1. Préparation 1.1. Anesthésie des rats <ol><li> Placer le rat dans une chambre remplie au préalable avec de l&#39;isoflurane (en fonction de la taille de la chambre d&#39;environ 3 minutes à 5%) pour anesthésier le rat. </li><li> Une fois anesthésié, retirez le rat et le peser. </li><li> Placez le nez du rat dans le masque d&#39;anesthésie (isoflurane 2-3% en oxygène 1 L / min) pour maintenir l&#39;anesthésie. Pendant l&#39;anesthésie avec l&#39;isoflurane, les fréquences cardiaques de rats diminuent à 300-340 bpm (380-420 bpm chez la souris). </li></ol> 1.2. Insérez une veine de la queue canule <ol><li> Laver la queue du rat avec de l&#39;eau tiède (38 ° C) et du savon pour permettre aux vaisseaux sanguins pour être plus facilement visibles. </li><li> Cathétériser soit veine, qui peut être facilement visible sur la face latérale de la queue. L&#39;utilisation d&#39;un cathéter iv G 22-24, commencer tentatives d&#39;environ 1/3 de la distance entre la pointe. </li><li> Si les premiers efforts ont échoué, réessayez plus proximale. </li><li> Prenez sam de sangsonnes pour l&#39;analyse de l&#39;hématocrite (nécessaire pour calculer la fraction du volume extracellulaire = ECV). </li><li> Fixer le cathéter iv avec de la colle de peau et de ruban adhésif. </li></ol> 1.3. Le positionnement des électrodes <ol><li> Nettoyez toutes les coussinets avec un tampon d&#39;alcool saturé ou avec de l&#39;eau et du savon. </li><li> Quatre électrodes sont nécessaires, une pour chaque pied. </li><li> Fixez les électrodes sur le milieu de la patte et fixez-les avec du ruban adhésif. </li><li> Twist ou tresser les câbles ECG autour de l&#39;autre afin de minimiser la formation de boucles qui causer des interférences avec le signal ECG. </li></ol> 2. Numérisation 2.1. Le positionnement de l&#39;animal et de surveillance <ol><li> Placez le rat en décubitus dorsal ou sujettes sur le tube de l&#39;imagerie et de positionner le coeur au centre de la bobine. </li><li> Disposer le rat de sorte que son nez se repose dans le cône qui délivre isoflurane (2-3% en oxygène 1 L / min). Le rat est autorisé à respirerlibrement dans l&#39;ensemble de la procédure d&#39;imagerie. </li><li> Placer la sonde du thermomètre à l&#39;orifice anal et le fixer sur la table avec du ruban adhésif. </li><li> La température corporelle est maintenue à 38 ± 1 ° C par un système de chauffage à eau chaude. Le tapis chauffant est placé sous l&#39;aspect inférieur de l&#39;animal, qui s&#39;étend à l&#39;extérieur de la bobine. S&#39;il vous plaît voir la représentation schématique du dispositif expérimental IRM (figure 2) pour plus de détails. </li><li> Connecter les électrodes ECG, une fois que le signal ECG est stable commencer imagerie. </li></ol> 2.2. Paramètres de protocole scan / Imaging <ol><li> Dans cette étude, un système Philips Ingenia 3.0T IRM clinique avec une bobine de solénoïde avec un diamètre intérieur de 70 mm a été utilisée [configuration système requise MR sont un petit trou (par exemple 16 cm) ou gros calibre (taille humaine, par exemple 65 cm) avec dédiée petit animal bobine, les capacités de déclenchement ECG pour le rythme cardiaque jusqu&#39;à 500/min, l&#39;approvisionnement en oxygène et un système d&#39;évacuation des gaz anesthésiques]. </li><li> Commencez par une enquête pour localiser le coeur au centre du champ IRM de vue. </li><li> Une fois que la position est correcte, continuer avec deux chambres et quatre chambre ciné vues IRM pour déterminer la géométrie de l&#39;empilement des images de l&#39;axe court. </li><li> Pour SALLI, la position mi-cavité tranche de l&#39;axe court sur les images en deux et à quatre chambre (PreSALLI). Une combinaison de la durée d&#39;acquisition 4000 ms et 4000 ms Durée de relaxation permet un recouvrement suffisant de l&#39;aimantation le long de l&#39;axe z et évite la surchauffe des gradients. Pour permettre l&#39;analyse fonctionnelle, phases devraient être fixés à au moins 12, avec sous-échantillonnage temporel de facteur 2 pour accélérer l&#39;acquisition. </li><li> Injecter l&#39;agent de contraste à base de gadolinium dans le cathéter à demeure, sans déplacer le rat. Attendez cinq minutes. </li><li> Commencez à planifier SALLI comme multislice pile de l&#39;axe court, composé d&#39;au moins 7 tranches (tranche épaisseur 2,4 mm). Positionner les tranches de telle sorte que la plus distale est en dessous de la pointe du coeur et til haut niveau est juste en aval des valves cardiaques. Faire en sorte que les axes courts sont perpendiculaires à la cloison. Presque toutes les 30 minutes (environ trois Sallis) d&#39;injecter une nouvelle dose de produit de contraste. </li><li> Lorsque l&#39;acquisition de l&#39;image est terminée, retirez le rat à partir du scanner et lui permettre de se remettre de l&#39;anesthésie. </li></ol> 3. Reconstruction de l&#39;image reconstruction de l&#39;image peut être effectué soit en ligne en utilisant les paramètres de reconstruction prédéfinis ou hors ligne à l&#39;aide d&#39;un outil dédié à la reconstruction de l&#39;image: 3.1. Reconstruction en ligne <ol><li> Différents paramètres peuvent être définis, notamment: </li></ol><ul><li> Pour la cartographie T1: emplacement et la largeur de la fenêtre de reconstruction à l&#39;intérieur du cycle cardiaque (par exemple de 50 à 100 ms pour atteindre systolique carte T1 à 300/min taux de coeur) </li><li> Pour IR-préparés (LGE) images: l&#39;emplacement et la largeur du temps d&#39;inversion (TI) fenêtre et nombre d&#39;images à wi reconstruitmince que la fenêtre (par exemple TI 100-300 ms, 5 images, de générer 5 images LGE avec TI 100-150-200-250-300 msec). </li></ul> 3.2. Hors ligne reconstruction <ol><li> Lorsque vous utilisez un logiciel dédié (GyroTools, Zürich, Suisse) pour la reconstruction de l&#39;image, extraire les trois ensembles de données (Cine MR, récupération inversion et cartes T1) d&#39;une manière plus interactive. </li><li> Ajustez la définition de bout en systole ou à la fin de diastole pour le T1 en sélectionnant l&#39;image de ciné correspondant. </li><li> Visualiser des cartes T1 sous forme de cartes de couleur. Trouvez les valeurs exactes en passant la souris sur une zone d&#39;intérêt. Les images peuvent être stockées dans différents formats d&#39;image pour une analyse plus poussée (par exemple, le calcul de l&#39;ECV de pré-et post-contraste valeurs T1 du myocarde et une piscine de sang) 12. </li></ol>

