This work was supported by a grant (N&#176; 32016) of the Swiss Cardiovascular Foundation to RT.

Male C57BL/6J mice (10 weeks, 25 - 30g, n=60) are used in this protocol. Animals receive humane care in compliance with the guidelines formulated by the French Ministry of Agriculture and of Higher Education and Research, and all procedures are performed in accordance with the European Community Council Directive of November 24, 1986 (86/609/EEC) and the French laws. The protocol was approved by the &#34;Regional Ethics Committee for Animal Experimentation CREMEAS&#34; (#2016092816207606).
1. Pr...

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L., Otis, M., Gallo-Payet, N. <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+blood+pressure+and+morphological+traits+in+cardiovascular-related+organs+in+13+different+inbred+mouse+strains.">Characterization of blood pressure and morphological traits in cardiovascular-related organs in 13 different inbred mouse strains.</a> J. Appl. Physiol. 97 (1), 369-376 (2004).</li><li>Almeida, A. C., van Oort, R. J., Wehrens, X. H. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transverse+aortic+constriction+in+mice.">Transverse aortic constriction in mice.</a> J. Vis. Exp. (38), (2010).</li><li>Hu, P., Zhang, D., Swenson, L., Chakrabarti, G., Abel, E. D., Litwin, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Minimally+invasive+aortic+banding+in+mice:+effects+of+altered+cardiomyocyte+insulin+signaling+during+pressure+overload.">Minimally invasive aortic banding in mice: effects of altered cardiomyocyte insulin signaling during pressure overload.</a> Am. J. Physiol. Heart Circ. Physiol. 285 (3), 1261-1269 (2003).</li><li>Faerber, 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=Induction+of+heart+failure+by+minimally+invasive+aortic+constriction+in+mice:+Reduced+peroxisome+proliferator-activated+receptor+&#978;+coactivator+levels+and+mitochondrial+dysfunction.">Induction of heart failure by minimally invasive aortic constriction in mice: Reduced peroxisome proliferator-activated receptor &#978; coactivator levels and mitochondrial dysfunction.</a> J. 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The aim of this protocol is to present a step-by-step illustration of the surgical technique for minimally invasive transverse aortic constriction in mice. Detailed technical description of transverse aortic constriction in mice has been reported by other authors2,8. However, these investigators perform surgery following intubation and ventilation of animals. The use of an additional step of intubation-ventilation increases the complexity and duration of the whol...

Over the past years, the study of heart failure has been conducted in viable animal models1. Compared to large animal models of heart failure, small animal models have numerous potential advantages. Beside lower costs of housing and maintenance, small animal models are accessible to more researchers due to the less complex facilities needed2.
Mouse heart failure models offer many of the same advantages as the rat models. In addition to reduced housing costs3, mouse models benefit from the availability of relevant transgenic and knockout (KO) strains. The possibility of cell type-specific, inducible KO or transgenic strategies make the mouse an invaluable tool to study the pathogenesis of heart failure and to try to identify novel therapeutic regimens3.
Among the mouse models of heart failure currently used4, transverse aortic constriction (TAC) which was first described by Rockman5 is the preferred model to generate pressure overload-induced left ventricular hypertrophy (LVH)1,3. The greatest advantage of this model is the ability to allow stratification of LVH2, although left ventricular remodeling in response to TAC is variable among different mouse strains. In particular, C57BL/6 mice develop rapid LV dilation after TAC that may not occur with other strains4,6,7.
The sudden onset of hypertension achieved with TAC causes an approximately 50% increase in LV mass within 2 weeks, allowing to rapidly examine the activity of pharmacological or molecular interventions aiming at modulating the development of LVH4. The acute induction of severe hypertension by TAC does not exactly reproduce the progressive left ventricular hypertrophy and remodeling observed in the clinical setting of aortic stenosis or arterial hypertension. Nevertheless, this model is used by many investigators to identify and modify novel therapeutic targets in heart failure4.
Performing TAC in mice requires greater surgical expertise than that required for other techniques used to induce LVH and subsequent heart failure2. Most authors perform this procedure by intubating and ventilating the animal2,8, which makes this procedure more demanding and time-consuming and adds to the surgical burden for the animal. Only few investigators have used minimally invasive TAC in their study with brief reference to the surgical procedure9,10,11.
The aim of this protocol is to describe step-by-step a simplified and user-friendly technique of minimally invasive transverse aortic constriction in mice, highlighting the critical stages of the procedure. By following these key steps, one can easily perform this technique.

