Action Potential Duration Gradient Protects the Right Atrium from Fibrillating
Bibliographic record
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia. It is characterized by rapid and disorganized electrical activity in the atria. Atrial arrhythmias can be triggered from an ectopic focus, i.e., an abnormal impulse originating in an area other than the sinus node, generating reentrant waves. The regional ionic heterogeneities found in the atria cause a gradual shortening of the action potential duration (APD) with increased distance from the sinoatrial node. It is generally thought that the only electrophysiological consequence of the spatial dispersion of cardiac action potentials (AP) is the enhancement of reentry. This paper investigates the effect of a gradient in APD on arrhythmogenesis via computer simulations. A gradient of ionic properties was introduced into a computationally efficient computer model of the canine atria to produce a smooth distribution of APDs. The window of vulnerability for ectopic beat-induction of reentry was determined for both left atrium (LA) and the right atrium (RA) stimulation, with and without an APD gradient. The shortened windows of vulnerability in the RA, due to the addition of the APD gradient, suggests a protective mechanism against AF. The left atrial window of vulnerability was slightly longer from ionic dispersion.
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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 | 0.000 |
| 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 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".