"We have described characteristic patterns observed using the Electrocardiocorder-AVSEP system for recording continuous electrocardiograms on both active and inactive subjects. We have extended previously well recognized observations made in conventional electrocardiography to the effect that the S-T segment in the normal varies somewhat from time to time, and T wave varies much more. We have shown examples in normal subjects of unusually flat ST-T segments with unusual variation in contour. We have also developed some appreciation of how often and how much the total AVSEP pattern can change during dynamic situations, especially the magnitude of normal T wave changes. The appearance of common arrhythmias as seen in this system, as well as some of the artifacts associated with it, has also been demonstrated. Examples of how this system develops patterns which differ in some respects from those seen in conventional electrocardiograms have been described and illustrated, especially those differences which arise from the nature of this new electrocardiographic recording and presentation system. (Examples are the features we have termed for convenience the pre-T notch and the post-T dip.) The reliability of the Electrocardiocorder-AVSEP system as originated at the Holter Foundation Laboratory has been demonstrated under a wide variety of circumstances during an extended series of trials. We emphasize the need for familiarity with the idiosyncrasies of this system and its patterns before drawing clinical conclusions from the observations.

This partial review of our experiences with the Electrocardiocorder-AVSEP system as used in 230 subjects establishes these new devices as practical tools for observing electrocardiographic phenomena continuously during a wide range of dynamic situations."