Historical Milestones of Electrical Signal Recording and Analysis

Aside from the discovery of the cardiac conduction system (Table 1) and advancements in the electrotherapy of cardiac arrhythmias (Table 2), the development of electrocardiography was the key issue for a more detailed understanding of arrhythmogenesis as a cause and correlate of cardiac disorders (Table 3). After the first documentation of a cardiac action potential by Rudolph von Koelliker and Heinrich Müller in 1856, two decades later Augustus Desiré Waller (Fig. 1) recorded the first human electrocardiogram. After qualifying as a medical doctor Waller joined the department of physiology at the University of London where he studied in John Burdon Sanderson’s laboratories the electrical activity of the excised mammalian heart. In 1884 he was appointed lecturer in physiology at St. Mary’s Hospital London where he used a capillary electrometer, an instrument invented 15 yr earlier by the French scientist Gabriel Lippmann, to record cardiac potentials in animals (Fig. 2). In 1887, he was able to obtain the first human electrocardiogram from the body surface and published his findings in the Journal of Physiology: “A demonstration on man of electromotive changes accompanying the hearts beat (45).” Waller also proved that the electrical phenomenon preceded the muscle contraction, thus excluding the possibility that the recorded activity was only an artifact. Furthermore, he recognized that it was not essential for the recording that the electrodes Historical Milestones of Electrical Signal Recording and Analysis