Abstract 13332: Assessment of Myocardial Oxygenation Response to Vasoactive Breathing Maneuvers in Patients With Repaired Dextro-Transposition of the Great Arteries an OS-CMR Study
Bibliographic record
Abstract
Introduction: Long-term outcomes of patients with repaired Dextro-transposition of the great arteries (D-TGA) by arterial switch operation (ASO) are excellent. However, studies have suggested impaired myocardial blood flow reserve. Oxygen-sensitive cardiac magnetic resonance (OS-CMR) with vasoactive breathing maneuvers (BM) offers a contrast-free tool for evaluating myocardial oxygenation. Hypothesis: Evaluate myocardial oxygenation reserve and microvascular function in repaired D-TGA post-ASO using OS-CMR with BM. Methods: In this single-center study, we analyzed OS-CMR images (basal and mid-left ventricular slices) of 9 D-TGA post-ASO patients (mean age 29 ±6.52yrs, 33.3% females) and 10 healthy participants (mean age 33 ±8.9 yrs, 40% females) who completed the BM. The BM consisted of free breathing, then hyperventilation, causing vasoconstriction, then breath hold, causing vasodilatation. End-systolic OS-CMR signal intensity (SI) was measured at baseline, after hyperventilation (closest to 0 sec of breath hold), and at closest to 30 sec of breath hold. Changes in SI (ΔSI) in % were calculated in response to the different periods and compared using independent samples t-test. Results: In the D-TGA cohort, the coronary response to hyperventilation was abnormal compared to healthy subjects (5.8±19.9% vs -15.1±13.3%, p=0.01). No difference was observed in ΔSI% during breath hold (mean TGA:3.0±10.5% vs mean healthy:5.7±6%, p=0.5). No differences were observed in mid-slices for either period. Conclusions: Our findings suggest patients with D-TGA may have an impaired vasoconstrictor response to a hyperventilation maneuver. Further studies should explore the associated pathophysiology and potential impact on clinical management.
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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 | 0.000 | 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) | 0.001 | 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".