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		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="20">
			<td height="20" style="width:216px;height:20px;">Surgical microscope</td>
			<td style="width:108px;">Olympus</td>
			<td style="width:171px;">SZX2-TR30</td>
			<td style="width:63px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Razor</td>
			<td>Rowenta</td>
			<td>Nomad TN3650FO</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="width:495px;height:20px;">Sutures:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Polypropylene 7/0</td>
			<td>Ethicon</td>
			<td>BV-1X</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Polypropylene 6/0</td>
			<td>BBraun</td>
			<td>C0862061</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Silk 6/0 ligature&#160;</td>
			<td>FST</td>
			<td>18020-60</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Polypropylene 4/0</td>
			<td>Ethicon</td>
			<td>8683</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Polypropylene 5/0</td>
			<td>Ethicon</td>
			<td>Z303</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="width:495px;height:20px;">Drugs:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Ketamin</td>
			<td>Merial</td>
			<td>Imalg&#232;ne 1000, LBM154AD</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Xylazine</td>
			<td>Bayer</td>
			<td>Rompun 2%, KP09PPC</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Buprenorphine</td>
			<td>Ceva</td>
			<td>Vetergesic, 072013</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="width:495px;height:20px;">Instruments:&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Bone nippers</td>
			<td>Fine Surgical Tools</td>
			<td>16101-10</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Ligation aid</td>
			<td>Fine Surgical Tools</td>
			<td>18062-12</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Tying forceps</td>
			<td>Fine Surgical Tools</td>
			<td>18026-10</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Needle holder Crile-Wood</td>
			<td>Fine Surgical Tools</td>
			<td>12003-15</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Microsurgery forceps&#160;</td>
			<td>Fine Surgical Tools</td>
			<td>11003-12</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Microsurgery forceps&#160;</td>
			<td>Fine Surgical Tools</td>
			<td>11002-12</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Tissue forceps</td>
			<td>Fine Surgical Tools</td>
			<td>11021-12</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Microsurgery needle holder</td>
			<td>Fine Surgical Tools</td>
			<td>12076-12</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Microsurgery scissors</td>
			<td>Fine Surgical Tools</td>
			<td>91501-09</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Mayo scissors</td>
			<td>Fine Surgical Tools</td>
			<td>14511-15</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">11-blade knife</td>
			<td>Fine Surgical Tools</td>
			<td>10011-00</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="width:495px;height:20px;">RNA extraction and qPCR:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">TriReagent</td>
			<td>Euromedex</td>
			<td>TR-118-200</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Rneasy Mini kit</td>
			<td>Qiagen</td>
			<td>74704</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Qubit Fluorimetric RNA assay</td>
			<td>Fisher Scientific</td>
			<td>10034622</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">RNA 6000 Nano kit</td>
			<td>Agilent</td>
			<td>5067-1511</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">High Capacity cDNA kit</td>
			<td>Fisher Scientific</td>
			<td>10400745</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Taqman Master Mix</td>
			<td>Fisher Scientific</td>
			<td>10157154</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Taqman BNP primers</td>
			<td>Fisher Scientific</td>
			<td>Mm01255770_g1</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="width:216px;height:20px;">Taqman ANP primers</td>
			<td>Fisher Scientific</td>
			<td>Mm01255747_g1&#160;</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Taqman ACE primers</td>
			<td>Fisher Scientific</td>
			<td>Mm00802048_m1</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Taqman Col1a1 primers&#160;</td>
			<td>Fisher Scientific</td>
			<td>Mm00801666_g1</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Taqman TGFb primers</td>
			<td>Fisher Scientific</td>
			<td>Mm01178820_m1</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Taqman Gapdh primers</td>
			<td>Fisher Scientific</td>
			<td>Mm99999915_g1</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">ABIPrism&#160; Thermocycler</td>
			<td>Applied Biosystems</td>
			<td>7000</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="width:495px;height:20px;">Software:</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">GraphPad Prism</td>
			<td>GraphPad</td>
			<td>Prism 7</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="width:495px;height:20px;">Animal food</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="27">
			<td height="27" style="width:216px;height:27px;">Complete diet for adult rats/mice</td>
			<td style="width:108px;">Safe</td>
			<td style="width:171px;">UB220610R</td>
			<td></td>
		</tr>
	</tbody>
</table>

