Moderated Posters 251Gap junction uncoupling during ischaemia activates normally quiescent purkinje-myocardial junctions resulting in accelerated and more complex activation patterns52The role of gαi2 signalling in cardiac electrophysiology53Midline atrial tachycardia: mapping and differentiation54A multicentre experience of percutaneous left atrial appendage occlusion using different technologies in the united kingdom55Opportunistic screening for atrial fibrillation during flu clinics56Primary care achievement of anticoagulation in atrial fibrillation: as assessed by the quality and outcomes framework57Is combined ablation for paroxysmal atrial fibrillation using balloon cryoablation and radiofrequency ablation superior to either technique alone? long-term follow up and cost analysis58Impact of voltage mapping to guide whether or not to perform ablation of the posterior wall in patient with persistent atrial fibrillation:
Bibliographic record
Abstract
Introduction: The His-Purkinje system activates ventricular myocardium through Purkinje-Myocardial Junctions (PMJs).It has been suggested that most PMJs are normally non-functional at baseline due to source-sink mismatches at these junctions.We hypothesised that gap junctional uncoupling at the PMJs during acute ischaemia facilitates propagation across a greater number of functional PMJs, thereby leading to accelerated but more complex activation patterns.Methods: In aortic-perfused rabbit hearts (n ¼ 8), the right ventricles (RV) were exposed, preserving the Purkinje system (Figure ), and the endocardium optically mapped.Activation of the RV endocardium during atrial pacing was recorded during 40 minutes of global ischemia followed by 30 minutes reperfusion.A corresponding detailed 3D computer model of rabbit ventricles incorporating the Purkinje system was constructed to test the hypothesis.Results: Optical mapping studies revealed that the percentage of RV area activated within the first 5ms decreased from baseline 53 + 6% to 43 + 8% during early ischemia (,20 min), and paradoxically then increased to 59 + 8%, with more complex activation (p , 0.001).This coincided with more surface breakthroughs at more PMJs during late ischaemia (Figure ).Activation normalised after reperfusion.In the computer model, a 6% reduction in conductivity was sufficient to render quiescent PMJs active.Increasing the fraction of functioning PMJs from 5% to 100% accelerated endocardial activation from 27.1 to 15.8 ms, compensating for reduced conduction velocity.Surface breakthroughs increased, as did the complexity of activation, matching the experiments.Conclusion: At baseline, most PMJs are quiescent.Ischaemia-induced closure of gap junction channels reduces conduction velocity, but as the uncoupling progresses, more PMJs become functional due to reduced source-load mismatch.The altered, more complex, activation patterns during ischaemia may be pro-arrhythmic as they increase the pathways for meandering wavefronts and the likelihood of wave collision.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.255 | 0.044 |
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".