What is a Holter monitor?
The 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 doctor's office. A standard or "resting" ECG is one of the simplest and fastest
tests used to evaluate the heart. Electrodes (small, plastic patches that stick to
the skin) are placed at certain points on the chest and abdomen. The electrodes are
connected to an ECG machine by wires. Then, 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, the rhythm of the heart beats (steady or irregular),
and 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 fatigue (tiredness), and palpitations
and a resting ECG doesn’t show a clear cause. You wear the same kind of ECG electrode
patches on your chest, and the electrodes are connected by wires to a small, portable
Certain arrhythmias (abnormal heart rhythms) may occur only now and then. Or, they
may occur only under certain conditions, such as stress or activity. Arrhythmias of
this type 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 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 can't 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), 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 a 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
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. If the
electrodes are on for a long time, they 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 before 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 medicines
- 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.
- You do not need to fast (not eat or drink).
- Based on your medical condition, your healthcare provider may request other specific
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:
- You will be asked to remove any jewelry or other objects that may interfere with the
- 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 clip to a belt or pocket.
- 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.
- 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.
- You will be instructed 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,
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 after a Holter monitor recording.
Tell your healthcare provider if you develop any signs or symptoms you had before
the recording (for example, chest pain, shortness of breath, dizziness, or fainting).
Your healthcare provider may give you other instructions after the procedure, depending
on your particular 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 will you get the results
- Who to call after the test or procedure if you have questions or problems
- How much will you have to pay for the test or procedure