technique of minimally invasive transverse aortic constriction in mice for induction of left ventricular hypertrophy

Transverse aortic constriction (TAC) in mice is one of the most commonly used surgical techniques for experimental investigation of pressure overload-induced left ventricular hypertrophy (LVH) and its progression to heart failure. In the majority of the reported investigations, this procedure is performed with intubation and ventilation of the animal which renders it demanding and time-consuming and adds to the surgical burden to the animal. The aim of this protocol is to describe a simplified technique of minimally invasive TAC without intubation and ventilation of mice. Critical steps of the technique are emphasized in order to achieve low mortality and high efficiency in inducing LVH.
Male C57BL/6 mice (10-week-old, 25-30 g, n=60) were anesthetized with a single intraperitoneal injection of a mixture of ketamine and xylazine. In a spontaneously breathing animal following a 3-4 mm upper partial sternotomy, a segment of 6/0 silk suture threaded through the eye of a ligation aid was passed under the aortic arch and tied over a blunted 27-gauge needle. Sham-operated animals underwent the same surgical preparation but without aortic constriction. The efficacy of the procedure in inducing LVH is attested by a significant increase in the heart/body weight ratio. This ratio is obtained at days 3, 7, 14 and 28 after surgery (n = 6 - 10 in each group and each time point). Using our technique, LVH is observed in TAC compared to sham animals from day 7 through day 28. Operative and late (over 28 days) mortalities are both very low at 1.7%.
In conclusion, our cost-effective technique of minimally invasive TAC in mice carries very low operative and post-operative mortalities and is highly efficient in inducing LVH. It simplifies the operative procedure and reduces the strain put on the animal. It can be easily performed by following the critical steps described in this protocol.

Operative and late survival 
The operative survival was very high, 98.3% (59 out of 60) for the entire series (TAC and sham-operated animals). The only operative death was due to a bleeding complication in a mouse planed for sham operation. Post-operative survival during the observation period of 28 days was also excellent, by 98.3% (58 out of 59). The only late post-operative death occurred in a TAC mouse on day (D) 16, possibly of cardiac origin.
<p class="jove...

Watch this Scientific Journal Video about Technique of Minimally Invasive Transverse Aortic Constriction in Mice for Induction of Left Ventricular Hypertrophy at JoVE.com

Technique of Minimally Invasive Transverse Aortic Constriction in Mice for Induction of Left Ventricular Hypertrophy

The aim of this protocol is to describe step-by-step the technique of minimally invasive transverse aortic constriction (TAC) in mice. By elimination of intubation and ventilation which are mandatory for the commonly used standard procedure, minimally invasive TAC simplifies the operative procedure and reduces the strain put on the animal.

Transverse aortic constriction (TAC) in mice is one of the most commonly used surgical techniques for experimental investigation of pressure ...

