Changes in the Qrs Complex of the Electrocardiogram During Sleep and Exercise

摘要

Changes in the QRS complex in normal healthy individuals during sleep were identified and studied in order to determine whether they are due to alteration in the cardiac signal or in the transfer function. A knowledge of the mechanism of the changes could provide useful information on the nature of sleep. The following conclusions were reached: (1) The surface ECG is a function of both the electrical activity of the heart and the transfer of the signals to the body surface. (2) An analysis of the transfer function extends the usefulness of the ECG. (3) Three modes of R and S amplitude changes occur during sleep. The abrupt change in mean value, the beat by beat variability of the amplitudes and the gradual change of mean amplitude may assist the analysis of sleep. (4) The response of the QRS waveform to inspiration has two components, namely a step response caused by movement of the heart with the diaphragm, and a transient response possibly caused by ventricular volume changes. (5) The amplitudes of the R and S waves change in a defined pattern during exercise. (6) Changes of the R and S wave amplitudes may reflect changes in left ventricular end diastolic volume.