1. Preparación 1.1. Anestesia de las ratas <ol><li> Coloque la rata en una cámara rellenada previamente con isoflurano (dependiendo del tamaño de la cámara alrededor de 3 minutos de 5%) para anestesiar la rata. </li><li> Una vez anestesiado, retire la rata y pesarlo. </li><li> Coloque la nariz de la rata en la máscara de anestesia (isoflurano 2-3% de oxígeno en 1 L / min) para mantener la anestesia. Durante la anestesia con isoflurano, las tasas de corazón de ratas disminuyen a 300-340 latidos por minuto (lpm 380-420 en ratones). </li></ol> 1.2. Insertar una cánula vena de la cola <ol><li> Lavar la cola de la rata con agua tibia (38 ° C) y jabón para permitir que los vasos sanguíneos sean más fáciles de ver. </li><li> Canular ya sea la vena, que se puede ver fácilmente en la cara lateral de la cola. Uso de un G catéter iv 22-24, comenzar intentos aproximadamente 1/3 de la distancia desde la punta. </li><li> Si los esfuerzos iniciales no tienen éxito, vuelva a intentar más proximal. </li><li> Tomar muestras de sangre,ple para el análisis de hematocrito (necesario para calcular la fracción de volumen extracelular = VCE). </li><li> Asegure el catéter iv con pegamento de la piel y la cinta. </li></ol> 1.3. Posicionamiento de los electrodos <ol><li> Limpie todas las almohadillas con alcohol hisopo saturado o con agua y jabón. </li><li> Se necesitan cuatro electrodos, uno para cada pie. </li><li> Conecte los electrodos a la mitad de la almohadilla plantar y fijarlos con cinta adhesiva. </li><li> Giro o trenzar los cables de ECG alrededor de la otra para minimizar la formación de bucles que podrían causar interferencias con la señal de ECG. </li></ol> 2. Exploración 2.1. Posicionamiento del animal y el seguimiento <ol><li> Coloque la rata en una posición supina o prona en el tubo de imagen y posicionar el corazón en el centro de la bobina. </li><li> Organizar la rata de modo que su nariz se apoya en el cono que proporciona anestesia con isoflurano (2-3% de oxígeno en 1 L / min). La rata se le permite a la respiraciónlibremente por todo el procedimiento de imagen entera. </li><li> Coloque el sensor del termómetro en el orificio anal y fijarlo en la mesa con cinta adhesiva. </li><li> La temperatura corporal se mantiene a 38 ± 1 ° C por un sistema de calefacción de agua caliente. La estera de calentamiento se coloca bajo el aspecto inferior del animal que se extiende fuera de la bobina. Por favor, ver la representación esquemática de la configuración experimental MRI (Figura 2) para más detalles. </li><li> Conecte los electrodos de ECG, una vez que la señal de ECG es estable comenzarán imágenes. </li></ol> 2.2. Parámetros del protocolo Scan / Imágenes <ol><li> En este estudio se utilizó un sistema de Ingenia 3.0T MRI clínica Philips con una bobina de 70 mm de diámetro interior [los requisitos del sistema de RM son un pequeño orificio (por ejemplo, 16 cm) o de gran calibre (tamaño humano, por ejemplo, 65 cm) con pequeño animal dedicado bobina, capacidades sincronización con el ECG de ritmo cardíaco hasta 500/min, el suministro de oxígeno y un sistema de eliminación de gases anestésicos]. </li><li> Comience con una encuesta para localizar el corazón en el centro de la RM de campo de vista. </li><li> Una vez que la posición es correcta, continuar con dos cámaras y cuatro cámaras de cine vistas de MRI para determinar la geometría de la pila de imágenes según el eje corto. </li><li> Para SALLI, posición de media cavidad rebanada eje corto de las dos y las imágenes de cuatro cámaras (PreSALLI). Una combinación de 4.000 mseg duración adquisición y 4000 mseg duración relajación permite una recuperación suficiente de la magnetización a lo largo del eje z y evita el sobrecalentamiento de los gradientes. Para habilitar el análisis funcional, las fases se deben establecer en al menos 12, con submuestreo temporal del factor 2 para acelerar la adquisición. </li><li> Inyectar el agente de contraste gadolinio en el catéter permanente, sin mover la rata. Espere cinco minutos. </li><li> Comience a planificar SALLI como multicorte pila eje corto, que consta de al menos 7 rebanadas (grosor de corte 2,4 mm). Coloque las rodajas de modo que el más distal está por debajo de la punta del corazón y tque el nivel superior es justo distal a las válvulas cardíacas. Trate de asegurarse de que los ejes cortos son perpendiculares al tabique. Casi cada 30 minutos (en torno a tres Sallis) inyectar una nueva dosis de agente de contraste. </li><li> Una vez finalizada la adquisición de imágenes retire la rata del escáner y permite que se recupere de la anestesia. </li></ol> 3. Reconstrucción de imágenes Reconstrucción de las imágenes se puede realizar ya sea en línea con los parámetros predefinidos de reconstrucción, o fuera de línea utilizando una herramienta específica reconstrucción de la imagen: 3,1. Online Reconstrucción <ol><li> Varios parámetros pueden ser definidos incluyendo: </li></ol><ul><li> Para el mapeo T1: ubicación y la anchura de la ventana de la reconstrucción en el ciclo cardiaco (por ejemplo, de 50 a 100 mseg para lograr sistólica mapa T1 a la tasa 300/min corazón) </li><li> Para (LGE) Imágenes IR preparados: la ubicación y el ancho de la inversión de tiempo (TI) Ventana y el número de imágenes que se van wi reconstruidadelgada que la ventana (por ejemplo, TI 100-300 ms, 5 imágenes, para generar 5 imágenes LGE con TIs 100-150-200-250-300 ms). </li></ul> 3.2. Desconectado Reconstrucción <ol><li> Cuando se utiliza un paquete de software dedicado (GyroTools, Zürich, Suiza) para la reconstrucción de la imagen, extraer los tres conjuntos de datos (Cine mapas T1 MR, recuperación de la inversión y) de una manera más interactiva. </li><li> Ajuste la definición de final de la sístole o al final de la diástole del T1 al seleccionar la imagen de cine correspondiente. </li><li> Visualiza mapas de T1 como mapas de colores. Encontrar los valores exactos por los que pasa el ratón sobre un área de interés. Las imágenes se pueden guardar en varios formatos de imagen para su posterior análisis (por ejemplo, el cálculo de la ECV de pre y valores T1 post-contraste de miocardio y la piscina de sangre) 12. </li></ol>

