Bradycardia (Slow Heartbeat)

What is bradycardia?

Bradycardia is a very slow heart rate. The normal adult heart rate, or pulse, ranges from about 50 to 100 beats per minute. A heart rate that stays below 50 beats per minute is called bradycardia.

What is the cause?

Bradycardia happens when your heart's natural pacemaker, the sinus node, slows down. You may also have a very slow heart rate if the signal is not sent to the heart's lower chambers (the ventricles) through the proper pathway (the AV node). Bradycardia may happen because:

• The brain does not send a message to the heart that the heart needs to beat faster.
• The sinus or AV node is damaged. The damage may be related to heart disease, aging, or birth defects. It might be caused by certain medicines, including those used to control abnormal heart rates or high blood pressure.

Bradycardia may be the result of medical problems such as:

• hypothermia (very low body temperature)
• hypothyroidism (very low level of thyroid hormones).

Very slow heart rates can be normal in athletes and people with a very active lifestyle. Regular exercise helps the heart to pump blood efficiently, so fewer heart contractions are needed to supply the body's needs. Also, it is normal for the heart rate to be a lot slower during sleep.

What are the symptoms?

Your only symptom may be a very slow heartbeat. Or you may also have fainting spells, dizziness, weakness, or an unusual lack of energy.

How is it diagnosed?

Your healthcare provider will ask about your medical history, including which medicines you take. He or she will examine your heart and lungs. You may have blood tests to check for diseases. You may have a chest X-ray. You will have an electrocardiogram (ECG) to measure the electrical activity of your heart.

Your provider may want you to wear a Holter monitor for 1 to 3 days, or to carry another type of monitor with you for several weeks. The Holter monitor is a portable ECG used to detect heart rhythm disturbances.

How is it treated?

Many times, bradycardia does not need to be treated until it causes severe symptoms. When bradycardia occurs as a side effect of medicine, the problem can be treated by reducing the dosage of medicine or taking a different medicine. If hypothyroidism is causing a slow heart rate, it is treated with thyroid hormones.

If the symptoms are severe and are not caused by medicine or a thyroid problem, the usual treatment is a permanent pacemaker. A pacemaker is a device placed in the chest that helps control the heartbeat.

How long will the effects last?

When bradycardia occurs as a side effect of medicine, it will go away as soon as the medicine is out of your system. Bradycardia caused by hypothyroidism usually is successfully treated with thyroid hormones. Other forms of bradycardia resulting from sinus or AV node problems can be cured with a permanent pacemaker.

How can I take care of myself?

• Take your medicines as prescribed.
• Call your healthcare provider if your pulse stays under 50 beats a minute. This is especially important if you have dizziness, weakness, lack of energy, or fainting spells.

How can I help prevent bradycardia?

The best prevention is to have a heart-healthy lifestyle:

• Keep a healthy weight.
• Eat a healthy diet.
• Stay fit with the right kind of exercise for you.
• Decrease stress.
• Don’t smoke.
• Limit your use of alcohol.