Ablating Myocardium Using Nanosecond Pulsed Electric Fields: Preclinical Assessment of Feasibility, Safety, and Durability.

BACKGROUND: Unlike conventional microsecond pulsed electrical fields that primarily target the cell membranes, nanosecond pulses are thought to primarily electroporate intracellular organelles. We conducted a comprehensive preclinical assessment of catheter-based endocardial nanosecond pulsed field ablation in swine. METHODS: A novel endocardial nanosecond pulsed field ablation system was evaluated in a total of 25 swine. Using either a low-dose (5-second duration) or high-dose (15-second duration) strategy, thoracic veins and discrete atrial and ventricular sites were ablated. Predetermined survival periods were <1 (n=1), ≈2 (n=7), ≈7 (n=6), 14 (n=2), or ≈28 (n=9) days, and venous isolation was assessed before euthanasia. Safety assessments included evaluation of esophageal effects, phrenic nerve function, and changes in venous caliber. All tissues were subject to careful gross pathological and histopathologic examination. RESULTS: All (100%) veins (13 low-dose, 34 high-dose) were acutely isolated, and all reassessed veins (6 low-dose, 15 high-dose) were durably isolated. All examined vein lesions (10 low-dose, 22 high-dose) were transmural. Vein diameters (n=15) were not significantly changed. Of the animals assessed for phrenic palsy (n=9), 3 (33%) demonstrated only transient palsy. There were no differences between dosing strategies. Thirteen mitral isthmus lesions were analyzed, and all 13 (100%) were transmural (depth, 6.4±0.4 mm). Ventricular lesions were 14.7±4.5 mm wide and 7.1±1.3 mm deep, with high-dose lesions deeper than low-dose (7.9±1.2 versus 6.2±0.8 mm; P=0.007). The esophagus revealed nontransmural adventitial surface lesions in 5 of 5 (100%) animals euthanized early (2 days) post-ablation. In the 10 animals euthanized later (14-28 days), all animals demonstrated significant esophageal healing-8 with complete resolution, and 2 with only trace fibrosis. CONCLUSIONS: A novel, endocardial nanosecond pulsed field ablation system provides acute and durable venous isolation and linear lesions. Transient phrenic injury and nontransmural esophageal lesions can occur with worst-case assessments suggesting limits to pulsed field ablation tissue selectivity and the need for dedicated assessments during clinical studies.

Evaluating Real-World National and Regional Trends in Definitive Closure in U.S. Burn Care: A Survey of U.S. Burn Centers.

To better understand trends in burn treatment patterns related to definitive closure, this study sought to benchmark real-world survey data with national data contained within the National Burn Repository version 8.0 (NBR v8.0) across key burn center practice patterns, resource utilization, and clinical outcomes. A survey, administered to a representative sample of U.S. burn surgeons, collected information across several domains: burn center characteristics, patient characteristics including number of patients and burn size and depth, aggregate number of procedures, resource use such as autograft procedure time and dressing changes, and costs. Survey findings were aggregated by key outcomes (number of procedures, costs) nationally and regionally. Aggregated burn center data were also compared to the NBR to identify trends relative to current treatment patterns. Benchmarking survey results against the NBR v8.0 demonstrated shifts in burn center patient mix, with more severe cases being seen in the inpatient setting and less severe burns moving to the outpatient setting. An overall reduction in the number of autograft procedures was observed compared to NBR v8.0, and time efficiencies improved as the intervention time per TBSA decreases as TBSA increases. Both nationally and regionally, an increase in costs was observed. The results suggest resource use estimates from NBR v8.0 may be higher than current practices, thus highlighting the importance of improved and timely NBR reporting and further research on burn center standard of care practices. This study demonstrates significant variations in burn center characteristics, practice patterns, and resource utilization, thus increasing our understanding of burn center operations and behavior.