Estamos agradecidos por los recursos proporcionados por la Escuela de Medicina de Harvard / Brigham and Women's Hospital Cardiovascular Physiology Core Laboratory. Este trabajo fue apoyado en parte por el financiamiento de las subvenciones hl088533, HL071775, HL093148 y HL099073 (RL) de los Institutos Nacionales de Salud. MB recibió un premio de beca postdoctoral afiliado a la Asociación Americana del Corazón. KU ha recibido un premio de beca postdoctoral afiliado a los fundadores de la Asociación Americana del Corazón. SC fue apoyado por un premio de la Fundación Ellison.

1. Preparación de imágenes para análisis
<ol><li>Obtenga imágenes ecocardiográficas murinas o humanas en modo B en la vista paraesternal de eje largo. Ajuste la configuración de compensación de ganancia de tiempo y la colocación del enfoque de transmisión para optimizar la visualización del VI y otras estructuras cardíacas en la vista paraesternal, según la práctica habitual. Asegúrese de que todas las imágenes se guardan en formato de archivo DICOM. Las vistas estandarizadas de la imagen colocan la pared ventricular izquierda inferolateral en la base del marco. Los marcos deben mostrar la totalidad del miocardio y el pericardio del ventrículo izquierdo. La resolución debe ser lo suficientemente alta como para demarcar el borde pericárdico, la pared miocárdica y el borde endocárdico del ventrículo izquierdo. Descartar imágenes con exceso de abandono o artefactos de imagen.</li>
	<li>Importe un archivo de imagen para su análisis en la plataforma de software ImageJ v1.46 como un archivo DICOM. Convierta el archivo en un archivo de imagen de 8 bits.</li>
	<li>Desplácese a través de fotogramas consecutivos del ciclo cardíaco hasta alcanzar un marco diastólico final de calidad adecuada. Como alternativa, seleccione el marco diastólico final en un programa de visualización ecocardiográfica y, a continuación, exporte a un formato de archivo de .jpg de alta resolución para su uso en ImageJ. Identifique las tramas más cercanas a la diástole final utilizando la onda R del trazado de ECG y, a continuación, identifique la mejor trama que capture el LV con la dimensión interna máxima. Considere este marco único el marco diastólico final.</li>
	<li>Se sugiere que los usuarios se cegarán a la identidad del sujeto al seleccionar las regiones de interés.</li>
</ol>2. Muestreo de ROI
<ol><li>Selección de referencia pericárquica. Al seleccionar la región pericárcica de interés (ROI), trate de capturar la heterogeneidad del tejido pericárquio. Tenga en cuenta que el brillo y el contraste de la imagen se pueden ajustar para la selección del ROI, según sea necesario, sin ningún efecto en los resultados del análisis.<ol>
<li>Usando la herramienta de dibujo de rectángulo de ImageJ, seleccione un rectángulo con longitud que se aproxime al tercio medio de la pared pericárquica inferolateral basal.</li>
		<li>Cambie el tamaño del ROI rectangular para abarcar el ancho del pericardio utilizando la herramienta de dimensionamiento del ROI.</li>
		<li>Gire el ROI para que se encuentra dentro de la región pericárquica utilizando la herramienta de rotación de ImageJ.</li>
		<li>Realice los ajustes necesarios en las esquinas del ROI pericárquica. Capturar una región pericárdica final de interés que se encuentra dentro del tercio medio de la pared pericárdica, e incluye el ancho de la pared pericárdica sin extenderse hacia las regiones miocárdicas o extra-cardíacas. Trate de capturar la misma ubicación relativa y el mismo porcentaje del área pericárcica total para todas las medidas realizadas en un estudio determinado.</li>
