Bradycardia (Slow Heart Rate)

Topic Overview

What is bradycardia?

Having bradycardia (say “bray-dee-KAR-dee-uh”) means that your heart beats very slowly. For most people, a heart rate of 60 to 100 beats a minute while at rest is considered normal. If your heart beats less than 60 times a minute, your doctor may diagnose bradycardia.

A slow heart rate is sometimes normal and can be a sign of being very fit. Healthy young adults and athletes often have heart rates of less than 60 beats a minute.

In other people, bradycardia is a sign of a problem with the heart’s electrical system. It means that the heart's natural pacemaker is not working right or that the electrical pathways of the heart are disrupted. In severe forms of bradycardia, the heart beats so slowly that it does not pump enough blood to meet the body's needs. This can be life-threatening.

What causes bradycardia?

Bradycardia can be caused by:

• Changes in the heart that are the result of aging.
• Diseases that damage the heart's electrical system. These include coronary artery disease, heart attack, and infections such as endocarditis and myocarditis.
• Conditions that can slow electrical impulses through the heart. Examples include having a low thyroid level (hypothyroidism) or an electrolyte imbalance, such as too much potassium in the blood.
• Some medicines for treating heart problems or high blood pressure, such as beta-blockers, antiarrhythmics, and digoxin.

What are the symptoms?

A very slow heart rate may cause you to:

• Feel dizzy or lightheaded.
• Feel short of breath and find it harder to exercise.
• Feel tired.
• Have chest pain or a feeling that your heart is pounding or fluttering (palpitations).
• Feel confused or have trouble concentrating.
• Faint, if a slow heart rate causes a drop in blood pressure.

Some people don't have symptoms, or their symptoms are so mild that they think they are just part of getting older.

You can find out how fast your heart is beating by taking your pulse. If your heartbeat is slow or uneven, talk to your doctor.

How is bradycardia diagnosed?

Your doctor may be able to diagnose bradycardia by doing a physical exam, asking questions about your past health, and doing an electrocardiogram (EKG or ECG). An EKG measures the electrical signals that control heart rhythm, so it is the best test for bradycardia.

But bradycardia often comes and goes, so a standard EKG done in the doctor’s office may not find it. An EKG can identify bradycardia only if you are actually having it during the test.

You may need to use a portable (ambulatory) electrocardiogram. This lightweight device is also called a Holter monitor or a cardiac event monitor. You wear the monitor for a day or more, and it records your heart rhythm while you go about your daily routine.

You may also have blood tests to find out if another problem is causing your slow heart rate.

How is it treated?

How bradycardia is treated depends on what is causing it. Treatment also depends on the symptoms. If bradycardia does not cause symptoms, it usually is not treated.

• If damage to the heart’s electrical system causes your heart to beat too slowly, you will probably need to have a pacemaker. A pacemaker is a device placed under your skin that helps correct the slow heart rate. People older than 65 are most likely to have a type of bradycardia that requires a pacemaker.
• If another medical problem, such as hypothyroidism or an electrolyte imbalance, is causing a slow heart rate, treating that problem may cure the bradycardia.
• If a medicine is causing your heart to beat too slowly, your doctor may adjust the dose or prescribe a different medicine. If you cannot stop taking that medicine, you may need a pacemaker.

The goal of treatment is to raise your heart rate so your body gets the blood it needs. If severe bradycardia is not treated, it can lead to serious problems. These may include fainting and injuries from fainting, as well as seizures or even death.

What can you do at home for bradycardia?

Bradycardia is often the result of another heart condition, so taking steps to improve your heart health will usually improve your overall health. The best steps you can take are to:

• Control your cholesterol and blood pressure.
• Eat a low-fat, low-salt diet.
• Get regular exercise. Your doctor can tell you what level of exercise is safe for you.
• Quit smoking, if you smoke.

Get emergency help if you faint, have chest pains, or have severe shortness of breath. Call your doctor right away if your heart rate is slower than usual, you feel like you might pass out, or you notice increased shortness of breath.

Pacemakers

People who get pacemakers need to be careful around strong magnetic or electrical fields, such as MRI machines or magnetic wands used at airports. If you get a pacemaker, your doctor will give you information about the type you have and what precautions to take.

For example, call your doctor right away if you have symptoms that could mean your device is not working right, such as:

• Your heartbeat is very fast or slow, skipping, or fluttering.
• You feel dizzy, lightheaded, or like you might faint.
• You have shortness of breath that is new or getting worse.

Health Tools

Health Tools help you make wise health decisions or take action to improve your health.

	Decision Points focus on key medical care decisions that are important to many health problems.
	Heart Rate Problems: Should I Get a Pacemaker?
	Actionsets are designed to help people take an active role in managing a health condition.
	Heart Problems: Living With a Pacemaker or ICD

Frequently Asked Questions

Learning about bradycardia:	What is bradycardia? What are the types of bradycardia? Who gets bradycardia? How does the heart’s electrical system work? What is heart block? What is sick sinus syndrome?
Being diagnosed:	What is a medical history and physical exam for slow heart rate? What is the tilt table test? What is ambulatory heart monitoring? What is an exercise test? What is an electrophysiology study?
Getting treatment:	What are the different types of bradycardia, and how are they treated? How is a pacemaker used to treat bradycardia? Should I get a pacemaker?
Ongoing concerns:	What are the risks of complications with different types of bradycardias? How can bradycardia make me pass out? How can I keep track of my symptoms?
Living with a pacemaker or ICD	What do I need to know about living with a pacemaker or ICD? Can I exercise with a pacemaker? How do I check my pacemaker? What is telephone monitoring for pacemakers? What's new in pacemaker technology?

