Bradycardia is a condition in which the heart beats more slowly than expected. It can occur in healthy people under certain circumstances, but it may also be associated with an underlying medical condition or a problem with the heart’s electrical conduction system. Not every case of a slow heart rate is dangerous, but if it occurs with dizziness, fainting, shortness of breath, or chest pain, medical evaluation is necessary.
So, what are the causes of bradycardia, what symptoms should you watch for, and how is bradycardia treated?
What Is Bradycardia?
Bradycardia is a condition in which the resting heart rate of an adult is below 60 beats per minute (bpm). However, this number does not necessarily mean that the condition is abnormal. Heart rate may fall below 60 bpm during sleep or in some young, physically fit individuals without causing any health problems.
What matters is whether the heart is able to provide adequate blood flow to meet the body’s needs. When the heart beats too slowly and cannot supply enough blood to the brain, organs, and tissues, symptoms such as fatigue, dizziness, shortness of breath, or fainting may occur.
Therefore, evaluating bradycardia requires consideration of the heart rate, symptoms, underlying cause, and overall health, rather than relying on a single heart-rate reading.
Common Causes of Bradycardia
The causes of bradycardia are diverse, ranging from normal physiological changes to heart conditions and other health problems.
1. Increased Parasympathetic Activity
Heart rate can decrease when the body is relaxed or during sleep. In some healthy people, particularly those who are physically fit, a low resting heart rate may occur without affecting their health.
2. Problems With the Sinus Node and the Heart’s Electrical Conduction System
The sinus node is the heart’s natural pacemaker that generates the electrical signals responsible for each heartbeat. When the sinus node does not function properly, the heart rate may become slow or alternate between fast and slow rhythms.
In addition, atrioventricular (AV) block occurs when electrical signals traveling from the upper chambers of the heart to the lower chambers are slowed or interrupted. This can also cause a slow heart rate.
3. Heart Disease or Damage to the Heart Muscle
Damage to heart tissue caused by aging, heart disease, a previous heart attack, myocarditis, or complications following heart surgery can affect the heart’s electrical conduction system and lead to bradycardia.
4. Hypothyroidism and Metabolic Disorders
Hypothyroidism can slow many of the body’s metabolic processes, including the heart rate. Abnormal levels of electrolytes such as potassium or calcium can also affect the heart’s electrical activity.
5. Certain Medications
Some medications can lower the heart rate, particularly medications that affect the cardiovascular or nervous systems. Therefore, when bradycardia occurs, a doctor may review all medications the patient is taking, including over-the-counter medicines and supplements.
Do not stop taking a medication or change its dosage on your own simply because you notice a slow heart rate.
6. Sleep Apnea
Obstructive sleep apnea can cause abnormal changes in heart rate during sleep. If you have loud snoring, episodes of stopped breathing during sleep, or excessive daytime sleepiness, your doctor may consider evaluating you for sleep apnea.
Symptoms of Bradycardia to Watch For
Bradycardia may cause no symptoms at all. However, when the heart rate becomes too slow to provide enough blood to the body, symptoms may include:
- Fatigue or low energy
- Dizziness or lightheadedness
- Weakness or unusual tiredness during physical activity
- Shortness of breath
- Reduced exercise tolerance
- Confusion or difficulty concentrating
- Feeling faint or actually fainting
- Chest pain or discomfort
In particular, an irregular heart rate accompanied by dizziness, fainting, or shortness of breath should be evaluated to determine whether it is related to an arrhythmia or an abnormality in the heart’s electrical conduction system.
Read more: Causes of Heart Disease: Key Risk Factors to Know
When Should You See a Doctor for Bradycardia?
If you frequently notice a slow heart rate at rest, especially if it is new or accompanied by symptoms, you should seek medical evaluation rather than simply monitoring it at home for an extended period.
A doctor may ask about when your symptoms occur, your existing medical conditions, medications, and cardiovascular history. This evaluation helps distinguish physiological bradycardia from bradycardia caused by an underlying medical condition.
Seek emergency medical care if bradycardia occurs with fainting, significant difficulty breathing, or persistent chest pain. These may indicate that circulation is being seriously affected.
How Is Bradycardia Diagnosed?
An electrocardiogram (ECG) is one of the most important tests for evaluating bradycardia because it can record the heart rate and electrical activity of the heart at the time of testing.
Depending on the situation, a doctor may recommend additional tests, including:
- Holter ECG: Monitors the heart’s electrical activity over a longer period to detect abnormalities that may occur intermittently.
- Blood tests: May help identify potentially reversible causes, such as electrolyte abnormalities or thyroid dysfunction.
- Exercise stress testing: May be considered in certain cases to assess how the heart rate responds to physical activity.
- Sleep evaluation: May be recommended when sleep apnea is suspected.
The choice of tests depends on the patient’s symptoms and the suspected underlying cause. Not everyone with bradycardia needs all of these tests.
How Is Bradycardia Treated?
Treatment of bradycardia depends on its cause, severity, and the patient’s symptoms. If bradycardia causes no symptoms and is not associated with a serious medical condition, a doctor may recommend monitoring without specific treatment.
If the cause is related to medication, a doctor may consider adjusting the medication or changing the treatment plan when appropriate. When bradycardia is caused by hypothyroidism, electrolyte abnormalities, sleep apnea, or another treatable condition, addressing the underlying cause may help improve the heart rate.
In some cases of severe bradycardia caused by an abnormality in the heart’s electrical conduction system that cannot be corrected by treating the underlying cause, a doctor may consider a pacemaker to help maintain an appropriate heart rate.
Therefore, you should not attempt to increase your heart rate or take medication on your own before the underlying cause has been identified.
Can Bradycardia Be Prevented?
Not all cases of bradycardia can be prevented, particularly when they are related to aging or abnormalities of the heart’s electrical conduction system.
However, maintaining cardiovascular health, managing blood pressure and underlying medical conditions, avoiding smoking, limiting alcohol, exercising appropriately, and taking medications as prescribed may help reduce the risk of heart damage and certain heart rhythm disorders.
If you are being treated for heart disease or develop new symptoms, inform your doctor so that your condition and treatment plan can be reassessed when necessary.
Bradycardia is not always a sign of disease. Some healthy people may have a low heart rate at rest or during sleep without requiring treatment. However, bradycardia accompanied by dizziness, fatigue, shortness of breath, chest pain, or fainting may indicate that the heart is not providing adequate circulation or that there is a problem with the heart’s pacemaker or electrical conduction system.
If you notice a slow heart rate that persists, recurs, or occurs together with unusual symptoms, seek medical evaluation to identify the underlying cause and determine the appropriate management. In particular, do not take medication on your own to change your heart rate without medical guidance.
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