The study of the heart as an electrical organ has fascinated physiologists and physicians for nearly a century and a half. Matteucci ( 1) studied electrical current in pigeon hearts, and Kölliker and Müller (2) studied discrete electrical activity in association with each cardiac contraction in the frog. Study of the human ECG awaited the discoveries of Waller (3) and, most important Einthoven (4), whose use and development of the string galvanometer permitted the standardization and widespread use of that instrument. Almost simultaneously, anatomists and pathologists were tracing the atrioventricular (A–V) conduction system. Many of the pathways, both normal and abnormal, still bear the names of the men who described them. This group of men included Wilhem His ( 5), who discovered the muscle bundle joining the atrial and ventricular septae that is known as the common A–V bundle or the bundle of His.
During the first half of the twentieth century, clinical electrocardiography gained widespread acceptance; and, in feats of deductive reasoning, numerous electrocardiographers contributed to the understanding of how the cardiac impulse in man is generated and conducted. Those researchers were, however, limited to observations of atrial (P wave) and ventricular (QRS complex) depolarizations and their relationships to one another made at a relatively slow recording speed (25 mm/sec) during spontaneous rhythms. Nevertheless, combining those carefully made observations of the anatomists and the concepts developed in the physiology laboratory, these researchers accurately described, or at least hypothesized, many of the important concepts of modern electrophysiology. These included such concepts as slow conduction, concealed conduction, A–V block, and the general area of arrhythmogenesis, including abnormal impulse formation and reentry. Some of this history was recently reviewed by Richard Langendorf (6). Even the mechanism of pre-excitation and circus movement tachycardia were accurately described and diagrammed by Wolferth and Wood from the University of Pennsylvania in 1933 ( 7). The diagrams in that manuscript are as accurate today as they were hypothetical in 1933. Much of what has followed the innovative work of investigators in the first half of the century has confirmed the brilliance of their investigations