Transmural unipolar electrogram morphology is achieved within 7s at the posterior left atrial wall during pulmonary vein isolation: VISITAG™ Module-based lesion assessment during radiofrequency ablation

Abstract

Aims To assess the occurrence of a histologically validated measure of transmural (TM) atrial ablation -pure R unipolar electrogram (UE) morphology change -at first-ablated left atrial posterior wall (LAPW) sites during contact force (CF)-guided pulmonary vein isolation (PVI). significantly greater impedance drop (median 13.5Ω versus 9.9Ω; p=0.003). Importantly, neither the first-site RF duration (14.9 versus 15.0s) nor the maximum ablation catheter tip distance moved (during RF) were significantly different, yet the mean CF was significantly higher at right-sided sites (16.5g versus 11.2g; p=0.002). Concurrent impedance and objectively annotated bipolar electrogram (BE) data demonstrated ~6-8Ω impedance drop and ~30% BE decrease at the time of first pure R UE morphology change. Methods and results ConclusionUsing objective ablation site annotation, TM UE morphology change was typically achieved within 7s at the LAPW, with significantly greater ablative effect evident at left-sided sites. The methodology described in this report represents a novel and scientifically more rigorous foundation towards future research into the biological effects of RF ablation in vivo.. CC-BY-NC-ND4.0 International license peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/234799 doi: bioRxiv preprint first posted online Dec. 15, 2017; 3 KeywordsAtrial fibrillation; contact force catheter ablation; pulmonary vein isolation; unipolar electrogram; VISITAG™ Module . CC-BY-NC-ND 4.0 International license peer-reviewed) is the author/funder. It is made available under aThe copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/234799 doi: bioRxiv preprint first posted online Dec. 15, 2017; 4 Condensed abstractThrough appropriate use of the VISITAG™ Module and CARTOREPLAY™, unipolar electrogram morphology change indicative of histologically confirmed transmural atrial ablation in animal models, was proven to occur typically within 7s, during first-site contact force-guided ablation at the left atrial posterior wall during pulmonary vein isolation.. CC-BY-NC-ND4.0 International license peer-reviewed) is the author/funder. It is made available under a The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/234799 doi: bioRxiv preprint first posted online Dec. 15, 2017; 5What's New?• The VISITAG™ Module provides objective, automated ablation site annotation and may be used to record and identify biophysical parameters at positions of stable radiofrequency (RF) energy delivery in vivo.• CARTOREPLAY™ permits electrogram analyses at annotated sites; together, these modules permit evaluation of histologically validated unipolar electrogram (UE) criteria for transmural (TM) atrial ablation, following pulmonary vein isolation (PVI).• At first-ablated left atrial posterior wall sites, RF-induced UE morphology change from RS to pure R occurred in 98%. The time to pure R UE morphology change w...

Assessment of the transmural unipolar electrogram morphology change radius during contact force-guided pulmonary vein isolation using the VISITAG™ Module and CARTOREPLAY™

“…8 Furthermore, recent in vivo data have demonstrated significantly greater RF ablation energy effect at left versus right-sided LAPW sites during PVI; i.e. noted from our earlier work 13 and also suggested by a report into "forced" ablation power reduction during LAPW ablation according to oesophageal location, where both maximal measured intraluminal temperature (41 o C) and lowest forced power reduction (15.9W) occurred with leftsided oesophageal location compared to central / right-sided course. These data suggest that any single derived target value for LAPW CF-guided RF ablation may incur greater risk of extra-cardiac thermal trauma at left-sided locations, and/or non-TM RF delivery during rightsided ablation.…”

“…Retrospective analysis of VISITAG™ Module and CARTOREPLAY™ data was performed at first and second-annotated LAPW ablation sites following single-operator PVI, for the same previously reported consecutive group of unselected patients with symptomatic AF undergoing PVI according to current treatment indications 3 and as previously descrtibed. 13 8 Briefly, all procedures were undertaken using general anaesthesia (GA) and intermittent positive pressure ventilation (IPPV), with temperature-controlled CF-guided RF at 30W delivered using Agilis™ NxT sheath (St Jude Medical Inc., Minneapolis, MA) support. We calculated the catheter tip (position) SD and maximum displacement (from the mean position) at each annotated site from exported VISITAG™ Module data using R 3.3.3.…”

“…These findings were explained neither by differences in RF duration (~15s) nor maximum catheter tip distance moved, and occurred despite significantly greater mean contact force (CF) at right-sided sites. 13 However, when aiming for ≤ 6mm inter-ablation site distance during continuous RF application, "per protocol" subsequently annotated sites required minimum target RF duration of ~9s. 15 Therefore, the purpose of this present report was to retrospectively investigate the onset timing of TM UE morphology change at secondannotated LAPW sites according to the distance from site 1, thereby aiming to identify the radius of TM ablation effect resulting from this previously developed approach to PVI.…”

Ablation catheter motion detection during contact force and VISITAG™ Module-guided pulmonary vein isolation

“…Therefore, even with ACCURESP™ "off", respiratory motion may represent an important determinant of the recently identified heterogeneity in RF effect during PVI. 9,22,23 Furthermore, cardiac cycle-induced motion may represent another important determinant of catheter instability, although atrial overdrive pacing during RF delivery has been demonstrated to improve catheter stability and impedance reduction; 24 this technique was also used in this present report.…”

“…(1) Studies of RF delivery during PVI in humans have provided evidence of greater effect at left-sided LA posterior wall (LAPW) sites 8,9 , therefore any protocol without suitable energy dosing adjustment is likely to incur increased risk of extra-cardiac thermal trauma;…”