The clinical value of vectorcardiography.

SOME WORKERS, with great enthusiasm about the clinical value of vectorcardio-grams, may, after reading this article, believe it should be classified under some heading other than Clinical Progress, but the writer hopes that the discussion will at least point out clearly the relationship between ordinary electrocardiograms and vectorcardiograms and some of the problems relating to the registration of the latter. If these matters are clearly understood, much of the uncertainty regarding the clinical value of vectorcardiograms, expressed by some, as well as the overenthu-siasm relative to their diagnostic value displayed by others should disappear. In the simplest possible terms, vectorcar-diograms are only a different technic for displaying electrical information contained in two electrocardiograms of the conventional type. The idea is not new, since Einthoven, Fahr, and deWaart1 in 1913 suggested the use of vectorcardiographic representation of the standard leads, and Mann2 in 1920 actually constructed from these leads figures that he called monocardiograms. These loops were very similar to vectorcardiograms recorded today in the frontal plane, but his work stimulated little interest and was largely ignored. In 1938 Schellong,3 in Germany, and Wilson and Johnston,4 in this country, almost simultaneously described technics for recording electrocardiographic information as vector figures using the cathode-ray oscillograph and the name vectorcardiogram was suggested as a suitable term for these records. Since electrodes on the extremities were used for all of this early work, vectorcardiograms in the frontal plane only were recorded. The cathode-ray oscillograph is essentially a special type of vacuum tube shaped like an Erlenmeyer flask with a suitable filament or heater emitting large numbers of electrons in the small end or neck of the tube. These electrons are concentrated into a small beam by properly placed, positively charged, focusing electrodes and further accelerated by other positively charged electrodes so the highly concentrated and rapidly moving beam of electrons passes from the small neck of the tube and strikes the inside surface of the larger circular base of the tube near its center. This inner surface is coated with special materials that emit visible radiation, usually blue or green, as a result of the bombardment with electrons. Thus, if the electron beam is in its normal position, at the central axis of the tube, it will cause a brilliant blue or greenish spot to appear at the center of the base of the tube. If the tube is to function as a recording …