NIH grant HL070241 to P.D.

All methods and procedures described here have been approved by the Institutional Animal Care and Use Committee (IACUC) of Tulane University School of Medicine.
1. Tools and instruments for AAB model creation
<ol>
	<li>Obtain disinfectants, such as 70% isopropyl alcohol and povidone-iodine.</li>
	<li>Obtain ketamine and xylazine for anesthesia and buprenorphine for analgesia.</li>
	<li>Obtain a heating pad and heavy absorbency disposable underpad with the dimensions of 18 inches x 30 inches....

<ol>
	<li>McMurray, J. J., Petrie, M. C., Murdoch, D. R., Davie, A. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+epidemiology+of+heart+failure:+public+and+private+health+burden.">Clinical epidemiology of heart failure: public and private health burden.</a> European Heart Journal. 19 (Suppl P), P9-P16 (1998).</li><li>Berk, B. C., Fujiwara, K., Lehoux, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ECM+remodeling+in+hypertensive+heart+disease.">ECM remodeling in hypertensive heart disease.</a> Journal of Clinical Investigation. 117 (3), 568-575 (2007).</li><li>Frey, N., Olson, E. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+hypertrophy:+the+good,+the+bad,+and+the+ugly.">Cardiac hypertrophy: the good, the bad, and the ugly.</a> Annual Review of Physiology. 65, 45-79 (2003).</li><li>Hill, J. A., Olson, E. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+plasticity.">Cardiac plasticity.</a> New England Journal of Medicine. 358 (13), 1370-1380 (2008).</li><li>Kehat, I., Molkentin, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+pathways+underlying+cardiac+remodeling+during+pathophysiological+stimulation.">Molecular pathways underlying cardiac remodeling during pathophysiological stimulation.</a> Circulation. 122 (25), 2727-2735 (2010).</li><li>Rothermel, B. A., Hill, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Autophagy+in+load-induced+heart+disease.">Autophagy in load-induced heart disease.</a> Circulation Research. 103 (12), 1363-1369 (2008).</li><li>Barrick, C. 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=Parent-of-origin+effects+on+cardiac+response+to+pressure+overload+in+mice.">Parent-of-origin effects on cardiac response to pressure overload in mice.</a> American Journal of Physiology-Heart and Circulatory Physiology. 297 (3), H1003-H1009 (2009).</li><li>Barrick, C. J., Rojas, M., Schoonhoven, R., Smyth, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+response+to+pressure+overload+in+129S1/SvImJ+and+C57BL/6J+mice:+temporal-+and+background-dependent+development+of+concentric+left+ventricular+hypertrophy.">Cardiac response to pressure overload in 129S1/SvImJ and C57BL/6J mice: temporal- and background-dependent development of concentric left ventricular hypertrophy.</a> American Journal of Physiology-Heart and Circulatory Physiology. 292 (5), H2119-H2130 (2007).</li><li>Lygate, C. A., 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=Serial+high+resolution+3D-MRI+after+aortic+banding+in+mice:+band+internalization+is+a+source+of+variability+in+the+hypertrophic+response.">Serial high resolution 3D-MRI after aortic banding in mice: band internalization is a source of variability in the hypertrophic response.</a> Basic Research in Cardiology. 101 (1), 8-16 (2006).</li><li>Chaanine, A. H., Hajjar, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+the+Differential+Progression+of+Left+Ventricular+Remodeling+in+a+Rat+Model+of+Pressure+Overload+Induced+Heart+Failure.+Does+Clip+Size+Matter?.">Characterization of the Differential Progression of Left Ventricular Remodeling in a Rat Model of Pressure Overload Induced Heart Failure. Does Clip Size Matter?.</a> Methods in Molecular Biology (Clifton, N.J.). 1816, 195-206 (2018).</li><li>Chaanine, A. H., 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=Mitochondrial+Integrity+and+Function+in+the+Progression+of+Early+Pressure+Overload-Induced+Left+Ventricular+Remodeling.">Mitochondrial Integrity and Function in the Progression of Early Pressure Overload-Induced Left Ventricular Remodeling.</a> Journal of the American Heart Association. 6 (6), (2017).</li><li>Chaanine, A. H., 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=Potential+role+of+BNIP3+in+cardiac+remodeling,+myocardial+stiffness,+and+endoplasmic+reticulum:+mitochondrial+calcium+homeostasis+in+diastolic+and+systolic+heart+failure.">Potential role of BNIP3 in cardiac remodeling, myocardial stiffness, and endoplasmic reticulum: mitochondrial calcium homeostasis in diastolic and systolic heart failure.</a> Circulation: Heart Failure. 6 (3), 572-583 (2013).</li><li>Takagawa, 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=Myocardial+infarct+size+measurement+in+the+mouse+chronic+infarction+model:+comparison+of+area-+and+length-based+approaches.">Myocardial infarct size measurement in the mouse chronic infarction model: comparison of area- and length-based approaches.</a> Journal of Applied Physiology (Bethesda, Md. : 1985). 102 (6), 2104-2111 (2007).</li><li>Vietta, G. G., 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=Early+use+of+cardiac+troponin-I+and+echocardiography+imaging+for+prediction+of+myocardial+infarction+size+in+Wistar+rats.">Early use of cardiac troponin-I and echocardiography imaging for prediction of myocardial infarction size in Wistar rats.</a> Life Sciences. 93 (4), 139-144 (2013).</li><li>Frangogiannis, N. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+inflammatory+response+in+myocardial+injury,+repair,+and+remodelling.">The inflammatory response in myocardial injury, repair, and remodelling.</a> Nature Reviews. Cardiology. 11 (5), 255-265 (2014).</li><li>Doggrell, S. A., Brown, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rat+models+of+hypertension,+cardiac+hypertrophy+and+failure.">Rat models of hypertension, cardiac hypertrophy and failure.</a> Cardiovascular Research. 39 (1), 89-105 (1998).</li></ol>

