The time course of exit and entrance block during cryoballoon pulmonary vein isolation
Bibliographic record
Abstract
AIMS: The dynamic time course of entrance and exit block during pulmonary vein isolation (PVI) is unknown. The purpose of this series was to dynamically evaluate the manifestation of entrance and exit conduction block during simultaneous circumferential PVI. METHODS AND RESULTS: Pacing manoeuvres were performed during cryoballoon ablation of left-sided pulmonary veins (PVs) in 30 consecutive patients with a history of drug-refractory paroxysmal atrial fibrillation. At the onset of ablation continuous pacing was performed from the PV at a cycle length of 600 ms until the appearance of exit block. Once exit block was demonstrated, uninterrupted pacing was immediately transitioned to the distal coronary sinus (CS) catheter and continued at 600 ms throughout the rest of the cryoapplication. The timing of exit block, entrance block, and corresponding cryoballoon temperature were noted for all patients. In the 45 PVs when real-time PV recordings were available during cryothermal ablation, the presence of exit block was reliably demonstrated to precede entrance block (P < 0.0001) by a median of 5 s [interquartile range (IQR) 3, 12; median temperature at isolation -39°C (IQR -30, -45); nadir ablation temperature -53°C (IQR -48, -59)]. In all cases, when uninterrupted pacing was transitioned from the PV to the distal CS, entrance conduction from the left atrium to PV remained intact. CONCLUSION: Circumferential PV ablation results in progressive PVI, beginning with unidirectional exit block, and followed by entrance block. As exit block reliably precedes entrance block, we are able to provide justification for the exclusive use of entrance conduction block as the endpoint of cryoballoon-based PVI.
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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".