		<li>Aplique el algoritmo a la selección a través de las herramientas de análisis de ImageJ (consulte la sección 3).</li>
	</ol>
</li>
	<li>Selección miocárdica. Una vez más, trate de capturar la heterogeneidad del tejido miocárdico dentro del tercio medio de la pared miocárdica inferolateral basal. Tenga en cuenta que el brillo y el contraste de la imagen se pueden ajustar para la selección del ROI, según sea necesario, sin ningún efecto en los resultados del análisis.<ol>
<li>Seleccione un rectángulo que abarque el ancho de la pared miocárdica, excluyendo el endocardio y el epicardio. Asegúrese de que la selección miocárdica se encuentra adyacente a la selección pericárdica y en el mismo ángulo theta. No incluya áreas del músculo papilar dentro del área de selección.</li>
		<li>Rotar el ROI miocárdico de tal manera que se encuentre paralelo a la selección pericárdica.</li>
		<li>Haga los ajustes necesarios en las esquinas del ROI miocárdico. Aísle una región miocárdica final de interés que se encuentre dentro del tercio medio de la pared miocárdica y capture el ancho de la pared sin extenderse a las regiones pericárdicas o intraluminales.</li>
		<li>Aplique el algoritmo a la selección a través de una macro ImageJ.</li>
	</ol>
</li>
</ol>3. Análisis y procesamiento de datos
<ol><li>Instale la macro ImageJ llamada "getHistogramValues.txt".</li>
	<li>Utilice la herramienta de análisis de histograma ImageJ para obtener una vista previa de la distribución de los valores de intensidad de la señal dentro del ROI (realice este paso para la selección pericárdica y para la selección miocárdica).</li>
	<li>Utilice la macro ImageJ para registrar estos valores de densidad de señal para el ROI (realice este paso para la selección pericárdica y para la selección miocárdica).<ol>
<li>Asigne un valor de intensidad de 0 (más oscuro) a 255 unidades (más brillantes) a cada píxel dentro de la selección.</li>
		<li>Organice los valores de intensidad jerárquicamente, en orden de intensidad creciente, para producir una distribución de la intensidad de la señal.</li>
		<li>Seleccione e informe de los siguientes valores de percentiles para la distribución: percentil 20, percentil 50 (mediana) y percentil80.</li>
	</ol>
</li>
	<li>Normalizar las intensidades miocárdicas utilizando la referencia pericárdica.<ol>
<li>Normalizar dividiendo los valores de intensidad del percentil miocárdico por los correspondientes valores de percentiles pericárdicos de intensidad12,o restando el valor del percentil miocárdico de intensidad del valor percentil pericárdico de intensidad13.</li>
		<li>Reportar valores para los cuatro métodos analíticos: valores normalizados de miocardio a pericárdico para el percentil 20, percentil 50 (mediana) y 80percentil.</li>
	</ol>
</li>
</ol>4. Cuantificación de la variabilidad cíclica
<ol><li>Aplicar algoritmo a selecciones miocárdicas a través de marcos consecutivos del archivo DICOM, moviéndose a través del ciclo cardíaco. Compare las diferencias en las distribuciones de intensidad entre fotogramas, prestando atención a los fotogramas sistólicos y diastólicos finales. Todos los análisis de imágenes descritos anteriormente se realizan fuera de línea en imágenes ecocardiográficas no invasivas previamente adquiridas y almacenadas digitalmente en formato DICOM. Todos los protocolos del estudio fueron aprobados por la junta de revisión institucional de Brigham and Women y el Comité institucional de cuidado y uso de animales del Área Médica de Harvard.</li>
</ol>