All authors report no conflict of interest.

Following PO related to AAB in rat, the LV undergoes concentric remodeling by increasing LV wall thickness, known as concentric LVH, as a compensatory mechanism to counteract for the increase in LV wall stress. Increase in LV wall thickness becomes noticeable during the first week following AAB and reaches its maximum thickness at 2-3 weeks post-AAB. During this time period, activation of maladaptive signal transduction pathways lead to progressive enlargement of the LV with increases in LV volumes, a process known as ec...

Heart failure (HF) is a prevalent disease and is associated with high morbidity and mortality1. Rodent pressure-overload (PO) models of HF, produced by ascending or transverse aortic banding, are commonly used to explore molecular mechanisms leading to HF and to test potential novel therapeutic targets in HF. They also mimic changes seen in human HF secondary to prolonged systemic hypertension or severe aortic stenosis. Following PO, the left ventricular (LV) wall gradually increases in thickness, a process known as concentric LV hypertrophy (LVH), to compensate and adapt for the increase in LV wall stress. However, this is associated with the activation of a number of maladaptive signaling pathways, which lead to derangements in calcium cycling and homeostasis, metabolic and extracellular matrix remodeling and changes in gene expression as well as enhanced apoptosis and autophagy2,3,4,5,6. These molecular changes constitute the trigger for the initiation and propagation of myocardial remodeling and transition into a decompensated HF phenotype.
Despite the use of inbred rodent strains and standardization of clip size and surgical technique, there is tremendous phenotypic variability in LV chamber structure and function in aortic banding models7,8,9. The phenotypic variability encountered after PO in rat, Sprague-Dawley strain, is described elsewhere10,11. Of those, two HF phenotypes are encountered with evidence of myocardial remodeling and activation of signal transduction pathways leading to a state of heightened oxidative stress. This is associated with metabolic remodeling, altered gene expression and changes in posttranslational modification of proteins, altogether playing a role in the remodeling process10,12. The first is a phenotype of moderate remodeling and early systolic dysfunction (MOD) and the second is a phenotype of overt systolic HF (HFrEF).
The PO model of HF is advantageous over the myocardial infarction (MI) model of HF because the PO-induced circumferential and meridional wall stresses are homogeneously distributed across all segments of the myocardium. However, both models suffer from variability in the severity of PO10,11 and in infarct size13,14 along with intense inflammation and scarring at the infarct site15 as well as adhesion to the chest wall and surrounding tissues, which are observed in the MI model of HF. Moreover, the rat PO induced HF model is challenging to create as it is associated with high mortality and failure rates10, with only 20% of the operated rats developing the MOD HF phenotype10.
The MOD is an attractive HF phenotype and constitutes an evolution of the traditionally created HFrEF phenotype as it allows for early targeting of signal transduction pathways that play a role in myocardial remodeling, especially when it pertains to perturbations in mitochondrial dynamics and function, myocardial metabolism, calcium cycling and extracellular matrix remodeling. These pathophysiological processes are highly evident in the MOD HF phenotype11. In this manuscript, we describe how to create the MOD and HFrEF phenotypes and we address pitfalls while performing the ascending aortic banding (AAB) procedure. We also elaborate on how to best characterize by echocardiography the two HF phenotypes, MOD and HFrEF, and how to differentiate them from other phenotypes that fail to develop severe PO or that develop severe PO and concentric remodeling but without significant eccentric remodeling.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Adson forceps</td>
			<td>F.S.T.</td>
			<td>11019-12</td>
			<td>surgical tool</td>
		</tr>
		<tr>
			<td>Alm chest retractor with blunt teeth</td>
			<td>ROBOZ</td>
			<td>RS-6510</td>
			<td>surgical tool</td>
		</tr>
		<tr>
			<td>Graefe forceps, curved</td>
			<td>F.S.T.</td>
			<td>11152-10</td>
			<td>surgical tool</td>
		</tr>
		<tr>
			<td>Halsted-Mosquito Hemostats, straight</td>
			<td>F.S.T.</td>
			<td>13010-12</td>
			<td>surgical tool</td>
		</tr>
		<tr>
			<td>Hardened fine iris scissors, straight</td>
			<td>Fine Science Tools F.S.T.</td>
			<td>14090-11</td>
			<td>surgical tool</td>
		</tr>
		<tr>
			<td>hemoclip traditional-stainless steel ligating clips</td>
			<td>Weck</td>
			<td>523435</td>
			<td>surgical tool</td>
		</tr>
		<tr>
			<td>Mayo-Hegar needle holder</td>
			<td>F.S.T.</td>
			<td>12004-18</td>
			<td>surgical tool</td>
		</tr>
		<tr>
			<td>mechanical ventilator</td>
			<td>CWE inc</td>
			<td>SAR-830/AP</td>
			<td>mechanical ventilator for small animals</td>
		</tr>
		<tr>
			<td>Weck stainless steel Hemoclip ligation</td>
			<td>Weck</td>
			<td>533140</td>
			<td>surgical tool</td>
		</tr>
	</tbody>
</table>