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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. 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Todos los procedimientos con animales se realizaron de conformidad con las Directrices para el Cuidado y Uso de Animales de Laboratorio, y aprobadas por las autoridades locales de cuidado de los animales. No hay conflictos de interés declarado.

Aquí presentamos un método para generar múltiples modalidades (cine MR, inversión-recuperación y los mapas T1) imágenes de RM en pequeños animales. Investigación animal pequeño juega un papel cada vez más importante en la investigación de la enfermedad cardiovascular, y CMR es una herramienta poderosa que nos permite estudiar la función, la estructura y composición del tejido del miocardio. Sin embargo, los pequeños CMR animal tiene una serie de desafíos únicos debido a las altas tasas de corazón y el p...

La miocarditis es una de las principales causas de la insuficiencia cardiaca aguda, muerte súbita, y la miocardiopatía dilatada crónica 7. CMR se ha establecido como la técnica estándar de oro para la medición de la función y para el análisis de tejidos in vivo. Nuevas técnicas de imagen y mejoras en la formación de imágenes no sólo podrían mejorar el diagnóstico de la miocarditis, sino también ayudar al estudio de la fisiopatología y la identificación de dianas terapéuticas velocidad 8-10. Imágenes de pequeños animales es una herramienta importante para el estudio de las enfermedades cardiovasculares. Las técnicas utilizadas habitualmente en clínica CMR, como el realce tardío de gadolinio (RTG) no pueden ser fácilmente transferidos a pequeña CMR animal, debido a las altas tasas de corazón de los animales, pero ya se pudo demostrar 11. La pequeña recuperación de la inversión Look-Locker animales (SALLI) enfoque genera datos de imágenes multimodales establece teniendo en cuenta la evaluación integral tanto de la función cardiaca y la morfología (Figuras 1 aº 3). Aquí se muestra, en detalle, el procedimiento y la configuración para obtener imágenes de animales pequeños con un protocolo típico SALLI. En particular, se muestra la reconstrucción y el análisis de los conjuntos de datos de formación de imágenes 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