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	<li>Messroghli, D. R., Nordmeyer, S., Buehrer, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+animal+Look-Locker+inversion+recovery+(SALLI)+for+simultaneous+generation+of+cardiac+T1+maps+and+cine+and+inversion+recovery-prepared+images+at+high+heart+rates:+initial+experience.">Small animal Look-Locker inversion recovery (SALLI) for simultaneous generation of cardiac T1 maps and cine and inversion recovery-prepared images at high heart rates: initial experience.</a> Radiology. 261 (1), 258-2565 (2011).</li><li>Messroghli, D. R., Nordmeyer, S., Dietrich, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+diffuse+myocardial+fibrosis+in+rats+using+small-animal+Look-Locker+inversion+recovery+T1+mapping.">Assessment of diffuse myocardial fibrosis in rats using small-animal Look-Locker inversion recovery T1 mapping.</a> Circ. Cardiovasc. Imaging. 4 (6), 636-640 (2011).</li><li>Flett, A. S., Hayward, M. P., Ashworth, M. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Equilibrium+contrast+cardiovascular+magnetic+resonance+for+the+measurement+of+diffuse+myocardial+fibrosis:+preliminary+validation+in+humans.">Equilibrium contrast cardiovascular magnetic resonance for the measurement of diffuse myocardial fibrosis: preliminary validation in humans.</a> Circulation. 122 (2), 138-144 (2010).</li><li>Arheden, H., Saed, M., Higgins, C. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+the+distribution+volume+of+gadopentetate+dimeglumine+at+echo-planar+MR+imaging+to+quantify+myocardial+infarction:+comparison+with+99mTc-DTPA+autoradiography+in+rats.">Measurement of the distribution volume of gadopentetate dimeglumine at echo-planar MR imaging to quantify myocardial infarction: comparison with 99mTc-DTPA autoradiography in rats.</a> Radiology. 211 (3), 698-708 (1999).</li><li>Messroghli, D. R., Walters, K., Plein, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myocardial+T1+mapping:+application+to+patients+with+acute+and+chronic+myocardial+infarction.">Myocardial T1 mapping: application to patients with acute and chronic myocardial infarction.</a> Magn. Reson. Med. 58 (1), 34-40 (2007).</li><li>O H-Ici, D., Ridgway, J., Kuehne, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiovascular+magnetic+resonance+of+myocardial+edema+using+a+short+inversion+time+inversion+recovery+(STIR)+black-blood+technique:+Diagnostic+accuracy+of+visual+and+semi-quantitative.">Cardiovascular magnetic resonance of myocardial edema using a short inversion time inversion recovery (STIR) black-blood technique: Diagnostic accuracy of visual and semi-quantitative.</a> 14 (1), (2012).</li><li>Sagar, S., Liu, P. P., Cooper, L. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myocarditis.">Myocarditis.</a> Lancet. 379, 738-747 (2012).</li><li>Skouri, H. N., Dec, G. W., Friedrich, M. G., Cooper, L. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Noninvasive+imaging+in+myocarditis.">Noninvasive imaging in myocarditis.</a> J. Am. Coll. Cardiol. , 2085-2093 (2006).</li><li>Zagrosek, A., Abdel-Aty, H., Boy&#233;, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+magnetic+resonance+monitors+reversible+and+irreversible+myocardial+injury+in+myocarditis.">Cardiac magnetic resonance monitors reversible and irreversible myocardial injury in myocarditis.</a> JACC Cardiovasc. Imaging. 2 (2), 131-138 (2009).</li><li>Friedrich, M. G., Sechtem, U., Schulz-Menger, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiovascular+magnetic+resonance+in+myocarditis:+a+JACC+White+Paper.">Cardiovascular magnetic resonance in myocarditis: a JACC White Paper.</a> J. Am. Coll. Cardiol. 54, 1475-1487 (2009).</li><li>Korkusuz, H., Esters, P., Naguib, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+myocarditis+in+a+rat+model:+late+gadolinium+enhancement+with+histopathological+correlation.">Acute myocarditis in a rat model: late gadolinium enhancement with histopathological correlation.</a> Eur. Radiol. 19 (11), 2672-2678 (2009).</li><li>Ugander, M., Oki, A. J., Hsu, L. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+volume+imaging+by+magnetic+resonance+imaging+provides+insights+into+overt+and+sub-clinical+myocardial+pathology.">Extracellular volume imaging by magnetic resonance imaging provides insights into overt and sub-clinical myocardial pathology.</a> Eur. Heart J. 33 (10), 1268-1278 (2012).</li><li>Gilson, W. D., Kraitchman, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+magnetic+resonance+imaging+in+small+rodents+using+clinical+1.5.">Cardiac magnetic resonance imaging in small rodents using clinical 1.5.</a> T and. 3 (1), 35-45 (2007).</li><li>Messroghli, D. R., Radjenovic, A., Kozerke, S., Higgins, D. M., Sivananthan, M. U., Ridgway, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modified+Look-Locker+inversion+recovery+(MOLLI)+for+high-resolution+T1+mapping+of+the+heart.">Modified Look-Locker inversion recovery (MOLLI) for high-resolution T1 mapping of the heart.</a> Magnetic resonance in medicine. 52 (1), 141-146 (2004).</li></ol>

