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Basic Electrophysiology of the Pulmonary Veins and Their Role in Atrial Fibrillation:

The role of the pulmonary veins (PVs) in atrial fibrillation (AF) exploded into the widespread consciousness of the medical community with the groundbreaking demonstration of their importance by Haissaguerre’s group in 1997.1 Many subsequent clinical investigators confirmed these findings, and the PVs of AF patients now are regularly succumbing to the onslaughts of a host of torments in the (generally fruitful) attempt to suppress AF. As good practitioners, we have rapidly pursued the how of PV ablation, and we have a bit more slowly begun to address the why of the important role of PVs in AF. Before Haissaguerre’s work, we knew very little (and possibly cared even less) about the electrical activity of PVs. Over the past few years, there has been extensive investigation of PV electrical function in normal animals and in animal models of AF. In combination with clinical investigations, the results have provided us with some hints about why the PVs are important in AF, but they have posed a host of new questions. The aim of this article is to synthesize the available information about the potential basic mechanisms of PV involvement in AF and to derive from this synthesis some directions that need to be taken to resolve the major outstanding issues.