Bradycardia is a slower than normal heart rate.
The adult heart (at rest) beats at about 60 to 80 beats per minute. 55 to 60 beats per minute would be considered bradycardia for an adult. Infants, however, have a much higher at rest heart rate (110 to 130 beats per minute), thus, bradycardia in infants would be a rate below 100 beats per minute.
Slower than average heart rates are normal in people who are physically fit and people who are sleeping. Many athletes who train regularly have resting heart rates of 40 to 60 beats per minute.
Bradycardia can also occur secondary to certain illnesses (such as decreased thyroid function, certain gastrointestinal disorders, and jaundice), or the abuse of certain drugs. People with known heart disease (including hypertension) who are being treated with medications that slow the heart (such as beta-blockers and certain calcium channel blockers) can experience bradycardia.
It may be a temporary consequence of certain types of heart attack. Bradycardia is common in elderly people (whether or not they suffer from arteriosclerosis) and infants with certain types of congenital heart disease.
When symptoms occur, they are usually fatigue, shortness of breath, light-headedness or fainting. Athletes and those with "trained" hearts generally have no symptoms.
A very slow heart rate may cause you to:
- Feel dizzy or lightheaded.
- Feel short of breath and find it harder to exercise.
- Have chest pain or a feeling that your heart is pounding or fluttering (palpitations).
- Feel confused or have trouble concentrating.
- Faint, if a slow heart rate causes a drop in blood pressure.
Some people don't have symptoms, or their symptoms are so mild that they think they are just part of getting older.
Bradycardia can be caused by:
- Changes in the heart that are the result of aging.
- Diseases that damage the heart's electrical system. These include coronary artery disease, heart attack and infections such as endocarditis and myocarditis.
- Conditions that can slow electrical impulses through the heart. Examples include having a low thyroid level (hypothyroidism) or an electrolyte imbalance, such as too much potassium in the blood.
- Some medicines for treating heart problems or high blood pressure, such as beta-blockers, antiarrhythmics, and digoxin.
How bradycardia is treated depends on what is causing it. Treatment also depends on the symptoms. If bradycardia does not cause symptoms, it usually is not treated.
If damage to the heart’s electrical system causes your heart to beat too slowly, you will probably need to have a pacemaker. A pacemaker is a device placed under your skin that helps correct the slow heart rate. People older than 65 are most likely to have a type of bradycardia that requires a pacemaker.
If another medical problem, such as hypothyroidism or an electrolyte imbalance, is causing a slow heart rate, treating that problem may cure the bradycardia.
If a medicine is causing your heart to beat too slowly, your doctor may adjust the dose or prescribe a different medicine. If you cannot stop taking that medicine, you may need a pacemaker.
The goal of treatment is to raise your heart rate so your body gets the blood it needs. If severe bradycardia is not treated, it can lead to serious problems. These may include fainting and injuries from fainting.