Microvascular function variation in a healthy population: Insights from Oxygenation-Sensitive CMR
Notice bibliographique
Résumé
Microvascular dysfunction has significant impacts on patient prognosis even in absence of obstructive coronary artery disease, and may predict future cardiovascular events. Factors like age, sex, and body composition contribute to vascular dysfunction over the lifetime. In otherwise healthy individuals the impact of these factors is unclear. Oxygenation-sensitive cardiovascular magnetic resonance imaging (OS-CMR) is a validated methodology to examine vascular function which exploits the blood oxygen level dependent effect, in which deoxygenated hemoglobin acts as an innate contrast agent in a magnetic field. Through varied OS-CMR signal intensities, regional tissue oxygenation changes during vasodilation are detected. Previous research utilizing OS-CMR observed blunted vascular function in many cardiovascular pathologies. Vasoactive breathing maneuvers, a period of paced hyperventilation followed by a voluntary maximal breath hold, are an endogenous alternative to pharmaceutical vasodilation in OS-CMR. Carbon dioxide variations, inducing vasoconstriction during hyperventilation and vasodilation during the breath hold, act on endothelial cells to modulate vascular tone. The breathing-induced myocardial oxygenation reserve (B-MORE) describes the myocardial oxygenation response during breathing maneuvers. This endothelial-dependent mechanism may provide a valuable assessment of microvascular function, based on meaningful biomarkers instead of secondary surrogate markers such as blood flow or tracer uptake. Previous work demonstrated a transmural gradient of vascular function during endothelial-independent adenosine vasodilation in subjects with risk factors but no cardiovascular disease. In a similar cohort, breathing maneuvers may provide valuable insight into microvascular dysfunction before the onset of cardiovascular disease. The thesis aims to investigate tissue oxygenation variation as a marker of microvascular function in healthy subjects, providing a better understanding of microvascular dysfunction pathophysiology in such populations. The included study retrospectively assessed the impact of demographic factors on global and regional B-MORE in healthy adults from 4 prospective OS-CMR studies in Montreal, Canada. We hypothesize that demographic factors will impart slight changes to microvascular function across the lifetime, differentially impacting B-MORE. This thesis includes the first study investigating factors impacting B-MORE in healthy subjects. Several factors differentially impacted microvascular function within the cohort. This indicates that in a healthy population, sex and body composition, including height and body size analysis, are associated with microvascular function and thus lead to baseline value variations. Female sex-specific risk factors may be associated with reduced function (lower B-MORE values). Further research is needed to fully understand the impact of healthy aging on the microvasculature over the lifetime, as it may be impacted by factors not assessed in this study. Future work should investigate the prognostic value and utility of B-MORE as a marker of microvascular function. Blunted B-MORE may indicate an increased risk for cardiovascular events. As breathing maneuvers employ endothelial-dependent vasodilation it is possible that slight B-MORE variations seen in healthy subjects reflect the biological spectrum of microvascular (endothelial) function. If validated by the invasive reference standards of microvascular function, this methodology could provide a non-invasive and informative test of microvascular function and tissue status. Given the relationship of B-MORE to factors affecting the vasculature in healthy individuals, it appears to be a sensitive marker to detect microvascular dysfunction at an early, subclinical stage. A methodology of this nature may be instrumental in diagnosing early microvascular disease, improving the prognosis of those at risk of ischemic heart disease
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,002 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,001 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».