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(Circulation Research. 2003;93:1018.)
© 2003 American Heart Association, Inc.

Editorials

Atrioventricular Nodal Electrophysiology

Still Exciting After All These Years

Andrew L. Wit

From the Department of Pharmacology and Center for Molecular Therapeutics, Columbia University, College of Physicians and Surgeons, New York, NY.

Correspondence to Andrew L. Wit, PhD, Department of Pharmacology, College of Physicians and Surgeons of Columbia University, 630 W 168th St, New York, NY 10032. E-mail alw4@columbia.edu

Key Words: atrioventricular node • pacemakers • arrhythmias • gap junctions

An extract of the first 250 words of the full text is provided, because this article has no abstract.

The anatomical atrioventricular node was first described by Tawara in 1906.¹ Although some surmised the node to be the region responsible for delay between contraction of atria and ventricles, Erlanger in 1912 localized the major portion of delay to a latency at the transition between atrial and nodal fibers.² Nearly a century of research on properties of the atrioventricular (AV) node has substantiated the suggestion of Hoffman and Cranefield³ in 1960 that the term "atrioventricular node" should be used to describe "the entire complex of fibers functionally interposed between atrial fibers proper and His bundle fibers proper" (page 132) and not just the compact node of Tawara, since nodal-like properties have been found outside the compact node.^4–8 Thus, the posterior nodal extension, the focus of the study by Dobrzynski et al⁹ in this issue of Circulation Research, is now included as part of the electrophysiological AV node. Identified as a nodal structure by its histological features, a bundle of tightly packed small cells extending posteriorly along the tricuspid annulus,¹⁰ it has nodal-like electrophysiological properties (low-amplitude slowly rising action potentials and slow activation) and it is likely the slow pathway in AV nodal reentry.^6–8,11 Dobrzynski et al,⁹ by characterizing properties of this region further through the use of immunofluorescent techniques (see below), have provided additional evidence that it is indeed part of the electrophysiological AV node.

Among the properties that were assigned to the AV node is the ability to initiate heart beats. In fact, Engelmann described "AV nodal rhythm" . . . [Full Text of this Article]