What is a Holter (24-hour ambulatory electrocardiogram) monitor?

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From the Guidelines

A Holter monitor is a portable, battery-operated device that continuously records your heart's electrical activity for 24 to 72 hours or longer, allowing for symptom rhythm correlation through a patient event diary and patient-activated annotations. This device is used to detect irregular heart rhythms (arrhythmias) that may occur intermittently, and is typically recommended for patients who experience symptoms like palpitations, dizziness, or fainting that might indicate a heart rhythm problem, or to evaluate the effectiveness of heart medications or pacemakers 1. The procedure is painless and non-invasive, allowing patients to maintain normal activities except for showering or bathing.

Some key features of a Holter monitor include:

  • Continuous recording for 24-72 hours or longer
  • Symptom rhythm correlation through a patient event diary and patient-activated annotations
  • Portable and battery-operated, allowing for ease of use and mobility
  • Can be used to detect irregular heart rhythms, evaluate the effectiveness of heart medications or pacemakers, and monitor patients with symptoms like palpitations, dizziness, or fainting.

According to the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope, a Holter monitor is suitable for patients with symptoms frequent enough to be detected within a short period (24-72 hours) of monitoring 1. During monitoring, patients will keep a diary of activities and symptoms to help correlate events with the heart rhythm recordings. After the monitoring period, the device will be returned to the healthcare provider for analysis to identify any abnormalities in the heart's electrical activity.

From the Research

Definition and Purpose of Holter Monitor

  • A Holter monitor is a type of electrocardiographic (ECG) recording device used to document symptomatic episodes of palpitations or other cardiac arrhythmias over a period of time, typically 24 hours 2.
  • The primary purpose of a Holter monitor is to detect and record arrhythmias, which can be challenging to diagnose using traditional methods, especially in patients with paroxysmal palpitations or dizziness 2.

Comparison with Other Monitoring Devices

  • Studies have compared the diagnostic value of Holter ECG with patient-activated event recorders, such as the OMRON portable HeartScan ECG Monitor, in detecting arrhythmias in patients with paroxysmal palpitations or dizziness 2.
  • The results showed that patient-activated event recorders, like HeartScan, were more effective in diagnosing clinical arrhythmias (89%) compared to Holter monitoring (1.8%) 2.
  • Other monitoring devices, such as 30-day external continuous monitoring and implantable loop recorders, are also available for documenting arrhythmias in patients with palpitations 3.

Clinical Applications

  • Holter monitoring is commonly used in the diagnosis and management of patients with palpitations, dizziness, or other symptoms suggestive of cardiac arrhythmias 2, 3.
  • The choice of monitoring device depends on the frequency and duration of symptoms, as well as the patient's underlying medical condition 3.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Comparison of the patient-activated event recording system vs. traditional 24 h Holter electrocardiography in individuals with paroxysmal palpitations or dizziness.

Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology, 2014

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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