We thank Fred Roberts for exemplary technical support and also appreciate the help from the histology core in Beth Israel Hospital. We thank Brigham Women&#8217;s Hospital Cardiovascular Physiology Core for providing with the instrumentation and the funds for this work. This work was supported in part by a Department of Medicine Sundry Fund.

NOTE: Toutes les procédures ont été réalisées chez des souris en conformité avec American Veterinary Medical Association (AVMA) directives et approuvés institutionnel de protection des animaux et l&#39;utilisation comités (IACUC) protocoles. 1. Conception de l&#39;étude <ol><li> Utilisez ancienne 8-10 semaines mâle C57BL / 6 (BW ~ 25 g) dans l&#39;étude. </li><li> Aléatoire souris (n = 11) en deux groupes, le groupe d&#39;étude sélectionné pour baguage aortique (n = 8), et le groupe de contrôle (n = 3) à subir opération fictive par thoracotomie. </li><li> Préparer l&#39;animal pour l&#39;imagerie par enlever les poils de la poitrine à l&#39;aide crème dépilatoire qui est de qualité médicale. </li><li> Effectuez une première échographie (section 2) 24 heures avant baguage aortique pour déterminer les paramètres de base au Jour 1, entre une fourchette de 1% et 2,5% d&#39;isoflurane (mélangé avec 100% d&#39;O 2 par ogive) de l&#39;anesthésie induite. </li><li> Choisir un agent anesthésique médicalement approuvé (isoflurane) et surveiller le degré d&#39;anesthésie (2-3% à induCE, et 1,0% pour maintenir). REMARQUE: l&#39;anesthésie adéquate est crucial dans le maintien de rythme cardiaque à des taux physiologiques normaux (environ 500 battements / min). </li><li> Confirmer la profondeur de l&#39;anesthésie par une perte de mouvement de l&#39;animal en réponse à un réflexe pédale retrait. Utilisez paralube vétérinaire onguent sur les yeux pour prévenir la sécheresse sous anesthésie. </li><li> Effectuer la chirurgie au jour 0 20,21. </li><li> Pour cerclage aortique, ligaturer l&#39;aorte en utilisant une suture 7-0 en soie autour d&#39;une aiguille 26 G conique placé sur l&#39;arc. NOTE: Les détails concernant le protocole expérimental, y compris les procédures de baguage aortiques chirurgicales, ont été précédemment décrit 20,21. </li><li> Effectuer échographie post-chirurgie (section 2) lors de la Journée (s) 2, 6 et 13. </li><li> Euthanasier les souris le jour 14 et récolter les cœurs pour l&#39;évaluation histologique. Euthanasier les animaux en utilisant une surdose de pentobarbital suivie de l&#39;élimination d&#39;un organe vital tel que le cœur. Arrêter les cœurs dans diastole et fixer avec du formol. Utilisez la procédure de la récolte de cœur qui a été décrit précédemment 22. </li><li> Fixer tous les tissus cardiaques avec une solution de formaline tamponnée à 10%. Pour trichrome coloration, intégrer tissus dans de la paraffine avant la coupe. Utilisez les détails de coloration trichrome qui ont été bien illustré précédemment 14,23. </li><li> Analyser les données en utilisant un logiciel hors ligne (section 3). </li></ol> 2. Protocole Imaging <ol><li> Images d&#39;axes long et court de l&#39;artère coronaire septale (SCA) (mode B) <ol><li> Utilisation de la sonde MS550D avec une fréquence de 40 MHz centre de connectés au port actif, définir le préréglage pour &quot;imagerie cardiaque&quot; de l&#39;application. </li><li> Avec la position couchée animale sur la plate-forme chauffée, et sous anesthésie contrôlée par cône de nez, positionner la sonde à l&#39;aide du système ferroviaire pour obtenir la vue parasternale long axe (de PSLAX) (figure 1A). Toujours se assurer que l&#39;animal est gardé au chaud sur le platfor préchauffém et la température corporelle est maintenue à des niveaux physiologiques. </li><li> Tournez