- Understanding a Slow Heart Rate
- What to know about a slow heart rate
- Slow Heartbeat
- Bradycardia in a Man With Acute Chest Pain
- Bradycardia (Slow Heart Rate)
- Topic Overview
- What is bradycardia?
- What are the symptoms of bradycardia?
- Risk factors
- How is it diagnosed?
Understanding a Slow Heart Rate
It’s common for everyone’s heart beat rate to slow down at rest, but some people have a chronically slow heart rate that causes symptoms such as fatigue and lightheadedness.
This condition is called bradycardia, and it’s more common as you age. Mild cases of bradycardia don’t have symptoms, but in severe cases it can cause chest pain, shortness of breath, and may even lead to cardiac arrest.
Are you doing everything you can to manage your heart condition? Find out with our interactive checkup.
A normal heart beat rate is between 60 and 100 beats a minute, says Joshua D. Moss, MD, a cardiologist at the Heart Rhythm Center at the University of Chicago Medical Center. Bradycardia is defined as having a heart rate of less than 60 beats a minute. In reality, you can have periods when your heart beat rate goes below 60 and not have bradycardia, Dr. Moss says. It can happen when you’re sleeping, or it can occur in highly conditioned athletes when they’re at rest.
How Bradycardia Is Detected
You may be prompted to find out if you have a slow heart rate if you have certain symptoms. However, some people with the condition don’t have any symptoms.
Typical symptoms include excess fatigue — to the point of feeling exhausted from walking or climbing stairs — and lightheadedness. When bradycardia is more severe, you may experience shortness of breath, chest pain, and fainting. If severe bradycardia goes untreated, it could lead to cardiac arrest, meaning the heart stops beating, and that can lead to death.
Not everyone with bradycardia has symptoms. Your doctor may discover a slow heart rate during a routine office visit — another good reason for regular check-ups — and will probably send you for an electrocardiogram and other tests, Moss says. If the tests find that you do have mild bradycardia and you don’t have symptoms, your doctor will keep an eye on your condition, but you may not need treatment.
What Causes Bradycardia
Your heart has a built-in pacemaker called the sinoatrial (SA) node that tells your heart how quickly to beat. As you age, the sinoatrial node can slow down, and that slows down your heart beat rate. Another cause of bradycardia is when the atrioventricular (AV) node stops working well and leads to a slower heart rate, Moss says. The AV node, in normal circumstances, receives the electrical impulse from the SA node, and carries the impulse throughout the bottom chambers of the heart. This electrical impulse is designed to stimulate mechanical contraction, which in turn, pumps blood throughout the body.
The most common cause of problems with the SA or AV nodes is aging. An SA node that stops firing properly typically begins when people are in their seventies, although a congenital problem can cause it to happen in younger people.
Heart disease can accelerate these problems, so maintaining good heart health by exercising and eating a healthy diet can keep your heart beat rate in a healthy range.
In some cases, a slow heart rate can be the result of blood pressure medication, which can lower your heart rate.
How Bradycardia Is Treated
A bradycardia prognosis depends on the cause. If it’s a serious dysfunction of the AV node that’s causing the slow heart rate, doctors recommend getting a pacemaker, whether or not you’re having symptoms. “We worry that in such cases there’s a risk that it can get worse without warning and lead to cardiac arrest,” Moss explains.
But it’s more common for elderly patients to have a dysfunction of the SA node or a less severe problem with the AV node, Moss says. In these situations, the recommendation is based on symptoms. If symptoms are mild and you can do the activities that you want to do, then your doctor may decide to watch the condition over time. If not, you may need a pacemaker.
If your blood pressure medication is causing bradycardia, your doctor may consider changing the drug. But if you must be on that specific medication, you may need a pacemaker as well.
Fortunately, bradycardia is generally not serious. As long as your doctor is aware of your slow heart rate and you get any treatment you need, you should still be able to do all of the activities you love to do.
What to know about a slow heart rate
Share on PinterestPeople who engage in intense cardiovascular activity may have a slow heart rate, as their hearts are efficient.
Some people have only moderate bradycardia. Others only experience occasional bradycardia.
Although it is vital that anyone with a slow heart rate seeks medical guidance, not everyone will require treatment. When bradycardia causes no other symptoms, and when a person does not have an underlying condition, a slow heart rate may be a harmless or minor issue.
