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(Atrioventricular [AV] Block—Adult)
- First-degree heart block—This is the mildest form of heart block. In this case, the electrical signals from the SA node move more slowly than normal to the AV node, but all signals reach the ventricles. There are usually no symptoms, and heartbeat and rhythm are normal. This type of heart block is often found in well-trained athletes.
Second-degree heart block—A second-degree heart block means that some of the electrical signals are not reaching the ventricles. This causes dropped beats. There are two types of second-degree heart block:
- Type I second-degree heart block, also called Mobitz Type I or Wenckebach’s AV block—The electrical signals become increasingly delayed with each heartbeat, causing a beat to be missed.
- Type II second-degree heart block, also called Mobitz Type II—In this type of heart block, some of the electrical signals do not reach the ventricles. This is less common, but more serious.
- Third-degree, or complete, heart block—This is the most serious type of heart block. In this condition, no electrical signals are able to reach the ventricles. The ventricles compensate by contracting on their own, but at a much slower rate than is safe for the heart to maintain full function.
|Anatomy of the Heart|
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- History of heart disease
- Use of medications such as beta blockers, calcium channel blockers, or digitalis
- Chest pain
- Shortness of breath
- Obtain treatment for any condition that may cause heart problems or heart disease. This will help prevent heart block.
- If possible, avoid medications that can cause heart block, such as beta blockers, calcium channel blockers, and digitalis.
- Maintain a healthy weight and lifestyle. Get regular exercise, eat a heart-healthy diet, and minimize stress.
- Avoid excessive consumption of alcohol and caffeine.
- Stop smoking.
American College of Cardiology http://www.acc.org
American Heart Association http://www.heart.org
Heart Rhythm Society http://www.hrsonline.org
Canadian Cardiovascular Society http://www.ccs.ca
Heart and Stroke Foundation of Canada http://ww2.heartandstroke.ca
Conduction disorders. American Heart Association website. Available at: http://www.heart.org/HEARTORG/Conditions/Arrhythmia/AboutArrhythmia/Conduction-Disorders%5FUCM%5F302046%5FArticle.jsp. Updated October 25, 2012. Accessed March 22, 2013.
Fauci AS, Braunwald E, Isselbacker KJ, et al. Harrison’s Principles of Internal Medicine . 14th ed. New York, NY: McGraw-Hill; 1998.
Gregoratos G. Indications and recommendations for pacemaker therapy. Am Fam Physician . 2005;71(8):1563-1570. Also available at: http://www.aafp.org/afp/2005/0415/p1563.html. Accessed on March 22, 2013.
Heart block. Heart Rhythm Society website. Available at: http://www.hrsonline.org/Patient-Resources/Heart-Diseases-Disorders/Heart-Block#axzz2OHs4EXZq. Accessed March 22, 2013.
- Reviewer: Michael J. Fucci, DO
- Review Date: 12/2013
- Update Date: 01/14/2014