Abstract 18181: Left Ventricular Myocardial Mechanics at Rest and During Exercise in Children After Arterial Switch Operation
Bibliographic record
Abstract
Introduction: Arterial switch operation (ASO) is the standard surgical procedure for transposition of the great arteries allowing a complete anatomical and physiological repair. In these patients the functional impact of myocardial perfusion on global and regional myocardial function has not been investigated. Stress echocardiography with visual myocardial assessment has been used to detect regional myocardial dysfunction. Studying LV mechanics using speckle-tracking echocardiography during exercise could provide more quantitative information. The aim of the study was to study the myocardial response to exercise in children after ASO using semi-supine cycle ergometry stress echocardiography (SSCE). Materials and Methods: Forty children after ASO and 29 age and gender matched controls were included. Median age was 14 years. A stepwise SSCE protocol was used. LV global longitudinal strain and circumferential strain was measured in all subjects at rest and at incremental heart rate. Results: Resting HR was similar between groups, peak HR was lower in the ASO group compared with controls (142 ±11 vs 157±14 bpm, p=0.0007). LV global longitudinal strain was lower at rest (19±2.3% vs. 21±2.5%, p=0.004) but not at peak exercise (22.7±5.6 % vs. 24±4.5 % p=0.2) in the ASO group compared to controls. No significant difference was found in LV global circumferential strain at rest (23.7±2.3% vs. 24±3.2 %, p=0.6) and peak exercise (28±2.6% vs. 27.9±4.1 %, p=0.9). Also when plotted versus heart rates the increase in longitudinal and circumferential strain values were not significantly different. Conclusions: These data show that circumferential and longitudinal myocardial deformation during exercise is preserved in children after ASO compared to controls. Earlier data obtained using Tissue Doppler in the same study cohort, showed a normal increase in systolic tissue Doppler velocities. These data suggest a preserved LV reserve during exercise in this patient cohort.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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) | 0.002 | 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".