Page 86 - ADD-ON ABLATION SURGERY IN PATIENTS WITH ATRIAL FIBRILLATION

Chapter 9
There exists a clear rationale for this approach, as some ablation lesions that are incorporated into the well-established Cox-Maze lesions cannot be accomplished using a minimally invasive, off-pump surgical approach. Indeed, while some lesions can be easily performed through the transverse sinus, as seen previously, efficacy and safety of other ablation lesions such as the ablation line to the mitral annulus are the main challenges. In addition, the coronary sinus (CS), which is used as the epicardial landmark for the mitral annulus, is unreliable and may leave a gap89. An attempt to address this problem was made by Edgerton et al90.who developed the ‘Dallas lesion’ in which a line was made connecting to the anterior annulus at the junction of the left and non-coronary cusps of the aortic root. Nevertheless, this line might not be trans-mural due to the inability of RF energy to effectively penetrate fatty tissue associated with the dome of the left atrium and the superior vena cava.This is an indication for mapping conduction block, which can be checked by using a hybrid approach. In contrast, a mitral isthmus lesion can easily and safely be carried out (or completed) endocardially by the electrophysiologist (EP).
Another potential advantage of the hybrid procedure is that, from the EP’s point of view, there is no longer a risk of phrenic nerve and oesophageal injury because these structures can be protected by the surgeon if necessary, as well as no risk of tamponade as the pericardium is open. Furthermore, by reducing the total number of endocardial ablations the risk of emboli during these ablations should be potentially reduced91.
Also add-on surgery could move towards a multidisciplinary approach involving cardiac surgeons and EPs in order to combine, in one step, a surgical technique with a percutaneous endocardial ablation in order to limit the shortcomings of both techniques and, at the same time, to combine their advantages. Lesions are more likely to be transmural when burning from the inside outwards and from the outside inwards simultaneously and the EP can check the completeness of the lines and add an endocardial ‘touch-up’ in case of incomplete isolation of one of the pulmonary veins or if the connecting lesions are not transmural.The potential for improved outcomes derives from combining levels of expertise. Surgeons are very good at making linear lesions and EPs at mapping for completeness. Furthermore, as discussed above, a more extensive lesion set beyond the pulmonary veins to include targets along the LA substrate is often necessary in persistent and long-standing persistent AF.
However, the effectiveness and safety of the hybrid procedure as add-on surgery
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