Toutes les procédures d&#39;animaux ont été effectuées en conformité avec les lignes directrices pour le soin et l&#39;utilisation des animaux de laboratoire, et approuvés par les autorités locales de protection des animaux. Aucun conflit d&#39;intérêt déclaré.

Nous présentons ici une méthode pour générer des multi-modalité (ciné MR, inversion-récupération et T1 cartes) IRM chez les petits animaux. La recherche du petit animal joue un rôle de plus en plus important dans la recherche de la maladie cardio-vasculaire, et CMR est un outil puissant qui nous permet d&#39;étudier la composition fonction, la structure et le tissu du myocarde. Toutefois, les petites CMR animal a un certain nombre de défis uniques en raison de la fréquence cardiaque élevée et la petite tai...

La myocardite est une cause majeure d&#39;insuffisance cardiaque aiguë, la mort subite, et une cardiomyopathie dilatée chronique 7. CMR a été établi que la technique de référence pour la mesure de la fonction et à l&#39;analyse des tissus in vivo. Techniques et les améliorations en matière d&#39;imagerie imagerie novatrices pourraient non seulement améliorer le diagnostic de myocardite, mais aussi aider l&#39;étude de la physiopathologie et l&#39;identification de la vitesse des cibles thérapeutiques 8-10. Imagerie du petit animal est un outil important pour l&#39;étude des maladies cardio-vasculaires. Techniques couramment utilisées dans les essais cliniques CMR, comme la fin de gadolinium (LGE) ne peuvent pas facilement être transférés à petit CMR animaux en raison des taux élevés de coeur de l&#39;animal, mais pourraient déjà être présentés 11. La petite reprise d&#39;inversion Look-Locker animale (SALLI) approche génère des données d&#39;image multi-modales fixe permettant l&#39;évaluation globale de fois la fonction cardiaque et de la morphologie (Figures 1 ae 3). Ici, nous montrons, dans le détail, la procédure et la configuration pour imagerie du petit animal avec un protocole typique SALLI. En particulier, nous montrons la reconstruction et l&#39;analyse des ensembles de données d&#39;imagerie T1.

