Dynamic ECG in normal subjects.

A study by dynamic electrocardiography has been carried out for 24 hours on 100 healthy subjects (50 males and 50 females), of ages included between 20 and 70 years. Recording were carried out during an average working day. Average high, mean and low heart rates have been calculated in the 24 hours, at various times of the day, during mental work, physical effort, sexual activity (20 cases) and sleep. Sinus arrhythmias of various degrees (bradycardia, S-A blocks) have been observed overall in 16% of cases. Incidence was higher in younger subjects (12%) as compared with the older group (4%), and during sleep (75%) as compared to periods of wakefulness (25%). Supraventricular and ventricular arrhythmias hae occurred respectively in 20 and 21% of all subjects. Both types of arrhythmias (S.V. and V.) occurred more frequently in older subjects (34 and 32%) as compared to the younger group (10 and 5%). Supraventricular ectopic beats were more frequent during wakefulness (59.3%) rather than during sleep (40.7%); vice-versa, ventricular ectopic beats have been noticed to appear more frequently during sleep (74.5%), than during wakefulness (25.5%). Overall, arrhythmias have not been common (less than 500 ectopic beats/24 hours and less than 50 ectopic beats/hour), and only rarely they were repetitive. During our study we have observed ST changes or upward deviation, but in all cases a definite pathological significance was missing.