Abstract
IntroductionCatheter ablation for persistent atrial fibrillation (PsAF) produces suboptimal results with at least 50% recurrence at one year. Better results have been achieved with surgical approaches, at the cost of greater morbidity and mortality.
Aims
1. To assess the feasibility of endo-epicardial atrial fibrillation (AF)ablation using the percutaneous intentional coronary venous exit carbon dioxide insufflation technique and evaluate electro anatomical characteristics of the epicardium such as epicardial adipose tissue and epicardial surface electrograms.
2. To investigate the hypothesis that epicardial activation of the LA and endo-epicardial dissociation contribute to the maintenance of PsAF in humans.
3. To further understand the underlying mechanisms of PsAF, using both endocardial and epicardial data, in patients who have not undergone atriotomy.
Methods
Twenty patients with either PsAF or long-standing PsAF underwent endo-epicardial (AF)ablation using the intentional coronary venous exit carbon dioxide insufflation technique, performed via the percutaneous route via a subxiphoid approach, to achieve epicardial access. Whilst in AF 30 second segments were recorded from two catheters simultaneously which were placed in corresponding endocardial and epicardial positions within the left atrium (LA). All patients had undergone pulmonary vein isolation only prior and underwent re-isolation of pulmonary veins as required and linear ablation endocardially comprising posterior wall isolation via a roof and inferior line and an anterior mitral line. Patients underwent computed tomography coronary angiography which was post processed using inHEART (Pessac, France) with segmentation for epicardial adipose tissue undertaken.
Results
Endo-epicardial atrial fibrillation (AF) ablation using the percutaneous intentional coronary venous exit carbon dioxide insufflation technique to facilitate epicardial access is feasible4with a 5% rate of complication when performed in high volume centres by experienced operators, with low rates of persistent arrhythmia recurrence. Endo-epicardial dissociation is found in a high proportion of uniform wavefronts in patients with persistent AF. Epicardial adipose tissue thickness has a significant inverse relationship with voltage of bipolar epicardial electrograms.
Conclusion
Endo-epicardial ablation via a percutaneous route is feasible. This thesis provides novel information on endo-epicardial dissociation in AF with data obtained using firstly a percutaneous technique in humans, eliminating the electrical disruption caused by atriotomy. Endo-epicardial dissociation was found in a high proportion of individual wavefronts in patients with persistent AF suggesting that this could potentially be a mechanism which leads to high arrhythmia recurrence rates following endocardial ablation alone. Epicardial adipose tissue (EAT) thickness has been found to have a significant inverse relationship with voltage of bipolar epicardial electrograms suggesting that EAT significantly effects the characteristics of epicardial bipolar electrograms and that differentiation between scar and adipose tissue epicardially can be challenging when undertaking electroanatomical mapping and requires further analysis of electrogram features. The findings of this thesis contribute a significant body of knowledge to the subject of endo-epicardial AF ablation and may have important implications for future arrhythmia management.
| Date of Award | Nov 2024 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Barbara Philips (Supervisor), Dr John Silberbauer (Supervisor) & Dr Ian Mann (Supervisor) |