The Interpretation of the Normal Electrocardiogram. A Critical and Experimental Study

INTRODUCTION Waller,¹in 1888, was the first to demonstrate that the action currents arising from the heart muscle during its contraction were conducted out to the peripheral tissues in sufficient strength to be detected by leading off from the limbs to an electrometer. It was not, however, until the improvement and adaptation to physiological work of the thread galvanometer by Einthoven,²in 1903, that any considerable interest in this matter was aroused. In the nine years since Einthoven's first publication, a very large and rapidly increasing literature on the subject of the electrocardiogram has appeared, and great interest has developed as a result of its evident clinical and physiological importance. Notwithstanding the great amount of work that has been done, the various workers in this field are by no means agreed as to the interpretation of the normal electrocardiogram, and as a result, the interpretation of