The heart rate tends to decline with age, which means older people may experience episodes of bradycardia. While this is typical, it still warrants investigation by a doctor.
Exercise strengthens the heart. Athletes, especially those who engage in intense cardiovascular activity, tend to have more efficient hearts. This may slow their pulse because their heart does not have to pump as hard or as fast to supply blood to the rest of their body.
Some medical conditions may also cause a slow heart rate.
These include the following:
Problems with the heart’s natural pacemaker
The heart’s natural pacemaker, or sinoatrial node, helps regulate heartbeat. Problems affecting this can cause a person’s heart to beat unusually slow or fast, which doctors call tachycardia.
A condition that doctors call sick sinus syndrome refers to problems with the natural pacemaker. Typically, another heart health problem, such as scar tissue in the heart, complications of diabetes, or coronary artery disease, causes these problems.
Other heart electrical issues
The heart communicates by sending electrical signals. For example, one chamber of the heart sends electrical signals to another, telling it how and when to squeeze blood into the next chamber.
The pacemaker helps regulate this electrical system. If the heart is not able to send the correct electrical signals, due to a blockage or heart disease, it can cause bradycardia.
Complete heart block is a type of electrical issue that makes it impossible for electrical signals to travel from the atria — the top two chambers of the heart — to the ventricles, which are the bottom two chambers. In complete heart block, the top two chambers may have totally different rhythms to the bottom two.
Some metabolic disorders can slow the heart rate. One of the most common is hypothyroidism, in which the thyroid does not produce enough thyroid hormones.
Hypothyroidism can affect the health of the blood vessels, which may slow the heart rate. People with hypothyroidism may also have a high diastolic blood pressure — a diastolic measurement identifies the pressure in the arteries between heartbeats, and is the bottom number on a blood test reading. A person has a high diastolic blood pressure if the test shows a reading above 80.
Thyroid disorders are common and may affect young and otherwise healthy people. Between 4 and 10 percent of people in the United States have hypothyroidism.
Damage to the heart from congestive heart failure, coronary artery disease, previous heart attacks, and other heart problems may affect the heart’s electrical system, making the heart pump more slowly and less effectively.
Some medications, including medications for heart disease and high blood pressure, may lower heart rate. Beta-blockers, which doctors prescribe for a rapid heart rate and some other heart conditions, may also slow heart rate.
People taking a new medication who experience symptoms of bradycardia should contact a doctor.
Doctors use the term hypoxia when the body cannot get enough oxygen, which may slow down the heart rate.
Hypoxia is a medical emergency, and it can occur when a person is choking or having a severe asthma attack. Chronic medical conditions, such as chronic obstructive pulmonary disease, may also cause hypoxia.
When hypoxia lowers the heart rate, it is essential to treat the underlying cause.
Types of Slow Heart Rhythms
Sinus Node Dysfunction – An abnormally slow natural “pacemaker” in the heart. The heart has a group of cells in the upper chamber (right atrium) called the sinus node that triggers an electrical signal, or impulse, to the lower chambers (left and right ventricles) to contract, causing a heartbeat about once every second at rest. The sinus node can increase its rate of “firing,” depending on the body’s needs. This natural pacemaker can wear out and fire too slowly or sometimes fail to fire, resulting in slow heart rates (sinus bradycardia).
- First Degree Heart Block – Each impulse from the upper chambers of the heart reaches the lower chambers, but more slowly than normal. The heart rate is normal and this does not usually cause symptoms.
- Second Degree Heart Block – (sometimes called Mobitz Type I (Wenckebach) or MobitzÂ Type II Heart Block). Some impulses, but not all, are carried from the upper chambers of the heart to the lower chambers. This may cause some symptoms
- Third Degree Heart Block – (also called Complete Heart Block). The impulses from the upper chambers are “blocked,” and none get through to the lower chambers. A slower, less reliable natural pacemaker in the heart temporarily takes over to keep the heart beating, but this can cause a very slow heart rate, fainting, and other symptoms.
Tachy-brady syndrome – It is possible for the same person to have a slow heartbeat when the heart is in normal rhythm and periods of fast, irregular heartbeats (supraventricular tachycardias) at other times. Sometimes, medications needed to control the fast heart rate can worsen the already slow heart rate. People with this syndrome often complain of palpitations, lightheadedness, and fainting (syncope).
