Bradycardia

Updated: 2024-12-13

Overview

Bradycardia

Bradycardia

Bradycardia, shown on the right, is a slower than typical heart rhythm that often starts in the area of the heart called the sinus node. A typical heart rhythm is shown in the image on the left.

Bradycardia (brad-e-KAHR-dee-uh) is a slow heart rate. The hearts of adults at rest usually beat between 60 and 100 times a minute. If you have bradycardia, your heart beats fewer than 60 times a minute.

Bradycardia can be a serious problem if the heart rate is very slow and the heart can't pump enough oxygen-rich blood to the body. If this happens, you may feel dizzy, very tired or weak, and short of breath. Sometimes bradycardia doesn't cause symptoms or complications.

A slow heart rate isn't always a concern. For example, a resting heart rate between 40 and 60 beats a minute is common in some people, particularly healthy young adults and trained athletes. It also is quite common during sleep.

If bradycardia is severe, a pacemaker may be needed to help the heart beat at an appropriate rate.

Symptoms

A slower than typical heartbeat is called bradycardia. If the slow heartbeat stops the brain and other organs from getting enough oxygen, symptoms may include:

• Chest pain.
• Confusion or memory problems.
• Dizziness or lightheadedness.
• Feeling very tired, especially during physical activity.
• Fainting or near-fainting.
• Shortness of breath.

When to see a doctor

Many things can cause symptoms of bradycardia. It's important to get a fast, accurate diagnosis and appropriate care. Make an appointment for a health checkup if you are worried about a slow heart rate.

If you faint, have difficulty breathing or have chest pain lasting more than a few minutes, call 911 or emergency medical services.

Causes

Typical heartbeat

In a typical heart rhythm, a tiny cluster of cells at the sinus node sends out an electrical signal. The signal then travels through the atria to the atrioventricular (AV) node and then passes into the ventricles, causing them to contract and pump out blood.

Bradycardia can be caused by:

• Heart tissue damage related to aging.
• Damage to heart tissues from heart disease or heart attack.
• A heart condition that you're born with, called a congenital heart defect.
• Inflammation of heart tissue, called myocarditis.
• A complication of heart surgery.
• An underactive thyroid gland, called hypothyroidism.
• Changes in the level of body minerals such as potassium or calcium.
• A sleep disorder called obstructive sleep apnea.
• Inflammatory disease, such as rheumatic fever or lupus.
• Certain medicines, including sedatives, opioids, and some used to treat heart and mental health conditions.

To better understand the causes of bradycardia, it may help to know how the heart typically beats. The typical heart has four chambers.

• The two upper chambers are called the atria.
• The two lower chambers are called the ventricles.

Within the heart's upper right chamber is a group of cells called the sinus node. The sinus node is the heart's natural pacemaker. It creates the signal that starts each heartbeat. Bradycardia happens when these signals slow down or are blocked.

Things that cause changes in heart signaling that can lead to bradycardia include:

• Bradycardia-tachycardia syndrome. In some people, problems in the sinus node at the top of the heart cause alternating slow and fast heart rates.
• Heart block, also called atrioventricular block. In this condition, the heart's electrical signals don't move correctly from the upper chambers to the lower chambers.

Risk factors

Bradycardia is often associated with damage to heart tissue from some type of heart disease. Anything that increases the risk of heart problems can increase the risk of bradycardia. Risk factors include:

• Older age.
• High blood pressure.
• Smoking.
• Heavy alcohol use.
• Illegal drug use.
• Stress and anxiety.

Complications

Possible complications of bradycardia include:

• Frequent fainting.
• Heart failure.
• Sudden cardiac arrest or sudden cardiac death.

Prevention

Preventing heart disease may help lower the risk of bradycardia.

The American Heart Association recommends these steps:

• Get regular exercise. Ask your healthcare team about how much and what type of exercise is best for you.
• Eat nutritious foods. Eat a healthy diet that's low in salt and solid fats and rich in fruits, vegetables and whole grains.
• Keep a healthy weight. Being overweight increases the risk of heart disease. Talk with your care team to set realistic goals for body mass index (BMI) and weight.
• Control blood pressure and cholesterol. High blood pressure and high cholesterol increase the risk of heart disease. Make lifestyle changes and take medicines as directed to manage high blood pressure or high cholesterol.
• Don't smoke or use tobacco. If you smoke and can't quit on your own, talk to a healthcare professional about methods or programs to help.
• Limit or do not drink alcohol. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and up to two drinks a day for men.
• Manage stress. Intense emotions may affect the heart rate. Getting more exercise, practicing mindfulness and connecting with others in support groups are some ways to reduce and manage stress.
• Get good sleep. Poor sleep may increase the risk of heart disease and other chronic conditions. Adults should aim to get 7 to 9 hours of sleep daily. Go to bed and wake at the same time every day, including on weekends. If you have trouble sleeping, talk to a healthcare professional about strategies that might help.

