Anterior position of dispersive patch for esophageal protection during atrial fibrillation ablation. A pilot feasibility study

Abstract

Funding Acknowledgements Type of funding sources: None. Introduction Ablation for atrial fibrillation (AF) carries a significant risk of esophageal injury. Current methods of esophageal protection are invasive, expensive and their cost-effectiveness can be questioned. Standard placement of dispersive patch (DP) at patient’s back exposes esophagus to radio-frequency (RF) current-mediated thermal injury and such complications as esophageal wall ulceration, peri-esophageal injury or life-threatening atrio-esophageal fistula. Redirecting RF current by DP repositioning to anterior chest can theoretically protect oesophagus from thermal injury, however, such an approach has not yet been investigated. Aim To determine feasibility of anterior DP position for treatment of AF using RF catheter ablation (RFCA)-based system. Methods We retrospectively analysed consecutive patients undergoing RFCA-based pulmonary vein isolation (PVI) using multi-electrode PVAC catheter with DP located either in anterior or traditional-posterior position. Two additional patients underwent point-by-point RFCA and mapping of PV ostia with impedance measurements during RFCA performed using anterior and posterior DP positioning. Results 62 patients (25 females, age 60 ± 12 years) underwent PVI using PVAC: 40 patients in posterior and 22 in anterior DP group. There were no major complications during procedures. There was no significant difference in AF recurrence rate between anterior and posterior DP groups during one-year follow up (log rank p = 0.065). In two additional consecutive patients (1 female, age 74 ± 2 years) undergoing point-by-point RFCA a total number of 30 measurements around PV ostia were performed. There was a significant difference between impedance values in anterior vs posterior DP positions (134 ± 7 Ω vs 122 ± 8 Ω, p = 0.0004). Conclusions Anterior position of dispersive electrode for PV isolation using RFCA-based systems is safe, feasible, atraumatic and is not associated with any additional cost. Apart from redirecting RF current away from the esophagus, anterior dispersive patch placement is associated with higher impedance values which can act as an additional protection. Possible prevention of esophageal complications using anterior dispersive patch positioning needs to be determined in prospective studies. Abstract Figure. AF-free survival and impedance

Anterior vs. posterior position of dispersive patch during radiofrequency catheter ablation: insights fromin silicomodelling

“…A recent pilot study compared the anterior and posterior positions of the DP during AF ablation. 8 Despite the very small sample size (64 patients), the authors found a significant difference between baseline impedance in anterior vs. posterior DP positions (134 ± 7 vs. 122 ± 8 Ω). Although they found no significant difference in AF recurrence rate during one-year follow up, they suggested that anterior DP might (i) redirect RF current away from the oesophagus to improve the procedural safety and (ii) act as an additional protection given higher impedance values would reduce the energy delivered to the tissue.…”

“…Our model’s results did not reproduce the trend found by Futyma et al . 8 regarding a higher baseline impedance (∼12 Ω) when the DP is positioned on the anterior side. In contrast, we observed a tendency to higher values (up to 8 Ω) with a posterior DP position during posterior LA RFCA.…”

“…Some groups have proposed that an anterior DP location may direct the current path away from posterior structures (such as the oesophagus) and towards anterior structures [such as right ventricular (RV) outflow tract tissue]. 8–12 Computer modelling affords the opportunity to assess and control numerous variables to form predictions about complex biophysical systems, including RFCA. 13 , 14 The present study uses an in silico model of posterior LA and anterior RV RFCA to test the hypothesis that the DP location does not significantly affect the current distribution around the catheter tip during RFCA but may affect lesions size through differences in impedance due to factors far from the catheter tip, such as tissue composition and catheter tip-to-DP distance rather than redirecting the current itself.…”

Effect of dispersive electrode position (anterior vs. posterior) in epicardial radiofrequency ablation of ventricular wall: A computer simulation study

“…Repositioning the PD in the anterior area of the patient's chest has been suggested as a strategy to redirect the RF current and increase lesion size in some cases in which the posterior position (standard option) failed to eliminate the arrhythmia. 13,14 The problem with this strategy is that it has not been clinically validated, due to the anecdotal nature of the reported cases and the uncertainty about whether success was really achieved by repositioning the PD or by reapplying the RF at the same site. In fact, in a previous computer modeling study we found that the differences in lesion size between both DP positions were possibly due to the differences in baseline impedance, 18 as reported in Ref.…”

“…Previous studies on endocardial RFCA suggested that the position of the DP could have an impact on the lesion size, [13][14][15][16][17] especially when the DP is repositioned from the posterior side (patient's back) to the anterior position (patient's chest). However, by computer modeling results, we have recently shown that the DP position (anterior vs. posterior) does not in fact redirect the RF current towards that position.…”