la sonde (avec encoche pointant caudale) vers la droite de telle sorte que l&#39;angle de la sonde est de 15 ° à la ligne gauche parasternal (grand axe vue) (figure 1B). </li><li> Ajustez l&#39;angle de la sonde en inclinant légèrement le long de l&#39;axe y de la sonde pour obtenir une vue longitudinale sur toute la longueur de la SCA dans le centre de l&#39;écran (figure 1B). </li><li> Une fois les sites appropriés (valve aortique et l&#39;artère pulmonaire) sont considérés, magasin ciné l&#39;image en utilisant le taux de rafraîchissement le plus élevé possible. </li><li> En utilisant le &quot;xy&quot; axes micro-manipulateurs (figure 1D), ajuster la position de la sonde pour obtenir l&#39;image la plus claire de la SCA. </li><li> Tournez la sonde 90 ° (avec encoche pointant caudale) dans le sens horaire de sorte que fin crantée de la sonde se trouve à gauche de la ligne médiane (axe court) (figure 1C). </li></ol></li><li> Images de l&#39;axe longues et courtes de SCA (Color-Doppler Mode) <ol><li> Une fois une image de mode B est capturé ou stocké cine, cliquez sur la touche Doppler couleur sur le clavier pour activer la couleur Doppler fenêtre acoustique (figure 2). REMARQUE: Cela permet d&#39;isoler l&#39;artère coronaire (flèche blanche indique SCA) soit à la longue (figure 2A) ou à l&#39;axe court (figure 2C). La couleur rouge est vu en temps réel et est indicative de la direction d&#39;écoulement (éloignement de la valve aortique). </li><li> Assurez-vous que la profondeur de mise au point (indiqué par une flèche jaune sur la droite de l&#39;écran d&#39;image), se trouve au centre de l&#39;artère coronaire. </li><li> Assurez-vous que les données sont enregistrées, en utilisant la clé ciné-magasin, à la fréquence d&#39;image le plus élevé possible (&gt; 100 images / s). </li></ol></li><li> PW imagerie Doppler du SCA (pulsé-Wave ou en mode PW) <ol><li> En mode Doppler couleur, cliquez sur la clé PW pour faire apparaître une ligne jaune-indicateur sur l&#39;artère coronaire (figure 2, en rouge). </li><li> Placer le jaunePW ligne au milieu de l&#39;artère coronaire en vue, à un angle qui est parallèle à la directivité de l&#39;écoulement. Notez que les mesures de vitesse sont fortement dépendantes de l&#39;angle d&#39;acquisition d&#39;image. </li><li> Ajustez l&#39;angle de flux (touche d&#39;angle PW) et le volume de l&#39;échantillon (touche SV) tel que la clé d&#39;angle PW est de 60 ° ou moins et le volume de l&#39;échantillon capture circuler dans le centre de la SCA. </li><li> Utilisation magasin ciné pour capturer les formes d&#39;onde qui indiquent la vitesse de l&#39;écoulement coronaire au pic de systole (S) et la diastole (D) (figures 3A et 3B), en utilisant 1% et 2,5% d&#39;isoflurane. </li></ol></li></ol> 3. Calcul et analyse des données <ol><li> Sélectionnez le temps de vitesse intégrante outil (VTI) pour obtenir le pic systolique et diastolique vitesses des images présentées sur les figures 3A et 3B. </li><li> Calculer l&#39;indice de la réserve coronaire (CFR) comme le rapport de hyperémique (2,5% d&#39;isoflurane) crête diastolique ffaible vitesse de ligne de base (1% d&#39;isoflurane) de la vitesse d&#39;écoulement diastolique maximale. </li><li> Calculer le rapport S / D que la vitesse de pointe de vitesse de débit coronaire systolique / diastolique pic coronarienne flux. Déterminer le rapport au départ (1% d&#39;isoflurane) et au hyperémie (2,5% d&#39;isoflurane). </li><li> Pour les paramètres de la fonction cardiaque standard tels que FS, FAC, LVM, reportez-vous aux manuels du fabricant pour effectuer l&#39;analyse des données en utilisant un logiciel propriétaire ou reportez-vous au document JoVE de Cheng 2. </li></ol>