<ol>
	<li>Yamada, S., Komuro, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrated+backscatter+for+the+assessment+of+myocardial+viability.">Integrated backscatter for the assessment of myocardial viability.</a> Curr. Opin. Cardiol. 21, 433-437 (2006).</li><li>Mimbs, J. W., O'Donnell, M., Bauwens, D., Miller, J. W., Sobel, B. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+dependence+of+ultrasonic+attenuation+and+backscatter+on+collagen+content+in+dog+and+rabbit+hearts.">The dependence of ultrasonic attenuation and backscatter on collagen content in dog and rabbit hearts.</a> Circ. Res. 47, 49-58 (1980).</li><li>Picano, E., 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=In+vivo+quantitative+ultrasonic+evaluation+of+myocardial+fibrosis+in+humans.">In vivo quantitative ultrasonic evaluation of myocardial fibrosis in humans.</a> Circulation. 81, 58-64 (1990).</li><li>Mizuno, R., 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+ultrasonic+tissue+characterization+for+estimating+histological+abnormalities+in+hypertrophic+cardiomyopathy:+comparison+with+endomyocardial+biopsy+findings.">Myocardial ultrasonic tissue characterization for estimating histological abnormalities in hypertrophic cardiomyopathy: comparison with endomyocardial biopsy findings.</a> Cardiology. 96, 16-23 (2001).</li><li>Mizuno, R., Fujimoto, S., Saito, Y., Nakamura, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-invasive+quantitation+of+myocardial+fibrosis+using+combined+tissue+harmonic+imaging+and+integrated+backscatter+analysis+in+dilated+cardiomyopathy.">Non-invasive quantitation of myocardial fibrosis using combined tissue harmonic imaging and integrated backscatter analysis in dilated cardiomyopathy.</a> Cardiology. 108, 11-17 (2007).</li><li>Marini, C., 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=Cyclic+variation+in+myocardial+gray+level+as+a+marker+of+viability+in+man.+A+videodensitometric+study.">Cyclic variation in myocardial gray level as a marker of viability in man. A videodensitometric study.</a> Eur. Heart. J. 17, 472-479 (1996).</li><li>Komuro, K., 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=Sensitive+detection+of+myocardial+viability+in+chronic+coronary+artery+disease+by+ultrasonic+integrated+backscatter+analysis.">Sensitive detection of myocardial viability in chronic coronary artery disease by ultrasonic integrated backscatter analysis.</a> J. Am. Soc. Echocardiogr. 18, 26-31 (2005).</li><li>Ciulla, 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=Echocardiographic+patterns+of+myocardial+fibrosis+in+hypertensive+patients:+endomyocardial+biopsy+versus+ultrasonic+tissue+characterization.">Echocardiographic patterns of myocardial fibrosis in hypertensive patients: endomyocardial biopsy versus ultrasonic tissue characterization.</a> J. Am. Soc. Echocardiogr. 10, 657-664 (1997).</li><li>Maceira, A. M., Barba, J., Varo, N., Beloqui, O., Diez, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasonic+backscatter+and+serum+marker+of+cardiac+fibrosis+in+hypertensives.">Ultrasonic backscatter and serum marker of cardiac fibrosis in hypertensives.</a> Hypertension. 39, 923-928 (2002).</li><li>D'Hooge, 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=High+frame+rate+myocardial+integrated+backscatter.+Does+this+change+our+understanding+of+this+acoustic+parameter.">High frame rate myocardial integrated backscatter. Does this change our understanding of this acoustic parameter.</a> Eur. J. Echocardiogr. 1, 32-41 (2000).</li><li>Finch-Johnston, A. E., 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=Cyclic+variation+of+integrated+backscatter:+dependence+of+time+delay+on+the+echocardiographic+view+used+and+the+myocardial+segment+analyzed.">Cyclic variation of integrated backscatter: dependence of time delay on the echocardiographic view used and the myocardial segment analyzed.</a> J. Am. Soc. Echocardiogr. 13, 9-17 (2000).</li><li>Di Bello, V., 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=Increased+echodensity+of+myocardial+wall+in+the+diabetic+heart:+an+ultrasound+tissue+characterization+study.">Increased echodensity of myocardial wall in the diabetic heart: an ultrasound tissue characterization study.</a> J. Am. Coll. Cardiol. 25, 1408-1415 (1995).</li><li>Takiuchi, 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=Quantitative+ultrasonic+tissue+characterization+can+identify+high-risk+atherosclerotic+alteration+in+human+carotid+arteries.">Quantitative ultrasonic tissue characterization can identify high-risk atherosclerotic alteration in human carotid arteries.</a> Circulation. 102, 766-770 (2000).</li><li>Querejeta, R., 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=Serum+carboxy-terminal+propeptide+of+procollagen+type+I+is+a+marker+of+myocardial+fibrosis+in+hypertensive+heart+disease.">Serum carboxy-terminal propeptide of procollagen type I is a marker of myocardial fibrosis in hypertensive heart disease.</a> Circulation. 101, 1729-1735 (2000).</li></ol>

