Bradycardia

What is bradycardia?

An average healthy adult heart has a resting heart rate between 60 and 100 beats per minute (bpm). Bradycardia is a type of cardiac arrhythmia where your heart rate is below the healthy average. Specifically, this condition applies to a resting heart rate below 60 bpm. A resting rate below 40 bpm is often considered a threshold for severe bradycardia. However, a low heart rate doesn’t always present symptoms and may not pose a risk for some individuals. Knowing when to worry about a low heart rate can depend on numerous other health factors. 

A heart rate that's too low can vary between individuals, although most people fall into the average range. Younger adults and highly athletic people may have relatively low resting heart rates without experiencing symptoms of bradycardia. A resting heart rate is measured when a person is awake but relatively inactive. In contrast, sleeping heart rates can range between 40 and 50 bpm. 

Tachycardia is another type of cardiac arrhythmia. While bradycardia is a condition that deals with a slow heart rate tachycardia refers to a fast heart rate (over 100 bpm). Although the conditions are inverse, they can have some overlap.
 

Bradycardia symptoms 

Many bradycardia symptoms result from reduced oxygen caused by a low heart rate. Blood carries oxygen to the organs. When your heart isn’t pumping blood fast enough, the organs may not get enough oxygen. This problem can be especially noticeable when the brain becomes oxygen deprived. If you experience the following symptoms, contact your doctor:

• Chest pain
  
• Disorientation and memory difficulties
  
• Dizziness or lightheadedness 
  
• Fainting or feeling faint
  
• Frequent fatigue from minimal exertion
  
• Shortness of breath
  
• Tiring from relatively low levels of physical exertion 
  

Are you experiencing symptoms and concerned about a low heart rate? The heart specialists at Mass General Brigham are available to answer questions about your heart health. 

What causes bradycardia? 

Bradycardia can result from many causes. In general, the more potential risks a person has, the higher the chance of developing bradycardia. Some common low heart rate causes include:

• Chemical imbalances in the blood
• Complications from heart surgery
• Congenital heart defects 
  
• Damage to the heart tissue from aging, heart disease, or heart attacks
  
• Hypothyroidism (when thyroid glands are underperforming)
  
• Inflammatory diseases
  
• Myocarditis (inflammation of the heart tissue)  
  
• Obstructive sleep apnea (when your breathing pauses numerous times while sleeping)
  
• Sick sinus syndrome
• Some medications and controlled substances
  

What are the risk factors of bradycardia? 

Bradycardia is more likely to develop in individuals with heart disease. An increased risk of heart disease can also increase your risk of developing bradycardia. Common risk factors include:

• Age (the risk increases as you age)
  
• Frequent stress and anxiety
  
• Heavy alcohol consumption 
  
• High blood pressure
  
• Smoking
  
• Using illicit and recreational drugs
  
• Certain medications 
  

How is bradycardia diagnosed? 

Early detection may begin with a regular physical checkup. If your doctor notices a low heart rate while listening to your heart with a stethoscope, they may request an electrocardiogram (ECG). These tests use electronic sensor pads set (with a temporary adhesive) on the chest to detect heart rates. 

Your doctor may also monitor your heart with a portable ECG. Because bradycardia can be intermittent, a portable ECG has a better chance of detecting bradycardia. ECGs can help physicians collect enough data to determine if a patient has bradycardia and what might be compounding or causing it. For instance, an ECG might detect an unusually low heart rate while sleeping, which could indicate a sleep apnea complication. 

When diagnosing bradycardia, your doctor will monitor your resting heart rate to see if it falls below 60 bpm. If they detect bradycardia, more tests may be needed to learn how this condition impacts you. Specifically, doctors may order a tilt table test and a stress exercise test. The first is a table that slowly tilts while you lay on it, helping to determine if different positions cause fainting. The second test determines how much the bradycardia impacts your oxygen levels during exercise. 

How is bradycardia treated? 

Doctors have a variety of ways to treat bradycardia, depending on the circumstances and the severity. In cases with minimal to no symptoms, treatment may not be needed. In cases where another illness or condition causes bradycardia, treatment of the bradycardia will often require treatment of the underlying condition.

Bradycardia treatments can range from lifestyle changes to medications and surgery.

How to prevent bradycardia  

You can’t prevent bradycardia, but you may be able to reduce your risks by following some heart-healthy practices.

• Avoid smoking
  
• Manage high blood pressure and high cholesterol
  
• See your doctor for regular checkups 
  
• Drink alcohol minimally or not at all
  
• Follow a healthy diet
  
• Maintain a healthy weight 
  
• Reduce stress and anxiety 
  
• Exercise regularly