Focal Transcatheter Cryoablation: Is a Four‐Minute Application Still Required?
Bibliographic record
Abstract
Focal Transcatheter Cryoablation Introduction The standard 4‐minute application time for transcatheter cryoablation was determined in the 1990s when the system employed less potent chlorofluorocarbon refrigerants. The current refrigerant, nitrous oxide, generates substantially colder temperatures, with a faster cooling rate. Methods and Results We conducted a preclinical study on 32 mongrel dogs with stratified randomization of right atrial, right ventricular, and left ventricular chambers to 2‐minute versus 4‐minute application times using 8‐mm electrode tip cryocatheters (Freezor Max, Medtronic CryoCath LP, Montreal, Canada). Animals were sacrificed one month after the procedure. Three‐dimensional morphometric analyses were conducted in a blinded fashion. A total of 193 identified ablation lesions were processed for histological analyses, 102 with 2‐minute applications and 91 with 4‐minute applications. Ablation lesion surface area (167.8 ± 21.6 mm2 vs. 194.3 ± 22.6 mm2, P = 0.40), maximum depth (4.4 ± 0.2 mm vs. 4.5 ± 0.2 mm, P = 0.71), and volume (125.7 ± 69.5 mm3 vs. 141.0 ± 83.5 mm3, P = 0.25) were similar between groups. Overall, 90.2% of ablation lesions in the right atrium were transmural, 45.6% in the right ventricle, and 2.4% in the left ventricle, with no differences between 2‐minute and 4‐minute application times (P = 0.55). Thrombus was detected on the endocardial surface of 0.0% and 3.3% of ablation lesions created with 2‐minute and 4‐minute application times, respectively (P = 0.10). Conclusion Single 2‐minute and 4‐minute application times result in catheter ablation lesions of similar size using the modern cryoablation system with nitrous oxide as a refrigerant. While these findings suggest the potential to reduce the standard 4‐minute application time, further studies are required to compare clinical efficacy.
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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 | 0.005 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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".