This heart rhythm problem may also cause shortness of breath or chest pain. Treating tachy-brady syndrome usually requires having a pacemaker to prevent the heart from beating too slowly and taking medications to stop the heart from beating too fast.
Symptoms of Slow Heart Rhythms
Slow heart rhythms, or bradycardia, can cause the following symptoms:
- Difficulty walking, climbing stairs, or exercising
- Shortness of breath
- Passing out (syncope)
Treating of Slow Heart Rhythms
Both heart medications and medications used to treat other illnesses can cause bradycardia. In these cases the risks and benefits of continuing those medications must be thought about carefully. Usually, unless the causes are temporary or there are medications that can be changed, the treatment for bradycardia that causes symptoms is a pacemaker.
Bradycardia means your heart rate is slow. This can be completely normal and desirable, but sometimes it can be an abnormal heart rhythm (arrhythmia). If you have bradycardia and you have certain symptoms along with the slow heart rate, then it means your heartbeat is too slow.
A normal resting heart rate for most people is between 60 and 100 beats per minute (bpm). A resting heart rate slower than 60 bpm is considered bradycardia. Athletic and elderly people often have a heart rate slower than 60 bpm when they are sitting or lying down, and a heart rate less than 60 bpm is common for many people during sleep.
To understand bradycardia, it helps to understand the heart’s electrical system, which is what makes the heart beat.
Your heart has a natural pacemaker called the sinus node (SA node), which is made of a small bunch of special cells. Impulses start at the SA node and move through the walls in the upper chambers of your heart (atria). The impulses cause the atria to contract and push blood into the lower chambers of your heart (ventricles).
Next, the impulse travels down an electrical pathway to the AV node. The AV node is in the center of your heart, in between the atria and ventricles. The AV node acts like a gate that slows the electrical signal before it moves into the ventricles.
The final part of your heartbeat happens when the electricity moves through a pathway of fibers in the ventricles called His-Purkinje Network. This causes the ventricles to contract and force blood out of the heart to the lungs and body.
This cycle is repeated every time your heart beats.
What are symptoms of bradycardia?
You may not have any symptoms of bradycardia. But if you do have a slow heart rate and any of these symptoms, call your doctor:
- Syncope/passing out
- Heart palpitations/fluttering
- Feeling short of breath
- Chest pain
- Lack of energy
Causes of bradycardia
Bradycardia can be caused by:
- A problem with your SA node (sick sinus syndrome)
- A problem with your AV node or any of the electrical pathways through the heart (heart block)
- Illness or medical problems such as:
- Injury to the heart due to heart attack, endocarditis or a medical procedure
- Inflammation of the heart muscle
- Low thyroid function
- Electrolyte imbalance in the blood
- Sleep apnea
- Congenital heart defect
- Valvular heart disease
- Lyme disease
- Certain medications, including beta blockers and heart rhythm medications
Share Facebook Twitter LinkedIn Email Get useful, helpful and relevant health + wellness information enews
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
The main symptom of bradycardia is a heart rate below 60 beats per minute. This abnormally low heart rate can cause the brain and other organs to become oxygen-deprived, which can lead to symptoms such as:
- Shortness of breath
- Chest pain
- Memory difficulties
- Quickly tiring during physical activity
In rare cases when bradycardia goes undiagnosed for an extended period of time, the following complications can occur:
- Cardiac arrest
- High blood pressure
Causes and Risk Factors
Bradycardia is caused by a disruption in the heart’s electrical system that controls the heart rate. This disruption can come from four possible causes:
- Sinoatrial node problems – the sinoatrial node, often referred to as the sinus node, is considered to be the natural pacemaker of the heart. This group of cells triggers electrical impulses to the heart, causing it to contract. When this node isn’t working properly it can trigger much slower electrical impulses causing the heart to beat slower.
- Dysfunctional conduction pathways – electrical impulses travel in the heart via conduction pathways. When these pathways do not work properly, the heart rate is affected — a condition often referred to as an atrioventricular block or heart block, of which there are three forms:
- First degree – all of the electrical signals from the atria reach the ventricles, although they are transmitted slower than normal.