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The authors report no disclosures.

Dans cette étude sur la base d&#39;ultrasons, l&#39;évaluation non invasive de l&#39;écoulement coronaire a été réalisée de façon reproductible en temps réel, au fil des jours, chez des souris expérimentales en direct; En outre, le protocole a démontré le potentiel de détecter un dysfonctionnement de l&#39;artère coronaire qui était présent à un stade précoce et a été associée à une carence en perfusion myocardique. Cette méthode pourrait finalement être exploité comme outil clinique pour la str...

Clinique sténose aortique (AS) est bien connu pour favoriser une augmentation progressive du ventricule gauche (VG) postcharge. Pour compenser cette augmentation chronique charge hémodynamique, l&#39;hypertrophie ventriculaire gauche (HVG) se ensuit comme une réponse adaptative de 1,2. Le développement de LVH est souvent associée à des anomalies de la microcirculation coronaire. On pense que la dysfonction microvasculaire contribue à l&#39;ischémie chronique chez ces patients 5. En plus de débit coronaire 3,4, réserve coronaire (CFR) représente changement fonctionnel des artères coronaires 1,3 et est défini comme le rapport entre la vitesse d&#39;écoulement maximale dans hyperémie à la vitesse d&#39;écoulement de base ou de débit reposant 4,6,7 de vitesse. CFR est diminuée pendant le remodelage du VG 1-3,5-9 et est utilisé comme un indice de l&#39;ampleur de la gravité du dysfonctionnement fonctionnel coronaire 1,10,17. Il est connu pour être altérée dans de nombreuses formes de cardiomyopathie dilatée 10 s et aussi coronairestenosis 6. CFR est aussi un marqueur pronostique pour mauvais résultats cliniques 12. Le remodelage du VG dans le cadre d&#39;un dysfonctionnement cardiaque tel que l&#39;ischémie ou l&#39;hypertrophie ventriculaire gauche est également accompagnée d&#39;une fibrose extensive, les variations de la microcirculation coronaire et l&#39;épaississement des artères coronaires 1,2. En raison de ces changements dans la physiologie coronaire, il est probable remodelage des artères coronaires. Cela contribue à atténuer les effets de la faible diffusion de l&#39;oxygène et LV dysfonction diastolique qui pourrait résulter dans la susceptibilité à l&#39;ischémie myocardique 1,2,13. Les souris génétiquement modifiées sont désormais un outil expérimental très répandue pour mimer les conditions de maladies humaines telles que l&#39;athérosclérose coronarienne 5,7,10,12,17. En particulier, le modèle de surcharge de pression chez la souris a été largement étudiée 14,17. Le modèle de constriction trans-aortique (TAC) a été montré pour être associée à une fibrose extensive, et coronary sténose résulte, en partie, à partir de l&#39;épaississement médian des artères coronaires et avec accompagnement des changements dans les profils de débit coronaire 1,11,17,19 semblables à ce qui est considéré dans le cadre de l&#39;hypertrophie ventriculaire gauche chez les humains. Bien qu&#39;il soit connu que la surcharge de pression prolongée conduit à une insuffisance cardiaque décompensée dans environ 4-8 semaines, les effets sur la dynamique des flux coronaire et la réserve de débit dans ces modèles, tôt dans le processus de progression de la maladie, et à différents stades après le baguage, sont encore être clairement délimitée. De nombreuses souches de souris sont actuellement disponibles pour l&#39;utilisation de la recherche, y compris bien caractérisé LDLR - / - ou ApoE - / - souris 10-12, et ceux-ci ont incité le développement de techniques sensibles pour évaluer la fonction cardiovasculaire et la morphologie chez les souris vivant 11-15. Ces techniques comprennent l&#39;IRM, PET, CT contraste, des ultrasons à haute fréquence et la tomographie par faisceau d&#39;électrons 2,9,17,19, qui offrent tous des alternatives prometteuses à invasiveméthodes telles que cathétérismes cardiaques et coronarographie 12. Cependant, chez les souris avec de très petite taille des artères coronaires et le rythme cardiaque élevé (HR), l&#39;imagerie de la circulation coronarienne constitue encore un défi technique pour de nombreuses techniques actuellement disponibles 4,12. Fait intéressant, il ya eu une augmentation exponentielle des progrès techniques dans le domaine de l&#39;échocardiographie Doppler transthoracique (TTDE), y compris le développement de la haute fréquence de balayage de réseau têtes avec des fréquences centrales de 15 à 50 MHz permettant résolutions axiales d&#39;environ 30 à 100 um, à des profondeurs de 8-40 mm, et des cadences de plus de 400 cadres-capturés / sec. À son tour, techniques basées TTDE-ont émergé comme un outil potentiellement puissant pour l&#39;imagerie de grands navires 2 ou même plus petits comme les artères coronaires 5,12. Une autre avancée critique qui a permis aux enquêteurs de mener des études d&#39;imagerie diagnostique du système vasculaire dans un petitnimals est l&#39;utilisation soigneusement contrôlée des anesthésiques qui maintiennent la rythme cardiaque et respiratoire des animaux lors de l&#39;imagerie 11. L&#39;entretien de l&#39;anesthésie contrôlée est particulièrement important pour les études liées à la vasodilatation chez la souris, et l&#39;effet de l&#39;anesthésie doit également être explorées plus avant dans ce contexte 10,11. Chez l&#39;homme, d&#39;autre part, les mesures de CFR TTDE dérivés sont devenus un outil plus couramment utilisée pour l&#39;évaluation des artères coronaires sténosées épicardiques et non obstrué, principalement dans descendante antérieure gauche (LAD) de l&#39;artère coronaire 5,16. Cependant, le rôle pronostique du CFR et les changements de débit coronaire chez les patients asymptomatiques ou souris avec fonction systolique préservée LV au repos a été beaucoup moins exploré 16. Par conséquent, le but de l&#39;étude était d&#39;abord établir un protocole clair, étape par étape, pour évaluer les changements dans le débit coronarien utilisant TTDE dans un modèle de souris de surcharge de pression; secondes, cette étude a examiné le signe pronostiqueificance du CFR et les changements de débit coronaire en réponse à la pression de surcharge de stress chez ces souris. Nous émettons l&#39;hypothèse que l&#39;évaluation du CFR et de débit coronaire à base TTDE peut être utile dans la détection précoce de la dysfonction coronarienne qui peut précéder une dysfonction ventriculaire gauche.