Other Places To Get Help

Organizations

American Heart Association (AHA)
7272 Greenville Avenue
Dallas, TX  75231
Phone:	1-800-AHA-USA1 (1-800-242-8721)
Web Address:	www.heart.org
Visit the American Heart Association (AHA) website for information on physical activity, diet, and various heart-related conditions. You can search for information on heart disease and stroke, share information with friends and family, and use tools to help you make heart-healthy goals and plans. Contact the AHA to find your nearest local or state AHA group. The AHA provides brochures and information about support groups and community programs, including Mended Hearts, a nationwide organization whose members visit people with heart problems and provide information and support.
Heart Rhythm Society
1400 K Street NW
Suite 500
Washington, DC  20005
Phone:	(202) 464-3400
Fax:	(202) 464-3401
Web Address:	www.hrsonline.org
The Heart Rhythm Society provides information for patients and the public about heart rhythm problems. The website includes a section that focuses on patient information. This information includes causes, prevention, tests, treatment, and patient stories about heart rhythm problems. You can use the Find a Specialist section of the website to search for a heart rhythm specialist practicing in your area.
National Heart, Lung, and Blood Institute (NHLBI)
P.O. Box 30105
Bethesda, MD  20824-0105
Phone:	(301) 592-8573
Fax:	(240) 629-3246
TDD:	(240) 629-3255
Email:	nhlbiinfo@nhlbi.nih.gov
Web Address:	www.nhlbi.nih.gov
The U.S. National Heart, Lung, and Blood Institute (NHLBI) information center offers information and publications about preventing and treating: Diseases affecting the heart and circulation, such as heart attacks, high cholesterol, high blood pressure, peripheral artery disease, and heart problems present at birth (congenital heart diseases). Diseases that affect the lungs, such as asthma, chronic obstructive pulmonary disease (COPD), emphysema, sleep apnea, and pneumonia. Diseases that affect the blood, such as anemia, hemochromatosis, hemophilia, thalassemia, and von Willebrand disease.

Related Information

• Atrial Fibrillation
• Cardiac Rehabilitation
• Coronary Artery Disease
• Supraventricular Tachycardia

References

Other Works Consulted

• Baddour LM, et al. (2010). Update on cardiovascular implantable electronic device infections and their management. A scientific statement from the American Heart Association. Circulation, 121(3): 458–477.

• Cheng S, et al. (2009). Long-term outcomes in individuals with prolonged PR interval or first-degree atrioventricular block. JAMA, 301(24): 2571–2577.

• Epstein AE, et al. (2008). ACC/AHA/HRS 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the ACC/AHA/NASPE 2002 Guideline Update for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices): Developed in Collaboration With the American Association for Thoracic Surgery and Society of Thoracic Surgeons. Circulation, 117(21): e350–e408. [Correction in Circulation, 120(5): e34–e35.]

• Gregoratos G, et al. (2002). ACC/AHA/NASPE 2002 guideline update for implantation of cardiac pacemakers and antiarrhythmia devices: Summary article. Circulation, 106(16): 2145–2161.

• Hayes DL, Zipes DP (2008). Cardiac pacemakers and cardioverter-defibrillators. In P Libby et al., eds., Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th ed., vol. 1, pp. 831–861. Philadelphia: Saunders Elsevier.

• Olgin JE, Zipes DP (2008). Bradyarrhythmias section of Specific arrhythmias: diagnosis and treatment. In P Libby et al., eds., Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, 8th ed., vol. 1, pp. 909–913. Philadelphia: Saunders Elsevier.

• Vijayaraman P, Ellenbogen KA (2004). Bradyarrhythmias and pacemakers. In V Fuster et al., eds., Hurst's The Heart, 11th ed., pp. 893–925. New York: McGraw-Hill.

• Wilkoff BL, et al. (2008). HRS/EHRA expert consensus on the monitoring of cardiovascular implantable electronic devices (CIEDS): Description of techniques, indications, personnel, frequency and ethical considerations. Heart Rhythm, 5(6): 907–925. Available online: http://www.hrsonline.org/Policy/ClinicalGuidelines/upload/cieds_guidelines.pdf.

• Wolbrette DL, Naccarelli GV (2007). Bradycardias: Sinus nodal dysfunction and atrioventricular conduction disturbances. In EJ Topol et al., eds., Textbook of Cardiovascular Medicine, 3rd ed., pp. 1038–1049. Philadelphia: Lippincott Williams and Wilkins.

Credits

By	Healthwise Staff
Primary Medical Reviewer	Caroline S. Rhoads, MD - Internal Medicine
Specialist Medical Reviewer	John M. Miller, MD - Electrophysiology
Last Revised	November 18, 2010

By:	Healthwise Staff	Last Revised: November 18, 2010
Medical Review:	Caroline S. Rhoads, MD - Internal Medicine John M. Miller, MD - Electrophysiology
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