- Second degree – only some of the electrical signals from the atria reach the ventricles. When a signal does not reach the ventricles, the heart beat it was meant to trigger does not occur.
- Third degree – none of the electrical impulses make it from the atria to the ventricles. When this happens, a natural pacemaker in the ventricles may step in to take over regulating the heartbeat, although at a rate that is slower than normal.
Other risk factors that may contribute to a disruption of the electrical impulses associated with bradycardia include:
- Congenital heart disease
- Infection of the heart tissue
- Heart surgery
- Hypothyroidism or other metabolic condition
- Damage caused by a heart attack or heart disease
- Electrolyte imbalance in the blood
- Obstructive sleep apnea
- Inflammatory diseases (rheumatic fever or lupus)
- Certain medications
Bradycardia can affect patients of all ages, genders and ethnicities. However, older patients are at an increased risk as well as patients with the following risk factors:
- High blood pressure (hypertension)
- Heavy alcohol use
- Use of recreational drugs
- Psychological stress or anxiety
Bradycardia in a Man With Acute Chest Pain
1. Brady WJ, Swart G, DeBehnke DJ, et al. The efficacy
of atropine in the treatment of hemodynamically
unstable bradycardia and atrioventricular
block: prehospital and emergency department considerations.
2. Swart G, Brady WJ, DeBehnke DJ, et al. Acute
myocardial infarction complicated by hemodynamically
unstable bradyarrhythmia: prehospital and
emergency department treatment with atropine.
Am J Emerg Med. 1999;17:647-652.
3. Braunwald E, Zipes DP, Libby P, eds. Heart Disease:
A Textbook of Cardiovascular Medicine. 6th ed.
Philadelphia: WB Saunders Company; 2001.
4. Rardon DP, Miles WM, Zipes DP. Atrioventricular
block and dissociation. In: Zipes DP, Jalife J, eds.
Cardiac Electrophysiology: From Cell to Bedside. 3rd
ed. Philadelphia: WB Saunders; 2000:451-459.
5. Brush JE, Brand DA, Acamparo D, et al. Use of
the initial electrocardiogram to predict in-hospital
complications of acute myocardial infarction. N Engl
J Med. 1985;312:1137-1141.
6. Yusuf S, Pearson M, Sterry H, et al. The entry
ECG in the early diagnosis and prognostic stratification
of patients with suspected acute myocardial infarction.
Eur Heart J. 1984;5:690-696.
7. Zehender M, Kasper W, Kauder E, et al. Eligibility
for and benefit of thrombolytic therapy in inferior
wall myocardial infarction: focus on the prognostic
importance of right ventricular infarction. J Am Coll
8. Brady WJ, Harrigan RA, Chan TC. Hypotension
in a man with acute MI. Consultant. 2006;46:65-70.
Bradycardia (Slow Heart Rate)
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, it is slower than normal.
A slow heart rate can be normal and healthy. Or it could be a sign of a problem with the heart’s electrical system.
For some people, a slow heart rate does not cause any problems. It 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 isn’t working right or that the electrical pathways of the heart are disrupted. Sometimes, the heart beats so slowly that it doesn’t pump enough blood to meet the body’s needs. This can cause symptoms, such as feeling dizzy or weak. In some cases, it can be life-threatening.
What causes bradycardia?
Bradycardia can be caused by many things. Examples include:
- 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.
- Many types of medicines. Examples include antidepressants, heart medicines, and opioids.
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 take your pulse to diagnose bradycardia. Your doctor might also do a physical exam, ask questions about your past health, and do an electrocardiogram (EKG or ECG). An EKG measures the electrical signals that control heart rhythm.
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 wear or carry a device called a portable, or ambulatory, electrocardiogram. Examples include a Holter monitor and a cardiac event monitor. You might use it for a day or more. 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 doesn’t cause symptoms, it may not be treated. You and your doctor can decide what treatment is right for you.
- 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 an implanted device that helps correct the slow heart rate.
- 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.
The goal of treatment is to raise your heart rate and relieve symptoms. For certain types of bradycardia, treatment may help prevent serious problems. These problems include fainting, injuries from fainting, and even death.
What can you do at home for bradycardia?
Bradycardia is often the result of another heart condition, so taking steps to live a heart-healthy lifestyle will usually improve your overall health. The steps include:
- Having a heart-healthy eating plan that includes vegetables, fruits, nuts, beans, lean meat, fish, and whole grains. Limit alcohol, sodium, and sugar.