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ultrasound based assessment of coronary artery flow and coronary flow reserve using the pressure overload model in mice

Transthoracic Doppler echocardiography (TTDE) is a clinically useful, noninvasive tool for studying coronary artery flow velocity and coronary flow reserve (CFR) in humans. Reduced CFR is accompanied by marked intramyocardial and pericoronary fibrosis and is used as an indication of the severity of dysfunction. This study explores, step-by-step, the real-time changes measured in the coronary flow velocity, CFR and systolic to diastolic peak velocity (S/D) ratio in the setting of an aortic banding model in mice. By using a Doppler transthoracic imaging technique that yields reproducible and reliable data, the method assesses changes in flow in the septal coronary artery (SCA), for a period of over two weeks in mice, that previously either underwent aortic banding or thoracotomy. 
During imaging, hyperemia in all mice was induced by isoflurane, an anesthetic that increased coronary flow velocity when compared with resting flow. All images were acquired by a single imager. Two ratios, (1) CFR, the ratio between hyperemic and baseline flow velocities, and (2) systolic (S) to diastolic (D) flow were determined, using a proprietary software and by two independent observers. Importantly, the observed changes in coronary flow preceded LV dysfunction as evidenced by normal LV mass and fractional shortening (FS). 
The method was benchmarked against the current gold standard of coronary assessment, histopathology. The latter technique showed clear pathologic changes in the coronary artery in the form of peri-coronary fibrosis that correlated to the flow changes as assessed by echocardiography. 
The study underscores the value of using a non-invasive technique to monitor coronary circulation in mouse hearts. The method minimizes redundant use of research animals and demonstrates that advanced ultrasound-based indices, such as CFR and S/D ratios, can serve as viable diagnostic tools in a variety of investigational protocols including drug studies and the study of genetically modified strains.

Parmi les 11 souris qui ont été étudiés (bagués, n = 8 et faux, n = 3), les images adéquates et reproductibles ont été obtenus par un seul observateur à plusieurs points dans le temps: au départ (D-1), D2, D6 et D13 . En outre, la vitesse d&#39;écoulement au niveau du site a été mesurée comme constrictive 2225 ± 110,9 mm / s, par rapport à 277,5 ± 10,51 mm chez les souris sham le jour / s après la chirurgie (p &lt;0,05). L&#39;augmentation de la vitesse est la vérification de la mise en place réussie...

Watch this Scientific Journal Video about Ultrasound Based Assessment of Coronary Artery Flow and Coronary Flow Reserve Using the Pressure Overload Model in Mice at JoVE.com

Ultrasound Based Assessment of Coronary Artery Flow and Coronary Flow Reserve Using the Pressure Overload Model in Mice

Coronary flow reserve (CFR) is useful for assessment of myocardial oxygen demand and evaluation of cardiovascular risk. This study establishes a step-by-step transthoracic Doppler echocardiographic (TTDE) method for longitudinal monitoring of the changes in CFR, as measured from coronary artery in mice, under the experimental pressure overload of aortic banding.

Évaluation Basé échographie de l&#39;artère coronaire de débit et de Flow Reserve coronaire Utilisation de la surcharge de pression modèle chez la souris

Transthoracic Doppler echocardiography (TTDE) is a clinically useful, noninvasive tool for studying coronary artery flow velocity and coronary flow ...

ultrasound-based-assessment-coronary-artery-flow-coronary-flow

Research

JoVE Journal

Medicine

14.8K vues.  Brigham and Women's Hospital, Harvard Medical School. Coronary flow reserve (CFR) is useful for assessment of myocardial oxygen demand and evaluation of cardiovascular risk. This study establishes a step-by-step transthoracic Doppler echocardiographic (TTDE) method for longitudinal monitoring of the changes in CFR, as measured from coronary artery in mice, under the experimental pressure overload of aortic banding.

Vidéo: Ultrasound Based Assessment of Coronary Artery Flow and Coronary Flow Reserve Using the Pressure Overload Model in Mice

