Effects of dobutamine stress on cardiac contraction synchronism in a canine model
Bibliographic record
Abstract
In cardiac resynchronization therapy, many devices need to be optimized to take into account the magnitude and characteristics of patients' ventricular mechanical dyssynchrony. The optimization process is mostly performed at rest; however, mechanical resynchronization might be more important under stress, while patients need to improve their cardiac efficiency. The objective of this study was to observe if levels of cardiac stress could modify the ventricular contraction synchronism. Cardiac stress was induced with dobutamine infusion in eight healthy canine subjects. Hemodynamic and ventricular synchronism assessments were performed by left ventricular pressure measurements and radionuclide tomographic-gated blood pools. Cardiac output increased from 2.8 ± 1.0 at rest to 5.7 ± 2.2 L min(-1) at 20 µg kg(-1) min(-1), while the ventricular performance (dP/dtmax) increased from 1588 ± 374 to 8004 ± 710 mmHg s(-1). At baseline, the interventricular delay (in degrees) was -6.3 ± 2.6°, the left ventricle contraction preceding the right. The delay significantly increased to -21.6 ± 3.1° with dobutamine stress (p < 0.0001). On assessment of the left intraventricular synchrony, septal-to-lateral delay was -6.9 ± 5.1° at baseline which revealed a preceded contraction of the left lateral wall from the septum. Cardiac stress produced a significant modulation (p = 0.01), with an inversion of the contraction pattern, the septum contraction preceding the lateral wall contraction by 15.5 ± 5.6° at maximum dobutamine infusion; a significant linear trend (p < 0.001) was found between cardiac stress levels and septal-to-lateral delays. Cardiac activity levels modified the ventricular synchronism supporting the fact that optimizations of cardiac resynchronization devices could be improved by taking cardiac stress into account.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.001 |
| Research integrity | 0.001 | 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".