- Being active on most, if not all, days of the week. Your doctor can tell you what level of exercise is safe for you.
- Losing weight if you need to, and staying at a healthy weight.
- Not smoking.
- Managing other health problems, such as high blood pressure, high cholesterol, and diabetes.
Get emergency help if you fainted or if you have symptoms of a heart attack 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.
Most people who get pacemakers lead normal, active lives. You will need to avoid things that have strong magnetic and electrical fields. These can keep your device from working right. But most electronic equipment and appliances are safe to use.
Your doctor will check your pacemaker regularly. Call your doctor right away if you have symptoms that could mean your device isn’t 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.
What is bradycardia?
Bradycardia means that your heart beats very slowly. For most people, that heart rate is between 60 and 100 beats per minute (bpm) when resting.
A low heart rate (fewer than 60 bpm) may sometimes be normal and can be a sign of being very fit. Top athletes may have a pulse rate of fewer than 40 bpm. This normal slow heartbeat doesn’t cause any problems and does not need any treatment. Bradycardia may also occur in older endurance athletes and may then need treatment with a pacemaker.
However, sometimes bradycardia is caused by an underlying medical condition and does cause symptoms. Bradycardia may be a sign of a problem with the heart’s electrical system. It means that the heart’s natural pacemaker isn’t working right or that the electrical pathways of the heart are disrupted. In severe forms of bradycardia, the heart beats so slowly that it doesn’t pump enough blood to meet the body’s needs. This can cause symptoms and can be life-threatening.
What are the symptoms of bradycardia?
Bradycardia may not cause any symptoms. However, bradycardia may cause you to feel:
- Dizzy or light-headed. You might even experience faints or sudden collapse.
- Short of breath, especially with exercise.
- Very tired.
- A pain in your chest or a thumping or fluttering feeling in your chest (palpitations).
- Confused or that you are having trouble concentrating.
There are many possible causes. Bradycardia may be normal, especially in young very fit people. Otherwise the possible causes include:
- Abnormal conduction of the electrical impulse that stimulates the heart to pump blood around your body. Read more about abnormal heart rhythms (arrhythmias).
- Damage to the heart caused by a heart attack (myocardial infarction).
- High blood pressure (hypertension).
- Congenital heart disease. (A congenital condition is a condition that you are born with.)
- Infection of heart tissue (myocarditis).
- A complication of heart surgery.
- Underactive thyroid gland (hypothyroidism).
- Medications – eg, beta-blockers or digoxin.
How is it diagnosed?
- Taking your pulse rate reveals a very slow heartbeat.
- The first tests will include blood tests and a tracing of your heart (electrocardiogram, or ECG).
- Bradycardia often comes and goes, so you may need a portable (ambulatory) ECG.
The treatment depends on the underlying cause and the symptoms. If the bradycardia isn’t causing any symptoms there is no need for any treatment unless treatment is needed for the underlying cause of the bradycardia.
If damage to the heart’s electrical system causes your heart to beat too slowly, you may need to have a pacemaker. A pacemaker is a device placed under your skin that helps correct the low heart rate. People who have a pacemaker can lead normal, active lives; however, this will also depend on the underlying condition.
If another medical problem, such as hypothyroidism or an imbalance of salts (electrolytes), is causing a low heart rate then treating the cause will often cure the bradycardia.
If a medicine is causing your heart to beat too slowly, your doctor may lower the dose of the medicine or change it to a different medicine.
Always obtain emergency help if you, or someone near you, have collapsed or if you have symptoms of a heart attack, such as severe chest pain or severe shortness of breath. Call your doctor right away if your heart rate is slower than usual and you feel like you might pass out, or you notice increased shortness of breath.
For most people, bradycardia will not cause any complications. Any complications will depend on the underlying cause of the slow heart rate.
If severe bradycardia isn’t treated, it can lead to serious problems. These may include sudden collapse, fits (seizures) or even death.
Bradycardia can be caused by heart disease, so healthy lifestyle advice is very important. This includes healthy eating, not smoking, reducing body weight (if overweight) and taking regular exercise. See the separate leaflet called Cardiovascular Disease (Atheroma) for more details.