Page 83 - ADD-ON ABLATION SURGERY IN PATIENTS WITH ATRIAL FIBRILLATION

the bipolar RF has the advantage of limiting the burn to the width of the clamp whereas the unipolar pen produces a burn several millimetres wider and releases hot energy which is not confined entirely to the myocardial tissue thus increasing the odds of damage to extracardiac structures.Therefore, due to these limitations of unipolar energy sources, there is an apparent trend towards the implementation of the Cox-Maze IV through the application of the bipolar RF clamp on a pattern of LA lesions70.
The importance of completeness of lesion set has been demonstrated by Gaita et al71 who showed that the final set of lines is a key point in patients with permanent AF and valvular heart disease. Furthermore, Gillinov and coworkers67 confirmed the value of left atrial lesion sets in the surgical management of permanent AF. In contrast, in our experience there was no difference in AF recurrence in patients who received or not a roof line, an inferior line or a left atrial appendage (LAA) to left pulmonary veins (LPVs) line and the absence of these lesions was not associated with a higher incidence of AF recurrence at multivariate competing risk analysis, independent of the type of preoperative AF. However our results could be explained by the higher number of patients at follow-up receiving a connecting line with a unipolar RF device applied from the endocardial surface, which could have had limited efficacy in creating transmural connecting lesions. This is also confirmed by the sub-analysis carried out on patients having LA linear connecting lines either with the unipolar pen or bipolar clamp which showed that a higher percentage of patients having LA lines performed with the bipolar clamp were in NSR off-AAD with cumulative incidences significantly lower compared to those who had additional LA lesions made with the unipolar pen.
Another key point of our study is that right atrial ablations in addition to left-
sided lines led to better long-term rhythm outcome.
Based on the study findings of Haïssaguerre et al72, who documented focal ectopies
arising from the pulmonary veins, and of Sueda et al.73 who demonstrated the
presence of left atrial foci during intraoperative AF, the concept of approaching
only the left atrium during anti-arrhythmic surgery was developed. Nonetheless, 9 Chauvin et al74 observed in explanted hearts, some striated muscle cells around
the coronary sinus connecting the inferior right atrium. Furthermore, Lin et al75 showed some specific right atrial “trigger zones” where paroxysmal AF may be induced and these authors found that the ablation of these sites may eliminate AF and that recurrent atrial flutter or tachycardia is a complication of performing isolated left atrial lesions.
General discussion
201