Page 85 - ADD-ON ABLATION SURGERY IN PATIENTS WITH ATRIAL FIBRILLATION

atrial aspect of the mitral valve leaflet and the epicardial connections (e.g. the Ligament of Marshall) across the mitral isthmus line further make this line uneasy to perform and they may represent a possible obstacle to successful MI ablation. At the beginning of our experience, we employed only monopolar ablation.With the introduction of the bipolar clamp, we started using bipolar RF to ablate the complex anatomy of this area in combination with the unipolar pen or, more recently, only with the bipolar clamp.
From sub-analysis these three sub-groups had comparable cumulative incidences of AF (p<0.001). Therefore, our study confirms that the bipolar RF clamp was unable to create a lesion all the way to the mitral annulus probably because of the thickness of the AV groove in that area, although transmurality has been reported by an experimental study achieved with bipolar radiofrequency in this area85. In addition, the use of a second unipolar device to complete the mitral line was ineffective and did not improve rhythm outcome.
For these reasons, many surgeons prefer to complete a MI ablation with a cryoprobe because cryoablation should preserve more of the fibrous skeleton of the heart, making it ideal for ablation near valvular tissue86.This calls for further studies comparing cryoablation and RF for making mitral isthmus lesions.
Future perspectives: The hybrid ablation. Is it applicable to add-on surgery?
Chapter 8 provides an overview of the hybrid procedure for the treatment of stand-alone AF.
From this overview, the hybrid treatment resulted to be a safe technique. Indeed, either mortality (0.8%) or complications rate (4.1%) were low. In addition, only three patients (0.8%) required a conversion to sternotomy and none experienced thromboembolic events.
Freedom from AF off-AAD at follow-up ranged from 85.7% to 92% in papers
employing bipolar RF and from 36.8% to 88.9% in those utilizing monopolar
RF. With specific reference to AAD-free success rate by type of AF, it ranged 9 from 60% to 91.6% in paroxysmal AF, from 50% to 77.7% in persistent AF and
from 20% to 100% in LSP-AF. However, these figures were very high in papers
utilizing bipolar radiofrequency (100%, 100%, 81.8%) and compare favourably
with minimally invasive-beating heart surgery87, 88.
The hybrid approach combines, in one step, a thoracoscopic epicardial ablation
with a percutaneous catheter ablation procedure.
General discussion
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