Bradycardia is a slower than normal heart rate. The heart usually beats between 60 and 100 times a minute in an adult at rest. If you have bradycardia (brad-e-KAHR-de-uh), your heart beats fewer than 60 times minute.
Bradycardia can be a serious problem if the heart doesn't pump enough oxygen-rich blood to the body. For some people, however, bradycardia doesn't cause symptoms or complications.
An implanted pacemaker and other treatments may correct bradycardia and help your heart maintain an appropriate rate.
If you have bradycardia, your brain and other organs may not get the supply of oxygen they need. As a result, you may experience these bradycardia symptoms:
When a slow heart rate is normal
When to see a doctor
If you faint, have difficulty breathing or have chest pain lasting more than a few minutes, get emergency care or call 911 or your local emergency number. Seek emergency care for anyone experiencing these symptoms.
Bradycardia is caused by something that disrupts the normal electrical impulses controlling the rate of your heart's pumping action. Many things can cause or contribute to problems with your heart's electrical system, including:
Electrical circuitry of the heart Your heart is made up of four chambers — two upper chambers (atria) and two lower chambers (ventricles). The rhythm of your heart is normally controlled by a natural pacemaker — the sinus node — located in the right atrium. The sinus node produces electrical impulses that initiate each heartbeat.
From the sinus node, electrical impulses travel across the atria, causing the atria to contract and pump blood into the ventricles. The electrical impulses then arrive at a cluster of cells called the atrioventricular node (AV node).
The AV node transmits the signal to a specialized collection of cells called the bundle of His. These cells transmit the signal down a left branch serving the left ventricle and a right branch serving the right ventricle. When the electrical impulse travels down these branches, the ventricles contract and pump blood — the right ventricle sending oxygen-poor blood to the lungs and the left ventricle sending oxygen-rich blood to the body.
Bradycardia occurs when electrical signals slow down or are blocked.
Sinus node problems
In some people the sinus node problems may result in alternating slow and fast heart rates (bradycardia-tachycardia syndrome).
Heart block (atrioventricular block)
A normal heartbeat begins when a tiny cluster of cells called the sinus node sends an electrical signal (1). The signal then travels through the atria and passes through another group of cells called ...
Complications of untreated bradycardia vary depending on how slow the heart rate is, where the electrical conduction problem occurs and what kind of damage may be present in heart tissue. If bradycardia is significant enough to cause symptoms, possible complications of the slow heart rate may include:
Risk factors related to heart disease
Preparing for your appointment
Whether you first see your family doctor or get emergency care, you'll likely be referred to a heart specialist (cardiologist) for one or more appointments for a complete diagnostic assessment.
If possible, take along a family member or friend who can give some moral support and help you keep track of new information. Because there may be a lot of ground to cover, it will be helpful to prepare as much as possible.
What you can do
List your questions from most important to least important in case time runs out. Basic questions to ask your doctor include:
In addition to the questions you've prepared to ask your doctor, don't hesitate to ask additional questions that may come up during your appointment.
What to expect from your doctor
Tests and diagnosis
Your doctor will order a series of tests to measure your heart rate, establish a link between a slow heart rate and your symptoms, and identify conditions that may be causing bradycardia.
Your doctor may also have you use a portable ECG device at home to provide more information about your heart rate and to help establish a correlation between a slow heart rate and the onset of symptoms. These devices include:
Your doctor may also use an ECG monitor while performing other tests to understand the impact of bradycardia. These tests include:
Laboratory and other tests
Treatments and drugs
Treatment for bradycardia depends on the type of electrical conduction problem, the severity of symptoms, and the cause of your slow heart rate.
Treating underlying disorders
Change in medications
Most pacemakers also capture and record information that your cardiologist can use to monitor your heart. You will have regularly scheduled follow-up appointments to check your heart and ensure the proper function of your pacemaker.
The most effective way to prevent bradycardia is to reduce your risk of developing heart disease. If you already have heart disease, monitor it and follow your treatment plan to lower your risk of bradycardia.
Prevent heart disease
Monitor and treat existing heart disease
Last Updated: 2011-05-26
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