Abnormal Heart Rhythms
An abnormal heart rhythm, or arrhythmia, is a change in either the speed or pattern of the heartbeat. During an arrhythmia the heart may beat too slowly, too rapidly, or irregularly. An arrhythmia may be experienced as a skipping or fluttering sensation in the chest (palpitation). It may also cause lightheadedness, fainting spells, chest pain, or shortness of breath. Sometimes, arrhythmias may go unnoticed. An arrhythmia becomes serious when the heart beats too slowly or too rapidly to pump blood effectively, or when there is a threat to the person's life. How Doctors Diagnose Arrhythmias
If your doctor suspects you have an arrhythmia, he or she may order one or more diagnostic tests to check for an arrhythmia and determine whether it is causing your symptoms. The electrocardiogram (ECG or EKG) is a simple test that records the electrical activity of your heart. The ECG tracing is a series of waves that represent the electrical events in the heart. By carefully examining the sequence of electrical events on the ECG, doctors are able to diagnose arrhythmias. Holter monitoring is a continuous recording of the ECG, usually for 24 hours, while the patient goes about his or her usual daily activities. The test is useful for detecting arrhythmias that may not appear during a resting ECG at the doctor's office. The event recorder is carried over a period of days or weeks, and is used to record abnormal heart rhythms that occur infrequently. When symptoms occur, the patient activates the recorder. The ECG recording can be transmitted over the telephone to the doctor's office or hospital. When the basic tests do not provide all of the necessary information, an EP study may be done to find out exactly what the problem is and what can be done to control it. Types of Arrhythmias
There are two general types of arrhythmias:
- Rapid Heart Rhythms
- Slow Heart Rhythms
Here is a brief description of the most common arrhythmias that may require an EP study. (Keep in mind that not every arrhythmia described here will require an EP study.) Rapid Heart Rhythms
Rapid heart rhythms (tachycardias) may originate in the atria, AV node, or ventricles. Because the ventricles do most of the pumping, rapid rhythms in the ventricles are generally more serious.
Supraventricular Tachycardia (SVT)
SVT is a series of very rapid heartbeats that begin in the heart's upper chambers. SVT may occur when an extra pathway exists in the atria, in the AV node, or between the atria and ventricles.
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