No se declaran conflictos de intereses.

Describimos el protocolo para un algoritmo del análisis de la imagen que cuantifique la distribución sonográfica de la intensidad de la señal y, a su vez, ofrezca una medida sustituta de la microestructura del miocardio. Las características estandarizadas del protocolo, incluida la selección, el tamaño y el posicionamiento del ROI y la región de referencia, sirven para minimizar la variabilidad basada en el usuario y el sujeto. Se demuestra que cuando se aplica a las imágenes ecocardiográficas de un solo marco ...

La ecocardiografía es una modalidad ampliamente accesible de la proyección de imagen que se utiliza comúnmente para caracterizar y para cuantificar no invasor cambios en estructura y la función cardiacas. Las evaluaciones ultrasónicas del tejido cardíaco pueden incluir análisis de la intensidad de la señal de retrospersión dentro de una región dada de interés en un solo punto en el tiempo, así como a lo largo del ciclo cardíaco. Estudios previos han sugerido que las medidas de intensidad de la señal sonográfica pueden identificar la presencia subyacente de desorden de la fibra miocárdica, tejido miocárdico viable versus no viable, y fibrosis intersticial1-3. Nos referimos a la 'microestructura' miocárdica como la arquitectura tisular que se puede caracterizar, mediante análisis sonográfico, más allá de las mediciones lineales de tamaño bruto y morfología. En consecuencia, se han utilizado análisis de la intensidad de la señal sonográfica para evaluar las alteraciones microestructurales del tejido miocárdico en el contexto de la miocardiopatía hipertrófica y dilatada4,5,la enfermedad arterial coronaria crónica6,7y la cardiopatía hipertensiva8,9. Sin embargo, las técnicas previamente establecidas se han basado predominantemente en el valor integrado o medio de las intensidades de la señal de retrospersión, que pueden ser susceptibles a la variabilidad del ruido aleatorio5,los datos con alias de velocidades de fotogramas bajas10,y los retrasos de tiempo para los algoritmos basados en la variación cíclica11.
Adjunto, describimos el método de usar un algoritmo ultrasonido-basado del análisis de la imagen que extienda de métodos anteriores; este algoritmo se centra en un único marco diastólico final para el análisis de imágenes y explica la distribución completa de los valores de intensidad de la señal derivados de una muestra miocárdica dada. Mediante el uso del pericardio como referencia en el marco12,13,el algoritmo cuantifica de forma reproducible la variación en las distribuciones de intensidad de la señal sonográfica y ofrece una medida sustitutiva mejorada de la microestructura miocárdica. En un protocolo paso a paso, describimos métodos para preparar imágenes para su uso, muestrear regiones de interés y procesar datos dentro de regiones seleccionadas de interés. También mostramos resultados representativos de la aplicación del algoritmo a imágenes ecocardiográficas adquiridas de ratones y seres humanos con exposición variable a la tensión de poscarga en el ventrículo izquierdo.

