Characteristics of Ice Impedance Recorded From a Ring Electrode Placed at the Anterior Surface of the Cryoballoon
Bibliographic record
Abstract
BACKGROUND: The success of cryoablation of the pulmonary vein isolation (PVI) is dependent on transmural and circumferential ice formation. We hypothesize that rising impedance recorded from a ring electrode placed 2 mm from the cryoballoon signifies ice formation covering the balloon surface and indicates ice expansion. The impedance level enables titration of the cryoapplication time to avoid extracardiac damage while ensuring PVI. METHODS AND RESULTS: In 12 canines, a total of 57 pulmonary veins were targeted for isolation. Two cryoapplications were delivered per vein with a minimum of 90 and maximum of 180-second duration. Cryoapplication was terminated on reaching a 500 Ω change from baseline. Animals recovered 38±6 days post-procedure, and veins were assessed electrically for isolation. Heart tissue was histologically analyzed. Extracardiac structures were examined for damage. PVI was achieved in 100% of the veins if the impedance reached 500 Ω in <90 seconds with freeze time of 90 seconds. When 500 Ω was reached >90 to 180 seconds (142.60±29.3 seconds), 90% PVI was achieved. When the final impedance was between 200 and 500 Ω with 180 seconds of freeze time, PVI was achieved in 86.8%. For impedance of <200 Ω, PVI was achieved in 14%. No extracardiac damage was recorded. CONCLUSIONS: Impedance rise of 500 Ω at <90 seconds with freeze time of 90 seconds resulted in 100% PVI. Impedance measurements from the nose of the balloon is a direct measure of ice formation on the balloon. It provides real-time feedback on the quality of the ablation and defines the cryoapplication termination time based on ice formation, limiting ice expansion to extracardiac tissues.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".