The authors have nothing to disclose.

The protocol follows the guidelines of the Institutional Animal Care and Use Committee of University of Washington.
1. Surgical Procedure and Preparation for Imaging
<ol>
	<li>Subject C57BL/6 mice to TAC or sham surgery as previously described10.</li>
	<li>One week after TAC or sham surgery, anesthetize the mouse in the induction chamber with 2% isoflurane mixed with 1 L/min O2. Confirm proper anesthetization by unresponsiveness to toe or tail pinching. Use veterinary ointment on eyes to prevent dryness while under anesthesia.&#160;Remove the chest hair by applying hair removal cream. Disinfect mouse skin with 70% ethanol.</li>
	<li>Secure the mouse to an animal-handling platform in the supine position. To maintain a steady level of anesthesia, use a nosecone to deliver 0.5 - 1% isoflurane mixed with 1 L/min O2.</li>
	<li>Apply electrode gel to the paws of the mouse and tape them to the electrode pad.</li>
	<li>Insert a rectal probe to monitor body temperature. Maintain the body temperature at 37 &#176;C via a heating pad or lamp.</li>
	<li>Apply a layer of pre-warmed ultrasound gel to the mouse chest, mainly the area overlying the heart.&#160;&#160;Note: remove ultrasound gel and dry the mouse with sterile gauze after the imaging procedure.</li>
</ol>
2. In the Aortic Arch View, Use B-mode and Doppler Imaging to Evaluate Transverse Aortic Constriction
<ol>
	<li>Use the B-mode setting to obtain the aortic arch view in order to visualize the aorta, major arterial branches, and the constriction site.
	<ol>
		<li>Tilt the left side of the platform up as far as possible to rotate the mouse into left decubitus position. Hold the ultrasound transducer by stand in vertical position and place it on the chest along the right parasternal line, with the notch pointing towards the chin of the mouse.&#160;Note: Do not compress the mouse thorax when lowering the transducer; minimal amount of pressure is required.</li>
		<li>Tilt the transducer up at the level of scapula and rotate slightly clockwise until aortic arch comes into view. Observe the transverse aortic constriction site, which is located between the branching of innominate artery (IA) and left common carotid artery (LCCA) (Figure 1). 
		Note: No constriction is detected in sham-operated mouse.</li>
	</ol>
	</li>
	<li>Click the &#34;color Doppler&#34; button on the workstation to switch to color Doppler mode to monitor directionality and velocity of the blood flow across the constriction site. Acquire and store images by clicking the &#34;cine store&#34; button.</li>
	<li>Click the &#34;PW Doppler&#34; button to switch to pulse wave Doppler mode, and place sample volume (the dashed cursor box) immediately distal to the constriction site to search for the stenotic jet with the highest velocity, then click the &#34;PW Doppler&#34; button to obtain waveforms of aortic flow and measure peak velocity (Figure 2).</li>
	<li>Calculate pressure gradient across the constriction site using the modified Bernoulli&#39;s equation: pressure gradient = 4 x Vmax2. Only include mice with a pressure gradient ranging from 40 to 80 mmHg for further analysis.</li>
</ol>
3. In the Parasternal Long Axis View, Use B-mode and M-mode Imaging to Assess Cardiac Dimensions and Contractility
<ol>
	<li>With the mouse lying in the supine position on the platform, hold the transducer in vertical fashion with the notch pointing to the mouse&#39;s head. Lower the transducer on the thorax parallel to the left parasternal line and rotate 30&#176; counter-clockwise.</li>
