How is bradycardia diagnosed?

Your doctor will ask about your family history of heart disease, cardiac arrhythmias and fainting spells. He or she also will review your current symptoms and your personal medical history, including your use of medications that may cause bradycardia. During the physical examination, your doctor will check your heart rate and rhythm, together with your pulse. This is because certain cardiac arrhythmias cause a mismatch of the pulse, which reflects the activity of the ventricles, and the heart sounds. Your doctor also will check for physical signs of thyroid abnormalities (enlarged thyroid gland, very dry skin, hair that is thin and dry).

Can bradycardia be prevented?

There are no general guidelines to prevent all forms of bradycardia. When bradycardia occurs as a side effect of medication, the problem can be prevented by either switching the drug or reducing its dose.

How is bradycardia treated?

In most cases, bradycardia in healthy, well-trained athletes does not need to be treated. In fact, in most people, bradycardia does not require treatment unless patients have symptoms that are clearly due to acslow heartbeat. The following are conditions that produce bradycardia that requires treatment: • Cardiac arrhythmias resulting from sinus-node dysfunction — In people with frequent, severe symptoms of sinus-node dysfunction, the main treatment is usually a permanent pacemaker, an implanted device that generates electrical impulses to regulate the heartbeat.

When should you see a doctor about bradycardia?

Call your doctor if your pulse is less than 60 beats per minute. This is especially important if you have been suffering from dizziness, weakness, lack of energy or fainting spells.

What is the outlook for bradycardia?

In well-trained athletes with normal bradycardia, the efficiency of the heart is often a reflection of overall good health, and the prognosis is excellent. In other people with bradycardia, the prognosis depends on the underlying disorder. For example, the prognosis is usually good in people with hypothyroidism, since treatment with thyroid hormones can relieve bradycardia and other symptoms related to low hormone levels. In some elderly patients, hormone dosages may need to be increased very slowly over several weeks to prevent straining the heart. At one time, the prognosis for people with third-degree A-V block was poor, with 50 percent of patients dying within one year of diagnosis.

Condition

Bradycardia

David Cohen, M.D.Published 10 August 20045 min read

Key points

Bradycardia is an abnormally low heart rate of less than 60 beats per minute.
Although bradycardia is a symptom in itself, it can occur with other symptoms, such as dizziness, weakness, lack of energy or fainting spells.
Your doctor will ask about your family history of heart disease, cardiac arrhythmias and fainting spells.
The duration of bradycardia depends on its underlying cause.

What Is It?

Bradycardia is an abnormally low heart rate of less than 60 beats per minute.

In normal adults, the heart beats regularly at a rate of 60 to 100 times per minute, and the pulse (felt at the wrist, neck, or elsewhere) matches the contractions of the heart's ventricles (the heart's two powerful lower chambers). The signal for a heartbeat comes from the heart's sinus node, the natural pacemaker located in the upper portion of the right atrium. From the sinus node, the heartbeat signal travels to the atrioventricular (A-V)node, located between the atria, and through the bundle of His (pronounced "hiss" — a series of modified heart-muscle fibers located between the ventricles) to the muscles of the ventricles. This triggers a contraction of the ventricles and produces a heartbeat.

Bradycardia, even as low as 50 beats per minute, can be normal in athletes and other people who lead physically active lifestyles. In these people, regular exercise maximizes the ability of the heart to pump blood efficiently, so fewer heart contractions are required to supply the body's needs. In other cases, bradycardia can be a form of cardiac arrhythmia, a heart-rate abnormality. Cardiac arrhythmia can be caused by a dysfunction of the sinus node, or it can be related to some disturbance in the passage of heartbeat signals through the A-V node and bundle of His. Also, bradycardia sometimes occurs as a side effect of certain medications, including propranolol (Inderal), atenolol (Tenormin), metoprolol (Toprol-XL), sotalol (Betapace), verapamil (Calan, Isoptin, Verelan) and diltiazem (Cardizem, Dilacor-XR). In addition, bradycardia may be seen in people suffering from certain underlying medical illnesses that are not specifically related to the heart, such as:

An abnormally low level of thyroid hormones (hypothyroidism)
Severe liver disease
An abnormally low body temperature (hypothermia)
Typhoid fever
Brucellosis (an infectious disease marked by fever, sweating and weakness that is transmitted to humans by direct contact with diseased animals or through ingestion of contaminated meat, milk or cheese)

Symptoms

Although bradycardia is a symptom in itself, it can occur with other symptoms, such as dizziness, weakness, lack of energy or fainting spells.

If bradycardia is the result of an underlying medical illness, there will be additional symptoms that are specific to that medical illness. For example, people whose bradycardia is due to severe hypothyroidism also can have constipation, muscle cramps, weight gain (often despite poor appetite), very dry skin, hair that is thin and dry, an abnormal sensitivity to cold temperatures and other symptoms related to low levels of thyroid hormones.

Written and revised by

David Cohen, M.D.

Our doctors write and review articles for accuracy and keep them up to date.

health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.

Explore health topics

Key points

Bradycardia is an abnormally low heart rate of less than 60 beats per minute.
Although bradycardia is a symptom in itself, it can occur with other symptoms, such as dizziness, weakness, lack of energy or fainting spells.
Your doctor will ask about your family history of heart disease, cardiac arrhythmias and fainting spells.
The duration of bradycardia depends on its underlying cause.

What Is It?

Bradycardia is an abnormally low heart rate of less than 60 beats per minute.

An abnormally low level of thyroid hormones (hypothyroidism)
Severe liver disease
An abnormally low body temperature (hypothermia)
Typhoid fever
Brucellosis (an infectious disease marked by fever, sweating and weakness that is transmitted to humans by direct contact with diseased animals or through ingestion of contaminated meat, milk or cheese)

Symptoms

Although bradycardia is a symptom in itself, it can occur with other symptoms, such as dizziness, weakness, lack of energy or fainting spells.

Written and revised by

David Cohen, M.D.

Our doctors write and review articles for accuracy and keep them up to date.

health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.

Bradycardia

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