Key result
Left-sided left atrial posterior wall ablation sites demonstrated significantly greater median impedance drop (13.6 vs 9.9 ohms, p<0.0001) compared to right-sided sites during intermittent positive pressure ventilation.
Why the study?
Prior studies show greater RF ablation effects at left-sided LAPW sites, but the mechanisms underlying this ablation heterogeneity during contact-force and VISITAG-guided PVI remained unclear.
Does high frequency jet ventilation compared to intermittent positive pressure ventilation alter the heterogeneity of radiofrequency ablation effects at the left atrial posterior wall during pulmonary vein isolation?
Observational (n=40)
No
Does high frequency jet ventilation compared to intermittent positive pressure ventilation alter the heterogeneity of radiofrequency ablation effects at the left atrial posterior wall during pulmonary vein isolation?
Heterogeneity of radiofrequency ablation effects at the left atrial posterior wall persists despite high frequency jet ventilation, likely driven by greater in-phase catheter-tissue contact surface area at left-sided sites.
Impedance asymmetry by side during IPPV may inform ablation settings; leaves open effects on lesion durability or safety.
Background Independent investigations demonstrate greater radiofrequency (RF) ablation effects at left- sided left atrial posterior wall (LAPW) sites. Objective To investigate mechanisms underlying RF ablation heterogeneity during contact-force (CF) and VISITAG™ Module (Biosense Webster)-guided pulmonary vein isolation (PVI). Methods Consecutive patients undergoing PVI during atrial overdrive pacing comprised 2 cohorts: intermittent positive pressure ventilation (IPPV, 14-16/min, 6-8ml/kg); high frequency jet ventilation (HFJV, 150/min, Monsoon III, Acutronic). Temperature-controlled (17ml/min, 48°C) RF data was retrospectively assessed at first-annotated (target 15s) LAPW sites: 30W during IPPV; 20W at left-sided sites during HFJV. Results Twenty-five and 15 patients underwent PVI during IPPV and HFJV, respectively. During IPPV, left versus right-sided median impedance drop (ImpD) was 13.6Ω versus 9.9Ω (p<0.0001) respectively and mean time to pure R unipolar electrogram (UE) morphology change 4.9s versus 6.7s (p=0.007) respectively. During HFJV, ImpD was greater at left-sided sites (9.7Ω versus 7.4Ω, p=0.21) and time to pure R UE significantly shorter: 4.3s versus 6.1s (p=0.02). Minimum case impedance subtracted from pre-RF baseline impedance (BI) generated site-specific ΔBI. Left-sided sites demonstrated significantly greater ΔBI, correlating strongly with Ln(ImpD) – IPPV r=0.84 (0.65 – 0.93), HFJV r=0.77 (0.35 – 0.93). At right-sided sites, ΔBI and Ln(ImpD) were without correlation during IPPV, but correlation was modest during HFJV (r=0.54, -0.007 – 0.84). Conclusions ΔBI may usefully indicate catheter-tissue contact surface area (SA). Consequently, greater left-sided LAPW RF effect may result from greater contact SA and in-phase catheter-tissue motion; HFJV may reduce right-sided out-of-phase catheter-tissue motion. Modifying RF delivery based on ΔBI may improve PVI safety and efficacy.
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David R. Tomlinson (2019) conducted an observational in Symptomatic atrial fibrillation (n=40). Left-sided left atrial posterior wall ablation vs. Right-sided left atrial posterior wall ablation was evaluated on Median impedance drop during intermittent positive pressure ventilation (p=<0.0001). Left-sided left atrial posterior wall ablation sites demonstrated significantly greater median impedance drop (13.6 vs 9.9 ohms, p<0.0001) compared to right-sided sites during intermittent positive pressure ventilation.
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