A Holter monitor is a type of portable electrocardiogram (ECG). It records the electrical activity of the heart continuously over 24 hours or longer while you are away from the healthcare provider's office.
A standard or "resting" ECG is one of the simplest and fastest tests used to evaluate the heart. Small, plastic patches (electrodes) are put on certain points on the chest and belly (abdomen). The electrodes are connected to an ECG machine by wires. The electrical activity of the heart can be measured, recorded, and printed. No electricity is sent into the body.
Natural electrical impulses coordinate contractions of the different parts of the heart. This keeps blood flowing the way it should. An ECG records these impulses to show how fast the heart is beating, and the rhythm of the heart beats (steady or irregular). It also records the strength and timing of the electrical impulses. Changes in an ECG can be a sign of many heart-related conditions.
Your healthcare provider may request a Holter monitor ECG if you have symptoms, such as dizziness, fainting, low blood pressure, ongoing tiredness, or palpitations and a resting ECG doesn’t show a clear cause. A Holter monitor may also be ordered if your resting ECG shows a problem, but more information is needed. You wear the same kind of ECG electrode patches on your chest, and the electrodes are connected by wires to a small monitor box (portable recording device).
Certain abnormal heart rhythms may occur only now and then. Or, they may occur only under certain conditions, such as stress or activity. These are hard to record on an ECG done in the office. Because of this, the healthcare provider might request a Holter monitor to get a better chance of catching any abnormal heartbeats or rhythms that may be causing the symptoms. Some Holter monitors also have an event monitor feature that you activate when you notice symptoms.
You will get instructions on how long you will need to wear the monitor (usually 24 to 48 hours). Your provider will also tell you how to keep a diary of your activities and symptoms during the test, and about any personal care and activity instructions. For example, you will need to keep the device dry while you are wearing it.
Some reasons your healthcare provider may ask for a Holter monitor recording or event monitor recording include:
To evaluate signs and symptoms that may be heart-rhythm related, such as chest pain, tiredness, shortness of breath, dizziness, or fainting
To identify irregular heartbeats or palpitations
To assess your risk for future heart-related events in certain conditions, such as thickened heart walls (hypertrophic cardiomyopathy), after a heart attack that caused weakness of the left side of the heart, or Wolff-Parkinson-White syndrome. In this syndrome, an abnormal electrical conduction pathway exists within the heart.
To see how well a pacemaker is working
To determine how well treatment for complex abnormal heart rhythms is working
To evaluate how fast or slow your heart rate gets during the day and whether you have any pauses in your heart rhythm
Your healthcare provider may have other reasons to recommend a Holter monitor.
The Holter monitor is an easy way to check the heart’s function. Risks of a Holter monitor are minimal and rare.
It can be hard to keep the electrodes stuck to your skin. Extra tape may be needed. It may be uncomfortable when the sticky electrodes and tape are taken off. If the electrodes are on for a long time, they may cause skin irritation or blistering.
There may be other risks depending on your specific health condition. Discuss any concerns with your healthcare provider before wearing the monitor.
Certain factors or conditions may interfere with or affect the results of the Holter monitor reading. These include:
Being near magnets, metal detectors, high-voltage electrical wires, and electrical appliances such as shavers, toothbrushes, and microwave ovens. Cell phones and mp3 players can also interfere with the signals. Keep them at least 6 inches away from the monitor box.
Smoking or using other forms of tobacco
Excessive sweating, which may cause the leads to loosen or come off
Your healthcare provider will explain the procedure to you and you can ask questions.
You don't need to fast (not eat or drink).
Based on your health condition, your healthcare provider may have other instructions for you.
A Holter monitor recording is generally done on an outpatient basis. Procedures may vary depending on your condition and your healthcare provider's practice.
Generally, a Holter monitor recording follows this process:
You will be asked to remove any jewelry or other objects that may interfere with the recording.
You will be asked to remove your clothing from the waist up so that electrodes can be attached to your chest. The technician will ensure your privacy by covering you with a sheet or gown and exposing only the necessary skin.
The areas where the electrodes patches are placed are cleaned, and in some cases, hair may be shaved or clipped so that the electrodes will stick closely to the skin.
Electrodes will be attached to your chest and abdomen. The Holter monitor will be connected to the electrodes with wires. The small monitor box may be worn over your shoulder like a shoulder bag, around your waist, or it may be clipped to a belt or pocket.
Find out if you will have to change the batteries in the monitor box. Be sure you know how to do it and have extra batteries on hand.
Once you have been hooked up to the monitor box and given instructions, you can return to your usual activities, such as work, household chores, and exercise, unless your healthcare provider tells you otherwise. This will let your healthcare provider find problems that may only occur with certain activities.
You may be told to keep a diary of your activities while wearing the monitor. Write down the date and time of your activities, particularly if any symptoms, such as dizziness, palpitations, chest pain, or other previously experienced symptoms, occur.
You should be able to go back your normal diet and activities, unless your healthcare provider instructs you differently.
Generally, there is no special care after a Holter monitor recording.
Tell your healthcare provider if you have any symptoms you had before the recording. For example, if you have chest pain, shortness of breath, dizziness, or fainting.
Your healthcare provider may give you other instructions after the procedure, depending on your situation.
Before you agree to the test or the procedure make sure you know:
The name of the test or procedure
The reason you are having the test or procedure
What results to expect and what they mean
The risks and benefits of the test or procedure
What the possible side effects or complications are
When and where you are to have the test or procedure
Who will do the test or procedure and what that person’s qualifications are
What would happen if you did not have the test or procedure
Any alternative tests or procedures to think about
When and how you will get the results
Who to call after the test or procedure if you have questions or problems
How much you will have to pay for the test or procedure