Utilising the pericardial CO2 insufflation technique to facilitate endo-epicardial AF ablation, achieving linear radiofrequency lesion sets, for persistent atrial fibrillation
Authors: Amin R , Julia Calvo J , Mccready J , Silberbauer J , Mann I 
Published: May 2022

Abstract

Funding Acknowledgements
Type of funding sources: None.

Background
High rates of persistent atrial fibrillation (PsAF) recurrence have been attributed to conduction gaps, non-transmural linear lesion sets and epicardial substrate. Hybrid thorascopic endo-epicardial AF ablation has been shown to reduce PsAF recurrence when compared to endocardial ablation alone, however with higher complication rates.

Aim
We propose that the percutaneous pericardial CO2 insufflation technique to access the pericardial space can be safely and effectively used for epicardial mapping and ablation of the left atrium (LA).

Methods
In a single centre, 15 patients with PsAF (6 with longstanding PsAF) and previous pulmonary vein isolation (PVI), underwent concurrent endo-epicardial AF ablation, using the subxiphoid percutaneous pericardial CO2 insufflation technique, whilst on uninterrupted anticoagulation. Endo-epicardial geometry and bipolar voltage maps were undertaken, and endocardial LA ablation performed comprising a roof, inferior and anterior mitral line (AML) (target LSI 5 for the inferior line and 6 on the roof and AML). If required, additional epicardial ablation was undertaken to establish PVI and linear lesion block.

Results
Epicardial access was achieved in all patients without acute bleeding complication. Epicardial mapping of the LA, in both transverse and oblique pericardial sinuses, was successful in all patients (Figure 1A, B). Excluding one roof line, all other linear lesions were blocked (44/45). Endocardial ablation alone achieved block in 67% (10 of 15) of roof lines, 87% (13 of 15) of inferior lines and 27% (4 of 15) of AMLs despite extensive endocardial ablation. Of AMLs requiring epicardial ablation, in 91% (10/11) block was achieved with ablation on the upper third of AML via the transverse sinus (Figure 1C). Epicardial ablation directly on the roof line via the transverse sinus was required to achieve block in 3 cases, and block achieved remotely on the upper third of the AML in another. Epicardial ablation on the mid inferior line was required in 2 cases to achieve block. Six patients had arrhythmia recurrence during the blanking period with 5 patients requiring DCCV and 1 patient chemically cardioverting. With a mean follow up time of 225 days, 2 patients have had paroxysmal self-terminating episodes of atrial arrhythmia with all patients off anti-arrhythmic medication.

Conclusion
Use of the subxiphoid percutaneous pericardial CO2 insufflation technique to achieve epicardial access for LA mapping and ablation is feasible and safe whilst on uninterrupted anticoagulation. Limited success in ablation for PsAF beyond PVI may be due to difficulty in creating trans-mural linear lesions. Epicardial ablation can be safely performed to achieve linear block in the roof, anterior and inferior LA. Epicardial fibrous structures such as the septopulmonary bundle and Bachmann’s bundle likely contribute to difficulty blocking roof lines and AMLs endocardially.