Bradycardia (Slow Heart Rate)

Overview

What is bradycardia?

Having bradycardia (say “bray-dee-KAR-dee-uh”) means 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.
• Stop smoking.
• Limit alcohol.
• Take your medicines as prescribed.
• See your doctor for regular follow-up care.

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.

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	Heart problems: Living with a pacemaker or ICD

Frequently Asked Questions

Cause

Bradycardia can be caused by:

• Conditions that damage the heart's electrical system and disrupt the regular, rhythmic impulses that keep the heart rate normal. These conditions include:
  • The aging process. A slow heart rate may develop as a result of age-related changes in the heart.
  • Coronary artery disease .
  • Heart attack .
  • Heart surgery.
  • Myocarditis .
  • Endocarditis .
  • Sarcoidosis .
  • Lyme disease .
• Conditions or medicines that slow the passing of electrical signals through the heart but are not the result of heart damage. These conditions include:
  • Hypothyroidism (underactive thyroid gland).
  • Electrolyte imbalances, such as abnormal blood levels of potassium (hyperkalemia).
  • In some people, certain circumstances, such as standing for a long time, pain, coughing, and vomiting, that stimulate the nervous system and slow the heart rate. The slow heart rate is usually temporary.
  • Heart medicines, such as beta-blockers , calcium channel blockers , antiarrhythmics , and digoxin .

Symptoms

Symptoms of bradycardia usually occur when the heart is not pumping enough blood to meet the body's needs. This often happens when the heart rate is very slow or remains slow for a long period of time.

Some people with bradycardia do not have symptoms. But if you have symptoms, they may include:

• Dizziness or lightheadedness.
• Fainting ( syncope ) or near-fainting.
• Tiredness (fatigue).
• Shortness of breath.
• Palpitations .
• Chest pain ( angina ).
• More difficulty exercising.
• Confusion or difficulty concentrating.

What Increases Your Risk

Your risk of developing an abnormally slow heart rate ( bradycardia ) is greater if you:

• Have certain types of heart disease.
• Are taking certain medicines.
• Are age 65 or older.
• Have recently had heart surgery.

When to Call a Doctor

Call 911 or other emergency services immediately if you experience any of the following:

• Fainting
• Severe shortness of breath
• Chest pain
• Signs of a heart attack or stroke

Call your health professional immediately if you have both a slower-than-usual heart rate and you:

• Feel like you might pass out.
• Have a pacemaker .
• Notice increased shortness of breath.
• Notice swelling in your feet and ankles.

Note that increased shortness of breath or swelling in your feet and ankles may be early symptoms of heart failure .

Call your doctor right away if you have a pacemaker or ICD and think you have an infection near the device. Signs of an infection include:

• Changes in the skin around your pacemaker or ICD, such as:
  • Swelling.
  • Warmth.
  • Redness.
  • Pain.
• Unexplained fever.

Watchful Waiting

Watchful waiting, which is taking a wait-and-see approach, is not appropriate if you have symptoms that may be caused by a slow heart rate .

Watchful waiting includes checking your heart rate. You can find out your heart rate by checking your pulse .

Who to See

The following health professionals can evaluate symptoms of a slow heart rate:

• Family medicine doctor
• Internist
• Cardiologist
• Nurse practitioner
• Physician assistant

Exams and Tests

A doctor can sometimes diagnose bradycardia by:

• Asking questions about your medical history.
• Doing a physical exam.
• Using an electrocardiogram (EKG, ECG).

An EKG also helps determine what type of slow heart rate you have. This noninvasive test can also provide information about contributing factors, such as a recent heart attack or other underlying heart conditions.

If your bradycardia comes and goes and is not recorded during the EKG that is done during your office visit, you may need ambulatory heart monitoring (Holter or cardiac event monitoring). This type of monitoring uses a portable EKG machine to record the electrical activity of your heart while you go about your daily routine.

To see if there are other conditions that may be causing your slow heart rate, you may have lab tests, such as a:

• Thyroid function, to check for hypothyroidism.
• Chemistry screen, to check for electrolyte imbalances.

If you take a cardiac medicine called digoxin, you may have blood tests to see whether high levels of digoxin could be causing bradycardia.

If the cause of your symptoms is still not clear, you may need other testing. This may include:

• Ambulatory heart monitoring, such as Holter or cardiac event monitoring.
• Exercise testing. This test uses EKG to record your heart's electrical activity during exercise.
• Tilt table testing.
• Electrophysiology study.

Treatment Overview

Treatment for bradycardia depends on its underlying cause, whether it is causing symptoms, and whether it is likely to get worse. After your doctor knows the exact cause of your slow heart rate, he or she will determine which treatment you need.

Typically, bradycardia needs to be treated if it is causing symptoms such as fainting or severe, disabling fatigue.

Initial treatment

In an emergency situation when the heart rate slows suddenly, such as after a heart attack, you may need medicines given intravenously for a short time to increase your heart rate.

If another heart condition has damaged your heart's electrical system, your doctor will check to see whether a pacemaker is right for you. You may receive a temporary pacemaker until a permanent pacemaker can be placed.

If an underlying disease, such as hypothyroidism or abnormal potassium levels, is causing your slow heart rate, your doctor will treat that condition. If your bradycardia is caused by heart medicines, such as beta-blockers , calcium channel blockers , antiarrhythmics , or digoxin , your doctor will try to adjust your medicines.