Animales de formación de imágenes por resonancia magnética pequeño es una herramienta importante para estudiar la función cardiaca y cambios en el tejido del miocardio. Las frecuencias cardíacas altas de animales pequeños (200 a 600 latidos / min) han limitado previamente el papel de RMC. Recuperación de la inversión Mira-Locker animal Pequeño (SALLI) es una secuencia de mapeo T1 para animales pequeños para superar este problema 1. Mapas T1 proporcionan información cuantitativa acerca de alteraciones de los tejidos y la cinética de agente de contraste. También es posible detectar los procesos de miocardio difusas tales como la fibrosis intersticial o edema 1-6. Por otra parte, a partir de un único conjunto de datos de imagen, es posible examinar la función del corazón y el infarto de cicatrización mediante la generación de cine y de recuperación de la inversión-preparados finales de gadolinio de tipo mejora de imágenes de RM 1. El video muestra presenta paso a paso los procedimientos para llevar a cabo pequeños animales RMC. Esta es presentada aquí con un Sprague-Dawl saludableey rata, sin embargo, naturalmente, que se puede extender a diferentes modelos cardíacos pequeños animales.

Aquí nos demuestran los resultados de una sana Sprague Dawley. Con una configuración de animales bien preparada hemos descrito antes, es posible obtener una señal de ECG estable. Al igual que los protocolos de RM cardíaca humana, comenzamos con un estudio para localizar el corazón. Si la posición de la rata en la bobina es correcta, continuamos con una vista de dos cámaras y una vista de cuatro cámaras para detectar la geometría de la pila SALLI. La técnica SALLI produce tres tipos...

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 mejorado resonancia magnética cardiaca (RMC) permite integral<em&gt; In vivo</em&gt; Evaluación del corazón en los modelos de pequeños animales de enfermedad cardiovascular. A continuación se detallan los procedimientos para llevar a cabo la CRM, la reconstrucción y el análisis utilizando Pequeño bloqueo Locker Recuperación Inversion Animal (SALLI) en ratas.

Evaluación de la función cardiaca y la morfología de miocardio utilizando pequeñas Look-locker Recuperación Inversion Animal (SALLI) MRI en ratas

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 vistas.  German Heart Institute Berlin. Contraste mejorado resonancia magnética cardiaca (RMC) permite integral In vivo Evaluación del corazón en los modelos de pequeños animales de enfermedad cardiovascular. A continuación se detallan los procedimientos para llevar a cabo la CRM, la reconstrucción y el análisis utilizando Pequeño bloqueo Locker Recuperación Inversion Animal (SALLI) en ratas.

Video: 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.

Evaluación de la función cardiaca y Energética en los corazones de ratón aislado utilizando 31 P espectroscopía de RMN

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

Investigación

Medicina

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.

Infarto agudo de miocardio en ratas

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.

Resonancia magnética y PET en modelos de ratón de infarto de miocardio

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.

Ascendente aórtica Constricción en ratas para la Creación de la sobrecarga de presión hipertrofia cardíaca Modelo

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.

Evaluación del ventrículo derecho Estructura y función en modelo de ratón de la constricción de la arteria pulmonar mediante ecocardiografía transtorácica

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 ecocardiográfico e histológico de la morfología cardiaca en el ratón

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.

En Vivo Evaluación del desarrollo del callo de fractura durante la cicatrización ósea en ratones usando un dispositivo de osteosíntesis de MRI-compatible para el fémur de ratón

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.

Normotérmica Ex Situ corazón perfusión en modo de trabajo: evaluación de la función cardiaca y el metabolismo

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.

El muestreo sanguíneo continuo en tomografía por emisión de positrones de animales pequeños permite la medición de la función de entrada arterial

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.

Evaluación ecocardiográfica de la anatomía cardíaca y la función en ratas adultas

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