<table border="1">
		<tbody>
		 <tr>
			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		 </tr>
		 <tr>
			<td>Adhesive Tape (Silkafix)</td>
			<td>Lohmann und Rauscher</td>
			<td>34327</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Gadopentetat-Dimeglumin (Magnevist)</td>
			<td>Bayer</td>
			<td>G-00012163</td>
			<td>2mmol/Kg</td>
		 </tr>
		 <tr>
			<td>Introcan Safety-W (G24)</td>
			<td>B. Braun</td>
			<td>4254503-01</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Red Dot, Neonatal Monitoring Electrode with Pre-Attached Lead Wire</td>
			<td>3M</td>
			<td>2269T</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Skin glue (Histoacryl)</td>
			<td>B. Braun</td>
			<td>1050052</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Scales (Typ 440)</td>
			<td>Kern</td>
			<td>95088</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Skin desinfection (Softasept N)</td>
			<td>B. Braun Petzold</td>
			<td>360250</td>
			<td></td>
		 </tr>
		 <tr>
			<td>Thermometer </td>
			<td>LumaSense Technologies</td>
			<td>Luxtron 812</td>
			<td></td>
		 </tr>
		</tbody>
 </table>

assessment of cardiac function and myocardial morphology using small animal look-locker inversion recovery (salli) mri in rats

L&#39;imagerie par résonance magnétique du petit animal est un outil important pour étudier la fonction cardiaque et des changements dans le tissu myocardique. Les fréquences cardiaques élevées de petits animaux (200 à 600 battements / min) ont déjà limité le rôle de l&#39;imagerie CMR. Petit récupération d&#39;inversion Look-Locker animale (SALLI) est une séquence de cartographie T1 pour les petits animaux de surmonter ce problème 1. Cartes T1 fournissent des informations quantitatives sur les altérations des tissus et de la cinétique de l&#39;agent de contraste. Il est également possible de détecter les processus du myocarde diffuses telles que la fibrose interstitielle ou un œdème 1-6. En outre, à partir d&#39;un seul ensemble de données d&#39;image, il est possible d&#39;examiner la fonction cardiaque et la cicatrisation du myocarde en générant ciné et l&#39;inversion récupération préparés fin de gadolinium amélioration de type IRM 1. La vidéo présentée montre, étape par étape, les procédures à effectuer des petits imagerie CMR animal. Ici, il est présenté avec une Sprague-Dawl santéey rat, mais naturellement elle peut être étendue à des petits modèles animaux cardiaques.

Ici, nous démontrons les résultats d&#39;une saine Sprague Dawley. Avec une installation animal bien préparés, nous avons décrit précédemment, il est possible d&#39;obtenir un signal ECG stable. Semblable à des protocoles d&#39;IRM cardiaques humaines, nous commençons par une enquête pour localiser le cœur. Si la position du rat dans la bobine est correcte, nous continuons avec une vue à deux chambres et une vue à quatre chambre à détecter la géométrie de la pile SALLI. La t...

Watch this Scientific Journal Video about Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery SALLI MRI in Rats at JoVE.com

Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery SALLI MRI in Rats

Contraste amélioré l&#39;imagerie par résonance magnétique cardiaque (CMR) permet complet<em&gt; In vivo</em&gt; Évaluation du cœur dans les petits modèles animaux de maladies cardiovasculaires. Ici, nous détaillons les procédures à effectuer CMR imagerie, la reconstruction et l&#39;analyse en utilisant Petit Inversion Recovery Lock-Locker animale (SALLI) chez le rat.

L&#39;évaluation de la fonction cardiaque et la morphologie du myocarde en utilisant de petits Inversion Recovery Look-casier animale (SALLI) IRM chez les rats

Small animal magnetic resonance  imaging is an important tool to study cardiac function and changes in myocardial  tissue. The high heart rates of small ...

assessment-cardiac-function-myocardial-morphology-using-small-animal

Research

JoVE Journal

Medicine

Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery (SALLI) MRI in Rats

12.6K vues.  German Heart Institute Berlin. Contraste amélioré l'imagerie par résonance magnétique cardiaque (CMR) permet complet In vivo Évaluation du cœur dans les petits modèles animaux de maladies cardiovasculaires. Ici, nous détaillons les procédures à effectuer CMR imagerie, la reconstruction et l'analyse en utilisant Petit Inversion Recovery Lock-Locker animale (SALLI) chez le rat.

