XI. The human electrocardiogram: a preliminary investigation of young male adults, to form a basis for pathological study

Abstract The adoption of the galvanometer and its employment for clinical purposes dates from the introduction of the newly modelled instrument or string galvanometer by Einthoven. The string galvanometer has proved an efficient instrument in deciphering all forms of irregularity of the ventricle, and has given clear interpretations of all derangements of the heart in which there is disorder in the sequence of contraction in its chambers. This new chapter of clinical medicine is rapidly closing, but while it has been written, a number of isolated observations have been placed on record, from which it is clear that the instrument may be employed for a further purpose. It is probable that it will give information of much value where the action of the heart, as a whole, is perfectly regular, and where the contraction, originating at the normal site of impulse formation, namely, the sino-auricular node, progresses at normal rates through the heart and along definite and recognised channels. Thus, it is known that in certain instances of cardiac enlargement some of the electric variations portrayed in the curves are exaggerated, decreased, or inverted, as compared to the normal and to each other. But it is evident that little progress can be made in the study of this subject until we have full knowledge of the normal electrocardiogram, and especially of the limits which may be reached by its several peaks and depressions in healthy subjects. As an initial step towards this end we have examined the curves of a large number of healthy young adults.