These electrodes are connected to a small piece of equipment that is attached to the patient's belt or hung around the neck, keeping a log of the heart's electrical activity throughout the recording period.

A 12-lead Holter system is used when precise ECG information is required to analyse the exact origin of the abnormal signals.

Inspired by a suggestion from cardiologist Paul Dudley White in the early 1950s, they redirected their efforts toward development of a wearable cardiac monitoring device.

The information is loaded on a computer, which counts ECG complexes; calculates summary statistics, such as average, minimum, and maximum heart rate; and finds parts of the recording that are worthy of further study.

Recordings from these 12-lead monitors are of a significantly lower resolution than those from a standard 12-lead ECG, and in some cases have been shown to provide misleading ST segment representation, even though some devices allow setting the sampling frequency up to 1000 Hz for special-purpose examinations such as detection of "late potential".

A person would have to listen for the full 24 hours; instead integrated automatic analysis determines different sorts of heart beats, rhythms, etc.

Incorrect attachment allows electromagnetic disturbance to add noise to the record, particularly with rapid patient movement, impeding processing.