Since the introduction of the string galvanometer by Einthoven (1901), various instruments have been developed (a technical review is given by Dunn & Rahm, 1950) to record the so-called electrocardiogram (ECG). Physical activity, changes in position and certain bodily functions such as digestion and sleep were found to be associated with changes in the ECG. The ECG is therefore recorded while the patient is lying down and relaxed. The length of such a resting ECG (also referred to as standard or 12-lead ECG) varies from 10 to 45 seconds. Transient phenomena can easily be missed in this way. lf desired, the length of the ECG can be extended. However, the patient is not free to move and the analysis of the large number of ECG complexes soon becomes burdensome. In 1944, Likoff et al described an instrument for the continuous recording of the electrocardiogram. This utilized an optica! system which reearcled the ECG complexes on 16mm film. The minute images could be projected on a screen or photographic paper at the size of an ordinary electrocardiogram. Hith this instrument they made ECG-recordings of up to 10 hours of patients undergoing surgery, of patients with transient arrhythmias, patients in whom a patent ductus was being ligated and of patients approaching death. In all cases, the patient was confined to a hospita! bed. It was nat necessary to watch the ECG continuously while it was being recorded. From this report, the value of continuous monitoring of the ECG was clear. It permitted study of transient phenomena and of the influence of various circumstances on the activity of the heart. Since then, electronic instruments have supersecled this optical design. However, the concept of continuous ECG-recording had taken root and different lines of development can be traeed in this area.

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R. van Strik (Roel) , J. Pool (Jan)
Erasmus University Rotterdam
Erasmus MC: University Medical Center Rotterdam

Velema, J. (1982, October 8). Prediction of cardiac death : an epidemiological study on the prognostic significance of 24-hour ECG-recording. Retrieved from