1207Pulsed Field Ablation: Acute and Chronic Safety and Lesion Efficacy
Bibliographic record
Abstract
Abstract Introduction Thermal ablation methods are the cornerstone of treatment for atrial fibrillation. However, they pose a risk to extra-cardiac structures and may result in inadequate efficacy. Nonthermal, pulsed-field ablation (PFA) delivery to cardiac tissues may create durable, efficacious lesions while avoiding collateral damage. Purpose The purpose of this preclinical GLP study was to assess acute and chronic electrical isolation combined with a pathology assessment of chronic lesion extent in response to PFA delivery to cardiac tissue, and to document any collateral damage. Methods Six pigs were treated with biphasic, bipolar PFA doses through a circular multi-electrode catheter. PFA was delivered at four locations at specified voltages: superior vena cava (SVC at 700V), right atrial appendage (RAA at 1500V), left atrial appendage (LAA at 1200V), and right pulmonary vein (RPV at 1500V). Phrenic nerve pacing thresholds and electrical block at SVC, RPV, and RAA sites were investigated acutely, and electrical block at the SVC sites chronically. Pigs were survived for 4 weeks. After euthanasia, necropsies and histopathological assessments documented the findings at the lesion sites and collateral tissues. Results Post PFA, entrance block was achieved in all SVC, RPV, and RAA sites. Histopathology showed characteristic replacement fibrosis of the myocardium at all ablation sites. The PFA lesions in the SVC and RPV were all continuously circumferential and histopathology did not detect any remaining myofiber conduits across the post-ablation fibrosis (consistent with the electrical assessments). PFA of the appendages caused wide-ranging fibrosis in the RAA, and limited fibrosis in the LAA. Histologically, the atrial fibrosis was almost exclusively transmural in both, with the RAA lesions overall diagnosed as circumferentially complete in all but one case. The right phrenic nerve (RPN) pacing thresholds were unchanged from baseline to the end of the procedure and were all <1.0V. The examined juxtaposed RPN segments exposed to PFA at the SVC and RPV sites were normal. None of the ablated targets was associated with stenosis, aneurysms, luminal thrombus or collateral damage on the abluminal side. Continuous lesion sites Conclusions This limited preclinical study evaluated the acute and chronic safety and efficacy of PFA in multiple cardiac and vascular treatment sites. In this porcine model, PFA results in acute and chronic electrical isolation, confirmed by pathology data, for all of the RPV and SVC targets. Pathology findings of the RAA revealed the ability to achieve chronic transmural lesions in highly trabeculated cardiac tissue. No collateral damage was seen to the adjacent RPN. Acknowledgement/Funding Medtronic
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".