Influence of various energy settings and overlap ratios on size and continuity of lesions in a laser balloon ablation in vitro model

Abstract

Introduction: The influence of power (Watt [W]) and total energy (Joule [J]) on lesion size and the optimal overlap ratio remain unclear in laser balloon (LB) ablation for atrial fibrillation. We aimed to evaluate lesion size and visible gaps after LB ablation with various energy settings and different overlap ratios in vitro model. Methods and Results:Chicken muscles were cauterized using the first-generation LB with single applications of full and a half duration of six energy settings (5.5 W/30 seconds [165 J] to 12 W/20 seconds [240 J]) and varying power (5.5-12 W) at the constant total energy (160 J). Three overlapped ablations with different ratios (25% and 50%) for each energy setting were also performed to evaluate the visible gap degree categorized from 1 (perfect) to 3 (poor). Twenty lesions were evaluated for each energy setting. In single applications of full duration, lesion depth, lesion volume, and maximum lesion diameter increased according to the total energy (all, P < .001) and were greater than in those of half duration in each energy setting (all, P < .05).However, applications with larger power created larger lesion volume and maximum lesion diameter at constant total energy (P < .05). The visible gap degree was better in all energy settings with 50% overlapped ablation than in those with 25% (all, P < .001).Conclusion: Lesion size depends not only on power but also on total energy in the LB ablation. Sufficiently overlapped ablations allow continuous lesion formation. K E Y W O R D S laser ablation experiment, laser balloon, laser energy setting, lesion size, optimal overlap ratio

Comparison of dragging ablation and point‐by‐point ablation with a laser balloon on linear lesion formation

“…We previously reported that overlapped point-by-point laser ablation made lesion depth larger than single-point laser ablation. 17 Therefore, we speculate that overlapped ablation has a synergistic effect with the previous lesion in case that overlapped ablation is performed while local tissue temperature is kept high. Dragging technique is also thought to allow acceptable deep lesion formation by persistent tissue warming (i.e., the effect of temperature stacking), leading to efficient lesion formation.…”

“…This experimental system is similar to that previously described. 17 Commercially obtained chicken breast skeletal muscles were structurally stable even after warming and cutting in the preexperimental study. Therefore, we used them as experimental material.…”

“…As the index of lesion continuity, we evaluated the visible gap degree as described previously, 17 F I G U R E 1 Experimental settings and ablation protocols. A, Laser was titrated to chicken muscles in a laser-shielding box (upper).…”

“…24 Furthermore, an adequate total energy per application and sufficient overlap ratio are considered necessary for deep lesion formation. 17 We newly demonstrated that the dragging laser ablation at high power provides deep and continuous lesion formation. However, dragging speed and power were considered to be important in size and continuity of the linear lesion in dragging laser ablation.…”

Predictors of phrenic nerve injury during pulmonary vein isolation for curing atrial fibrillation with balloon-based visually guided laser ablation.

“…Nagase et al and Okishige et al reported that the lesion depth, lesion volume, and maximum lesion diameter increased according to not only the laser output but also the delivered total laser energy in an in vitro model 17,18) . However, our study showed there was no significant difference in the mean output and delivered total energy between the groups with and without PNI.…”