	<li>Use B-mode imaging to obtain a full long axis &#34;sagittal&#34; view of the heart. Adjust the angle of the transducer and focus depth to visualize left ventricle, the intraventricular septal wall, and a slight portion of the right ventricular wall. Save the images for later measurements of cardiac wall thickness and chamber dimension. Using &#34;cardiac package&#34;, select parameters such as IVS or LVAW, LVID, and LVPW, and then click on the image to draw corresponding lines for each parameter to obtain the measurements.</li>
	<li>Observe cardiac wall movement patterns and check for possible motion abnormalities, including akinesia, hypokinesia, and asynchrony. 
	Note: Akinesia and hypokinesia denote complete and partial loss of movement of the cardiac wall, respectively. Asynchrony denotes irregular, uncoordinated cardiac wall movement.</li>
	<li>Switch to M-mode, place M-mode cursor perpendicular to the LV walls at the level of the papillary muscle, and acquire images for later measurement of cardiac dimensions and fractional shortening (Figure 3).</li>
</ol>
4. In the Parasternal Short Axis View, Use B-mode and M-mode Imaging to Assess Cardiac Morphology and Function
<ol>
	<li>From the parasternal long axis view, obtain parasternal short axis view by rotating the transducer 90&#176; clockwise. Adjust the transducer to give a horizontal cross-sectional &#34;transverse&#34; view of the heart in B-mode, with both papillary muscles clearly visible and located to the right (the 2 and 4 o&#39;clock position).</li>
	<li>Switch to M-mode and place the M-mode axis at the mid-level of the left ventricle. Acquire and store images for later measurements of cardiac wall thickness, chamber dimension, and fractional shortening (Figure 4). Using &#34;cardiac package&#34;, select parameters in SAX (short axis) including IVS or LVAW, LVID, and LVPW, and click on the image to draw corresponding lines for each parameter to obtain the measurements. 
	Note: Measurements obtained here should correlate closely to those obtained in the parasternal long axis view (Figure 5).</li>
</ol>
5. In the Apical Four-chamber View, Use Doppler Imaging to Assess Systolic and Diastolic Function
<ol>
	<li>Obtain the apical four-chamber view to visualize both left and right ventricles with the atria at the bottom of the screen. In B-mode, from the short axis view, tilt the upper left corner of the platform to angle the mouse&#39;s head down and orient the transducer towards the right shoulder of the mouse. This is essentially to achieve a &#34;coronal&#34; view of the heart looking up towards the apex.</li>
	<li>Visualize the mitral valve in B-mode, and switch to color Doppler mode, placing the sample volume (the dashed cursor box) at the tip of the mitral valve.</li>
	<li>Switch to PW Doppler mode to assess flow patterns across the mitral valve. Align the Doppler probe cursor parallel to the direction of mitral blood flow. Use a probe angle less than 20&#176; to determine peak velocity (Figure 6).</li>
	<li>Save the images for later measurements. Use &#34;cardiac package&#34; and select &#34;MV flow&#34;. Click each parameter and draw corresponding lines to obtain the measurements. Available measurements include: peak E velocity (early filling with active ventricular relaxation), peak A velocity (late filling with atrial contraction), mitral isovolumic relaxation and contraction times (IVRT and IVCT respectively), and ejection time (ET).</li>
	<li>Calculate myocardial performance index (MPI) by MPI = (IVCT + IVRT)/ET.</li>
</ol>
6. Post-procedural Treatment of Animal
<ol>
	<li>Give analgesia and/or sterile saline intraperitoneally to surgical animals when necessary.</li>
	<li>Allow the animal to recover on a heating pad in the prone position. Do not leave an animal unattended until it has regained sufficient consciousness to maintain sternal recumbency. Do not return an animal that has undergone the procedure to the company of other animals until fully recovered.</li>
</ol>