The overall goal of this protocol is to establish minimally invasive transverse aortic constriction in mice. This method can help answer key questions about implementing transverse aortic constriction in mice, such as how to create a passage under the aortic arch. The main advantages of this technique are that it is simple, user-friendly, and that it eliminates the need for intubating and ventilating the mice.I will be demonstrating the procedure with our postdoc Simona Nemska who will be performing the presurgical animal preparation and postoperative surveillance steps. On the day of the procedure, shave the neck and chest of an anesthetized mouse and disinfect the exposed skin with 70%ethanol. After confirming the appropriate level of sedation by toe pinch, secure the animal in the supine position onto a clean cork working pad.Next, use a number 11 knife blade to make a 10 millimeter longitudinal midline cervical incision from the suprasternal notch to the mid chest to expose the sternum. Using a Crile-Wood needle holder, pass a 4-0 monofilament polypropylene stay suture to retract the thyroid. And tape the suture to the working pad.Then move the working pad under a surgical microscope and use microsurgical forceps to bluntly separate the pretracheal muscles to uncover the trachea. Gently slide the closed tips of a pair of curved microsurgical forceps over the trachea and behind the sternum and carefully open and close the curved forceps to bluntly dissect the pleura. Use the straight microsurgical forceps to grasp the right supraclavicular muscles and gently pull up on the chest.Sliding the inferior tip of the bone nipper under the sternum, perform a three to four millimeter upper partial sternotomy, directing the lower part of the mini sternotomy slightly toward the left. Using a microsurgical needle holder, pass a 7-0 monofilament polypropylene stay suture from the inside to the outside of the second intercostal space on each side of the mini sternotomy. Use 7-0 monofilament polypropylene stay sutures to spread the sternal edges on each side.And use the curved forceps to gently move the pretracheal muscles, mediastinal fat, and thymus aside to visualize the aortic arch under low power magnification. To expose the soft tissue under the aortic arch, insert tying forceps under the arch with the tips closed and gently open the forceps. Use a second tying forceps to make a tunnel in the soft tissue under the aortic arch by gently opening and closing the forceps in the soft tissue.Then pass a piece of 6-0 silk ligature threaded through the eye of a ligation aid under the aortic arch, using a tying forceps to retrieve the suture from between the origin of the right innominate and left common carotid arteries. The singular most difficult step of the procedure is inserting the suture under the aortic arch. Taking adequate care while creating the tunnel under the arch will make the subsequent suture placement easier.Now use the straight forceps to position a blunted 27 gauge needle next to the aortic arch and use the two tying forceps to tie the suture snugly around the needle and the aorta between the right innominate and left common carotid arteries. When the suture has been secured, quickly but gently remove the needle to achieve a 0.4 millimeter diameter narrowing and a reproducible transverse 65 to 70%aortic constriction. After confirming hemostasis, remove the 7-0 monofilament polypropylene stay sutures used for spreading the sternal edges.Use a microsurgical needle holder to pass a simple 6-0 monofilament polypropylene suture from the outside to the inside of the left second intercostal space and from the inside to the outside of the right second intercostal space. Use the Crile-Wood needle holder to bring the sternal edges together with a 6-0 monofilament polypropylene suture. And close the skin with a 5-0 monofilament polypropylene running suture in one layer with a Crile-Wood needle holder.Then place the animal back in its cage in the prone position under warming with monitoring until full recovery. The efficacy of the left ventricular hypertrophy induction can be validated by comparing the heart weight to body weight ratios of the sham animals to that of the experimental animals at days three, seven, 14, and 28 postsurgery. The ratio significantly increases in the banded animals compared to the sham groups from postoperative day seven on, remaining significantly higher in the constricted animals up through day 28 postsurgery.The observed increase in the heart to body weight ratios is due solely to a rise in the left ventricle body weight ratio as the right ventricle body weight ratio remains comparable between the transverse aortic constriction and the sham operated animals over the entire observation period. In addition, the mRNA expression of the brain natriuretic peptide, a positive control for cardiac hypertrophy in the left ventricles, is significantly higher in the aortic banded animals compared to the control sham operated animals at day 14, further validating the efficiency of the technique. Once mastered, this technique can be completed in 20 minutes if it is performed properly.While attempting this procedure, it is important to use a ligation aid and tying forceps similar to those used in our protocol. After its development, this technique provided a reliable and simplified model for exploring the mechanisms involved in the genesis of pressure overload induced left ventricular hypertrophy. After watching this video, you should have a good understanding of how to perform minimally invasive transverse aortic constriction in mice with a special emphasis on the passage under the aortic arch.Don't forget that creating the passage under the aortic arch is the most critical step of the procedure, and using a ligation aid and tying forceps considerably reduces the risk of injury to the arch.