<table border="0" cellpadding="0" cellspacing="0" width="770">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">ImageJ v 1.46</td>
			<td style="width:268px;">NIH (Bethesda, MD)</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">open access software</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Power ShowCase</td>
			<td style="width:268px;">Trillium Technology (Ann Arbor, MI)</td>
			<td style="width:119px;"></td>
			<td>commercial software</td>
		</tr>
	</tbody>
</table>

ultrasonic assessment of myocardial microstructure

La ecocardiografía es una modalidad ampliamente accesible de la proyección de imagen que se utiliza comúnmente para caracterizar y para cuantificar no invasor cambios en estructura y la función cardiacas. Las evaluaciones ultrasónicas del tejido cardíaco pueden incluir análisis de la intensidad de la señal de retrospersión dentro de una región determinada de interés. Las técnicas previamente establecidas se han basado predominantemente en el valor integrado o medio de las intensidades de la señal de retrospersión, que pueden ser susceptibles a la variabilidad de los datos con alias de velocidades de fotogramas bajas y los retrasos de tiempo para los algoritmos basados en la variación cíclica. Adjunto, describimos un algoritmo ultrasonido-basado de la proyección de imagen que extiende de métodos anteriores, se puede aplicar a un solo marco de la imagen y explica la distribución completa de los valores de la intensidad de la señal derivados de una muestra del miocardio dada. Cuando se aplica a datos representativos de imágenes de ratones y humanos, el algoritmo distingue entre sujetos con y sin exposición a la resistencia crónica a la poscarga. El algoritmo ofrece una medida sustituta mejorada de la microestructura miocárdica y se puede realizar utilizando un software de análisis de imágenes de acceso abierto.

El análisis de la intensidad de la señal se realiza en 4 pasos principales(Figura 1),que incluyen: 1) selección y formato de imágenes, 2) roi de muestreo y áreas de referencia, 3) aplicación de algoritmos y 4) procesamiento de valores finales para producir relaciones de intensidad miocárdica a pericárdica. La selección y el tamaño del ROI están estandarizados para limitar la variabilidad interusuario e intrausuario (Figura 2). El posicionamiento de cada ROI también está esta...

Watch this Scientific Journal Video about Ultrasonic Assessment of Myocardial Microstructure at JoVE.com

Ultrasonic Assessment of Myocardial Microstructure

La ecocardiografía se utiliza comúnmente para caracterizar y cuantificar de forma no invasiva los cambios en la estructura y función cardíaca. Describimos un algoritmo de imagen ultrasonido-basado que ofrece una medida sustituta mejorada de microestructura del miocardio y se puede realizar usando el software de análisis de imagen de acceso abierto.

Evaluación ultrasónica de la microestructura miocárdica

Echocardiography is a widely accessible imaging modality that is commonly used to noninvasively characterize and quantify changes in cardiac structure and ...

ultrasonic-assessment-of-myocardial-microstructure

Research

JoVE Journal

Medicine

5.3K vistas.  Harvard Medical School. La ecocardiografía se utiliza comúnmente para caracterizar y cuantificar de forma no invasiva los cambios en la estructura y función cardíaca. Describimos un algoritmo de imagen ultrasonido-basado que ofrece una medida sustituta mejorada de microestructura del miocardio y se puede realizar usando el software de análisis de imagen de acceso abierto.

Video: Ultrasonic Assessment of Myocardial Microstructure

Magnetic Resonance Derived Myocardial Strain Assessment Using Feature Tracking

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF. Current technologies for CMR are time consuming and difficult to implement in clinical practice. Feature tracking is a technology that can lead to more automization and robustness of quantitative analysis of medical images with less time consumption than comparable methods.
Methods: An automatic or manual input in a single phase serves as an initialization from which the system starts to track the displacement of individual patterns representing anatomical structures over time. The specialty of this method is that the images do not need to be manipulated in any way beforehand like e.g. tagging of CMR images.
Results: The method is very well suited for tracking muscular tissue and with this allowing quantitative elaboration of myocardium and also blood flow.
Conclusions: This new method offers a robust and time saving procedure to quantify myocardial tissue and blood with displacement, velocity and deformation parameters on regular sequences of CMR imaging. It therefore can be implemented in clinical practice.

