The surgical treatment of atrial fibrillation: The importance of tissue geometry and effective refractory period

Abstract

Abstract Introduction: The Maze procedure was designed for the surgical treatment of atrial fibrillation (AF). It has had a high success rate but does have decreased efficacy in patients with enlarged atria. The purpose of this study was to determine the association between the probability of maintaining AF and the geometry and effective refractory period (ERP) of atrial tissue. Methods: Isolated canine (n = 14) right atriums were perfused with Krebs-Henseleit (KH) solution. Baseline ERPs were obtained with KH and KH with acetylcholine (10E-3.5 M) from predetermined sites on the atrium utilizing single extra stimulus while unipolar electrograms were recorded from 250 sites. The tissue was then partitioned utilizing bipolar radiofrequency ablation and the ERPs were measured again with and without acetylcholine. Any section of tissue that maintained AF was then divided until it was no longer inducible. ERPs were measured in all sections after each ablation. Results: Mapping demonstrated that each tissue area was electrically isolated after ablating, while dye infusion revealed no flow abnormalities. The probability of AF was found to be significantly correlated with increasing tissue areas, widths and weights (p Conclusions: The probability of sustained atrial fibrillation occurring was significantly associated with increasing tissue area, width and weight and decreasing effective refractory periods. These data may lead to a better understanding of the mechanism of AF, and help to design more effective surgical procedures in the future.