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Research

JoVE Journal

Medicine

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.

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

Assessment of Cardiac Morphological and Functional Changes in Mouse Model of Transverse Aortic Constriction by Echocardiographic Imaging

Transverse aortic constriction (TAC) in mice has been used as a valuable model to study mechanisms of cardiac hypertrophy and heart failure1. A reliable noninvasive method is essential to assess real-time cardiac morphological and functional changes in animal models of heart disease. Transthoracic echocardiography represents an important tool for noninvasive assessment of cardiac structure and function2. Here we used a high-resolution ultrasound imaging system to monitor myocardial remodeling and heart failure progression over time in a mouse model of TAC. B-mode, M-mode, and Doppler imaging were used to precisely assess cardiac hypertrophy, ventricular dilatation, and functional deterioration in mice following TAC. Color and pulse wave (PW) Doppler imaging was used to noninvasively measure pressure gradient across the aortic constriction created by TAC and to assess transmitral blood flow in mice. Thus transthoracic echocardiographic imaging provides comprehensive noninvasive measurements of cardiac dimensions and function in mouse models of heart disease.

The goal of this protocol is to noninvasively assess cardiac structural and functional changes in a mouse model of heart disease created by transverse aortic constriction, using B- and M-mode echocardiography and color/pulse wave Doppler imaging.

Transverse aortic constriction (TAC) in mice has been used as a valuable model to study mechanisms of cardiac hypertrophy and heart failure1. A reliable ...

Minimally Invasive Transverse Aortic Constriction in Mice

Minimally invasive transverse aortic constriction (MTAC) is a more desirable method for the constriction of the transverse aorta in mice than standard open-chest transverse aortic constriction (TAC). Although transverse aortic constriction is a highly functional method for the induction of high pressure in the left ventricle, it is a more difficult and lengthy procedure due to its use of artificial ventilation with tracheal intubation. TAC is oftentimes also less survivable, as the newer method, MTAC, neither requires the cutting of the ribs and intercostal muscles nor tracheal intubation with a ventilation setup. In MTAC, as opposed to a thoracotomy to access to the chest cavity, the aortic arch is reached through a midline incision in the anterior neck. The thyroid is pulled back to reveal the sternal notch. The sternum is subsequently cut down to the second rib level, and the aortic arch is reached simply by separating the connective tissues and thymus. From there, a suture can be wrapped around the arch and tied with a spacer, and then the sternal cut and skin can be closed. MTAC is a much faster and less invasive way to induce left ventricular hypertension and enables the possibility for high-throughput studies. The success of the constriction can be verified using high-frequency trans-thoracic echocardiography, particularly color Doppler and pulsed-wave Doppler, to determine the flow velocities of the aortic arch and left and right carotid arteries, the dimension of the blood vessels, and the left ventricular function and morphology. A successful constriction will also trigger significant histopathological changes, such as cardiac muscle cell hypertrophy with interstitial and perivascular fibrosis. Here, the procedure of MTAC is described, demonstrating how the resulting flow changes in the carotid arteries can be examined with echocardiography, gross morphology, and histopathological changes in the heart.

Minimally invasive transverse aortic constriction (MTAC) conserves the essentials of regular transverse aortic constriction (TAC) while eliminating the use of a ventilator with tracheal intubation. It proves to be a highly desirable method for high-throughput studies on left ventricular overload, particularly in translational studies.

Minimally invasive transverse aortic constriction (MTAC) is a more desirable method for the constriction of the transverse aorta in mice than standard ...