Use of a Hanging Weight System for Coronary Artery Occlusion in Mice

Murine studies of acute injury are an area of intense investigation, as knockout mice for different genes are becoming increasingly available 1-38. Cardioprotection by ischemic preconditioning (IP) remains an area of intense investigation. To further elucidate its molecular basis, the use of knockout mouse studies is particularly important 7, 14, 30, 39. Despite the fact that previous studies have already successfully performed cardiac ischemia and reperfusion in mice, this model is technically very challenging. Particularly, visual identification of the coronary artery, placement of the suture around the vessel and coronary occlusion by tying off the vessel with a supported knot is technically difficult. In addition, re-opening the knot for intermittent reperfusion of the coronary artery during IP without causing surgical trauma adds additional challenge. Moreover, if the knot is not tied down strong enough, inadvertent reperfusion due to imperfect occlusion of the coronary may affect the results. In fact, this can easily occur due to the movement of the beating heart.
Based on potential problems associated with using a knotted coronary occlusion system, we adopted a previously published model of chronic cardiomyopathy based on a hanging weight system for intermittent coronary artery occlusion during IP 39. In fact, coronary artery occlusion can thus be achieved without having to occlude the coronary by a knot. Moreover, reperfusion of the vessel can be easily achieved by supporting the hanging weights which are in a remote localization from cardiac tissues.
We tested this system systematically, including variation of ischemia and reperfusion times, preconditioning regiments, body temperature and genetic backgrounds39. In addition to infarct staining, we tested cardiac troponin I (cTnI)
as a marker of myocardial infarction in this model. In fact, plasma levels of cTnI correlated with infarct sizes (R2=0.8). Finally, we could show in several studies that this technique yields highly reproducible infarct sizes during murine IP and myocardial infarction6, 8, 30, 40, 41. Therefore, this technique may be helpful for researchers who pursue molecular mechanisms involved in cardioprotection by IP using a genetic approach in mice with targeted gene deletion. Further studies on cardiac IP using transgenic mice may consider this technique.

A murine model for myocardial ischemia and ischemic preconditioning is an important tool study cardioprotective mechanisms in vivo. Here, we report an easy applicable in situ model for cardiac IP using a hanging-weight system for coronary artery occlusion.

L&#39;utilisation d&#39;un système de poids suspendu pour une artère coronaire chez la souris

Murine studies of acute injury are an area of intense investigation, as knockout mice for different genes are becoming increasingly available 1-38. ...

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Médecine

Coronary Artery Ligation and Intramyocardial Injection in a Murine Model of Infarction

Mouse models are a valuable tool for studying acute injury and chronic remodeling of the myocardium in vivo. With the advent of genetic modifications to the whole organism or the myocardium and an array of biological and/or synthetic materials, there is great potential for any combination of these to assuage the extent of acute ischemic injury and impede the onset of heart failure pursuant to myocardial remodeling. 
Here we present the methods and materials used to reliably perform this microsurgery and the modifications involved for temporary (with reperfusion) or permanent coronary artery occlusion studies as well as intramyocardial injections. The effects on the heart that can be seen during the procedure and at the termination of the experiment in addition to histological evaluation will verify efficacy. 
Briefly, surgical preparation involves anesthetizing the mice, removing the fur on the chest, and then disinfecting the surgical area. Intratracheal intubation is achieved by transesophageal illumination using a fiber optic light. The tubing is then connected to a ventilator. An incision made on the chest exposes the pectoral muscles which will be cut to view the ribs. For ischemia/reperfusion studies, a 1 cm piece of PE tubing placed over the heart is used to tie the ligature to so that occlusion/reperfusion can be customized. For intramyocardial injections, a Hamilton syringe with sterile 30gauge beveled needle is used. When the myocardial manipulations are complete, the rib cage, the pectoral muscles, and the skin are closed sequentially. Line block analgesia is effected by 0.25% marcaine in sterile saline which is applied to muscle layer prior to closure of the skin. The mice are given a subcutaneous injection of saline and placed in a warming chamber until they are sternally recumbent. They are then returned to the vivarium and housed under standard conditions until the time of tissue collection. At the time of sacrifice, the mice are anesthetized, the heart is arrested in diastole with KCl or BDM, rinsed with saline, and immersed in fixative. Subsequently, routine procedures for processing, embedding, sectioning, and histological staining are performed. 
Nonsurgical intubation of a mouse and the microsurgical manipulations described make this a technically challenging model to learn and achieve reproducibility. These procedures, combined with the difficulty in performing consistent manipulations of the ligature for timed occlusion(s) and reperfusion or intramyocardial injections, can also affect the survival rate so optimization and consistency are critical.

Numerous genetic manipulations and/or intramyocardial injections of genes, proteins, cells, and/or biomaterials are superimposed upon the dimension of time in studies of acute ischemia/ reperfusion injury and chronic remodeling in mice. This video illustrates the microsurgical procedures for ischemia/reperfusion, permanent coronary artery ligation, and intramyocardial injection studies.

Ligature de l&#39;artère coronaire et injection intramyocardique dans un modèle murin d&#39;infarctus

Mouse models are a valuable tool for studying acute injury and chronic remodeling of the myocardium in vivo.  With the advent of genetic modifications to ...