Vidéo: Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery SALLI MRI in Rats

Assessment of Cardiac Function and Energetics in Isolated Mouse Hearts Using 31P NMR Spectroscopy

Bioengineered mouse models have become powerful research tools in determining causal relationships between molecular alterations and models of cardiovascular disease. Although molecular biology is necessary in identifying key changes in the signaling pathway, it is not a surrogate for functional significance. While physiology can provide answers to the question of function, combining physiology with biochemical assessment of metabolites in the intact, beating heart allows for a complete picture of cardiac function and energetics. For years, our laboratory has utilized isolated heart perfusions combined with nuclear magnetic resonance (NMR) spectroscopy to accomplish this task. Left ventricular function is assessed by Langendorff-mode isolated heart perfusions while cardiac energetics is measured by performing 31P magnetic resonance spectroscopy of the perfused hearts. With these techniques, indices of cardiac function in combination with levels of phosphocreatine and ATP can be measured simultaneously in beating hearts. Furthermore, these parameters can be monitored while physiologic or pathologic stressors are instituted. For example, ischemia/reperfusion or high workload challenge protocols can be adopted. The use of aortic banding or other models of cardiac pathology are apt as well. Regardless of the variants within the protocol, the functional and energetic significance of molecular modifications of transgenic mouse models can be adequately described, leading to new insights into the associated enzymatic and metabolic pathways. Therefore, 31P NMR spectroscopy in the isolated perfused heart is a valuable research technique in animal models of cardiovascular disease.

Assessment of Cardiac Function and Energetics in Isolated Mouse Hearts Using 31P NMR Spectroscopy

Langendorff-mode isolated heart perfusion, in conjunction with 31P NMR spectroscopy, combines the fields of biochemistry and physiology into one experiment. The protocol allows for the dynamic measurement of high energy phosphate content and turnover in the heart while concurrently monitoring physiologic function. When performed correctly, this is a valuable technique in the assessment of cardiac energetics.

L&#39;évaluation de la fonction cardiaque et Energétique dans les coeurs isolés de souris à l&#39;aide<sup&gt; 31</sup&gt; P NMR Spectroscopy

Bioengineered mouse models have become powerful research tools in determining causal relationships between molecular alterations and models of ...

Recherche

Médecine

Acute Myocardial Infarction in Rats

With heart failure leading the cause of death in the USA (Hunt), biomedical research is fundamental to advance medical treatments for cardiovascular diseases. Animal models that mimic human cardiac disease, such as myocardial infarction (MI) and ischemia-reperfusion (IR) that induces heart failure as well as pressure-overload (transverse aortic constriction) that induces cardiac hypertrophy and heart failure (Goldman and Tarnavski), are useful models to study cardiovascular disease. In particular, myocardial ischemia (MI) is a leading cause for cardiovascular morbidity and mortality despite controlling certain risk factors such as arteriosclerosis and treatments via surgical intervention (Thygesen). Furthermore, an acute loss of the myocardium following myocardial ischemia (MI) results in increased loading conditions that induces ventricular remodeling of the infarcted border zone and the remote non-infarcted myocardium. Myocyte apoptosis, necrosis and the resultant increased hemodynamic load activate multiple biochemical intracellular signaling that initiates LV dilatation, hypertrophy, ventricular shape distortion, and collagen scar formation. This pathological remodeling and failure to normalize the increased wall stresses results in progressive dilatation, recruitment of the border zone myocardium into the scar, and eventually deterioration in myocardial contractile function (i.e. heart failure). The progression of LV dysfunction and heart failure in rats is similar to that observed in patients who sustain a large myocardial infarction, survive and subsequently develops heart failure (Goldman). The acute myocardial infarction (AMI) model in rats has been used to mimic human cardiovascular disease; specifically used to study cardiac signaling mechanisms associated with heart failure as well as to assess the contribution of therapeutic strategies for the treatment of heart failure. The method described in this report is the rat model of acute myocardial infarction (AMI). This model is also referred to as an acute ischemic cardiomyopathy or ischemia followed by reperfusion (IR); which is induced by an acute 30-minute period of ischemia by ligation of the left anterior descending artery (LAD) followed by reperfusion of the tissue by releasing the LAD ligation (Vasilyev and McConnell). This protocol will focus on assessment of the infarct size and the area-at-risk (AAR) by Evan's blue dye and triphenyl tetrazolium chloride (TTC) following 4-hours of reperfusion; additional comments toward the evaluation of cardiac function and remodeling by modifying the duration of reperfusion, is also presented. Overall, this AMI rat animal model is useful for studying the consequence of a myocardial infarction on cardiac pathophysiological and physiological function.

The rat model of acute myocardial infarction (AMI) is useful to study the consequence of a MI on cardiac pathophysiological and physiological function.

Infarctus aigu du myocarde chez le rat

With heart failure leading the cause of death in the USA (Hunt), biomedical research is fundamental to advance medical treatments for cardiovascular ...

