1563-1570.

Heart block. Heart Rhythm Society website. Available at: Accessed March 22, 2013.

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