In a preclinical model, HP-SD ablation (90 W/4 s, T ≤65°C) produced an improved lesion-to-lesion uniformity, linear contiguity, and transmurality at a similar safety profile of conventional ablation.

Background An in-vivo animal thigh model is the standard technique for evaluation of ablation catheter technologies, including efficacy and safety of ablation. However, the biophysics of ablation in a thigh model may not be similar to a beating heart. Objective The aim of this study was to compare efficacy and safety of ablation between a thigh preparation model and a beating heart. Methods In 7 swine, radiofrequency (RF) ablation using a 3.5mm open irrigated catheter (Thermocool Smart Touch®) was performed sequentially in a thigh muscle and in-vivo beating ventricles. Ablation was performed at low (30W for 40Ssec) and high (40W for 60Sec) energy settings and at similar contact force. Ablation lesions were scanned in high-resolution and measured using electronic calipers. Results A total of 152 RF ablation lesions were measured (86 thigh and 66 heart). At low-energy, lesion width was greater in the thigh model (12.19±1.8mm vs. 8.99±2.1mm; p<0.001) while lesion depth was similar between the thigh and heart (5.71±0.8mm vs. 5.95±1.3mm, respectively; p=0.18). The planar cross-sectional lesion area was greater in the thigh model (thigh 54.8±10.8mm2 vs. heart 43.1±16.1mm2; p<0.001). At high-energy setting, lesion depth, width, and area were all greater in the thigh model (thigh 91.5±16.8mm2 vs. heart 56.0±15.5mm2; p<0.001). The incidence of steam pop and char formation was similar between the models. Conclusion The thigh preparation model is a reasonable technique for evaluation of ablation catheter technology, however it often results in overestimation of lesion size, especially at higher energy settings.

Delivery of high-power short-duration RF energy applications, facilitated by a novel ablation catheter system equipped with advanced TC technology, is feasible, safe, and results in the formation of effective ablation lesions.

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Background - Pulsed field ablation (PFA) is a nonthermal energy with potential safety advantages over radiofrequency ablation (RFA). This study investigated a novel PFA system- a circular multielectrode catheter ("PFA lasso") and a multichannel generator designed to work with Carto 3® mapping system. Methods - A 7.5F bidirectional circular catheter with 10 electrodes and variable expansion was designed for PFA (biphasic, 1800 Volts). This study included a total of 16 swine utilized to investigate the following 3 experimental aims: Aim 1 examined the feasibility to create a right atrial ablation line of block from the superior vena cava (SVC) to the inferior vena cava (IVC). Aim 2 examined the effect of PFA on lesion maturation including durability after a 30-day survival period. Aim 3 examined the effect of high intensity PFA (10 applications) on esophageal and phrenic nerve tissue in comparison to normal intensity RFA (1-2 applications). Histopathological analysis of all cardiac, esophageal and phrenic nerve tissue was performed. Results - Acute line of block was achieved in 12/12 swine (100%) and required a total PFA time of 14 sec (IQR:9-24.5) per line. Ablation line durability after 28&3 days was maintained in 11/12 (91.7%) swine. PFA resulted in transmural lesions in 179/183 (97.8%) sections and a median lesion width of 14.2mm. High intensity PFA (9 [IQR:8-14] application) had no effect on the esophagus while standard intensity RFA (1.5 [IQR:1-2] applications) resulted in deep esophageal tissue injury involving the muscularis propria and adventitia layers. High intensity PFA (16 [IQR:10-28] applications) has no effect on phrenic nerve function and structure while standard dose RFA (1.5 [IQR:1-2] applications) resulted in acute phrenic nerve paralysis. Conclusions - In this preclinical model, a multielectrode circular catheter and multichannel generator produced durable atrial lesions with lower vulnerability to esophageal or phrenic nerve damage.