Bradycardia: Causes, Symptoms, Treatment

Medically Reviewed by Jabeen Begum, MD on April 30, 2024
Written by Lori M. King, PhD
7 min read

Bradycardia (pronounced bray-duh-kaar-dee-uh) is a slow heart rate. Adults usually have a heart rate between 60 and 100 beats per minute, but if you have bradycardia, your heart beats fewer than 60 beats per minute.

Bradycardia may or may not be a problem. For instance, your heart rate slows down and may go below 60 beats per minute while you sleep. And some people with a high level of cardiovascular fitness, like athletes, may also have a heart rate that's between 40 and 60 beats per minute without any problems.

But for some people, if their heart rate drops below 60 beats per minute, their tissues don't get enough oxygen. In that case, it could be a clue that you have an issue with the electrical system in your heart, which can cause symptoms. 

Bradycardia vs tachycardia

Bradycardia and tachycardia (pronounced ta-kuh-kaar-dee-uh) are both problems with your heart rhythm. Where bradycardia is a slower-than-usual heart rhythm, tachycardia is a faster-than-usual heart rhythm. Generally, this is faster than 100 beats per minute.

Your heart has four chambers, two on the top called atria and two on the bottom called ventricles. 

In your upper right atrium, you have a group of cells called the sinus node. It makes the electrical signals that tell your heart to beat. If these signals slow down or are blocked, the time between your heartbeats also slow down.

 

Sinus bradycardia

This is the most common form of bradycardia. It's when your heart slows down to less than 60 beats per minute. This could be normal for you, especially if you're athletic. You probably don't need treatment unless you have symptoms.

Sinus bradycardia is unlikely to cause you complications unless your heart rate goes below 40 beats per minute. If your heart rate goes this low, your doctor may call it junctional bradycardia.

Sinus pause (also known as sinus arrest)

If you have sinus pause, your sinus node doesn't trigger your heart to beat every once in a while, so your heart may miss one or more beats.

You may have symptoms if your heart skips beats often or over an extended period of time. There may also be a risk of complications with this type of bradycardia.

Sick sinus syndrome

When your sinus node doesn't work well, you may develop sick sinus syndrome. You may have a slow heart rate or a combination of a fast and slow heart rate.

Tachy-brady syndrome

This type of bradycardia often happens in people with atrial fibrillation. It's caused by damage to your sinus node. It makes your heart rate alternate between too fast and too slow.

You may have symptoms like palpitations, lightheadedness, or fainting. You may also have complications and a higher risk of stroke.

Heart block

This happens when something blocks the signals from your sinus node, so your heart rate slows down.

You may or may not have symptoms with bradycardia, especially if you have a high level of fitness.

If you do have them, your symptoms may include:

  • Chest pain (Your doctor may call this angina.)
  • Feeling very tired (fatigue)
  • Heart palpitations (a fluttering feeling in your chest or being aware of your own heartbeat)
  • Shortness of breath
  • Memory problems, confusion, or trouble concentrating
  • Dizziness, lightheadedness, or fainting
  • Crankiness, agitation, or other personality changes

 

You should see your doctor if you have a slow heart rate and any symptoms that are worrying you. Also go see your doctor if you notice any new symptoms or your symptoms change.

You should call 911 and go to the emergency room if you have any of the following symptoms:

  • Chest pain lasting more than a few minutes
  • Shortness of breath or trouble breathing
  • Dizziness, lightheadedness, and fainting spells

Also, go the ER if you have symptoms that come on quickly, your symptoms change fast, or they get worse.