It's important to have regular health checkups. If you already have heart disease, take these steps to lower your risk of irregular heartbeats:

• Follow your treatment plan. Be sure you understand your treatment. Take all medicines as directed by your healthcare team.
• Tell your care team if your symptoms change. Also tell the healthcare team if you have new symptoms.

Diagnosis

To diagnose bradycardia, a healthcare professional examines you and listens to your heart with a stethoscope. You are usually asked questions about your symptoms and medical history.

Tests

Tests may be done to check your heart and look for conditions that can cause bradycardia.

• Blood tests. A sample of your blood may be tested to check for infections and changes in body chemicals, such as potassium. A blood test also may be done to check thyroid function.
• Electrocardiogram (ECG or EKG). This is the main test used to diagnose bradycardia. An ECG measures the electrical activity of the heart. It shows how the heart is beating. Sticky patches with sensors are placed on the chest and sometimes the arms and legs. Wires connect the electrodes to a computer, which displays or prints the results.
• Holter monitor. If a standard ECG doesn't show an irregular heartbeat, your healthcare professional may suggest a Holter monitor. This portable ECG device is worn for a day or more. It records the heart's activity during daily activities.
• Event recorder. This device is similar to a Holter monitor, but it records only at certain times for a few minutes at a time. You typically press a button when symptoms occur. It's worn for up to 30 days or until symptoms occur.
• Tilt table test. This test may be done if you've had fainting spells. A health professional checks your heart rate and blood pressure as you lie flat on a table. The table is tilted to put you in a standing position. The care professional watches how your heart and nervous system respond to the change in position.
• Stress exercise test. Some irregular heartbeats are triggered or made worse by exercise. During a stress test, the heart's activity is watched while you ride on a stationary bicycle or walk on a treadmill. If you can't exercise, you may be given medicine that affects the heart like exercise does.
• Sleep study. A sleep study may be suggested if you have repeated pauses in breathing during sleep, called obstructive sleep apnea. That condition may cause changes in the heartbeat.

Treatment

Treatment for bradycardia depends on how severe the symptoms are and the cause of the slow heart rate. If you don't have symptoms, treatment might not be needed.

Bradycardia treatment may include:

• Lifestyle changes.
• A change in medicines.
• A medical device called a pacemaker.

If another health problem, such as thyroid disease or sleep apnea, is causing the slow heart rate, treatment of that condition might correct bradycardia.

Medications

Many different medicines can affect the heartbeat. Some might cause bradycardia. Always tell your healthcare team about all the medicines you take. Include those bought without a prescription.

If a medicine you're taking is causing bradycardia, your healthcare professional may suggest a lower dosage. Or you may be changed to a different medicine.

Surgery or other procedures

If you have severe bradycardia symptoms and other treatments aren't possible, your health professional may suggest a device called a pacemaker.

A pacemaker is placed under the skin near the collarbone during a minor surgery. The device helps fix a slow heartbeat. When the heart beats too slowly, the pacemaker sends electrical signals to the heart to speed up the beat.

Preparing for an appointment

If you have an irregular heartbeat, you may be referred to a doctor trained in heart conditions. This type of health professional is called a cardiologist.

Medical appointments can be brief. There's often a lot to discuss. So it's a good idea to be prepared for your appointment. Here's some information to help you prepare for your appointment.

What you can do

• Be aware of any pre-appointment restrictions. When you make the appointment, ask if there's anything you need to do in advance. For example, you may be told not to eat or drink for a few hours before a cholesterol test.
• Write down any symptoms you're having, including any that may seem unrelated to bradycardia.
• Write down important personal information, including a family history of heart disease, stroke, high blood pressure or diabetes, and any major stresses or recent life changes.
• Make a list of all medicines, including those bought without a prescription. Include dosages. Also list vitamins or supplements that you're taking.
• Take someone with you, if possible. Someone who goes with you can help you remember information you're given.
• Write down questions to ask your care team.

For bradycardia, basic questions to ask your healthcare team include:

• What is likely causing my slow heart rate?
• What tests do I need?
• What's the most appropriate treatment?
• What are the possible complications?
• How will my heart be checked?
• How often do I need health checkups?
• How will other conditions I have or medicines I take affect my irregular heartbeat?
• Do I need to restrict my activities?
• Are there brochures or other printed material I can have? What websites do you recommend?

Don't hesitate to ask other questions.

What to expect from your doctor

Your healthcare team usually asks you questions, such as:

• Have you fainted?
• Does anything, such as exercise, make your symptoms worse?
• Do you smoke?
• Are you being treated for heart disease, high blood pressure, high cholesterol or other conditions that can affect your heart?