About—Bradycardia is a slower-than-normal heart rate. In most adults, bradycardia means a resting heart rate below 60 beats per minute (bpm). However, a heart rate below 60 bpm is not always a sign of disease. It can occur normally during sleep or in healthy, physically active people, including trained athletes. The heart’s electrical system controls the rate and rhythm of the heartbeat. When the heart beats too slowly, it may not pump enough blood to meet the body’s needs. Whether bradycardia requires treatment depends on its cause, how slow the heart rate is, and whether it causes symptoms.
Sinus bradycardia occurs when the heart’s natural pacemaker, called the sinus node, produces electrical signals more slowly than usual. It can be normal in healthy people, particularly during sleep or in well-trained athletes.
Sick sinus syndrome, also called sinus node dysfunction, occurs when the sinus node does not work properly. It can cause the heart rate to become too slow, too fast, or alternate between slow and fast rhythms.
Heart block occurs when electrical signals from the upper chambers of the heart do not travel normally to the lower chambers. Heart block may be:
First-degree heart block, in which electrical signals are delayed but still reach the lower chambers.
Second-degree heart block, in which some electrical signals fail to reach the lower chambers.
Third-degree or complete heart block, in which electrical signals from the upper chambers do not reach the lower chambers normally. This can cause a very slow heart rate and may require urgent medical treatment.
Reduced ability to exercise or perform usual activities
Symptoms may become more noticeable during physical activity because the body needs more oxygen and the heart may not be able to increase its rate adequately.
Bradycardia can have many possible causes. These include problems affecting the heart’s electrical system, certain medical conditions, medications, and changes associated with aging. Common causes include:
A problem with the electrical pathways through the heart
Aging-related changes in the heart’s electrical system
Certain medicines can also slow the heart rate. These may include some medicines used to treat high blood pressure and abnormal heart rhythms, such as beta blockers, some calcium channel blockers, and digoxin. Other medicines can also contribute to bradycardia in some people.
A resting heart rate below 60 bpm can be normal in physically fit people. Regular endurance exercise can make the heart more efficient, allowing it to pump an adequate amount of blood with fewer beats per minute. Athletes may therefore have a resting heart rate below 60 bpm without having a heart disorder. Medical evaluation is important when a slow heart rate is accompanied by symptoms such as fainting, dizziness, unusual fatigue, chest pain, or reduced exercise tolerance.
Heart rate normally decreases during sleep. Some people may therefore have a relatively slow heart rate while sleeping without having a heart problem. However, repeated or significant nighttime bradycardia may sometimes be associated with conditions such as obstructive sleep apnea. A healthcare professional may recommend further evaluation when symptoms or other findings suggest an underlying disorder.
Mild or symptom-free bradycardia may not cause complications. However, when the heart rate is too slow to maintain adequate blood flow, complications can occur. Possible complications include:
Recurrent fainting
Falls and injuries resulting from fainting or dizziness
Reduced ability to exercise
Persistent fatigue and weakness
Worsening symptoms of heart failure in some people
Low blood pressure
Rarely, serious complications caused by severely impaired heart function
The risk depends on the underlying cause and the severity of the slow heart rate.
A healthcare professional will usually begin with a medical history and physical examination. The doctor may ask about symptoms, medications, medical conditions, exercise habits, and any history of heart disease. Tests may include:
An ECG records the heart’s electrical activity and can show the heart rate and rhythm. It can also help identify certain types of heart block or other rhythm abnormalities.
If the slow heart rate occurs intermittently, a portable heart monitor may be used for a longer period. This can help identify episodes that may not occur during a standard ECG.
When sleep apnea is suspected, a healthcare professional may recommend a sleep study or other evaluation. Additional cardiac testing may be recommended depending on the suspected cause.
When bradycardia is caused by another medical condition, treating that condition may improve the heart rate. For example, treatment of hypothyroidism or correction of an electrolyte abnormality may resolve the slow heart rate.
If a medicine is contributing to bradycardia, a doctor may adjust the dose, change the medicine, or recommend another treatment. Do not stop a prescribed medicine on your own, because suddenly stopping certain medicines can be harmful.
A pacemaker may be recommended for some people with persistent symptomatic bradycardia or certain types of heart block. A pacemaker is a device that helps maintain an appropriate heart rate by delivering electrical impulses when the heart’s natural rhythm is too slow. Not everyone with a slow heart rate needs a pacemaker. The decision depends on the type of rhythm problem, symptoms, underlying cause, and other clinical findings.
Not every case of bradycardia can be prevented, particularly when it results from aging-related changes, inherited conditions, or other unavoidable causes. However, maintaining heart health may reduce the risk of some conditions that can contribute to abnormal heart rhythms. Helpful measures include:
Following a heart-healthy diet
Maintaining a healthy body weight
Exercising regularly as advised by a healthcare professional
Avoiding tobacco products
Limiting alcohol consumption
Managing blood pressure, cholesterol, and diabetes
Taking prescribed medicines exactly as directed
Attending regular medical checkups when recommended
Seeking treatment for conditions such as sleep apnea and thyroid disorders
A slower heart rate in children can have different normal ranges depending on the child’s age and circumstances. A heart rate that is normal for one child may be unusually slow for another. Children with symptoms such as fainting, dizziness, unusual fatigue, breathing difficulty, chest pain, or poor exercise tolerance should be evaluated by a healthcare professional. Infants and children with suspected heart rhythm disorders may require assessment by a pediatric cardiologist.
Some physically active people have a low resting heart rate because regular exercise can improve the efficiency of the cardiovascular system.
However, a slow heart rate that causes dizziness, fainting, unusual shortness of breath, chest discomfort, or a sudden decline in exercise performance should be medically evaluated.
No. A resting heart rate below 60 bpm can be normal in some healthy people, particularly athletes and during sleep. It becomes more concerning when it is associated with symptoms or an underlying heart or medical condition.
For most adults, a resting heart rate between 60 and 100 bpm is generally considered normal. Individual heart rates can vary depending on age, fitness, medications, activity level, and other factors.
Yes. Several medicines can slow the heart rate. Examples include some beta blockers, certain calcium channel blockers, and digoxin. A healthcare professional should review medicines when medication-related bradycardia is suspected.
Not always. A pacemaker is generally considered only in selected patients, particularly those with symptomatic or clinically significant problems involving the heart’s electrical system. The need for a pacemaker should be determined by a qualified healthcare professional.
It depends on the cause. Bradycardia caused by a temporary condition, medication, or reversible medical problem may improve after the underlying cause is addressed. Bradycardia caused by persistent problems with the heart’s electrical system may require ongoing treatment.
Medical Disclaimer:This article is intended for general educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional regarding medical concerns.