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R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Small+animal+models+of+heart+failure:+development+of+novel+therapies,+past+and+present.">Small animal models of heart failure: development of novel therapies, past and present.</a> Circ Heart Fail. 2 (2), 138-144 (2009).</li><li>Heineke, J., Molkentin, J. 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This work was supported in part by NIH/NHLBI grants R00HL0908076 and R01HL116507 (to Q.L.).

Echocardiography has been widely used to assess cardiac function in rodent models of heart disease2,6. Compared to invasive or terminal methodologies such as pressure-volume loop measurement11 and ex vivo working heart12, echocardiography provides a powerful, noninvasive tool to assess ongoing cardiac structural and functional changes in living animals. To obtain reliable data, it is important to maintain body temperature and heart rate within physiological range13 by ...

Mouse models of heart disease, such as TAC and myocardial infarction (MI), have been proven to be valuable to study disease mechanisms as well as to develop novel therapeutic strategies3. TAC initially induces compensatory hypertrophy, but prolonged pressure overload leads to cardiac dilatation and heart failure4. The tightness of the aortic constriction directly determines the degree of cardiac hypertrophy and its transition to heart failure. Noninvasive and reliable measurement of pressure gradient across the aortic constriction is essential for the success of these studies. Doppler imaging has been used to assess pressure gradient produced by TAC5, which is a noninvasive alternative for catheter-based pressure measurement.
Echocardiography has been widely used to noninvasively measure cardiac morphology as well as systolic and diastolic function in mice6-8. Two-dimensional B-mode imaging is used to detect abnormal movements or structural changes of the heart. One-dimensional M-mode imaging is used for quantification of cardiac dimensions and contractility. Color and PW Doppler imaging has recently been used on rodent ultrasound, which has broad applications for echocardiography, including measurement of flow directionality and velocity, as well as systolic and diastolic performance9. 
Longitudinal real-time monitoring of cardiac function using echocardiography in B-mode, M-mode, color and PW Doppler mode provides comprehensive assessment of cardiac structure and function in mice under physiological and pathological conditions. Here we provide a detailed description of the use of echocardiographic imaging to monitor dynamic cardiac morphological and functional changes in mice following TAC or sham surgery.

<table border="0" cellpadding="0" cellspacing="0" width="1022">
	<tbody>
		<tr height="41">
			<td height="41" style="height:41px;width:339px;">Anesthesia equipment</td>
			<td style="width:343px;">Harvard Apparatus, 84 October Hill Road 
			Holliston, MA</td>
			<td style="width:175px;">723015</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">Vevo 2100 Imaging System</td>
			<td style="width:343px;">VisualSonics Inc., 3080 Yonge Street Suite 6100, Box 66, Toronto, Ontario, Canada</td>
			<td style="width:175px;">Vevo 2100</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">Aquasonic ultrasound gel</td>
			<td style="width:343px;">Parker Laboratories, 286 Eldridge Rd, Fairfield, NJ&#160;</td>
			<td style="width:175px;">03-50</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">Isoflurane</td>
			<td style="width:343px;">Piramal Healthcare, Inc, 3950 Schelden Circle 
			Bethlehem, PA&#160;</td>
			<td style="width:175px;">NDC 66794-017-25</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:339px;">F/air anesthesia gas filter unit</td>
			<td style="width:343px;">A.M. Bickford, Inc, 12318 Big Tree Rd, Wales Center, NY&#160;</td>
			<td style="width:175px;">80120</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Figure 1 shows B-mode images of the aortic arch view of mouse heart subjected to sham (Figure 1A) or TAC surgery (Figure 1B). The aortic arch, innominate artery, left common carotid artery, and left subclavian artery are shown. Note that aortic constriction is clearly visible in TAC but not sham heart. Color Doppler images from aortic view are shown in Figure 2A. The waveforms of aortic flow across the constriction site w...

Watch this Scientific Journal Video about Assessment of Cardiac Morphological and Functional Changes in Mouse Model of Transverse Aortic Constriction by Echocardiographic Imaging at JoVE.com

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

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 ...

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18.1K Views.  University of Washington.  Het doel van dit protocol is om niet-invasief beoordelen cardiale structurele en functionele veranderingen in een muismodel van hart-en vaatziekten door dwarse aorta vernauwing, met behulp van B- en M-mode echocardiografie en kleur / pulse wave Doppler imaging. 

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

Echocardiographic Assessment of the Right Heart in Mice

Transgenic and toxic models of pulmonary arterial hypertension (PAH) are widely used to study the pathophysiology of PAH and to investigate potential therapies. Given the expense and time involved in creating animal models of disease, it is critical that researchers have tools to accurately assess phenotypic expression of disease. Right ventricular dysfunction is the major manifestation of pulmonary hypertension. Echocardiography is the mainstay of the noninvasive assessment of right ventricular function in rodent models and has the advantage of clear translation to humans in whom the same tool is used. Published echocardiography protocols in murine models of PAH are lacking.
In this article, we describe a protocol for assessing RV and pulmonary vascular function in a mouse model of PAH with a dominant negative BMPRII mutation; however, this protocol is applicable to any diseases affecting the pulmonary vasculature or right heart. We provide a detailed description of animal preparation, image acquisition and hemodynamic calculation of stroke volume, cardiac output and an estimate of pulmonary artery pressure.