MRI and PET in Mouse Models of Myocardial Infarction

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ideal model for testing novel therapeutic strategies.
In vivo magnetic resonance imaging (MRI) gives excellent views of the heart noninvasively with clear anatomical detail, which can be used for accurate functional assessment. Contrast agents can provide basic measures of tissue viability but these are nonspecific. Positron emission tomography (PET) is a complementary technique that is highly specific for molecular imaging, but lacks the anatomical detail of MRI. Used together, these techniques offer a sensitive, specific and quantitative tool for the assessment of the heart in disease and recovery following treatment.
In this paper we explain how these methods are carried out in mouse models of acute myocardial infarction. The procedures described here were designed for the assessment of putative protective drug treatments. We used MRI to measure systolic function and infarct size with late gadolinium enhancement, and PET with fluorodeoxyglucose (FDG) to assess metabolic function in the infarcted region. The paper focuses on practical aspects such as slice planning, accurate gating, drug delivery, segmentation of images, and multimodal coregistration. The methods presented here achieve good repeatability and accuracy maintaining a high throughput.

We describe how to perform MRI and PET imaging of the mouse heart. The protocol is tailored to assess treatment efficacy in models of myocardial infarction and heart failure.

IRM et la TEP dans les modèles de souris de l&#39;infarctus du myocarde

Myocardial infarction is one of the leading causes of death in the Western world. The similarity of the mouse heart to the human heart has made it an ...

Ascending Aortic Constriction in Rats for Creation of Pressure Overload Cardiac Hypertrophy Model

Ascending aortic constriction is the most common and successful surgical model for creating pressure overload induced cardiac hypertrophy and heart failure. Here, we describe a detailed surgical procedure for creating pressure overload and cardiac hypertrophy in rats by constriction of the ascending aorta using a small metallic clip. After anesthesia, the trachea is intubated by inserting a cannula through a half way incision made between two cartilage rings of trachea. Then a skin incision is made at the level of the second intercostal space on the left chest wall and muscle layers are cleared to locate the ascending portion of aorta. The ascending aorta is constricted to 50&#8211;60% of its original diameter by application of a small sized titanium clip. Following aortic constriction, the second and third ribs are approximated with prolene sutures. The tracheal cannula is removed once spontaneous breathing was re-established. The animal is allowed to recover on the heating pad by gradually lowering anesthesia. The intensity of pressure overload created by constriction of the ascending aorta is determined by recording the pressure gradient using trans-thoracic two dimensional Doppler-echocardiography. Overall this protocol is useful to study the remodeling events and contractile properties of the heart during the gradual onset and progression from compensated cardiac hypertrophy to heart failure stage.

We describe a stepwise procedure for creating pressure overload and left ventricular hypertrophy in Wistar rats by constriction of the ascending aorta using a small metallic clip. This model is extensively used for studying remodeling changes during cardiac hypertrophy and for identifying and evaluating strategies for regression of such changes.

Aortique ascendant constriction chez les rats pour la création de la surcharge de pression hypertrophie cardiaque Modèle

Ascending aortic constriction is the most common and successful surgical model for creating pressure overload induced cardiac hypertrophy and heart ...

Assessment of Right Ventricular Structure and Function in Mouse Model of Pulmonary Artery Constriction by Transthoracic Echocardiography

Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure1-3. Moreover, the RV is significantly affected in pulmonary diseases such as pulmonary artery hypertension (PAH). In addition, the RV is remarkably sensitive to cardiac pathologies, including left ventricular (LV) dysfunction, valvular disease or RV infarction4. To understand the role of RV in the pathogenesis of cardiac diseases, a reliable and noninvasive method to access the RV structurally and functionally is essential.
A noninvasive trans-thoracic echocardiography (TTE) based methodology was established and validated for monitoring dynamic changes in RV structure and function in adult mice. To impose RV stress, we employed a surgical model of pulmonary artery constriction (PAC) and measured the RV response over a 7-day period using a high-frequency ultrasound microimaging system. Sham operated mice were used as controls. Images were acquired in lightly anesthetized mice at baseline (before surgery), day 0 (immediately post-surgery), day 3, and day 7 (post-surgery). Data was analyzed offline using software.
Several acoustic windows (B, M, and Color Doppler modes), which can be consistently obtained in mice, allowed for reliable and reproducible measurement of RV structure (including RV wall thickness, end-diastolic&#160;and end-systolic dimensions), and function (fractional area change, fractional shortening, PA peak velocity, and peak pressure gradient) in normal mice and following PAC.
Using this method, the pressure-gradient resulting from PAC was accurately measured in real-time using Color Doppler mode and was comparable to direct pressure measurements performed with a Millar high-fidelity microtip catheter. Taken together, these data demonstrate that RV measurements obtained from various complimentary views using echocardiography are reliable, reproducible and can provide insights regarding RV structure and function. This method will enable a better understanding of the role of RV cardiac dysfunction.

