What Is Bradycardia?
A normal heart typically beats 60 to 80 times a minute. At this rate, the heart pumps about 5 liters of blood throughout your body per minute. However, if the signal rate is too slow, the chambers of your heart do not contract often enough to supply the proper amount of blood and oxygen to your body. When the heart beats slow this is called bradycardia. Bradycardia
Bradycardia can affect the very young to the very old, though it is most commonly diagnosed among the elderly. More than 600,000 people worldwide receive treatment each year for bradycardia.
What Causes Bradycardia?
The most common causes of bradycardia are a problem with the S-A node or a problem in the heart's electrical pathways. These problems result in heartbeats that don't sufficiently meet the needs of your body. To illustrate this idea, think of how a car works. If the accelerator is broken, the engine can't get enough gas to move the car as fast as you want. Similarly, if your heart's electrical system is not working normally, your body may not be receiving the extra fuel it needs to take a brisk walk.
Problems with the S-A Node
Sometimes, the heart's natural pacemaker stops working properly. The S-A node does not send signals frequently enough, which causes the heart to contract less often than it should. A slow heartbeat is typically less than 60 beats per minute (bpm).
Problems with the Electrical Pathway Between the Upper and Lower Heart (Heart Block)
Problems may also occur with the electrical pathway between the upper and lower heart. The electrical signals may be delayed in the A-V node or may fail to reach the ventricles all together. This condition is called heart block. Although the lower heart has a natural standby system that can produce its own signals, these signals are often too slow. As a result, heart block often means that the ventricles pump too slowly even though the S-A node may be sending out faster signals in an effort to increase heart rate.
Heart block may also cause a loss of AV synchrony. If the timing of contractions between the upper and lower heart is poor, the ventricles may not fill with enough blood before pumping. Your doctor may call this condition asynchrony.
What Are Typical Symptoms of Bradycardia?
Typical symptoms of bradycardia include fatigue, shortness of breath, and dizziness. Even routine activities, such as getting up from a chair or walking to the mailbox, may leave you short of breath. Often, the symptoms of bradycardia occur gradually, which causes many people to think they are "just tired" or "getting older" rather than that they are experiencing a heart problem.
How Is Bradycardia Diagnosed?
To diagnose bradycardia, your doctor will typically use an electrocardiogram (ECG) test. This is a painless test using electrode patches on your skin that shows how electrical signals travel through your heart and prints them out on paper. Your doctor can tell what kind of rhythm you have by looking at the printed pattern of your heartbeat.
Other diagnostic tests may include Holter monitors. Holters are monitors that are worn for a longer duration and record every heart beat for that period of time. Patients that have rare events maybe candidates for Event recorders. Event recorders are devices that are worn by the patient. These devices pick up arrhythmias automatically and also can be activated when patients feel symptoms. These recorders help correlate someone’s symptoms with heart rhythm disorders and record infrequent rhythms.
How Is Bradycardia Treated?
Bradycardia is most commonly treated with a pacemaker. A pacemaker alters the heart rate to help meet your body's needs. The pacemaker provides signals much like the heart's normal signals. Depending on your particular situation, a pacemaker may:
- Replace S-A node signals that are delayed or get lost on the pathway between the upper and lower heart
- Help maintain a normal timing sequence between the upper and lower heart
- Make sure the critical lower chambers of the heart always contract at an adequate rate