Ongoing treatment

Bradycardia is often caused by an underlying heart condition that has damaged the heart's electrical system. People older than 65 are most likely to develop one of several different types of bradycardia that usually require a permanent pacemaker .

If heart medicines such as beta-blockers , calcium channel blockers , antiarrhythmics , or digoxin are causing bradycardia, your doctor most likely will try first to adjust or change medicines. But many times the medicines cannot be stopped or adjusted, because they are needed to treat other heart conditions. In these cases, you may have a permanent pacemaker implanted so that you can continue to take critical medicines.

Treatment if the condition gets worse

Typically, pacemakers improve symptoms and may prolong life in people with bradycardia . But further treatment depends on the underlying cause of bradycardia. Many people have other underlying heart conditions, such as coronary artery disease , that require additional treatment.

If you have episodes of a slow heart rate alternating with a rapid, irregular heart rate ( atrial fibrillation ), you may have a higher risk for a stroke . With atrial fibrillation, erratic electrical impulses cause the upper chambers of the heart (atria) to quiver, or fibrillate. Because the atria do not pump effectively, blood pools there and can clot, significantly increasing the risk of stroke and death from stroke. A stroke can happen when the clot travels from the heart and blocks blood flow to the brain.

If you are at risk of a stroke, a pacemaker is usually used along with anticoagulant medicines, which reduce the risk of clotting and stroke. You may need other medicines to prevent a fast heart rate or to slow your heart rate during these episodes. The pacemaker does not treat the fast heart rhythm. But it may allow you to safely take medicines that can treat the fast rhythm.

Prevention

Reducing risk factors for heart disease may slow the development of coronary artery disease. Staying healthy can reduce the chance that you will develop bradycardia that is caused by coronary artery disease and other heart conditions.

You can lower your risk of getting coronary artery disease by:

• Not smoking.
• Lowering high blood pressure .
• Controlling diabetes .
• Lowering high cholesterol .
• Staying at a healthy weight.
• Eating a heart-healthy diet.
• Limiting alcohol to 1 alcoholic drink a day for women or 2 drinks a day for men.
• Exercising on most, preferably all, days of the week.
• Lowering the stress in your life.

People at high risk for heart disease and those with heart disease are encouraged to develop a specific program designed to reduce their risk factors. Since people with risk factors may have special exercise needs or diet concerns, they need to talk with their doctors about how to reduce their risks of developing heart disease and bradycardia.

For more information, see the topics Coronary Artery Disease and Cardiac Rehabilitation.

Living With Bradycardia

Since bradycardia is often the result of an underlying heart condition, making changes to improve your heart's condition will usually improve your overall health. Some of these changes include:

• Not smoking.
• Lowering high blood pressure .
• Controlling diabetes .
• Lowering high cholesterol .
• Staying at a healthy weight.
• Eating a heart-healthy diet.
• Limiting alcohol.
• Exercising on most, preferably all, days of the week.
• Lowering the stress in your life.

For more information on preventing coronary artery disease, see the topic Coronary Artery Disease.

Your doctor may ask you to monitor your heart rate and symptoms. It may be helpful to keep a symptom diary to record your heart rate when you have symptoms.

If you have a pacemaker for bradycardia, home monitoring and follow-up care are needed, including:

• Checking your pulse as directed by your doctor.
• Scheduling and going to your follow-up appointments. You will be monitored frequently right after you have your pacemaker inserted and when it is time to have the battery changed. Batteries last for 5 to 15 years, depending on which kind of pacemaker you have. Your doctor will give you specific information about your type of pacemaker. After initial monitoring, you will see your doctor regularly for checkups.
• Sending information from your pacemaker over the telephone (telephone monitoring) as instructed. Your doctor may ask you to send information from your pacemaker every few months for routine monitoring.

Heart problems: Living with a pacemaker or ICD

Medications

Medicines that increase heart rate are used to treat bradycardia in an emergency situation. This is needed if your heart rate slows suddenly, such as after a heart attack , or when your heart rhythm needs to be stabilized for a short time, such as when waiting to get a pacemaker. There are no medicines that effectively treat bradycardia for the long term.

If you have episodes of a slow heart rate alternating with a rapid, irregular heart rhythm ( atrial fibrillation ), you may have a higher risk for stroke . With atrial fibrillation, erratic electrical impulses cause the upper chambers of the heart (atria) to fibrillate, or quiver. Because the atria do not pump effectively, blood pools there and can clot. If the clot moves, it can cause a stroke.

If you are at risk of a stroke, a pacemaker is usually used along with anticoagulant medicines, which reduce the risk of clotting and stroke. Also, you may need to take medicine to prevent a fast heart rate or a slow heart rate during these episodes.

What to Think About

Medicines that increase the heart rate can make your heart work harder. As a result, they are only used with caution if you have a weakened heart, such as with heart failure , or you have had a heart attack .

Other Treatment

Often a pacemaker is surgically implanted to help the heart beat at a normal rate when you have bradycardia . A pacemaker is a small, battery-powered device that generates an electrical impulse in the heart. The pacemaker is programmed by your doctor to cause your heart to beat a certain number of times each minute.

Other Places To Get Help

Organizations

Related Information

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

References

Other Works Consulted

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• 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.
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