Version July 2025
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What is bradycardia? —
This is when a person's heartbeat is slower than usual.
How do normal heartbeats happen? —
A normal heartbeat starts with an electrical signal in a spot near the top of the heart. This signal follows a path to spread across the heart. As it spreads, it causes the heart muscle to squeeze. Each time the heart squeezes or "beats," it pumps blood all over the body.
Normally, the heart beats in a regular way about 60 to 100 times a minute. Your heart rate is lower when you are resting, and higher during physical activity.
What causes the heart to beat slowly? —
The heart can beat slowly if:
●Electrical signals start less often.
●The electrical signal gets slowed down or blocked as it spreads across the heart.
Having a slow heartbeat does not always mean there is a problem. Both children and adults can have bradycardia and still be healthy. For example, it is common for athletes to have a "resting" heart rate of less than 60 beats per minute. It is also common for people to have a slower heartbeat when they are sleeping.
Certain medicines, especially those used to treat heart problems or high blood pressure, can also cause bradycardia.
Other times, bradycardia is caused by a problem or condition, such as:
●A problem with the heart's electrical system
●Other heart problems, including recent heart surgery or a heart attack
●Certain infections
●Sleep apnea – This is when people stop breathing for short amounts of time during sleep.
●Anorexia – This is an eating disorder that makes people lose more weight than is healthy.
●Hypothyroidism – This happens when a gland in the neck, called the thyroid gland, makes too little thyroid hormone.
What are the symptoms of bradycardia? —
Some people have no symptoms. When people do have symptoms, they can include:
●Feeling lightheaded or dizzy
●Fainting, or feeling like you are going to faint
●Feeling tired, either all the time or only during exercise
●Chest pain
●Trouble breathing
●Eating less than usual, or acting tired (in babies)
Should I call my doctor or nurse? —
Yes. If you or your child has symptoms of bradycardia, call your doctor or nurse.
Is there a test for bradycardia? —
Yes. The doctor or nurse will ask about your symptoms and do an exam. They will check your pulse and listen to your heart.
To see if your heartbeat is slower than normal, they will do an electrocardiogram ("ECG"). This is a test that measures the electrical activity in the heart (figure 1).
Your doctor might want to record your heartbeat over the course of hours or days. If so:
●They will have you wear or carry a "Holter monitor" at home (figure 2). This device measures and records your heart's electrical activity.
●Keep doing your normal activities while you have the monitor.
●While you have the monitor, write down any symptoms you have. That way, your doctor can see if bradycardia is causing your symptoms.
After your doctor knows for sure you have bradycardia, they might do tests to look for the cause. These can include:
●Blood tests
●Tests to see how your heartbeat changes when you get certain medicines
How is bradycardia treated? —
Treatment depends on your symptoms and what's causing your bradycardia:
●People who have no symptoms usually do not need treatment.
●People who have symptoms usually need treatment. Your doctor might change or stop any medicines that could be slowing your heartbeat.
●Some people with bradycardia are treated with a "pacemaker." This device sits under the skin near a person's heart (figure 3) and sends electrical signals to the heart. These signals help the heart beat at a normal rate.
Patient education: Overview of heart arrhythmias (The Basics)
Patient education: Syncope (fainting) (The Basics)
Patient education: Sinus node dysfunction (The Basics)
Patient education: ECG and stress test (The Basics)
Patient education: Ambulatory heart monitoring (The Basics)
Patient education: Pacemakers (The Basics)
Patient education: Syncope (fainting) (Beyond the Basics)
Patient education: Pacemakers (Beyond the Basics)
