Bradycardia (Low Heart Rate)

What is bradycardia?

Bradycardia, or low pulse rate, refers to a heart rate that is slower than the normal heart rate. In bradycardia, the heart rate usually drops below 60 beats per minute. In a normal heart, the heart rate is between 60 and 100 beats per minute.

Bradycardia, a condition characterized by a slow heart rate, is a diagnosis that can have significant impacts on our health. Understanding this condition is crucial to ensure timely diagnosis and appropriate treatment. While a low heart rate during sleep and rest is considered normal, a persistently slow heart rate can lead to various complications. In some cases, a low heart rate can cause the heart to fail to pump enough blood, leading to fainting or more serious arrhythmias. Ignoring the symptoms of bradycardia can have serious consequences.

What causes bradycardia?

Bradycardia occurs for two reasons. These are

  1. Heartbeats begin to emerge less frequently from the SA node.
  2. Electrical conduction is slowed or blocked as it propagates through the heart (Figure-1).

Low heart rate is not always considered a disease. A person can have a low heart rate and be completely healthy. In athletes, the heart rate is usually below 60. Our heart rate can drop when we sleep. Some medicines can lower our heart rate.

However, the following can cause an abnormally low heart rate;

  • Disorders in the electrical system of the heart
  • Heart attack or heart surgery
  • Some infections
  • Sleep apnea
  • Anorexia: A type of eating disorder
Bradycardia (low heart rate)
Figure-1: Bradycardia (low heart rate)

What are the symptoms of bradycardia?

Bradycardia can be asymptomatic or cause mild symptoms. However, in severe situations, as there will be less blood flow than the body needs;

  • Dizziness
  • Fainting or feeling faint
  • Fatigue even when walking or resting
  • Shortness of breath
  • Chest pain

can lead to symptoms such as.

How is bradycardia diagnosed?

It is diagnosed by electrocardiography or rhythm holter recordings.

How is bradycardia treated?

The treatment of a low pulse depends on the cause of the low pulse and the symptoms it causes. In some cases, it may be sufficient to treat the underlying disease causing the low pulse (for example, correcting an underactive thyroid gland) or to change or reduce the dose of medication.

However, if symptoms are severe or there is a serious block in the electrical conduction within the heart, devices such as pacemakers may be used. Pacemakers are devices that send electrical impulses to maintain the heart’s normal rhythm. Such treatments can control the symptoms of bradycardia (low pulse) and improve the patient’s quality of life.

Some of the frequently asked questions about bradycardia, low pulse rate, are as follows.

Does bradycardia get better?

If you have bradycardia, i.e. a low pulse, the following are checked;

  • Does the heart rhythm come out where it should normally come out and is it normally transmitted to the ventricle?
  • Does your heart rate increase at the desired level with exercise?
  • Do you have any complaints?

A decision is made according to the answers to these questions. For example, let your resting heart rate be 50. If everything is normal except bradycardia on ECG, if you have no complaints, if your heart rate increases sufficiently with exertion (this is called chronotropic response), there is no need for any intervention. However, if your heart rate is 55 per minute but there is a problem on the ECG, for example if the conduction between the atria and ventricles is blocked, then a pacemaker may be needed. In bradycardia, not only heart rate but also other factors should be evaluated together.

Will a heart ablation help bradycardia?

In some patients, premature beats originating from the atria (also called atrial extrasystole) may cause bradycardia, that is, low pulse rate. In these patients, bradycardia can be corrected by ablation.

People with vasovagal syncope may also have a low resting heart rate. With cardioneuroablation treatment for vasovagal syncope, resting heart rate can also be increased.

Can low heart rate cause death?

In healthy, exercising people, the heart rate can drop to around 40, especially during sleep. This does not mean there is a disease. What is important here is that the working order of the atria and ventricles is preserved, that is, there is no AV block (heart block). If you do not have any complaints, if you do not feel dizzy, if you do not feel weakness, if there is no decrease in your effort capacity, it is not important that your pulse rate is 40-50 per minute.

Each patient is assessed to see whether the low pulse rate is associated with heart block and causes symptoms. An individual decision is made. If symptomatic bradycardia is present, it should be treated.

How high is too high for heart rate during exercise?

When you exercise, the maximum target heart rate is calculated. To find your own maximum rate, subtract your age from 220. If you are 40 years old, the maximum rate your heart rate should be when exercising is 220-40=180. You can raise your heart rate up to 85% of your maximum rate.

Reference: Bradycardia

Update: Feb 14, 2024

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Picture of Prof. Dr. Taylan Akgün
Prof. Dr. Taylan Akgün

He is a cardiologist specialised in the diagnosis and treatment of heart rhythm problems (ablation), pacemaker procedures.
He works in Istanbul province.

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