Right ventricle (RV) dysfunction is critical to the pathogenesis of cardiovascular disease, yet limited methodologies are available for its evaluation. Recent advances in ultrasound imaging provide a noninvasive and accurate option for longitudinal RV study. Herein, we detail a step-by-step echocardiographic method using a murine model of RV pressure overload.

Évaluation de ventriculaire droite Structure et fonction dans le modèle de souris de l&#39;artère pulmonaire constriction par échocardiographie transthoracique

Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure1-3. Moreover, ...

Echocardiographic and Histological Examination of Cardiac Morphology in the Mouse

An increasing number of genetically modified mouse models has become available in recent years. Moreover, the number of pharmacological studies performed in mice is high. Phenotypic characterization of these mouse models also requires the examination of cardiac function and morphology. Echocardiography and magnetic resonance imaging (MRI) are commonly used approaches to characterize cardiac function and morphology in mice. Echocardiographic and MRI equipment specialized for use in small rodents is&#160;expensive and requires a dedicated space. This protocol describes cardiac measurements in mice using a clinical echocardiographic system with a 15 MHz human vascular probe. Measurements are performed on anesthetized adult mice. At least three image sequences are recorded and analyzed for each animal in M-mode in the parasternal short-axis view. Afterwards, cardiac histological examination is performed, and cardiomyocyte diameters are determined on hematoxylin-eosin- or wheat germ agglutinin (WGA)-stained paraffin sections. Vessel density is determined morphometrically after Pecam-1 immunostaining. The protocol has been applied successfully to pharmacological studies and different genetic animal models under baseline conditions, as well as after experimental myocardial infarction by the permanent ligation of the left anterior descending coronary artery (LAD). In our experience, echocardiographic investigation is limited to anesthetized animals and is feasible in adult mice weighing at least 25 g.

Echocardiographic examination is frequently used in mice. Expensive high-resolution ultrasound devices have been developed for this purpose. This protocol describes an affordable echocardiographic procedure combined with histological morphometric analyses to determine cardiac morphology.

Examen échocardiographique et histologique de morphologie cardiaque chez la souris

An increasing number of genetically modified mouse models has become available in recent years. Moreover, the number of pharmacological studies performed ...

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The amount of the different tissues in the callus provides important information on the fracture healing progress. Available in vivo techniques to longitudinally monitor the callus tissue development in preclinical fracture-healing studies using small animals include digital radiography and &#181;CT imaging. However, both techniques are only able to distinguish between mineralized and non-mineralized tissue. Consequently, it is impossible to discriminate cartilage from fibrous tissue. In contrast, magnetic resonance imaging (MRI) visualizes anatomical structures based on their water content and might therefore be able to noninvasively identify soft tissue and cartilage in the fracture callus. Here, we report the use of an MRI-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice. The experiments demonstrated that the fixator and a custom-made mounting device allow repetitive MRI scans, thus enabling longitudinal analysis of fracture-callus tissue development.

In Vivo Evaluation of Fracture Callus Development During Bone Healing in Mice Using an MRI-compatible Osteosynthesis Device for the Mouse Femur

The evaluation of tissue development in the fracture callus during endochondral bone healing is essential to monitor the healing process. Here, we report the use of a magnetic resonance imaging (MRI)-compatible external fixator for the mouse femur to allow MRI scans during bone regeneration in mice.

In Vivo Évaluation du développement de cals de Fracture au cours de la guérison osseuse chez la souris en utilisant un dispositif d’ostéosynthèse IRM-compatible pour le fémur de souris

Endochondral fracture healing is a complex process involving the development of fibrous, cartilaginous, and osseous tissue in the fracture callus. The ...

Normothermic Ex Situ Heart Perfusion in Working Mode: Assessment of Cardiac Function and Metabolism

The current standard method for organ preservation (cold storage, CS), exposes the heart to a period of cold ischemia that limits the safe preservation time and increases the risk of adverse post-transplantation outcomes. Moreover, the static nature of CS does not allow for organ evaluation or intervention during the preservation interval. Normothermic ex situ heart perfusion (ESHP) is a novel method for preservation of the donated heart that minimizes cold ischemia by providing oxygenated, nutrient-rich perfusate to the heart. ESHP has been shown to be non-inferior to CS in the preservation of standard-criteria donor hearts and has also facilitated the clinical transplantation of the hearts donated after the circulatory determination of death. Currently, the only available clinical ESHP device perfuses the heart in an unloaded, non-working state, limiting assessments of myocardial performance. Conversely, ESHP in working mode provides the opportunity for comprehensive evaluation of cardiac performance by assessment of functional and metabolic parameters under physiologic conditions. Moreover, earlier experimental studies have suggested that ESHP in working mode may result in improved functional preservation. Here, we describe the protocol for ex situ perfusion of the heart in a large mammal (porcine) model, which is reproducible for different animal models and heart sizes. The software program in this ESHP apparatus allows for real-time and automated control of the pump speed to maintain desired aortic and left atrial pressure and evaluates a variety of functional and electrophysiological parameters with minimal need for supervision/manipulation.

