What is sinus bradycardia?

Sinus bradycardia is a type of slow heartbeat. The signal to start your heartbeat begins in a special group of cells called the sinoatrial (SA) node. Normally, the SA node fires the signal at about 60 to 100 times a minute. In sinus bradycardia, the node fires less than 60 times per minute.

Many adults and children have sinus bradycardia. But they don't have symptoms. Many of them don’t know that they have it. For them, it's normal. It doesn't mean there is a heart problem. It's very common in young people, athletes, and some older adults, especially during sleep. But it can also be a sign of a problem with the heart or other health problem.

Sinus bradycardia can happen off and on in response to certain things. Other times, it can be permanent. It's more likely to happen during deep sleep. It can happen with or without any other heart rhythm problems. In some people, sinus bradycardia goes back and forth with a heart rhythm that's too fast. The fast heart rhythm is called tachycardia. You might hear this called tachycardia-bradycardia syndrome, or "tachy-brady" for short.

What causes sinus bradycardia?

Many conditions can cause sinus bradycardia. In some cases, the cause is not known. When it causes problems, it is called pathophysiologic sinus bradycardia. Causes of this type include:

• Older age.

• The SA node being unable to consistently pace in a steady pattern (sick sinus syndrome).

• Inflammatory heart conditions such as pericarditis or myocarditis.

• Heart problems that exist at birth (congenital).

• Increased pressure inside the head; for example, in an injury to the brain.

• Heart attack (myocardial infarction).

• Obstructive sleep apnea.

• Medicines that affect the SA node and heart rate. These include beta-blockers or calcium channel blockers.

• Hypothyroidism.

• Certain rare genetic problems, such as myotonic dystrophy.

If sinus bradycardia is a normal event and doesn't cause symptoms, it's called physiologic sinus bradycardia. Causes of this type include:

• High-endurance athletic training.

• Pressure on the carotid sinus, for example, from a very tight collar.

• Vomiting or coughing.

• Straining when having a bowel movement.

• Sudden contact with cold water.

• Body temperature that's too low (hypothermia).

Who is at risk for sinus bradycardia?

Some health problems may increase the risk of sinus bradycardia, such as:

• Coronary artery disease.

• Diabetes.

• High blood pressure.

• Heart valve disease.

• Cardiomyopathy.

What are the symptoms of sinus bradycardia?

When sinus bradycardia causes symptoms, they may include:

• Feeling lightheaded or dizzy.

• Fainting.

• Fatigue.

• Shortness of breath.

• Less tolerance for exercise.

• Worse chest pain (if already present).

• Worse heart failure (if already present).

In very rare cases, it can lead to cardiac arrest.

How is sinus bradycardia diagnosed?

Your health care provider will ask about your health history and give you a physical exam. You will need a test called an electrocardiogram (ECG). This gives a picture of your heart rhythm. It's often enough to make the diagnosis. To check the heart for a longer period, you may get a continuous electrocardiogram, such as Holter or event monitoring.

Other tests to diagnose the condition may include:

• Blood tests to rule out other problems.

• Tests for sleep apnea.

• Exercise stress testing to check the heart rate’s response to exercise.

• Tests to check the heart's electrical activity and heart rhythm in more detail.

• Tests to study the autonomic nervous system. This is the nervous system that automatically controls different body functions).

• An echocardiogram, which is a heart ultrasound to check the heart muscle, heart valves, and heart size.

How is sinus bradycardia treated?

If you don’t have symptoms, you likely won’t need any treatment. But if you do have symptoms, you may need treatment. This may include treating the underlying cause. You may need to lower or stop medicines that may be slowing down your heart rate. These can include beta-blockers and calcium channel blockers. Some people may need a temporary or permanent pacemaker. This gives a small electrical impulse to increase the heart rate.

How to manage sinus bradycardia

You may need to manage sinus bradycardia with lifestyle changes. These include:

• Eating a low-salt, heart-healthy diet.

• Getting enough exercise.

• Taking medicines to treat unhealthy cholesterol levels or diabetes.

• Staying at a normal body weight.

When should you contact your doctor?

Contact your health care provider right away if you have severe symptoms, such as dizziness or fainting. If your symptoms are getting worse, see your provider as soon as possible.

Key points about sinus bradycardia

• Sinus bradycardia is a kind of slow heartbeat. It happens when the sinoatrial (SA) node fires less than 60 times a minute. In some cases, it is normal. But other times it can point to an underlying problem.

• It can be caused by some health conditions. But in some people, such as athletes and older adults, it’s normal.

• Most people with sinus bradycardia don’t have any symptoms.

• If you do have symptoms, your health care provider may lower the dose of or reduce any medicines that might be triggering it. Some people need a pacemaker.

• It's important to follow all your provider’s instructions carefully.

Next steps

Tips to help you get the most from a visit to your health care provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis. Note any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is advised and what the results could mean.

• Know what to expect if you don't take the medicine or have the test or procedure.

• If you have a follow-up visit, write down the date, time, and purpose for that visit.

• Know how you can contact your provider if you have questions.