Holter ECG: what kind of test is it and what does it show

The heart may "malfunction" not in the doctor's office but in the line for coffee or on the stairs. Holter ECG catches exactly such moments: the device continuously records the heart's electrical activity for 24 to 48 hours, sometimes up to 7 days. You live your normal life, while the recorder captures the rhythm and rate.

What a Holter ECG is

Holter monitoring (HM ECG) is a method of long-term electrocardiogram recording proposed by the biophysicist Norman Holter. Disposable adhesive electrodes are attached to the chest, and wires run from them to a small recorder: it is worn in a pocket or in a pouch on the neck or belt. Recording is done via 2, 3 or more channels, up to 12. The device runs on batteries, and the skin before attaching the electrodes is shaved, degreased and dried — otherwise the recording will have interference.

How Holter monitoring differs from a regular ECG

A regular ECG is a few minutes of rest on a couch. A Holter for the heart is 24-hour heart monitoring in motion: work, walks, sleep. The doctor sees how the rhythm responds to real load. While wearing the device, you keep a diary: the time and circumstances of unpleasant sensations, medication intake, changes in activity. It is precisely the comparison of the diary with the recording that turns a set of curves into a diagnosis.

What 24-hour heart monitoring shows

The recording answers specific questions: what the source of the rhythm is and what the rate is, whether there are supraventricular and ventricular extrasystoles (with their number and morphology), paroxysms of arrhythmias, rhythm pauses, changes in the PQ and QT intervals, intraventricular conduction disturbances, ST segment shifts and their relationship to load. Episodes of atrial fibrillation and flutter, tachycardias, and bradycardias are recorded. The function of an artificial pacemaker, if present, is assessed separately.

• Palpitations and irregular heartbeat
• Unexplained fainting and loss of consciousness
• Suspected painless ("silent") myocardial ischemia
• Assessment of pacemaker parameters
• Starting a new heart medication

When a Holter is prescribed

The indications are simple: complaints of palpitations and irregular heartbeat, unexplained fainting, monitoring after a heart attack, checking the function of a pacemaker. The method is popular in the diagnosis of cardiac rhythm and conduction disorders. At the same time, in the diagnosis of coronary artery disease, the result of Holter monitoring in most cases cannot serve as a criterion.

How to read a Holter ECG report

Normal means the absence of significant changes in rhythm and pattern, a rate that is not abnormally slow and not abnormally fast; fluctuations during the day are normal. Deviations are the arrhythmias from the list above, and some changes may indicate that the heart is not receiving enough oxygen. The recording is interpreted by a doctor: automatic classification is imperfect, and the recording is always reviewed and corrected. There is no generally accepted standard for wording, but the report must contain information about the rhythm, disturbances, pauses, intervals, the ST segment and pacemaker function, and the findings must be illustrated with ECG printouts. The result is sometimes ready the same day, but depending on the type of ECG, you may wait several weeks.

Limitations of the method and when a doctor is needed

Myth: if the Holter showed nothing, then the heart is fine. Fact: even a multi-day recording does not have high negative predictive value — a phenomenon that was not found does not prove its absence. For rare events, there are "on-demand" ECG recording and implantable devices for up to 2 years. While wearing the device, you cannot wash, and you should also avoid electric blankets, magnets, metal detectors and high-voltage areas. If skin irritation occurs at the electrode sites, contact the person who fitted the device.

Wearing a Holter by itself is not a reason to call an ambulance; 103 or 112 — if, against a background of cardiac symptoms, signs of a heart attack appear or fainting occurs.

A Holter is a tool, not a verdict: the numbers in the report are read by a doctor together with your diary. The material is for reference and does not replace consultation with a specialist.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer