Bradycardia (Slow Heartbeat)

What Is Bradycardia, or Slow Heartbeat?

Bradycardia is a heartbeat of less than 60 beats per minute. In most healthy people, a normal heart rate is 60 to 100 beats per minute (BPM). Although a resting heart rate below 60 beats is considered bradycardia, it doesn’t always signal a problem. What counts as an abnormally slow heartbeat for one person may not be the same for another. It can be affected by age and physical condition.

Athletic adults can have a heart rate below 60 BPM, and that is normal for them.
Your heart rate may fall below 60 BPM when you sleep but still be normal.

There are two types of bradycardia, sick sinus syndrome (SSS) and heart block.

Learn about common treatments for bradycardia.

Sick Sinus Syndrome

The sinus node in your heart is regarded as its natural pacemaker. The sinus node produces the electrical signals that initiate every heartbeat. If the sinus node is not functioning properly, you may develop sick sinus syndrome (SSS), which, while not a disease, is a set of signs or symptoms.

If you have SSS, your heartbeat may be too slow or it may speed up and slow down intermittently. This can mean that your heart does not pump enough blood to meet your body’s needs.

Common SSS symptoms include:

Rapid, fluttering, irregular heartbeats
Fatigue
Weakness
Fainting and near fainting
Dizziness and light-headedness
Shortness of breath
Chest pains
Insomnia
Confusion and memory issues

Causes of SSS symptoms include:

Scar tissue from previous heart surgeries
Medications for high blood pressure and heart disease
Age-related wear and tear to the heart

Heart Block

Heart block is a type of bradycardia that occurs when the beat that starts in the heart’s upper chambers is unable to pass normally to the lower chambers. It is sometimes called AV block because the electrical impulse slows or does not pass through the atrioventricular (AV) node between the heart’s upper and lower chambers to signal a typical contraction. This can result in your heart not pumping enough blood to meet your body’s needs.

Degrees of heart block

There are three different degrees or levels of heart block:

First-degree heart block: All of the electrical impulses from the upper chambers of the heart reach the lower chambers, but they are slower than normal. This mildest form of heart block does not usually cause problems.
Second-degree heart block: Not all of the electrical impulses pass from the upper to the lower chambers. This may cause some symptoms.
Third-degree heart block (also called complete heart block): None of the electrical impulses pass from the upper chambers of the heart to the lower chambers. The lower chambers start their own impulses to keep the heart beating. This can result in a very slow heart rate, fainting and other serious symptoms.

Some symptoms of heart block

Mild cases of heart block may have no symptoms. The symptoms of more serious forms may include:

Fatigue and weakness
Fainting and near fainting
Dizziness and light-headedness
Shortness of breath
Chest pain
Disturbed sleep
Confusion or memory impairment
Difficulty walking, climbing stars or exercising

Causes of heart block may include:

Coronary artery disease
Heart attack
High cholesterol and high blood pressure
Smoking, drug and alcohol abuse
Obesity
Sedentary lifestyle and stress
Medications
Family history of heart disease

NEXT: Tachycardia (Fast Heartbeat)

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Glossary

Bradycardia (Slow Heartbeat)

FAQs

Glossary

Understanding Arrhythmias: Sick Sinus Syndrome

Understanding Arrhythmias: Heart Block