The links between basic and clinical cardiac electrophysiology.

FORTY OR 50 years ago, the terms "clinical" and "basic" cardiac electrophysiology described two sides of the same coin. The clinical electrophysiologist was an electrocardiographer; the basic electrophysiologist used electrographic and electrocardiographic techniques to study the hearts of animals or isolated tissues obtained therefrom. Clinical and basic electrophysiol-ogists shared a common language and a common interest in the causes and treatment of cardiac arrhythmias, seeking the answers to questions such as: Why does the heart beat? How and where does the impulse conduct? What are the modulators of cardiac rhythm? What are the causes of dysrhythmic beats? Moreover, these questions were asked not only at the outset of the modern era of electrophysiology but are asked today as well. In the following pages I shall emphasize how the links between basic and clinical research have helped us attempt to answer some of these questions, and I shall consider some of the problems that have occurred along the way and some of the prospects for future collaboration. The modern era in basic and clinical electrophysiology. During the years after World War II, two events occurred that set the stage for the present relationship between basic and clinical investigation. The first was in a related field, neurophysiology, and culminated in the studies of Hodgkin and Huxley, in which the ionic determinants of the action potential of a single cell, the giant axon of the squid, were described. 1-4 The second event was the description, by Ling and Gerard in 1949, of glass capillary microelectrodes having sufficiently small tip diameters to permit impalement without injury of single muscle cells.5 Since these discoveries in the 1940s, electrophysi-ologists have had the means to investigate the cellular and subcellular basis for the control of cardiac rhythm. Their studies have incorporated many of the ideas and techniques of the biophysicist, the electrocardiog-rapher, and the neurophysiologist. The subsequent explosion of information can be understood in light of the following: in 1960, Hoffman and Cranefield coau-thored a 323 page book, a critical summary of the body of information concerning electrophysiology to that date.6 It was and remains a classic, encyclopedic in its scope and yet completely accessible to the careful reader. Although other fine volumes have been written since then, none has so completely captured this ever-expanding field. Recent volumes that may be comparable in the completeness of information provided have been multiauthored, reflecting the increased specialization of individuals …