Studies of the spatial vectorcardiogram in normal man.

The spatial vectorcardiograms of 75 normal subjects have been studied and some features of these records are described. The QRS st and T st-loops were found to have only two basic spatial configurations but with a variety of orientations thus giving widely different planar projections and in part accounting for the wide range of normal electrocardiograms. The significance of this and other findings is discussed and certain concepts pertinent to the study of the vectorcardiogram are presented. T HE CONCEPT of vectorcardiography is not a new one.1'9 Increasing interest in this technic is evidenced by the number of papers and monographs recently published .'0-13 This interest is stimulated particularly by the hope that spatial vectorcardiography will have clinical applications exceeding those of conventional electrocardiography. At present the many variations in methods of recording and analyzing vectorcardiograms create difficulties in comparing data from different laboratories. It is desirable that these procedures be standardized as early as possible to foster more general application of the vector-cardiogram. Despite this lack of uniformity, it is considered that a report of our experience with the vectorcardiogram of normal adults and of certain concepts which have evolved during the past several years of study of the vector-cardiogram in this laboratory would be of some interest. It should be realized that, since vectorcardiography is still an experimental method with no standardized reference system or nomenclature and since this series of subjects is small, the results convey merely a general impression of the normal as recorded with the tetrahedral reference system of Wilson and associates'4 and should by no means be construed as a complete description of all the possible variations that might be encountered in normal people under many different physio-logic circumstances. This report is also intended to present certain aspects of the general problem of vectorcardiography, including a discussion of the reference system employed in these studies. MATERIALS AND METHODS Studies were made on 71 male and four female medical students between the ages of 22 and 33 years who had no evidence of cardiovascular disease. A teleoroentgenogram of the chest was obtained for each subject, and careful fluoroscopic examination of selected subjects was performed to determine , insofar as possible, cardiac position. Electrocardiograms, including the standard limb leads, unipolar limb leads, precordial leads V, through V6, and a unipolar lead from an electrode placed 3 cm. to the left of the seventh dorsal vertebra (VB), …