Heart Rhythm Tests
Electrocardiogram (ECG or EKG)
An electrocardiogram, also called an ECG or EKG, is one of the simplest and fastest procedures used to evaluate the heart. Small plastic patches called electrodes are placed on the chest, arms and legs. Lead wires connect the electrodes to an ECG machine, which measures and records the heart's electrical activity for a physician to review and interpret.
Types of Electrocardiograms
Resting Electrocardiogram
A resting electrocardiogram monitors the heart's electrical activity while the patient is at rest.
Exercise Electrocardiogram
An exercise electrocardiogram monitors the heart's activity during physical exercise. The test may be used to:
- Evaluate exercise capacity
- Detect coronary artery disease and assess its severity
- Estimate cardiovascular risk
- Monitor the patient's response to treatment
Signal-Averaged Electrocardiogram
A signal-averaged electrocardiogram typically takes 15 to 20 minutes. A computer processes the information collected during the test to help identify cardiac abnormalities that may not appear on a standard ECG.
This test may be used when an arrhythmia is suspected but is not detected on a resting ECG. Because some arrhythmias occur only occasionally, they may not appear during the brief recording period of a resting ECG.
Holter Monitoring
A Holter monitor is a portable electrocardiogram device that continuously records the heart's electrical activity for 24 hours or longer. Small plastic patches called electrodes are placed on the chest and connected by lead wires to a portable recording device.
Because the monitor records for an extended period, it may detect abnormal heart rhythms that do not occur during a standard resting ECG.
Event Monitoring
Event monitoring is similar to Holter monitoring and is often ordered for the same reasons. Electrodes are placed on the chest and connected by lead wires to a portable recording device.
Unlike a Holter monitor, which records continuously for a specified period, an event monitor records the heart's electrical activity when symptoms occur and the patient activates the device.
An auto-trigger event monitor may be used when symptoms are rare or are suspected to occur during sleep. The device automatically records heart rhythms that are faster or slower than normal. It may also be activated manually when symptoms occur.
Electrophysiology (EP) Study
An electrophysiology study, also called an EP study, records the electrical activity and pathways of the heart. The test helps determine the cause of a heart rhythm disorder and identify the most appropriate treatment.
During an EP study, a physician may safely reproduce an abnormal heart rhythm. The physician may then administer medication or evaluate whether a procedure or implanted cardiac device is the best treatment option.
Why an EP Study May Be Needed
The heart's electrical system controls the speed and rhythm of the heartbeat. When a problem affects this system, the heart may beat too quickly, too slowly or irregularly. These abnormal heart rhythms, called arrhythmias, can interfere with the heart's ability to pump blood effectively.
To diagnose an arrhythmia, a physician may order an EP study. During this invasive test, one or more thin, flexible tubes called catheters are guided through blood vessels, typically in the groin, and into the chambers of the heart. The catheters record the heart's electrical signals and help identify where an abnormal rhythm begins.
What an EP Study Can Determine
An EP study can help a physician:
- Determine the cause of an abnormal heart rhythm
- Locate where the abnormal rhythm begins
- Identify the most appropriate treatment for the abnormal rhythm