Modified Technique for Coronary Artery Ligation in Mice

Myocardial infarction (MI) is one of the most important causes of mortality in humans1-3. In order to improve morbidity and mortality in patients with MI we need better knowledge about pathophysiology of myocardial ischemia. This knowledge may be valuable to define new therapeutic targets for innovative cardiovascular therapies4. Experimental MI model in mice is an increasingly popular small-animal model in preclinical research in which MI is induced by means of permanent or temporary ligation of left coronary artery (LCA)5. In this video, we describe the step-by-step method of how to induce experimental MI in mice.
The animal is first anesthetized with 2% isoflurane. The unconscious mouse is then intubated and connected to a ventilator for artificial ventilation. The left chest is shaved and 1.5 cm incision along mid-axillary line is made in the skin. The left pectoralis major muscle is bluntly dissociated until the ribs are exposed. The muscle layers are pulled aside and fixed with an eyelid-retractor. After these preparations, left thoracotomy is performed between the third and fourth ribs in order to visualize the anterior surface of the heart and left lung. The proximal segment of LCA artery is then ligated with a 7-0 ethilon suture which typically induces an infarct size ~40% of left ventricle. At the end, the chest is closed and the animals receive postoperative analgesia (Temgesic, 0.3 mg/50 ml, ip). The animals are kept in a warm cage until spontaneous recovery.

The surgical procedure used to induce experimental myocardial infarction in mice begins with left thoracotomy between the third and the fourth ribs in order to visualize the anterior surface of the heart and left lung. The left coronary artery is ligated, the chest is closed and the mouse is allowed to recover spontaneously.

Technique de modification de ligature de l&#39;artère coronaire chez la souris

Myocardial infarction (MI) is one of the most important causes of mortality in humans1-3. In order to improve morbidity and mortality in patients with MI ...

Ultrasound Assessment of Endothelial-Dependent Flow-Mediated Vasodilation of the Brachial Artery in Clinical Research

The vascular endothelium is a monolayer of cells that cover the interior of blood vessels and provide both structural and functional roles. The endothelium acts as a barrier, preventing leukocyte adhesion and aggregation, as well as controlling permeability to plasma components. Functionally, the endothelium affects vessel tone.
Endothelial dysfunction is an imbalance between the chemical species which regulate vessel tone, thombroresistance, cellular proliferation and mitosis. It is the first step in atherosclerosis and is associated with coronary artery disease, peripheral artery disease, heart failure, hypertension, and hyperlipidemia.
The first demonstration of endothelial dysfunction involved direct infusion of acetylcholine and quantitative coronary angiography. Acetylcholine binds to muscarinic receptors on the endothelial cell surface, leading to an increase of intracellular calcium and increased nitric oxide (NO) production. In subjects with an intact endothelium, vasodilation was observed while subjects with endothelial damage experienced paradoxical vasoconstriction.
There exists a non-invasive, in vivo method for measuring endothelial function in peripheral arteries using high-resolution B-mode ultrasound. The endothelial function of peripheral arteries is closely related to coronary artery function. This technique measures the percent diameter change in the brachial artery during a period of reactive hyperemia following limb ischemia.
This technique, known as endothelium-dependent, flow-mediated vasodilation (FMD) has value in clinical research settings. However, a number of physiological and technical issues can affect the accuracy of the results and appropriate guidelines for the technique have been published. Despite the guidelines, FMD remains heavily operator dependent and presents a steep learning curve. This article presents a standardized method for measuring FMD in the brachial artery on the upper arm and offers suggestions to reduce intra-operator variability.

Endothelial dysfunction is associated with numerous disease states and is predictive of adverse cardiovascular events in humans. Flow-mediated vasodilation (FMD) is a non-invasive ultrasound method of evaluating endothelial function. Methodological choices and operator experience may affect results. A systematic approach to FMD in human studies is discussed here.

Évaluation échographique de l&#39;endothélium-dépendante médiée par le flux vasodilatation de l&#39;artère brachiale en recherche clinique

The vascular endothelium is a monolayer of cells that cover the interior of blood vessels and provide both structural and functional roles. The ...

Permanent Ligation of the Left Anterior Descending Coronary Artery in Mice: A Model of Post-myocardial Infarction Remodelling and Heart Failure

Heart failure is a syndrome in which the heart fails to pump blood at a rate commensurate with cellular oxygen requirements at rest or during stress. It is characterized by fluid retention, shortness of breath, and fatigue, in particular on exertion. Heart failure is a growing public health problem, the leading cause of hospitalization, and a major cause of mortality. Ischemic heart disease is the main cause of heart failure.
Ventricular remodelling refers to changes in structure, size, and shape of the left ventricle. This architectural remodelling of the left ventricle is induced by injury (e.g., myocardial infarction), by pressure overload (e.g., systemic arterial hypertension or aortic stenosis), or by volume overload. Since ventricular remodelling affects wall stress, it has a profound impact on cardiac function and on the development of heart failure. A model of permanent ligation of the left anterior descending coronary artery in mice is used to investigate ventricular remodelling and cardiac function post-myocardial infarction. This model is fundamentally different in terms of objectives and pathophysiological relevance compared to the model of transient ligation of the left anterior descending coronary artery. In this latter model of ischemia/reperfusion injury, the initial extent of the infarct may be modulated by factors that affect myocardial salvage following reperfusion. In contrast, the infarct area at 24 hr after permanent ligation of the left anterior descending coronary artery is fixed. Cardiac function in this model will be affected by 1) the process of infarct expansion, infarct healing, and scar formation; and 2) the concomitant development of left ventricular dilatation, cardiac hypertrophy, and ventricular remodelling.
Besides the model of permanent ligation of the left anterior descending coronary artery, the technique of invasive hemodynamic measurements in mice is presented in detail.