An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that strain is a more sensitive and earlier marker for contractile dysfunction than the frequently used parameter EF.

Evaluación de Resonancia Magnética Derivado deformación miocárdica mediante función de seguimiento

Purpose: An accurate and practical method to measure parameters like strain in myocardial tissue is of great clinical value, since it has been shown, that ...

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 ...

Assessment of Cardiac Function and Myocardial Morphology Using Small Animal Look-locker Inversion Recovery (SALLI) MRI in 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 animals (200 to 600 beats/min) have previously limited the role of CMR imaging. Small animal Look-Locker inversion recovery (SALLI) is a T1 mapping sequence for small animals to overcome this problem 1. T1 maps provide quantitative information about tissue alterations and contrast agent kinetics. It is also possible to detect diffuse myocardial processes such as interstitial fibrosis or edema 1-6. Furthermore, from a single set of image data, it is possible to examine heart function and myocardial scarring by generating cine and inversion recovery-prepared late gadolinium enhancement-type MR images 1.
	The presented video shows step-by-step the procedures to perform small animal CMR imaging. Here it is presented with a healthy Sprague-Dawley rat, however naturally it can be extended to different cardiac small animal models.

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

Contrast enhanced cardiac magnetic resonance (CMR) imaging allows comprehensive in vivo assessment of the heart in small animal models of cardiovascular disease. Here we detail the procedures to perform CMR imaging, reconstruction and analysis using Small Animal Lock-Locker Inversion Recovery (SALLI) in rats.

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 ...

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 ...

Myocardial Infarction and Functional Outcome Assessment in Pigs

Introduction of newly discovered cardiovascular therapeutics into first-in-man trials depends on a strictly regulated ethical and legal roadmap. One important prerequisite is a good understanding of all safety and efficacy aspects obtained in a large animal model that validly reflect the human scenario of myocardial infarction (MI). Pigs are widely used in this regard since their cardiac size, hemodynamics, and coronary anatomy are close to that of humans. Here, we present an effective protocol for using the porcine MI model using a closed-chest coronary balloon occlusion of the left anterior descending artery (LAD), followed by reperfusion. This approach is based on 90 min of myocardial ischemia, inducing large left ventricle infarction of the anterior, septal and inferoseptal walls. Furthermore, we present protocols for various measures of outcome that provide a wide range of information on the heart, such as cardiac systolic and diastolic function, hemodynamics, coronary flow velocity, microvascular resistance, and infarct size. This protocol can be easily tailored to meet study specific requirements for the validation of novel cardioregenerative biologics at different stages (i.e. directly after the acute ischemic insult, in the subacute setting or even in the chronic MI once scar formation has been completed). This model therefore provides a useful translational tool to study MI, subsequent adverse remodeling, and the potential of novel cardioregenerative agents.

This protocol describes the porcine myocardial infarction (MI) model using a 90 min closed-chest coronary balloon occlusion of the left anterior descending artery (LAD), followed by reperfusion. Furthermore, the protocol for several outcome parameters, such as cardiac function, hemodynamics, microvascular resistance, and infarct size, are also presented.

Infarto de miocardio y la evaluación de resultados funcionales en los cerdos

Introduction of newly discovered cardiovascular therapeutics into first-in-man trials depends on a strictly regulated ethical and legal roadmap. One ...

