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Bradycardia: When the Heart Beats Too Slowly

The information below will help you understand what it means when the heart beats too slowly, which is also known as bradycardia. The described symptoms do not necessarily mean that you have significant health problems, but if the symptoms persist and you feel concerned, please contact your physician.

Woman clutching her chest

What Is Bradycardia?

Bradycardia means that the heart beats too slowly. This might even feel like a heartbeat is skipped from time to time. A normal heartbeat at rest is usually between 60 and 100 beats per minute. Well-trained athletes may have an even lower heartbeat without any underlying issues. This is due to the fact that their hearts “run” more efficiently. Their hearts pump more blood with each heartbeat than that of the average person. But if you are not an athlete, having a slow heartbeat can result in too little blood being pumped through your body. If the heart fails to supply the body with enough blood and oxygen, bradycardia (a slow heartbeat) can be a severe health issue. In some types of bradycardia, the blood supply is sufficient at rest, but the heart rate is not able to adapt to situations of physical or emotional stress. This failure to adapt the heart rate is known as chronotropic incompetence.

What Causes Bradycardia?

The heart has a natural pacemaker: the sinus node. Sometimes diseases, injuries or scar tissue can damage the sinus node so it causes the heartbeat to slow down. This disorder is called sick sinus syndrome (SSS) or sinus node dysfunction (SND). In some people, sinus node problems cause alternating slow and fast heart rates (bradycardia-tachycardia syndrome)1. A damaged sinus node may also cause the heartbeat not to accelerate at all in stressful or exciting situations.

Bradycardia may also result from conduction system disorders. The conductions system consists of the sinus node, atrioventricular node (AV node), bundle of His (named after the Swiss cardiologist Wilhelm His) and the bundle branches. The electrical impulse starts in the sinus node, travels to the AV node where the impulse is slowed down and then continues its way into the bundle of His. The bundle of His divides the pathway into two bundle branches and the impulse travels through those into the two ventricles to stimulate them.

If the impulse is blocked or delayed on its way from the atrium to the ventricle, the heartbeat will become too slow.

Here is a list of possible causes for a too slow heartbeat2:

  • Heart tissue damage related to aging
  • Damage to heart tissue from heart disease or heart attack
  • A heart condition present at birth (congenital heart defect)
  • Inflammation of heart tissue (myocarditis)
  • A complication of heart surgery
  • An underactive thyroid gland (hypothyroidism)
  • Imbalance of chemicals in the blood, such as potassium or calcium
  • Repeated pauses in breathing during sleep (obstructive sleep apnea)
  • Inflammatory disease, such as rheumatic fever or lupus
  • Certain medications, including sedatives, opioids, and drugs used to treat heart rhythm disorders, high blood pressure and certain mental health disorders

What are Symptoms of Bradycardia?3

How do you know that your heart is beating too slowly because of an underlying disease or problem? Well, there are a few symptoms that indicate that there might be a serious reason for a very slow heartbeat. Watch out for the following symptoms and talk to your physician if you suspect that something might be wrong.


  • Chest pain
  • Confusion or memory problems
  • Dizziness or lightheadedness
  • Easy tiring during physical activity
  • Fatigue
  • Fainting (syncope) or near-fainting
  • Shortness of breath 

Of course, these symptoms might be caused by a vast number of issues, but if they persist and cause concern, please get in contact with your physician.

Physician talking to a patient

How is Bradycardia Diagnosed?

To diagnose whether or not your heart is beating too slowly, the physician will most likely measure your pulse and use an electrocardiogram (ECG) to graph your heart´s electric activity. Sometimes, the ECG alone points to the underlying cause of bradycardia.

Diagnosing why you have bradycardia is very important for effective long-term therapy. In addition to the ECG, the physician might examine you further. These examinations might include blood tests, X-ray, ultrasound, and/or a specific examination of the blood vessel system. If your bradycardia is not detectable all of the time, the physician might want you to take a long-term ECG. In this case, you will be asked to wear a portable ECG that stays on for about 24 hours.

Alternatively, the physician may observe your heart’s electric activity over a long period of time with a heart monitor. Heart monitors are insertable and may stay inside your body for years. You can read more about them here.


A man laying down getting an ECG

How is Bradycardia Treated?

There are various ways to treat bradycardia. To find the right one, your cardiologist will first determine the cause why your heart is beating too slowly. In case your heart is permanently beating too slowly, your cardiologist may recommend a pacemaker.



Older woman excercising in a park

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