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Background: The efficacy of pulmonary vein isolation for the treatment of atrial fibrillation may be limited by the ability to make continuous and transmural lesions utilizing an ablation catheter. Gaps often persist between ablation lesions leading to failed electrical isolation and thus failed ablation. Recently, a deflectable fiberoptic endocardial visualization catheter has been introduced for use in imaging the coronary sinus using light in the visible spectrum. We utilize this catheter to visualize the endocardial surface and examine radiofrequency ablation lesions in porcine endocardium to determine the presence of gaps between radiofrequency lesions.Methods: Videos were taken of the lesions and shown to two readers who were asked to identify the gaps ranging from less than 0.1 mm-9.8 mm.Results: Ninety-four lesion gaps were reviewed. The readers demonstrated a combined accuracy of 98.4% at identifying gaps.Conclusions: Gaps between ablation lesions can be accurately identified down to less than 1 mm distances in vitro using a direct visualization catheter. Further studies are warranted to confirm these finding in vivo. [ABSTRACT FROM AUTHOR]

Background: The precise reasons for failure to cannulate the coronary sinus during biventricular device implantation are unknown. Visualization of the coronary sinus ostium during electrophysiology procedures may enhance understanding of how unusual anatomy can affect successful cannulation of the coronary sinus. Objectives: The aim of this study was to describe the morphology of valves at the coronary sinus ostium (CSO) visualized directly with an illuminated fiberoptic endoscope during implantation of biventricular devices. Methods: The coronary sinus anatomy of one hundred consecutive patients undergoing implantation of biventricular devices was investigated using a fiberoptic endocardial visualization catheter (EVC). Results: The CSO was clearly visualized in 98 patients using the EVC. A Thebesian valve was seen in 54% of these. Almost all Thebesian valves were positioned at the inferior (61%) or posterior (33%) aspect of the CSO. Only six patients had Thebesian valves that covered more than 70% of the CSO, but all were successfully implanted with a transvenous left ventricular pacing lead after cannulating the coronary sinus under direct visualization. Conclusions: Over half of patients undergoing biventricular device implantation have identifiable Thebesian valves. Even valves covering the majority of the ostial area may be traversed using direct visualization and modern catheterization techniques. [ABSTRACT FROM AUTHOR]