Primary Outcome Assessment in a Pig Model of Acute Myocardial Infarction

Mortality after acute myocardial infarction remains substantial and is associated with significant morbidity, like heart failure. Novel therapeutics are therefore required to confine cardiac damage, promote survival and reduce the disease burden of heart failure. Large animal experiments are an essential part in the translational process from experimental to clinical therapies. To optimize clinical translation, robust and representative outcome measures are mandatory. The present manuscript aims to address this need by describing the assessment of three clinically relevant outcome modalities in a pig acute myocardial infarction (AMI) model: infarct size in relation to area at risk (IS/AAR) staining, 3-dimensional transesophageal echocardiography (TEE) and admittance-based pressure-volume (PV) loops. Infarct size is the main determinant driving the transition from AMI to heart failure and can be quantified by IS/AAR staining. Echocardiography is a reliable and robust tool in the assessment of global and regional cardiac function in clinical cardiology. Here, a method for three-dimensional transesophageal echocardiography (3D-TEE) in pigs is provided. Extensive insight into cardiac performance can be obtained by admittance-based pressure-volume (PV) loops, including intrinsic parameters of myocardial function that are pre- and afterload independent. Combined with a clinically feasible experimental study protocol, these outcome measures provide researchers with essential information to determine whether novel therapeutic strategies could yield promising targets for future testing in clinical studies.

Reliable and accurate outcome assessment is the key for translation of preclinical therapies into clinical treatment. The current paper describes how to assess three clinically relevant primary outcome parameters of cardiac performance and damage in a pig acute myocardial infarction model.

La evaluación de resultado primaria en un modelo porcino de infarto agudo de miocardio

Mortality after acute myocardial infarction remains substantial and is associated with significant morbidity, like heart failure. Novel therapeutics are ...

Transthoracic Speckle Tracking Echocardiography for the Quantitative Assessment of Left Ventricular Myocardial Deformation

The value of conventional echocardiography is limited by differences in inter-individual image interpretation and therefore largely dependent on the examiners&#39; expertise. Speckle tracking Echocardiography (STE) is a promising but technically challenging method that can be used to quantitatively assess regional and global systolic and diastolic myocardial performance. Myocardial strain and strain rate can be measured in all three dimensions&#160;&#8212; radial, circumferential, longitudinal &#8212; of myocardial deformation. Standard cross-sectional two-dimensional B-mode images are recorded and subsequently postprocessed by automated continuous frame-by-frame tracking and motion analysis of speckles within the myocardium. Images are recorded as digital loops and synchronized to a 3-lead EKG for timing purposes. Longitudinal deformation is assessed in the apical 4-, 3-, and 2-chamber views. Circumferential and radial deformation are measured in the parasternal short axis plane.
Optimal image quality and accurate tissue tracking are paramount for the correct determination of myocardial performance parameters. Utilizing transthoracic STE in a healthy volunteer, the present article is a detailed outline of the essential steps and potential pitfalls of quantitative echocardiographic myocardial deformation analysis.

Speckle tracking echocardiography is an emerging diagnostic imaging technique for the quantitative assessment of global and regional myocardial performance. Standard view echocardiographic motion images are recorded and deformation parameters are subsequently measured by automated continuous frame-by-frame tracking and motion analysis of speckles within the B-mode images of the myocardium.

Transtorácica Ecocardiografía moteado de seguimiento para la evaluación cuantitativa de la deformación miocárdica ventricular izquierda

The value of conventional echocardiography is limited by differences in inter-individual image interpretation and therefore largely dependent on the ...

Histological Quantification of Chronic Myocardial Infarct in Rats

Myocardial infarction is defined as cardiomyocyte death due to prolonged ischemia; an inflammatory response and scar formation (fibrosis) follow the ischemic injury. Following the initial acute phase, chronic remodeling of the left ventricle (LV) modifies the structure and function of the heart. Permanent coronary ligation in small animals has been widely used as a reference model for a chronic model of MI. Thinning of the infarcted wall progressively develops to transmural fibrosis. Histological assessment of infarct size is commonly performed; nevertheless, a standardization of the methods for quantification is missing. Indeed, important methodological aspects, such as the number of sections analyzed and the sampling and quantification methods, are usually not described and therefore preclude comparison across investigations. Too often, quantification is performed on a single section obtained at the level of the papillary muscles. Because novel strategies aimed at reducing infarct expansion and remodeling are under investigation, there is an important need for the standardization of accurate heart sampling protocols. We describe an accurate method to quantify the infarct size using a systematic sampling of harvested rat heart and image analyses of trichromatic stained histological sections obtained from base to apex. We also provide evidence that calculating the expansion index (EI) allowed for infarct size assessment, taking into account changes of the left ventricle throughout the remodeling.