a rat model of pressure overload induced moderate remodeling and systolic dysfunction as opposed to overt systolic heart failure

In response to an injury, such as myocardial infarction, prolonged hypertension or a cardiotoxic agent, the heart initially adapts through the activation of signal transduction pathways, to counteract, in the short-term, for the cardiac myocyte loss and or the increase in wall stress. However, prolonged activation of these pathways becomes detrimental leading to the initiation and propagation of cardiac remodeling leading to changes in left ventricular geometry and increases in left ventricular volumes; a phenotype seen in patients with systolic heart failure (HF). Here, we describe the creation of a rat model of pressure overload induced moderate remodeling and early systolic dysfunction (MOD) by ascending aortic banding (AAB) via a vascular clip with an internal area of 2 mm2. The surgery is performed in 200 g Sprague-Dawley rats. The MOD HF phenotype develops at 8-12 weeks after AAB and is characterized noninvasively by means of echocardiography. Previous work suggests the activation of signal transduction pathways and altered gene expression and post-translational modification of proteins in the MOD HF phenotype that mimic those seen in human systolic HF; therefore, making the MOD HF phenotype a suitable model for translational research to identify and test potential therapeutic anti-remodeling targets in HF. The advantages of the MOD HF phenotype compared to the overt systolic HF phenotype is that it allows for the identification of molecular targets involved in the early remodeling process and the early application of therapeutic interventions. The limitation of the MOD HF phenotype is that it may not mimic the spectrum of diseases leading to systolic HF in human. Moreover, it is a challenging phenotype to create, as the AAB surgery is associated with high mortality and failure rates with only 20% of operated rats developing the desired HF phenotype.

Characterization of the HF phenotypes, that develop 8-12 weeks following AAB, could be easily performed via echocardiography. Representative M-mode images of Sham, Week 3 post-AAB, MOD and HFrEF phenotypes are presented in Figure 1A. Figure 1B and Figure 1C are showing the vascular clip size for the creation of the MOD HF phenotype and HFrEF phenotype, respective...

Watch this Scientific Journal Video about A Rat Model of Pressure Overload Induced Moderate Remodeling and Systolic Dysfunction as Opposed to Overt Systolic Heart Failure at JoVE.com

A Rat Model of Pressure Overload Induced Moderate Remodeling and Systolic Dysfunction as Opposed to Overt Systolic Heart Failure

We describe the creation of a rat model of pressure overload induced moderate remodeling and early systolic dysfunction where signal transduction pathways involved in the initiation of the remodeling process are activated. This animal model will aid in identifying molecular targets for applying early therapeutic anti-remodeling strategies for heart failure.

In response to an injury, such as myocardial infarction, prolonged hypertension or a cardiotoxic agent, the heart initially adapts through the activation ...

