[Demonstration of complex ventricular tachy-arrhythmias by long-term ECG monitoring: relationship to duration of monitoring].

Continuous long-term ECG monitoring over three 24-hour periods was undertaken in 42 patients with complex ventricular tachy-arrhythmias. The arrhythmias were divided by degree of severity. The lowest degree was assigned to frequent ventricular extrasystoles (more than 20 per hour). The next degree was assigned to ventricular bigeminal rhythm, while runs of extrasystoles were assigned the highest degree. In 30 patients the highest arrhythmia level was reached within the first 24-hours, in nine after a further 24 hours, in three during the third 24-hour period. Comparing the three periods of registration there were differences between the various arrhythmias, not of kind but of frequency of the arrhythmia. Simple VES and the complex forms differed in their occurrence: although of 33 patients with frequent VES (more than 20/h) 30 also had runs of VES, in six patients with runs of VES the frequency of extrasystoles was low (less than 20/h). In 70% of cases 24-hour monitoring was sufficient to record the highest level of ventricular tachy-arrhythmia. If, however, no severe arrhythmias have been recorded during this period, increasing the duration of monitoring to 48-hours can be useful. A third period or more is of little further value.