Hybrid Ablation of Atrial Fibrillation With Advanced Epi-Endocardial Mapping
While several approaches for endoscopic surgical ablation have described, the current video will focus on the technical details of a beating heart, epicardial linear box isolation and related mapping.
Briefly, a 3 ports right thoracoscopic approach is routinely adopted, then, following opening of the pericardial reflections, a dedicated guiding catheter allows for the advancement of the actual linear ablation probe.Once proper positioning has been confirmed, suction is started as to ensure proper contact between the probe and the epicardium as shown in the video.Then, both bipolar and unipolar radiofrequency is applied multiple times in order to improve lesion penetration, as previously described.
An intriguing opportunity is represented by the possibility to adopt the most sophisticated techniques for EP mapping also when performing surgical ablation. When analyzing the information gathered from the mapping, it is usually possible to observe on the top part the related voltage maps, then the ECG and finally the related electrograms. In particular, the voltage maps are color coded (purple meaning healthy tissue while red color being related to scar or low voltage tissue). In some instances, only mild remodeling may be observed, while in other cases a more significant tissutal heterogeneity can be detected.
Interestingly, once we started performing combined EPI and endocardial mapping, we were able to demonstrate the 3 dimensional substrate and the presence of epicardial breakthroughs also after failed ablations.
With respect to the procedural steps, the surgical part is not different than what previously described, expect for the addition of the mapping component at baseline and once tha ablation has been completed. Similarly, the transcatheter part follows the usual steps in terms of catheter positioning the coronary sinus, right ventricle and then trans-septal access to the left atrium. It is possible to appreciate the ease in manouvering such catheter also in the epicardial space as to obtain a complete epicardial mapping.
Once ablation is completed, it is often possible to observe spontaneous restoration of sinus rhythm, which can be documented both visually and via the mapping system. Finally, acute demonstration of effective creation of a box lesion set must be ensured at the of the procedure. Such end point may require also endocardial applications in some instances.
In the vast majority of cases, we also perform thoracoscopic epicardial exclusion of the left atrial appendage with an additional left access, and we have also performed mapping of such clipping procedure which has shown not only physical exclusion of the LAA but also the achievement of an effective electrical isolation.
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