Cycle Length Dynamics at the Onset of Postinfarction Ventricular Tachycardias Induced in Canines:
Bibliographic record
Abstract
INTRODUCTION: Postinfarction monomorphic ventricular tachycardias induced by programmed stimulation may display initial cycle length (CL) variations before stabilizing. METHODS AND RESULTS: To show that tachycardia onset dynamics depend on rate-dependent electrical properties of the reentrant substrate, we extracted activation times and maximum negative slopes of local activation complexes (-dV/dt(max)) from 191 unipolar electrograms recorded in the anterior left ventricular wall of anesthetized, 3-day-old infarct canine preparations. Measurements were made of the responses to programmed stimulation, as well as in early and later beats of tachycardias, which displayed either a constant trend in CL (group A, n = 5 preparations) or one in which CL prolongation occurred according to an exponential course before stabilizing (group B, n = 9). Stimulation protocols inducing the tachycardias were more aggressive and their CL was significantly shorter (CL = 159 +/- 24 msec) in group A than in group B (stabilized CL = 206 +/- 34 msec). Reentrant activity occurred in subepicardial areas in which the absolute value of -dV/dt(max) (absolute value(-dV/dtmax)) was heterogeneously depressed (<2 mV/msec). Absolute value(-dV/dtmax) was reduced and activation delay increased in the successive responses to extrastimuli. Further reductions in absolute value(-dV/dtmax) (10% to 23%) were shown to occur between early and later beats in 5 of the 9 tachycardias in group B (no change in the 4 others), and they were associated with localized prolongation of conduction times in reentrant pathways. In contrast, absolute value(-dV/dtmax) improved in all group A tachycardias (7% to 25%). CONCLUSION: This study provides evidence that the onset dynamics of postinfarction ventricular tachycardias are determined by interval-dependent electrical changes occurring in the reentrant substrate.
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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) | 0.001 | 0.002 |
| 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".