Bradycardia can be caused by many conditions. Some of the most common causes include:

  • Not getting enough electrolytes in your diet, especially calcium, magnesium, and potassium
  • Anorexia nervosa, an eating disorder
  • Inflammation in your heart (myocarditis), the inner lining of your heart (endocarditis), or the sac that holds your heart (pericarditis)
  • Infections, like strep throat, which can damage your heart valves
  • Rheumatic fever or rheumatic heart disease (This may be another complication of strep throat.)
  • Lyme disease, which is an infection you can get from a tick bite
  • Chagas disease, which is an infection you can get from a kissing bug bite
  • Certain medications, such as beta-blockers, calcium channel blockers, anti-arrhythmia drugs, narcotics, lithium, depressants, or cannabis
  • Heart surgery, such as valve repair and replacement
  • Radiation therapy

Anything that increases your risk of having heart problems can increase your risk of bradycardia, such as:

  • Older age
  • High blood pressure
  • Smoking
  • Heavy alcohol use
  • High levels of stress and anxiety
  • Using recreational drugs, especially narcotics and cannabis (marijuana)

Your doctor will likely diagnose you based on a physical exam and tests, such as:

EKG. This test measures your heart’s electrical activity using sensors (electrodes) that stick to the skin of your chest. These electrodes sense the electrical activity of your heart. It is the most important test your doctor will use to diagnose if you have bradycardia.

Holter monitor. This is a wearable version of an EKG, which records your heart's activity continuously over about 24 hours so your doctor can see your heart's rhythm over a longer time.

Event recorder. This is like a Holter monitor, but it records only at specific times for a few minutes. You may need to push a button whenever you notice symptoms, or the recorder may be set to automatically record whenever it detects a low heart rate.

Tilt table test. Your doctor may order this test if your bradycardia is causing fainting spells. It changes your position from lying down to standing and lets your doctor see if this change triggers a fainting spell.

Stress exercise test. Your doctor may order this test to see how your heart does while you ride an exercise bike or walk on a treadmill.

Sleep study. Your doctor may order this test to see if you have obstructive sleep apnea that is causing your slow heart rate.

Blood tests that detect things such as:

  • Electrolyte levels, especially calcium, potassium, and magnesium
  • Thyroid hormone levels (Low thyroid hormone levels can cause bradycardia.)
  • Troponin, which is a protein made by your heart when it has been damaged
  • Drugs that cause heart damage or bradycardia, in a test called a toxicology screen

 

If you have bradycardia, but you don't have symptoms, you likely won't need any treatment. If you do have symptoms, the treatment plan will be based on the likely cause of the problem. For instance, if the cause is hypothyroidism, or low thyroid function, treating that may take care of your slow heart rate. Or, your doctor may change medications that you take that might be slowing your heart. For instance, beta-blockers are sometimes prescribed to relax your heart muscle. But if they cause you to have a really slow heart rate, your doctor might lower your dose or give you a different drug.

Otherwise, your doctor may treat your bradycardia with:

Medication

If your heart rate is dangerously low, your doctor may treat you in the hospital with an IV drug, such as atropine, to speed up your heart rate. 

Temporary pacemaker

Your doctor may fit you with a device with electric contacts that attach to the skin of your chest. This device sends mild electrical currents into your body that cause your heart to beat.

Permanent pacemaker

If you have a sick sinus syndrome, your heart's natural pacemaker doesn't work, so you may need surgery to implant a permanent pacemaker into your chest. Leadless pacemakers are now available that your surgeon can insert with a minimally invasive procedure. These pacemakers are very small, and you will usually need less recovery time after one is inserted.

 

 

 

The best way to prevent bradycardia is to protect yourself from getting heart disease. Some ways to prevent heart disease include:

  • See your doctor for your regular checkups.
  • Take your medicines exactly as prescribed by your doctor.
  • Exercise regularly.
  • Eat a low-fat, low-salt, low-sugar diet rich in fruits, vegetables, and whole grains.
  • Maintain a healthy weight.
  • Keep your blood pressure and cholesterol under control.
  • Don't smoke.
  • If you drink alcohol, only drink moderately (no more than one to two drinks per day, depending on your body weight).

If you have heart disease, some steps you can take to lower your risk of getting bradycardia include:

  • Follow your doctor's treatment plan.
  • Report any new symptoms or changes in your symptoms to your doctor as soon as possible.

Bradycardia is a heart rate of less than 60 beats per minute. For some people, this may not cause any problems or symptoms. You should go to the ER if you have symptoms like chest pain, shortness of breath, or dizziness. Your doctor may be able to treat bradycardia by changing medicines that cause it. Otherwise, you may get a pacemaker, either a temporary or permanent one. The best way to prevent it is to take care of your heart.