Introduction: The spatial thermodynamics of very high power-short duration (vHPSD) radiofrequency (RF) application during pulmonary vein isolation (PVI) in in-vivo model has not been well characterized. This study was conducted to investigate the distance-temperature relationship during vHPSD-RF ablation. Methods: PVI was performed using the vHPSD catheter with the settings of 90W, RF time of 4 sec and 15mL/min irrigation in a canine model. Catheter contact force (CF) of 10-20g was defined as ‘normal’ and CF >20g as ‘firm’ CF. Tissue temperature was monitored using thermocouples implanted at the surface of the left atrial-pulmonary vein junction, left phrenic nerve, and the luminal esophagus. PVI using a standard contact-force sensing catheter (SCF) (settings of 35W, 30sec and 30mL/min irrigation) was performed for comparison. Results: A total of 334 TC profiles in 4 animals was investigated. Time to maximum tissue temperature (MTT) (6.0sec [vHPSD/normal CF] vs. 30.5 sec [SCF/normal CF], p<0.001; 8.0sec [vHPSD/firm CF] vs. 24.0sec [SCF/firm CF], p=0.022) was shorter with vHPSD than in SCF groups. MTT within 10mm from catheter-tip was lower in vHPSD ablation with normal CF than using SCF ablation (median 41.9°C [interquartile-range; 40.2-46.1] vs. 49.5°C [45.9-56.2], p=0.013). The distance margin to keep the MTT below 39ºC, 42ºC, and 50ºC were 4.9mm, 4.2mm, and 3.4mm, respectively in the vHPDS group. This margin was larger (8.0mm, 6.6mm, and 4.6mm) in the SCF group. Conclusion: Our study underscores that vHPSD creates greater resistive heating than conventional catheter ablation.

Background: Acute left atrial ridge (LAR) lesion was observed after atrial fibrillation ablation. However, the feature of LAR lesion has not been quantitatively evaluated and its influence on left atrial appendage closure (LAAC) combined procedure remained to be explored. We aimed to evaluate profile of acute LAR lesion and investigate its influence on LAAC procedure. Methods: LAR lesion profile was measured by transesophageal echocardiography (TEE) in 117 consecutive non-valvular AF patients underwent combined procedure of cryoballoon (CB) ablation and LAAC. Its correlation with baseline variables and clinical outcomes were thoroughly investigated. Results: Measurement of 96 available TEE image series showed 95 had prominent acute LAR lesion, with a greater change in width (Δwidth=3.6±2.3 mm) than thickness (Δthickness=2.6±3.5 mm), and correspondingly narrowed outer ostium (Δouter ostium diameter=-3.4±4.0 mm). While the inner ostium stayed unchanged. Logistic regression analysis showed that a higher nadir temperature when freezing left superior pulmonary vein (LSPV) led to a LAR lesion with greater width (2-fold wider) (adjusted odds ratio =1.16, 95% confidence interval 1.02-1.31). For evaluation of LAAC outcomes, residual flow occurred in 6 patients, 4 with Watchman had minimal residual flow at the inferior border, while 2 with LAmbre developed larger residual flow at the LAR side. Clinical outcomes were similar between groups divided by LAR lesion size. Conclusion: Acute LAR lesion frequently occurred following CB ablation combined procedure, and its width positively correlates with LSPV nadir temperature. It affects measurement of pacifier device but has no influence on plug device when performing combined procedure.

Introduction: His-Purkinje system (HPS) pacing emerges as an ideal strategy to restore cardiac synchrony. However, there is insufficient evidence to confirm the safety of HPS pacing in advanced age patients who are vulnerable to invasive procedures. Methods: We aimed to evaluate the short-term feasibility and safety of HPS pacing in symptomatic bradycardia patients over 85 years of age by comparing the pacing parameters and clinical outcomes with a younger cohort. 189 out of 198 consecutive patients underwent HPS pacing with symptomatic bradycardia were included. Among them 37 and 152 were aged over 85 years and below 85 years respectively. Peri- and post-procedure pacing parameters, cardiac function and clinical events were thoroughly evaluated during follow-up. Results: Compared with the younger cohort, the elderly had worse renal function and cardiac function. All 189 patients underwent successful HPS pacing, among whom 28 were paced at His-bundle. Paced QRS duration was shortened non-significantly compared with intrinsic, which showed no difference between cohorts. Pacing threshold and impedance decreased significantly without difference between cohorts. Lead dislodgement and pocket hematoma/infection only occurred in 2 (1.3%) and 4 (0.7%) younger patients, respectively. Through a 10.5±3.0 months follow-up, A non-significant improvement in cardiac function was indicated by echocardiographic indices. Clinical events incidences were comparable, except a higher incidence of myocardial infarction (8.1% vs 0.7%) observed in the advanced age cohort. Conclusion: Compared with the younger, HPS pacing could safely restore physiological conduction and reserve cardiac function in advanced age patients with symptomatic bradycardia.