Heart failure is the leading cause of hospitalization and a major cause of mortality. A model of permanent ligation of the left anterior descending coronary artery in mice is applied to investigate ventricular remodelling and cardiac dysfunction post-myocardial infarction. The technique of invasive hemodynamic measurements in mice is presented.

Ligature permanente de l&#39;artère interventriculaire antérieure coronaire chez la souris: Un modèle de post-infarctus du myocarde et de remodelage de l&#39;insuffisance cardiaque

Heart failure is a syndrome in which the heart fails to pump blood at a rate commensurate with cellular oxygen requirements at rest or during stress. It ...

Direct Re-implantation of Left Coronary Artery into the Aorta in Adults with Anomalous Origin of Left Coronary Artery from the Pulmonary Artery (ALCAPA)

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital anomaly which is one of leading causes of myocardial ischemia and infarction in children. If left untreated, it results in a 90% mortality rate in the first year of life. In patients who survive to the adulthood, the coronary steal phenomenon and retrograde left-sided coronary flow provide a substrate for chronic subendocardial ischemia, which may lead to left ventricular dysfunction, ischemic mitral regurgitation, malignant ventricular arrhythmias, and sudden cardiac death. The average age of life-threatening presentation is 33 years and of sudden cardiac death 31 years. Therefore, surgical correction is highly recommended as soon as the diagnosis is made, regardless of age. In adult-type ALCAPA originating from the right-facing sinus of the pulmonary artery, direct re-implantation of the ALCAPA into the aorta is the more physiologically sound repair technique to re-establish the dual-coronary perfusion system and is recommended. This protocol describes the technique of direct re-implantation of adult-type ALCAPA into the aorta.

Direct Re-implantation of Left Coronary Artery into the Aorta in Adults with Anomalous Origin of Left Coronary Artery from the Pulmonary Artery ALCAPA

Surgical correction of ALCAPA is highly recommended, regardless of age or the degree of intercoronary collateralization. This protocol presents a technique for the direct re-implantation of adult-type ALCAPA into the aorta to re-establish the dual-coronary perfusion. Whenever feasible, direct re-implantation is preferred to other surgical correction techniques.

Re-implantation directe de gauche de l&#39;artère coronaire dans l&#39;aorte chez les adultes atteints de gauche Origine anomale coronarienne de l&#39;artère pulmonaire (ALCAPA)

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) is a rare congenital anomaly which is one of leading causes of myocardial ...

Evaluation of Coronary Flow Reserve After Myocardial Ischemia Reperfusion in Rats

Coronary artery disease is the leading cause of death worldwide. After an acute myocardial infarction, early and successful myocardial intervention via recanalization of the coronary artery is the most effective strategy for reducing the size of ischemic myocardium. The coronary microvasculature cannot be visualized and imaged&#160;in vivo, but there are several invasive and noninvasive techniques that can be used to assess parameters which depend directly on coronary microvascular function. The endothelial function after ischemia reperfusion can be assessed also at the level of the coronary circulation via the coronary flow reserve (CFR).&#160;In this study, peak velocity of left anterior descending (LAD) coronary arteries was measured in rats in vivo via Transthoracic Doppler Echocardiography during resting and stress challenge (induced by Dobutamine). A normal heart can increase its coronary blood flow up to four times above the resting values during stress induction. Following ischemia reperfusion, we found a significantly diminished CFR, which can be used as a marker of coronary microvascular dysfunction. CFR has opened a window on the importance of microvascular dysfunction and has been shown to predict cardiovascular risk independent of whether the severe obstructive disease is present.

Coronary flow reserve (CFR), is defined as the ratio of maximal coronary blood flow to the resting coronary blood flow. We present a protocol for evaluating CFR in rats via ultrasound, which offers the opportunity to predict cardiovascular risk factors in the absence of obstructive coronary disease.

Évaluation de la réserve de flux coronaire après la réperfusion d'ischémie myocardique chez les rats

Coronary artery disease is the leading cause of death worldwide. After an acute myocardial infarction, early and successful myocardial intervention via ...

