Myocardial electrical alteration in canine preparations with combined chronic rapid pacing and progressive coronary artery occlusion
Bibliographic record
Abstract
Our objective was to create an animal preparation displaying long-term electrical alterations after chronic regional energetic stress without myocardial scarring. An Ameroid (AM) constrictor was implanted around the left circumflex coronary artery (LCx) 2 wk before chronic rapid ventricular pacing (CRP) was initiated at 240 beats/min for 4 wk (CRP-AM). Comparisons were made with healthy canines and canines with either AM or CRP. Unipolar electrograms were recorded from 191 sites in the LCx territory in open-chest, anesthetized animals during sinus rhythm and while pacing at 120-150 beats/min, with bouts of transient rapid pacing (TRP; 240/min). In CRP-AM and AM, ST segment elevation was identified at central sites and ST depression at peripheral sites, both increasing with TRP. In CRP-AM and CRP, the maximum negative slope of unipolar activation complexes was significantly depressed and activation-recovery intervals prolonged. Areas of inexcitability as well as irregular isocontour patterns displaying localized activation-recovery intervals shortening and gradients >20 ms between neighboring sites were identified in one-third of CRP-AM at slow rate, with increasing incidence and magnitude in response to TRP. In CRP-AM, programmed stimulation-induced marked conduction delay and block as well as polymorphic ventricular tachycardias, which stabilized into monomorphic tachycardias with the use of lidocaine or procainamide. Whole cell Na(+) current and channel protein expression were reduced in CRP-AM and CRP. Despite complete constrictor closure, small areas of necrosis were detected in a minority of CRP-AM. Long-term electrical alterations and their exacerbation by TRP contribute to arrhythmia formation in collateral-dependent myocardium subjected to chronic tachycardic stress.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".