The Evaluation of Coronary Artery Function During Normothermic <i>Ex Situ</i> Heart Perfusion
Notice bibliographique
Résumé
Background Heart transplantation (HTx) is a recognized therapy for terminal heart failure patients; however, it is limited by availability of suitable donors and quality of cardiac grafts. To expand heart donor pool, normothermic ex situ heart perfusion (ESHP) has emerged as a platform for reconditioning marginal donor hearts and consequently increasing the number and quality of organs available for transplant. It also allows continuous functional and metabolic assessment of donor hearts before transplantation. Myocardial function is highly dependent on myocardial perfusion. The coronary autoregulation is essential to maintain normal cardiac function. Our objective is to investigate coronary autoregulation during normothermic ESHP and find ways to protect myocardial function during heart preservation. Methods The hearts of anesthetized and intubated domestic breed pigs (N=12) will be harvested after cold cardioplegia arrest. After being mounted on a custom ESHP apparatus, the procured hearts will be perfused ex situ in a beating state in Langendorff mode for 1 hour and then will be switched to working heart system (heart rate=100 beats/minute) to be perfused at 37°C for 12 hours (whole blood based perfusate). Cardiac functional parameters was monitored in the entire interval. Coronary vascular resistance (CVR) was calculated as an indicator of coronary artery function. Myocardial oxygen consumption (MVO 2 ) was determined by coronary blood flow and oxygen extraction as a metabolic parameter. At 1 and 5 hours of perfusion, loading of the heart was varied by increasing or decreasing left atrial pressure to observe the corresponding response in coronary artery flow. Results During 12 hours normothermic perfusion, cardiac function declined over time as indicated by the cardiac index change at 5 and 11 hours compared with its baseline (p<0.05); myocardial oxygen consumption was decreased significantly (p<0.01, Fig. A). The coronary blood flow increased over time and coronary vascular resistance decreased, with significantly difference at T5 and T11 compared with T1 respectively (p<0.01, Fig. B). At T1 of perfusion, coronary artery flow shows strong correlation with left ventricle stroke work (p<0.01, R 2 =0.79, Fig. C); however, at T5, the regression line is significantly different (p<0.01), with relative lower slope (R 2 =0.36, Fig. D), which means as myocardial function demand increases, coronary artery flow increases less proportion than that in T1. Conclusion Our data suggests that regulation of coronary artery function is disturbed during ESHP leading to apparent excessive coronary blood flow over time. This is in contrast to a gradual reduction in myocardial function over time, suggesting that there is loss of coronary autoregulation. The theory of coronary autoregulation states that as myocardial functional demand increases, coronary blood flow increases as well. However, our data reveals a poor correlation between hemodynamics stress and coronary flow suggesting that this autoregulation phenomenon is disturbed. Whether the loss of coronary artery regulation cause the decline of cardiac function or the mechanism of disturbed autoregulation need to be further investigated. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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 | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 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 ».