A Holter monitor or a daily electrocardiogram was proposed by the American scientist Norman Holter as an electrophysiological diagnostic tool. This method involves a nonstop ECG recording for a day or more, depending on the situation.
A portable recorder that the patient wears throughout the study period records the electrocardiogram. The ECG recorder is usually attached to a belt or worn over the shoulder on a strap.
INDICATIONS FOR HOLTER MONITORING
The indications for Holter monitoring include all kinds of rhythm disturbances, complaints of palpitations or disruption of heartbeats, or when there have been possible episodes of loss of consciousness. Holter monitoring is also used to monitor pacemaker function and with painless forms of coronary artery disease, but in the latter case, the data obtained during the monitoring may not be the sole criterion for diagnosing coronary artery disease. Holter monitoring, even if it is done for several days, does not have high negative predicting values. This means that if a specific problem suspected and was not identified during the monitoring, this cannot be interpreted to mean the problem does not exist.
To identify problems which occur rarely, but with high clinical significance, there is also electrocardiogram recording on demand, which is a portable recorder that turns on when symptoms appear. The recorder can be activated by either a button or by hand. A subcutaneous recording device, for example the Reveal XT, can also perform Holter monitoring for up to two years. In this case, the ECG recording starts either when activated by the patient or according to pre-programmed criteria. Special disposable adhesive electrodes are used for contact with the body. The recording quality is improved by proper preparation of skin surfaces, which are degreased and slightly roughened.
HOW IS HOLTER MONITORING PERFORMED
Holter monitoring is done with the patient following habitual routines. This means that the person goes to work, goes out, and relaxes as they normally would. In addition to the ECG recording, the patient keeps a diary on their own, indicating the times when cardiovascular symptoms occur, when medications are taken and any changes in physical activity. During Holter monitoring the patient should not reduce activities. The patient is advised to perform normal, everyday tasks.
Analysis of the recorded electrocardiogram is done by decoders, most often by a computer with appropriate software. A modern Holter monitoring device is capable of automatically prescreening the recorded study data, which subsequently simplifies and accelerates the process of ECG interpretation by the doctor. At the same time, there is no perfect algorithm for automatic ECG analysis; therefore a doctor analyzes each recording.