Richard N. Fogoros, MD, is a retired medical professor and a board-certified physician and cardiologist.

Anisha Shah, MD, is a board-certified physician, interventional cardiologist, and a member of the American College of Cardiology.

The Holter monitor research is the first and is currently the most widely used type of Holter monitor (ECG). It is named after Norman J. Holter, the physicist who was primarily responsible for its invention in the 1950s. 

As with any type of Holter monitoring, the main purpose of Holter monitoring research is to analyze the electrical activity of the heart outside the clinical environment—that is, when a person is performing normal daily activities.

When a person conducts a Holter monitoring study, they wear the monitoring device for 24 or 48 hours, and then analyze the ECG recorded during this period for any arrhythmias that may have occurred during the monitoring period and any signs of myocardial ischemia.

Holter monitor studies are very effective in diagnosing arrhythmias, as long as they occur frequently enough. The test is very safe.

There are many types of arrhythmias. They can produce various symptoms, and their medical significance and treatment methods are also quite different. Therefore, if a person is suspected of having an arrhythmia, it is important to diagnose the exact nature of the arrhythmia in order to decide what measures (if any) need to be taken against it. This means that the arrhythmia must be captured on the ECG.

However, many arrhythmias occur rarely and are completely unpredictable-and usually only occur for a short period of time. When a healthcare provider happens to record a standard ECG (recording only a 12-second rhythm), the chance of catching one of these rare or transient arrhythmias is very small.

In addition, symptoms caused by arrhythmia may only last for a short time. When a person with symptoms can go to a medical institution to record an electrocardiogram, the symptoms (and the arrhythmia that caused them) have often disappeared.

The Holter monitor is designed to solve the problem of diagnosing occasional or transient arrhythmias. By recording every heartbeat that occurs over a long period of time, when a person is engaged in activities of daily living, the chance of detecting one of these transient arrhythmias is greatly increased.

When should the Holter study be conducted?

When a person has transient symptoms that may be explained by a heart rhythm disorder, the Holter monitor is most commonly used for research. In most cases, these symptoms are:

Less commonly, Holter monitoring studies can also be used to look for ischemic attacks that do not produce angina. Because this ischemia does not cause symptoms, it is often referred to as "silent ischemia." However, the ECG changes caused by ischemia in Holter studies are usually non-specific, and such ECG changes may be misleading. In this case, most cardiologists usually do not conduct Holter studies for this purpose unless they are dealing with patients who are known to have asymptomatic ischemia-such as patients who have been diagnosed with asymptomatic ischemia during a stress test, Or who has had a silent heart attack.

Therefore, so far, Holter monitor research is most commonly used to diagnose arrhythmia.

The Holter monitor study has almost no risks, except that the possibility of skin irritation at the electrode placement site is very small.

The Holter study is not always the best Holter monitoring. If there are good reasons to believe that the arrhythmia you are trying to diagnose is so rare that it is unlikely to occur within any given 24-48 hours, you can use a different type of Holter monitoring (or longer) should consider.

Knowing these details before the test can help relieve any fear or anxiety you are experiencing.

You and your healthcare provider will jointly decide a good time for the test. Almost any 24-48 hour period is usually sufficient, but it is best to choose a time when you are not traveling (to avoid the hassle of airport security), do not plan water activities, or activities that will make you sweaty (because you need Keep it dry while wearing the Holter monitor).

You need to go to an outpatient facility, usually at a local hospital, where a technician connects to your Holter monitor. This only takes a few minutes. At the end of the test, you may be asked to return to the same institution to remove Holter, but many Holter laboratories now use a delivery service to remove the recorder from your home after the test.

Although you can wear any comfortable clothes, a loose-fitting top is required so that the Holter monitor can be worn comfortably underneath.

You can eat and drink as usual before the test, and (unless your healthcare provider tells you otherwise) you can take normal medications. It is a good idea to take a shower before starting the Holter monitor research, because you will not be able to do so while wearing the monitor.

The cost of research varies. Almost all health insurance covers Holter monitoring research, as long as it is ordered by a licensed doctor. However, it is never a bad idea to check with your insurance company in advance.

