[Long term electrocardiography (Holter monitoring)]

During the past almost 50 years Holter monitoring has become an established non-invasive diagnostic tool in clinical electrophysiology. It allows ECG recording independent of stationary monitoring facilities during daily life and, therefore, contains much information. In the beginning the main interest was directed towards quantitative and qualitative assessment of arrhythmias, their circadian behaviour, and the circadian behaviour of the heart rate. With advances in technology the analysis spectrum of Holter monitoring expanded, and it was used also for detection of silent myocardial ischaemia. New digital recorders and computers with large capacities made it possible to measure every single heart beat very accurately, which was a prerequisite for heart rate variability and QT-interval analysis, which provided new knowledge about the autonomic modulation of the heart rate and the circadian dynamicity of the QT interval, respectively. Beyond arrhythmia analysis Holter monitoring was increasingly used to assess prognosis in different cardiac conditions. It can also be valuable in assessing transient symptoms possibly related to arrhythmias or device dysfunction, which will not necessarily be revealed by simple device control.