Normothermic ex situ heart perfusion (ESHP), preserves the heart in a beating, semi-physiologic state. When performed in a working mode, ESHP provides the opportunity to perform sophisticated assessments of donor heart function and organ viability. Here, we describe our method for myocardial performance evaluation during ESHP.

Normothermique Ex Situ coeur Perfusion en Mode de travail : évaluation de la fonction cardiaque et le métabolisme

The current standard method for organ preservation (cold storage, CS), exposes the heart to a period of cold ischemia that limits the safe preservation ...

Continuous Blood Sampling in Small Animal Positron Emission Tomography/Computed Tomography Enables the Measurement of the Arterial Input Function

For quantitative analysis and bio-kinetic modeling of positron emission tomography/computed tomography (PET/CT) data, the determination of the temporal blood time-activity concentration also known as arterial input function (AIF) is a key point, especially for the characterization of animal disease models and the introduction of newly developed radiotracers. The knowledge of radiotracer availability in the blood helps to interpret PET/CT-derived data of tissue activity. For this purpose, online blood sampling during the PET/CT imaging is advisable to measure the AIF. In contrast to manual blood sampling and image-derived approaches, continuous online blood sampling has several advantages. Besides the minimized blood loss, there is an improved resolution and a superior accuracy for the blood activity measurement. However, the major drawback of online blood sampling is the costly and time-consuming preparation to catheterize the femoral vessels of the animal. Here, we describe an easy and complete workflow for catheterization and continuous blood sampling during small animal PET/CT imaging and compared it to manual blood sampling and an image-derived approach. Using this highly-standardized workflow, the determination of the fluorodeoxyglucose ([18F]FDG) AIF is demonstrated. Further, this procedure can be applied to any radiotracer in combination with different animal models to create fundamental knowledge of tracer kinetic and model characteristics. This allows a more precise evaluation of the behavior of pharmaceuticals, both for diagnostic and therapeutic approaches in the preclinical research of oncological, neurodegenerative and myocardial diseases.

Here a protocol for continuous blood sampling during PET/CT imaging of rats to measure the arterial input function (AIF) is described. The catheterization, the calibration and setup of the system and the data analysis of the blood radioactivity are demonstrated. The generated data provide input parameters for subsequent bio-kinetic modeling.

L'échantillonnage continu de sang dans la tomographie d'émission de positron de petit animal/tomographie calculée permet la mesure de la fonction d'entrée artérielle

For quantitative analysis and bio-kinetic modeling of positron emission tomography/computed tomography (PET/CT) data, the determination of the temporal ...

Echocardiographic Assessment of Cardiac Anatomy and Function in Adult Rats

The use of experimental animal models has become crucial in cardiovascular science. Most studies using rodent models are focused on two-dimensional imaging to study the cardiac anatomy of the left ventricle and M-mode echo to assess its dimensions. However, this could limit a comprehensive study. Herein, we describe a protocol that allows an assessment of the heart chamber size, left ventricular function (systolic and diastolic) and valvular function. A conventional medical ultrasound machine was used in this protocol and different echo views were obtained through left parasternal, apical and suprasternal windows. In the left parasternal window, the long and short axis were acquired to analyze left chamber dimensions, right ventricle and pulmonary artery dimensions, and mitral, pulmonary and aortic valve function. The apical window allows the measurement of heart chamber dimensions and evaluation of systolic and diastolic parameters. It also allows Doppler assessment with detection and quantification of heart valve disturbances (regurgitation or stenosis). Different segments and walls of the left ventricle are visualized throughout all views. Finally, the ascending aorta, aortic arch, and descending aorta can be imaged through the suprasternal window. A combination of ultrasound imaging, Doppler flow and tissue Doppler assessment have been obtained to study cardiac morphology and function. This represents an important contribution to improve the assessment of cardiac function in adult rats with impact for research using these animal models.

A non-invasive protocol for transthoracic echocardiography assessment of cardiac anatomy and function for adult rats is presented in the current study. The heart valves, all four cardiac chambers and the ascending aorta, aortic arch and descending aorta are studied in detail.

Évaluation échocardiographique de l'anatomie cardiaque et de la fonction chez les rats adultes

The use of experimental animal models has become crucial in cardiovascular science. Most studies using rodent models are focused on two-dimensional ...