The Holter monitor consists of several tiny electrode patches attached to the skin. These patches are connected to the recording device by thin wires. Recording equipment (previously a small tape recorder, but today more common is a digital recorder no larger than a deck of cards), which can be hung around the neck or tied to a belt. Electrodes, wires, and recording equipment are all hidden under your clothes. At the end of the test, remove the electrodes and wires, and send the recording device back to the laboratory for analysis.

When you arrive at the Holter laboratory, the technician will place the electrodes (about 50 cents in size) in the appropriate locations on your chest and connect them to the monitor. Men may need to shave into small pieces for the electrodes to adhere properly.

The technician will help you decide how to wear the recording equipment, guide you on precautions, and tell you how to record your activities and symptoms. Then you will be dispatched on the way.

During the test, you will simply follow your normal procedures, with two big exceptions. First of all, you need to keep the Holter device dry-so don't shower, and don't bathe the chest area.

Second, you need to keep a diary of all the activities you perform and any symptoms you may experience while wearing the Holter monitor. In particular, your healthcare provider will be most interested in symptoms of dizziness, palpitations, fainting, chest pain, or shortness of breath. The exact time you experienced these symptoms will be compared with the ECG record at that time.

After the test is complete, you must either return to the Holter laboratory to take out the equipment, or take out the equipment yourself and return it (and your diary) through the delivery service used by the laboratory.

You should receive the results from your healthcare provider within one to two weeks and discuss possible next steps.

If you experience skin irritation caused by electrodes (which is not common), please call the Holter laboratory to discuss how to deal with it.

Your healthcare provider should contact you and inform you of the results, or a return visit should be scheduled in advance to discuss the results of your Holter study. 

When interpreting the results of the Holter study, it is important to remember that the most common purpose of this study is to determine whether your unexplainable symptoms are caused by an arrhythmia. This means that actually linking the symptoms to the concurrent arrhythmia is essential for making a diagnosis.

Many people (actually most people) occasionally experience a benign arrhythmia, but it does not cause any symptoms at all. Seeing such arrhythmia on the Holter report without concurrent symptoms indicates that the arrhythmia did not cause problems and (usually) does not require any further evaluation of the treatment.

On the other hand, when the symptoms are closely related to the arrhythmia, the arrhythmia can cause problems (at least, it produces symptoms) and is worth solving.

Your healthcare provider may also discuss with you other results displayed in the Holter monitor report, including your maximum, minimum, and average heart rate, and the total number of atrial premature beats (PAC) and ventricular premature beats (PVC) you may have , And any possible ischemic attacks.

If you are conducting a Holter study to look for asymptomatic ischemia, finding obvious signs of ischemia during the test may lead to further testing (perhaps nuclear stress testing or cardiac catheterization), or a change in your anti-ischemic treatment.

Holter monitoring research is the most widely used type of dynamic ECG monitoring. This test is very good at diagnosing transient arrhythmias that usually occur within any given 24-48 hours, and it is very safe.

Did you know that the most common heart disease is largely preventable? Our guide will show you what puts you at risk and how to control your heart health.

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Barrett P, Komatireddy R, Haaser S, etc. Comparison of 24-hour Holter ECG monitoring and 14-day new patch ECG monitoring. It's J Med. 2014;127(1):95.e11-95.e17. doi:10.1016/j.amjmed.2013.10.003

Cleveland Clinic. Diagnosis and testing of heart block. Updated on July 18, 2019.

Nishijima D, Lin A, Weiss R, etc. ECG predictors of arrhythmia in the elderly with syncope. Ann Emerg Med. 2018;71(4):452-461.e3. doi:10.1016/j.annemergmed.2017.11.014

Ramkumar S, Nerlekar N, D'Souza D, Pol D, Kalman J, Marwick T. Using single-lead portable ECG monitoring to detect atrial fibrillation: a systematic review and meta-analysis. BMJ Open. 2018; 8(9): e024178. doi:10.1136/bmjopen-2018-024178

American Heart Association. Holter monitor. Updated on July 31, 2015.

American Heart Association. Premature shrinkage-PAC and PVC. Updated on September 30, 2016.

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