Cardiac Preexcitation Syndromes [antikvár]

FOREWORD The Wolff-Parkinson-White (WPW) syndrome, the most common variety of preexcitation, has for some time held a fascination for those interested in clinical electrophysiology because it seems to represent a naturally occurring event which, if adequately understood, would unmask answers to many fundamental questions concerning mechanisms and treatment of cardiac arrhythmias. Thus, it has been described by Scherf and Neufeld [1] as the "Rosetta Stone" of electrocardiography. The historic overview of the preexcitation syndromes will be deferred to Dr. Burchell's authoritative chapter, but a few highlights deserve emphasis here because they graphically portray how elements of serendipity, courage, and luck played important roles in the unfolding of the mysteries of preexcitation. Although Kent is forever linked to the literature of preexcitation by his description of a node-like structure [2] in the right lateral atrioventricular groove, it is now accepted that this structure bears httle resemblance to the accessory atrioventricular connection known to form the basis of the WPW syndrome. Indeed, it is unlikely that Kent's "node" played any role in AV conduction, either in normal or abnormal hearts. Nevertheless, Kent succeeded in igniting a controversy which undoubtedly influenced Mines [3] to consider the possible role that such an "accessory pathway" might play in excitation of the human heart. Thus in 1914, Mines stated . some instances of paroxysmal tachycardia observed in man where auricles and ventricles beat with the same frequency might conceivably be explained along somewhat similar lines (i.e., circulating excitations). 1 now repeat this suggestion in the light of the new histological demonstration by Stanley Kent that the muscular connexion between auricles and ventricles in the human heart is multiple. Mines prophesized the possibility of surgical correction of such a reentry when he observed ••• in a favourable experiment, the vigorous circulating wave and its instantaneous arrest by section of the ring is a sight not easily forgotten. Courageous is the only way to describe the first attempt to surgically interrupt an accessory pathway. The immensity of the feat speaks for itself: Open heart surgery was performed to divide an invisible stream of electrons! This historic event was not anticipated. A fisherman from the coast of North Carolina presented to Duke University Medical Center in 1968 with refractory supraventricular tachycardia related to the WPW syndrome [2]. Attempts to control the tachycardia medically failed. Dr. Andrew Wallace (then Director of the Coronary Care Unit) had recently returned from the NIH where he had performed epicardial mapping studies on various forms of hypertrophy. He was continuing his mapping studies using facih-ties temporarily located in the laboratory of Dr. Will C. Sealy (Figure I-l), Chairman of the Department of Thoracic Surgery. Dr. Sealy in turn was known at the time to be interested in experimental surgical techniques to study car- FIGURE I-l. Will C. Sealy, M.D., the first surgeon to divide an accessory AV pathway in man.