A Minimally Invasive Model to Analyze Endochondral Fracture Healing in Mice Under Standardized Biomechanical Conditions

Bone healing models are necessary to analyze the complex mechanisms of fracture healing to improve clinical fracture treatment. During the last decade, an increased use of mouse models in orthopedic research was noted, most probably because mouse models offer a large number of genetically-modified strains and special antibodies for the analysis of molecular mechanisms of fracture healing. To control the biomechanical conditions, well-characterized osteosynthesis techniques are mandatory, also in mice. Here, we report on the design and use of a closed bone healing model to stabilize femur fractures in mice. The intramedullary screw, made of medical-grade stainless steel, provides through fracture compression an axial and rotational stability compared to the mostly used simple intramedullary pins, which show a complete lack of axial and rotational stability. The stability achieved by the intramedullary screw allows the analysis of endochondral healing. A large amount of callus tissue, received after stabilization with the screw, offers ideal conditions to harvest tissue for biochemical and molecular analyses. A further advantage of the use of the screw is the fact that the screw can be inserted into the femur with a minimally invasive technique without inducing damage to the soft tissue. In conclusion, the screw is a unique implant that can ideally be used in closed fracture healing models offering standardized biomechanical conditions.

This protocol describes a minimally invasive osteosynthesis technique using an intramedullary screw for standardized stabilization of femur fractures, which can be used to analyze endochondral bone healing in mice.

Bone healing models are necessary to analyze the complex mechanisms of fracture healing to improve clinical fracture treatment. During the last decade, an ...

A Closed-chest Model to Induce Transverse Aortic Constriction in Mice

Research on cardiac hypertrophy and heart failure is frequently based on pressure overload mouse models induced by TAC. The standard procedure is to perform a partial thoracotomy to visualize the transverse aortic arch. However, the surgical trauma caused by the thoracotomy in open-chest models changes the respiratory physiology as the ribs are dissected and left unattached after chest closure. To prevent this, we established a minimally invasive, closed chest approach via lateral thoracotomy. Herein we approach the aortic arch via the 2nd intercostal space without entering the chest cavities, leaving the mouse with a less traumatic injury to recover from. We perform this operation using standard laboratory settings for open chest TAC procedures with equal survival rates. Apart from maintaining physiological breathing patterns due to the closed chest approach, the mice seem to benefit by showing rapid recovery, as the less invasive technique appears to facilitate a fast healing process and to reduce immune response after trauma.

Here, we present a protocol of Transverse Aortic constriction (TAC) via a lateral thoracotomy. This technique is a minimally invasive, closed chest surgical procedure aiming to simulate pressure overload and heart failure in mice utilizing standard TAC laboratory settings.

Research on cardiac hypertrophy and heart failure is frequently based on pressure overload mouse models induced by TAC. The standard procedure is to ...

Studying Left Ventricular Reverse Remodeling by Aortic Debanding in Rodents

To better understand the left ventricular (LV) reverse remodeling (RR), we describe a rodent model wherein, after aortic banding-induced LV remodeling, mice undergo RR upon removal of the aortic constriction. In this paper, we describe a step-by-step procedure to perform a minimally invasive surgical aortic debanding in mice. Echocardiography was subsequently used to assess the degree of cardiac hypertrophy and dysfunction during LV remodeling and RR and to determine the best timing for aortic debanding. At the end of the protocol, terminal hemodynamic evaluation of the cardiac function was conducted, and samples were collected for histological studies. We showed that debanding is associated with surgical survival rates of 70-80%. Moreover, two weeks after debanding, the significant reduction of ventricular afterload triggers the regression of ventricular hypertrophy (~20%) and fibrosis (~26%), recovery of diastolic dysfunction as assessed by the normalization of left ventricular filling and end-diastolic pressures (E/e&#39;&#160;and LVEDP). Aortic debanding is a useful experimental model to study LV RR in rodents. The extent of myocardial recovery is variable between subjects, therefore, mimicking the diversity of RR that occurs in the clinical context, such as aortic valve replacement. We conclude that the aortic banding/debanding model represents a valuable tool to unravel novel insights into the mechanisms of RR, namely the regression of cardiac hypertrophy and the recovery of diastolic dysfunction.

