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Holter Monitor

What is a Holter monitor?

The Holter monitor is a type of electrocardiogram (ECG) used to record an ECG tracing of the heart continuously for 24 hours or longer. A standard or "resting" ECG is one of the simplest and fastest procedures used to evaluate the heart. Electrodes (small, plastic patches that stick to the skin) are placed at certain locations on the chest and abdomen. When the electrodes are connected to an ECG machine by wires, the electrical activity of the heart is measured, recorded, and printed. No electricity is sent into the body.

Natural electrical impulses coordinate contractions of the different parts of the heart to keep blood flowing the way it should. An ECG records these impulses to show how fast the heart is beating, the rhythm of the heart beats (steady or irregular), and the strength and timing of the electrical impulses as they move through the different parts of the heart. Changes in an ECG can be a sign of many heart-related conditions.

When symptoms, such as dizziness, fainting, low blood pressure, ongoing fatigue (tiredness), and palpitations, continue to occur and a resting ECG doesn’t show a clear cause, your health care provider may request an ECG tracing to be recorded over a long period, using the Holter monitor. You wear the same kind of ECG electrode patches on your chest, and the electrodes are connected by wires to a small, portable recording device.

Certain arrhythmias (abnormal heart rhythms) may occur only now and then, or may occur only under certain conditions, such as stress or activity. Arrhythmias of this type are hard to record on an ECG tracing that only runs for a few minutes. Because of this, the health care provider might request a Holter monitor to get a better chance of capturing 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), how to keep a diary of your activities and symptoms during the test, and personal care and activity instructions, which include keeping the device dry while you are wearing it.

Why might I need a Holter monitor?

Some reasons for your healthcare provider to request a Holter monitor recording or event monitor recording include:

  • To evaluate chest pain that cannot be reproduced with exercise testing
  • To evaluate other signs and symptoms that may be heart-related, such as tiredness, shortness of breath, dizziness, or fainting
  • To identify irregular heartbeats or palpitations
  • To assess risk for future heart-related events in certain conditions, such as hypertrophic cardiomyopathy (thickened heart walls due to an underlying genetic condition), after a heart attack that caused weakness of the left side of the heart, or Wolff-Parkinson-White syndrome (where an abnormal electrical conduction pathway exists within the heart)
  • To see how well an implanted pacemaker is working
  • To determine how well treatment for complex arrhythmias is working

There may be other reasons for your healthcare provider to recommend the use of a Holter monitor.

What are the risks of a Holter monitor?

The Holter monitor is an easy way to assess the heart’s function. Risks associated with the Holter monitor are rare.

It can be hard to keep the electrodes stuck to your skin, and extra tape may be needed. It may be uncomfortable when the sticky electrodes and tape are taken off. Prolonged application of the adhesive electrode patches may cause tissue breakdown or skin irritation at the application site.

There may be other risks depending on your specific medical condition. Be sure to discuss any concerns with your healthcare provider prior to wearing the monitor.

Certain factors or conditions may interfere with or affect the results of the Holter monitor reading. These include, but are not limited to:

  • Close proximity to 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 and should be kept at least 6 inches away from the monitor box.
  • Smoking or using other forms of tobacco
  • Certain medications
  • Excessive sweating, which may cause the leads to loosen or come off


How do I get ready for a Holter monitor?


  • Your healthcare provider will explain the procedure to you and you can ask questions.
  • Fasting (not eating or drinking) is not necessary.
  • Based on your medical condition, your healthcare provider may request other specific preparation.


What happens during a Holter monitor?

A Holter monitor recording is generally done on an outpatient basis. Procedures may vary depending on your condition and your healthcare providers practice.

Generally, a Holter monitor recording follows this process:

  1. You will be asked to remove any jewelry or other objects that may interfere with the reading.
  2. You will be asked to remove your clothing from the waist up in order to attach the electrodes to your chest. The technician will ensure your privacy by covering you with a sheet or gown and exposing only the necessary skin.
  3. 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.
  4. 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 clip to a belt or pocket.
  5. Find out if you will have to change the batteries in the monitor. Be sure you know how to do it and have extra batteries on hand.
  6. Once you have been hooked up to the monitor 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 allow your healthcare provider to identify problems that may only occur with certain activities.
  7. You will be instructed to keep a diary of your activities while wearing the monitor. You should 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.

What happens after a Holter monitor?

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 following a Holter monitor recording.

Notify your healthcare provider if you develop any signs or symptoms you had prior to the recording (for example, chest pain, shortness of breath, dizziness, or fainting).

Your healthcare provider may give you additional or alternate instructions after the procedure, depending on your particular situation.

Next steps

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
  • The risks and benefits of the test or procedure
  • When and where you are to have the test or procedure and who will do it
  • When and how will you get the results
  • How much will you have to pay for the test or procedure

Medical Reviewers:

  • Fraser, Marianne, MSN, RN
  • Stump-Sutliff, Kim, RN, MSN, AOCNS