This article provides a protocol for the echocardiographic assessment of right ventricular size and pulmonary hypertension in mice. Applications include phenotype determination and serial assessment in transgenic and toxin-induced mouse models of cardiomyopathy and pulmonary vascular disease.

Transgenic and toxic models of pulmonary arterial hypertension (PAH) are widely used to study the pathophysiology of PAH and to investigate potential ...

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

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

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

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

Noninvasive Assessment of Cardiac Abnormalities in Experimental Autoimmune Myocarditis by Magnetic Resonance Microscopy Imaging in the Mouse

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events of myocardial injuries, various mouse models of myocarditis have been widely used. This study involved experimental autoimmune myocarditis (EAM) induced with cardiac myosin heavy chain (Myhc)-&#945; 334-352 in A/J mice; the affected animals develop lymphocytic myocarditis but with no apparent clinical signs. In this model, the utility of magnetic resonance microscopy (MRM) as a non-invasive modality to determine the cardiac structural and functional changes in animals immunized with Myhc-&#945; 334-352 is shown. EAM and healthy mice were imaged using a 9.4 T (400 MHz) 89 mm vertical core bore scanner equipped with a 4 cm millipede radio-frequency imaging probe and 100 G/cm triple axis gradients. Cardiac images were acquired from anesthetized animals using a gradient-echo-based cine pulse sequence, and the animals were monitored by respiration and pulse oximetry. The analysis revealed an increase in the thickness of the ventricular wall in EAM mice, with a corresponding decrease in the interior diameter of ventricles, when compared with healthy mice. The data suggest that morphological and functional changes in the inflamed hearts can be non-invasively monitored by MRM in live animals. In conclusion, MRM offers an advantage of assessing the progression and regression of myocardial injuries in diseases caused by infectious agents, as well as response to therapies.

This study demonstrates the successful establishment of magnetic resonance microscopy imaging as a non-invasive tool to assess the cardiac abnormalities in mice affected with autoimmune myocarditis. The data indicate that the technique can be used to monitor the disease-progression in live animals.

Myocarditis is an inflammation of the myocardium, but only ~10% of those affected show clinical manifestations of the disease. To study the immune events ...

A Model of Cardiac Remodeling Through Constriction of the Abdominal Aorta in Rats

Heart failure is one of the leading causes of death worldwide. It is a complex clinical syndromethat includes fatigue, dyspnea, exercise intolerance, and fluid retention. Changes in myocardial structure, electrical conduction, and energy metabolism develop with heart failure, leading to contractile dysfunction, increased risk of arrhythmias, and sudden death. Hypertensive heart disease is one of the key contributing factors of cardiac remodeling associated with heart failure. The most commonly-used animal model mimicking hypertensive heart disease is created via surgical interventions, such as by narrowing the aorta. Abdominal aortic constriction is a useful experimental technique to induce a pressure overload, which leads to heart failure. The surgery can be easily performed, without the need for chest opening or mechanical ventilation. Abdominal aortic constriction-induced cardiac pathology progresses gradually, making this model relevant to clinical hypertensive heart failure. Cardiac injury and remodeling can be observed 10 weeks after the surgery. The method described here provides a simple and effective approach to produce a hypertensive heart disease animal model that is suitable for studying disease mechanisms and for testing novel therapeutics.

A rat model of abdominal aortic constriction that induces cardiac hypertrophy and remodeling is described. An efficient, highly-reproducible, and minimally-invasive method is used to provide a simple yet useful platform for research in myocardial hypertrophy and dysfunction.

Heart failure is one of the leading causes of death worldwide. It is a complex clinical syndromethat includes fatigue, dyspnea, exercise intolerance, and ...

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 ...

Echocardiographic and Histological Examination of Cardiac Morphology in the Mouse

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

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

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

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.

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 ...

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 ...

Echocardiographic Assessment of Cardiac Anatomy and Function in Adult Rats

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

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

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

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

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