The post-mortem assessment of myocardial infarction (MI) in rodents is based on quantification of the infarct on stained heart sections. We describe an accurate method to quantify the infarct size using systematic sampling of harvested rat hearts from base to apex and image analyses of trichrome-stained histological sections.

La cuantificación histológica de miocardio infarto crónico en ratas

Myocardial infarction is defined as cardiomyocyte death due to prolonged ischemia; an inflammatory response and scar formation (fibrosis) follow the ...

3D Whole-heart Myocardial Tissue Analysis

Cardiac regenerative therapies aim to protect and repair the injured heart in patients with ischemic heart disease. By injecting stem cells or other biologicals that enhance angio- or vasculogenesis into the infarct border zone (IBZ), tissue perfusion is improved, and the myocardium can be protected from further damage. For maximum therapeutic effect, it is hypothesized that the regenerative substance is best delivered to the IBZ. This requires accurate injections and has led to the development of new injection techniques. To validate these new techniques, we have designed a validation protocol based on myocardial tissue analysis. This protocol includes whole-heart myocardial tissue processing that enables detailed two-dimensional (2D) and three-dimensional (3D) analysis of the cardiac anatomy and intramyocardial injections. In a pig, myocardial infarction was created by a 90-min occlusion of the left anterior descending coronary artery. Four weeks later, a mixture of a hydrogel with superparamagnetic iron oxide particles (SPIOs) and fluorescent beads was injected in the IBZ using a minimally-invasive endocardial approach. 1 h after the injection procedure, the pig was euthanized, and the heart was excised and embedded in agarose (agar). After the solidification of the agar, magnetic resonance imaging (MRI), slicing of the heart, and fluorescence imaging were performed. After image post-processing, 3D analysis was performed to assess the IBZ targeting accuracy. This protocol provides a structured and reproducible method for the assessment of the targeting accuracy of intramyocardial injections into the IBZ. The protocol can be easily used when the processing of scar tissue and/or validation of the injection accuracy of the whole heart is desired.

This protocol describes a novel method for the 3D comparison of whole-heart myocardial tissue with MRI. This is designed for the accurate assessment of intramyocardial injections in the infarct border zone of a chronic porcine model of myocardial infarction.

El análisis del tejido de miocardio entero en 3D del corazón

Cardiac regenerative therapies aim to protect and repair the injured heart in patients with ischemic heart disease. By injecting stem cells or other ...

Ultrasonic-augmented Primary Adult Fibroblast Isolation

Primary adult fibroblasts have become an important tool to study fibrosis, fibroblast interactions and inflammation in all body tissues. Since primary fibroblasts cannot divide indefinitely due to myofibroblast differentiation or senescence induction, new cultures must be established regularly. However, there are several obstacles to overcome during the processes of developing a reliable isolation protocol and primary fibroblast isolation itself: the method&#8217;s degree of difficulty (especially for beginners), the risk of bacterial contamination, the required time until primary fibroblasts can be used for experiments, and subsequent cell quality and viability. In this study, a fast, reliable and easy-to-learn protocol to isolate and culture primary adult fibroblasts from mouse heart, lung, liver and kidney combining enzymatic digestion and ultrasonic agitation is provided.

We present a protocol to isolate primary adult fibroblasts in an easy, fast and reliable way, performable by beginners (e.g., students). The procedure combines enzymatic tissue digestion and mechanical agitation with ultrasonic waves to obtain primary fibroblasts. The protocol can easily be adapted to specific experimental requirements (e.g., human tissue).

Aislamiento de fibroblastos para adultos primarios aumentados por ultrasonidos

Primary adult fibroblasts have become an important tool to study fibrosis, fibroblast interactions and inflammation in all body tissues. Since primary ...