Murine Myocardial Infarction Model using Permanent Ligation of Left Anterior Descending Coronary Artery

Myocardial infarction (MI) and acute coronary diseases are among the most prominent causes of death in population with western lifestyle. The murine models of MI with permanent ligation of left-anterior descending (LAD) coronary artery closely mimics MI in humans. Murine models benefit from the extensive genetic engineering available nowadays. Here we propose a reproducible murine surgical model of myocardial infarction by permanent LAD coronary ligation. Our technique comprises anesthesia with ketamine/xylazine that can be rapidly reversed by administration of an antagonist, intubation without tracheotomy for mechanical-assisted ventilation, ventilation with application of extrinsic positive end-expiratory pressure (PEEP) to avoid alveolar collapse, a thoracotomy method limiting to the minimum surgical lesions made to skeletal muscles, and lung inflation without thoracentesis. This method is sparsely invasive, reproducible and reduces post-surgery mortality and complications.

Herein we describe a surgical procedure showing how to achieve permanent ligation of the left-anterior descending coronary artery in mice. This model is of high relevance to investigate the pathophysiology of myocardial infarction and the concomitant biological processes.

Modèle d'infarctus myocarde de Murine utilisant la ligation permanente de l'artère coronaire descendante antérieure gauche

Myocardial infarction (MI) and acute coronary diseases are among the most prominent causes of death in population with western lifestyle. The murine ...

In Vitro Model of Coronary Angiogenesis

Here, we describe an in vitro culture assay to study coronary angiogenesis. Coronary vessels feed the heart muscle and are of clinical importance. Defects in these vessels represent severe health risks such as in atherosclerosis, which can lead to myocardial infarctions and heart failures in patients. Consequently, coronary artery disease is one of the leading causes of death worldwide. Despite its clinical importance, relatively little progress has been made on how to regenerate damaged coronary arteries. Nevertheless, recent progress has been made in understanding the cellular origin and differentiation pathways of coronary vessel development. The advent of tools and technologies that allow researchers to fluorescently label progenitor cells, follow their fate, and visualize progenies in vivo have been instrumental in understanding coronary vessel development. In vivo studies are valuable, but have limitations in terms of speed, accessibility, and flexibility in experimental design. Alternatively, accurate in vitro models of coronary angiogenesis can circumvent these limitations and allow researchers to interrogate important biological questions with speed and flexibility. The lack of appropriate in vitro model systems may have hindered the progress in understanding the cellular and molecular mechanisms of coronary vessel growth. Here, we describe an in vitro culture system to grow coronary vessels from the sinus venosus (SV) and endocardium (Endo), the two progenitor tissues from which many of the coronary vessels arise. We also confirmed that the cultures accurately recapitulate some of the known in vivo mechanisms. For instance, we show that the angiogenic sprouts in culture from SV downregulate COUP-TFII expression similar to what is observed in vivo. In addition, we show that VEGF-A, a well-known angiogenic factor in vivo, robustly stimulates angiogenesis from both the SV and Endo cultures. Collectively, we have devised an accurate in vitro culture model to study coronary angiogenesis.

In vitro models of coronary angiogenesis can be utilized for the discovery of the cellular and molecular mechanisms of coronary angiogenesis. In vitro explant cultures of sinus venosus and endocardium tissues show robust growth in response to VEGF-A and display a similar pattern of COUP-TFII expression as in vivo.

Modèle in Vitro de l’angiogenèse coronaire

Here, we describe an in vitro culture assay to study coronary angiogenesis. Coronary vessels feed the heart muscle and are of clinical importance. Defects ...

Echocardiographic Characterization of Left Ventricular Structure, Function, and Coronary Flow in Neonate Mice

Echocardiography is a non-invasive procedure that enables the evaluation of structural and functional parameters in animal models of cardiovascular disease and is used to assess the impact of potential treatments in preclinical studies. Echocardiographic studies are usually conducted in young adult mice (i.e., 4-6 weeks of age). The evaluation of early neonatal cardiovascular function is not usually performed because of the small size of the mouse pups and the associated technical difficulties. One of the most important challenges is that the short length of the pups&#39; limbs prevents them from reaching the electrodes in the echocardiography platform. Body temperature is the other challenge, as pups are very susceptible to changes in temperature. Therefore, it is important to establish a practical guide for performing echocardiographic studies in small mouse pups to help researchers detect early pathological changes and study the progression of cardiovascular disease over time. The current work describes a protocol for performing echocardiography in mouse pups at the early age of 7 days old. The echocardiographic characterization of cardiac morphology, function, and coronary flow in neonatal mice is also described.

The present protocol describes the echocardiographic assessment of left ventricular morphology, function, and coronary blood flow in 7-day old neonate mice.

Caractérisation échocardiographique de la structure, de la fonction et du flux coronaire ventriculaire gauche chez les souris nouveau-nées

Echocardiography is a non-invasive procedure that enables the evaluation of structural and functional parameters in animal models of cardiovascular ...