ARRHYTHMIA DETECTOR

Typical Number in Hospital: 2

Cost Bands: 4

References: 3

Some forms of heart disease are characterized by variations in the time between successive heart beats. In extreme cases this can mean completely missed beats, or extra (ectopic) beats occurring between two otherwise normal beats.

Identifying these abnormalities used to be performed by inviting the patient to come into the coronary intensive care unit and have a skilled nurse watch a cardioscope display of the ECG for several days.

This is a task ideally suited to computer pattern recognition programs and such devices are now available which detect these abnormalities and store the key elements of the information (e.g. reproducing a short strip of the ECG record relating to each abnormal event).

There have been various generations of machines to detect arrhythmias ranging from tape loops or multi-head tape recorders which compared the timing between the incoming beats with those of a few seconds before, to full pattern recognition systems which identify ectopic beats not only from their abnormal time relationship to the main beats but also because the shape of the ECG is different.

A new and most important variant on arrhythmia detectors is the ambulatory monitoring schemes utilizing small tape recorders which collect 24 hours of the patient's ECG during normal daily tasks. The cassette tape record of each day's activity is read through a computer-type analyser at high speed the following day. Various derived indices of the behaviour of the heart rate can be produced and in some cases abnormalities of the ECG itself can be identified.

Arrhythmia detectors and monitors will be found in the coronary intensive care unit, possibly in the intensive therapy unit and in one or two high dependency units in the medical wards.