Holter

A Holter monitor, named after Norman J. Holter, is a portable device for continuous ambulatory electrocardiography. It records the heart’s electrical activity for typically 24 to 72 hours as the patient goes about daily activities, helping to detect intermittent arrhythmias and other rhythm disturbances that may not appear during a standard ECG performed in a clinic.

The system consists of a compact recorder worn on a belt or strap and several electrodes placed on the chest. Wires connect the electrodes to the recorder, which logs the heart’s rhythm over time. Patients may keep a diary of symptoms, activities, and times to correlate with the recorded ECG data. After the monitoring period, the device is returned or data are downloaded for analysis by software and a clinician.

Indications for use include evaluation of unexplained syncope or dizziness, palpitations, suspected intermittent arrhythmias, rate and rhythm assessment during therapy, and monitoring of pacemaker or implantable cardioverter-defibrillator function. It can also help assess heart-rate variability and detect pauses or conduction abnormalities.

Limitations include a relatively short recording window compared with longer-term or implantable monitors, susceptibility to motion and electrode artifacts, and skin irritation at the electrode sites. Adequate skin preparation and proper electrode placement are essential for reliable data. If events are infrequent, newer technologies such as extended event monitors or patch-based systems may be employed.