CHEST LEADS IN ELECTROCARDIOGRAPHY

At first sight it seems surprising that the electrocardiogram was not derived precordially from the beginning, i. e., as directly as possible. However, the fact that it was not is not so strange, for the limb leads give almost constant pictures, while chest leads show distinct changes when the exploring electrode is shifted. Moreover, the standard leads of Einthoven are adequate for a study of arrhythmia, and the problem of irregularity of the pulse has for many years been the leading one in cardiology. Though chest leads were used occasionally in the early days of electrocardiography, 1 their value was not generally appreciated until electrocardiographic research was made subservient to examination of the myocardium, at first especially in coronary thrombosis. It is to the credit of Wood and Wolferth and their co-workers 2 to have shown in a number of papers that a fourth lead may sometimes supply information of