Here we describe a step-by-step protocol of surgical aorta debanding in the well-established mice model of aortic-constriction. This procedure not only allows studying the mechanisms underlying the left ventricular reverse remodeling and regression of hypertrophy but also to test novel therapeutic options that might accelerate myocardial recovery.

To better understand the left ventricular (LV) reverse remodeling (RR), we describe a rodent model wherein, after aortic banding-induced LV remodeling, ...

Invasive Hemodynamic Assessment for the Right Ventricular System and Hypoxia-Induced Pulmonary Arterial Hypertension in Mice

Pulmonary arterial hypertension (PAH) is a chronic and severe cardiopulmonary disorder. Mice are a popular animal model used to mimic this disease. However, the evaluation of right ventricular pressure (RVP) and pulmonary artery pressure (PAP) remains technically challenging in mice. RVP and PAP are more difficult to measure than left ventricular pressure because of the anatomical differences between the left and right heart systems. In this paper, we describe a stable right heart hemodynamic measurement method and its validation using healthy and PAH mice. This method is based on open-chest surgery and mechanical ventilation support. It is a complicated procedure compared to closed chest procedures. While a well-trained surgeon is required for this surgery, the advantage of this procedure is that it can generate both RVP and PAP parameters at the same time, so it is a preferable procedure for the evaluation of PAH models.

Here, we present a protocol to perform an invasive hemodynamic assessment of the right ventricle and pulmonary artery in mice using an open-chest surgery approach.

Pulmonary arterial hypertension (PAH) is a chronic and severe cardiopulmonary disorder. Mice are a popular animal model used to mimic this disease. ...

A Pre-clinical Rat Model for the Study of Ischemia-reperfusion Injury in Reconstructive Microsurgery

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many areas of biomedical research due to its cost-effectiveness and its translation to humans. This protocol describes a method to create a preclinical free skin flap model in rats with ischemia-reperfusion injury. The described 3 cm x 6 cm rat free skin flap model is easily obtained after the placement of several vascular ligatures and the section of the vascular pedicle. Then, 8 h after the ischemic insult and completion of the microsurgical anastomosis, the free skin flap develops the tissue damage. These ischemia-reperfusion injury-related damages can be studied in this model, making it a suitable model for evaluating therapeutic agents to address this pathophysiological process. Furthermore, two main monitoring techniques are described in the protocol for the assessment of this animal model: transit-time ultrasound technology and laser speckle contrast analysis.

Here, we describe a pre-clinical animal model for studying the pathophysiology of ischemia-reperfusion injury in reconstructive microsurgery. This free skin flap model based on the superficial caudal epigastric vessels in the rat may also allow for the evaluation of different therapies and compounds to counteract ischemia-reperfusion injury-related damage.

Ischemia-reperfusion injury is the main cause of flap failure in reconstructive microsurgery. The rat is the preferred preclinical animal model in many ...

Operating Transverse Aortic Constriction with Absorbable Suture to Obtain Transient Myocardial Hypertrophy

Based on twice transverse aortic constrictions (TACs) in mice, it is proved that myocardial hypertrophic preconditioning (MHP) could attenuate cardiomyocyte hypertrophy and slow down progression to heart failure. For novices, however, the MHP model is usually quite difficult to establish because of the technical obstacles in ventilator operation, opening the chest repeatedly, and bleeding caused by debanding. To facilitate this model, to increase the surgical success rate and to reduce the incidence of bleeding, we switched to absorbable sutures for the first TAC combing with a ventilator-free technique. Using a 2-week absorbable suture, we demonstrated that this procedure could cause significant myocardial hypertrophy in 2 weeks; and 4 weeks after surgery, myocardial hypertrophy was almost completely regressed to the baseline. Using this protocol, the operators could master the MHP model easily with a lower operation mortality.

This protocol presents an improved method to obtain transient myocardial hypertrophy with absorbable suture, simulating left ventricular hypertrophy decrease after removing pressure overload. It could be valuable for the studies on myocardial hypertrophic preconditioning.

Based on twice transverse aortic constrictions (TACs) in mice, it is proved that myocardial hypertrophic preconditioning (MHP) could attenuate ...

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

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

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

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