The rat pressure overload induced moderate remodeling and early systolic dysfunction model is a milder version of the previously created rat pressure overload induced for systolic heart failure model. The study I love, study of the pathways involved in the initiation and propagation of cardiac remodeling, especially as it pertains to metabolic remodeling, myocardial dysfunction, and calcium cycling. Before beginning the procedure, adjust a vascular hemoclip ligation tool via precut seven inch piece of plastic to modify the clip to the appropriate internal area, depending on which heart failure model is desired.Next, confirm a lack of response to fetal reflex in the anesthetized rat and shave the hair under the right axilla at the right lateral thoracic area. Tape the animal's limbs to a plastic dissection board and intubate the animal with a 16-gauge angiocath. Initiate mechanical ventilation with tidal volumes of two milliliters at 50 cycles per minute and a fraction of inspired oxygen of 21 percent.A symmetrical rise in the chest wall should be observed with each breath. Carefully position the animal onto its left lateral side, and bend the tail in a U-shaped manner. Then gently tape the tail to the plastic board and disinfect the exposed skin with povidone iodine.Using a scalpel, make one to two centimeter horizontal skin incisions in the right axilla area one centimeter below the right axilla and dissect the thoracic muscular layer until the thoracic rib cage is reached. Make a one centimeter thoracotomy between the second and third rib and place a chest retractor into the incision before gently dissecting the two lobes of the thymus gland. Push the lobes to the side and use a curved gray forceps to carefully blunt dissect the ascending aorta from the superior vena cava.Once the ascending aorta has been isolated, use the forceps to carefully lift the vessel and place the vascular clip around the ascending aorta. Then use 2-0 monofilament suture to close the thorax before suturing the muscular layer of the chest via A-3-0 vicryl taper suture, and close the skin by a nylon 3-0 monofilament suture. For echocardiographic imaging, after sedation, remove the hair from the anterior chest of the rat and stabilize the animal in the supine position on a plastic dissection board.Acquire 2D parasternal long-axis and a 2D parasternal short-axis view clips at the level of the papillary muscle. Obtain M-mode images from the short parasternal axis view at the level of the papillary muscle to measure left ventricular septal and posterior wall thickness in diastole and the left ventricular end-diastolic and end-systolic diameters. Acquire 2D M-mode short parasternal axis view images at the level of the mid-papillary muscle to serve as a reference to obtain reliable serial and subsequent left ventricle measurements.Then obtain M-mode images of the long parasternal axis view at the level of the aortic valve to assess the relative aortic two-left atrium diameter and end-systole. Characterization of the heart failure phenotypes that develop eight to 12 weeks following ascending aortic banding can be easily performed via echocardiography. 2D long parasternal axis and 2D short parasternal axis echocardiography video clips can be used to measure the left ventricle length and area at end-diastole and end-systole in sham and MOD heart failure animals.In this 2D short parasternal axis view, the increased left ventricle hypertrophy and the MOD phenotype can be observed compared to the appearance of the left ventricle in the sham echocardiography image. Left ventricle and diastolic volume in the MOD heart failure phenotype usually ranges between 600 to 700 microliters with vary few animals exhibiting an end-diastolic volume greater than 700 microliters. The left ventricle and systolic volume in the MOD phenotype ranges between 120 to 160 microliters.In these representative pressure volume loop tracings of sham week three post-descending aortic banding, MOD and overt systolic heart failure animals, the left ventricle maximum pressure at week eight is increased dramatically in MOD and overt systolic heart failure animals compared to week three post-descending aortic banding animals. due to the mismatch between the growth of the animal and the aorta and the fixed created stenosis in the ascending aorta. In addition, week three post AAB animals are fully compensated at three weeks with a decrease in the left ventricle and diastolic and asystolic volumes compared to sham animals.Of note, the rat pressure overload induced heart failure model is associated with high mortality and failure rates with only about 20 percent of the rats that undergo ascending aortic banding transitioning to develop the MOD heart failure phenotype. The most important thing to remember is to properly characterize the phenotype of animals by echocardiography so that to narrow the biological variations observed between animals within the same group. In more dynamic assessment using pressure volume loop catheter can be used to assess relaxation, contract dysfunction, and myochardial stiffness.

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6.3K visualizações.  Tulane University. A sobrecarga de pressão do rato induzida remodelagem moderada e modelo de disfunção sistólica precoce é uma versão mais suave da sobrecarga de pressão de rato previamente criada induzida para o modelo de insuficiência cardíaca sistólica. O estudo que eu amo, estudo das vias envolvidas na iniciação e propagação da remodelagem cardíaca, especialmente no que diz respeito à remodelagem metabólica, disfunção do miocárdio e ciclismo de cálcio. Antes de iniciar o procedimento, a...