Bradycardia - At a Glance


 

Description

What is bradycardia?
Bradycardia is a condition in which the heart beats too slowly – usually less than 60 beats per minute. As a result, your body does not get enough oxygen and nutrients to function properly. Learn more.


Causes and Risk Factors

What causes bradycardia?
Bradycardia may be caused by a problem with your heart's natural pacemaker (sinoatrial or S-A node) or a problem with your heart's electrical pathways. Learn more.


Symptoms

What are the symptoms of bradycardia?
Someone with bradycardia may feel tired, light-headed, or dizzy. Learn more.


Diagnosis

How is bradycardia diagnosed?
To diagnose bradycardia, your doctor will typically use an electrocardiogram (ECG) test. Learn more.


Treatment

How is bradycardia treated?
Doctors may prescribe medications, a pacemaker, or both for the treatment of bradycardia. Learn more.


Success Stories

What is it like to have a pacemaker?
Patients with bradycardia can live full and active lives. Learn more.


 

Description

What is bradycardia?
A normal heart typically beats 60 to 80 times a minute. At this rate, the heart pumps about 5 liters of blood throughout your body per minute. However, if the signal rate is too slow, the chambers of your heart do not contract often enough to supply the proper amount of blood and oxygen to your body. This condition is called bradycardia.

 

Bradycardia - Watch the Video [00:07]

 

 

Bradycardia can affect the very young to the very old, though it is most commonly diagnosed among the elderly. More than 600,000 people worldwide receive treatment each year for bradycardia.

 

 

Causes and Risk Factors

What causes bradycardia?
The most common causes of bradycardia are a problem with the S-A node or a problem in the heart's electrical pathways. These problems result in heartbeats that don't sufficiently meet the needs of your body.

To illustrate this idea, think of how a car works. If the accelerator is broken, the engine can't get enough gas to move the car as fast as you want. Similarly, if your heart's electrical system is not working normally, your body may not receive the extra fuel it needs to take a brisk walk.

Problems with the S-A Node
Problems with the heart's natural pacemaker can cause bradycardia. These types of rhythms are called sick sinus syndrome. The S-A node may not send signals frequently enough, which causes the heart to contract less often than it should. A slow heartbeat is typically less than 60 beats per minute (bpm).

Problems with the S-A node can also show up with a heart rate that is not matched to the work you are doing. This is called “chronotropic incompetence.” When you have chronotropic incompetence, you may feel tired when you are doing activities. This can occur at the beginning, middle, or later in the activity. This is caused by a heart beat that is late or not fast enough to give your body the oxygen-rich blood it needs.

Bradycardia Rhythm and ECG Illustration

Problems with the electrical pathway between the upper and lower heart (heart block)
Problems may also occur with the electrical pathway between the upper and lower heart. The electrical signals may be delayed in the A-V node or may fail to reach the ventricles all together. This condition is called heart block. Although the lower heart has a natural standby system that can produce its own heartbeat, this heartbeat is often too slow and unreliable. As a result, heart block often means that the ventricles pump too slowly even though the S-A node may be sending out faster signals in an effort to increase heart rate.

Heart Block Rhythm and ECG Illustration

Heart block may also cause a loss of AV synchrony. If the timing of contractions between the upper and lower heart is poor, the ventricles may not fill with enough blood before pumping. Your doctor may call this condition asynchrony.

 

 

 

Syncope
Syncope, or fainting, is one of the top 10 reasons for ER visits in America.1 Syncope (SIN'ko-pe) is temporary loss of consciousness and posture, described as "fainting" or "passing out." It most often occurs when the blood pressure is too low (hypotension) and the heart doesn't pump a normal supply of oxygen to the brain.

 

Bev Seavers, Syncope - Watch the Video [00:35]

 

 

Neurocardiogenic syncope is called also vasovagal, vasodepressor, neurally-mediated syncope (NMS) or reflex-mediated syncope. From 25 percent to 40 percent of fainting disorders are due to neurocardiogenic syncope.1

Neurocardiogenic syncope may be experienced by normal persons with no evidence of heart disease. The fainting event is triggered by emotional stress, nausea, pain, etc., and causes a sudden drop in blood pressure or heart rate.

Neurocardiogenic syncope is the most common cause of fainting in young people. Some adolescents have frequent fainting spells, but many physicians who treat syncope report that most of their young patients have "grown out" of the condition by the time they reach their mid-twenties.

Treatment depends on the cause for fainting – blood pressure or heart rate drop. Your doctor will discuss treatment options with you.2

 

Symptoms

What are typical symptoms of bradycardia?
Typical symptoms of bradycardia include fatigue, shortness of breath, and dizziness. Even routine activities, such as getting up from a chair or walking to the mailbox, may leave you short of breath. Often, the symptoms of bradycardia occur gradually, which causes many people to think they are "just tired" or "getting older" rather than that they are experiencing a heart problem.

Diagnosis

How is bradycardia diagnosed?
To diagnose bradycardia, your doctor will typically use an electrocardiogram (ECG) test. This is a painless test using electrode patches on your skin that shows how electrical signals travel through your heart. An ECG can be printed out on paper. Your doctor can tell what kind of rhythm you have by looking at the printed pattern of your heartbeat.

 

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Treatment

How is bradycardia treated?
Bradycardia is most commonly treated with a pacemaker. A pacemaker changes the heart rate to help meet your body's needs. The pacemaker provides signals much like the heart's normal signals. Depending on your particular situation, a pacemaker may:

  • Replace S-A node signals that are delayed or get lost on the pathway between the upper and lower heart chambers
  • Help maintain a normal timing sequence between the upper and lower heart chambers
    Enable the lower chambers of the heart contract at an adequate rate
  • Enable the lower chambers of the heart contract at an adequate rate

 

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Image of Patient Dave Peterson

Success Stories

People living with a pacemaker.
Dave Peterson tells his story about living with bradycardia.

 

 

Next: Cardiomyopathy >>

 

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Note: Individual symptoms, situations, and circumstances may vary. Please consult your physician or qualified healthcare provider regarding your condition and appropriate medical treatment. The information provided is not intended to be used for medical diagnosis or treatment, or as a substitute for professional medical advice.

1. Centers for Disease Control and Prevention, DHHS Publication No. (PHS) 2008–1250, August 2008. National Hospital Ambulatory Medical Care Survey: 2006 Emergency Department Summary.
2. Epstein AE, et al. ACC/AHA/NASPE 2008 Practice Guidelines for Device-base Therapy of Cardiac Rhythm Abnormalities. J. Am. Coll. Cardiol. 2008;51;e1-e62.

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