This work was supported by Snedkermester Sophus Jacobsen og Hustru Astrid Jacobsens Fond, Helge Peetz og Verner Peetz og hustru Vilma Peetz Legat, Grosserer A.V. Lykfeldt og Hustrus Legat. Furthermore, the authors would like to acknowledge the staff of the animal facilities at the Department of Clinical Medicine, Aarhus University, for their support during the execution of the experimental work.

Creating a Murine Model of RV Hypertrophy and Failure by Pulmonary Trunk Banding

<ol>
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R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+models+of+pulmonary+hypertension+based+on+VEGF+receptor+blockade-induced+endothelial+cell+apoptosis.">New models of pulmonary hypertension based on VEGF receptor blockade-induced endothelial cell apoptosis.</a> Pulm Circ. 2 (4), 434-442 (2012).</li><li>Hessel, M. H., Steendijk, P., Den Adel, B., Schutte, C. I., Van Der Laarse, A. <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+right+ventricular+function+after+monocrotaline-induced+pulmonary+hypertension+in+the+intact+rat.">Characterization of right ventricular function after monocrotaline-induced pulmonary hypertension in the intact rat.</a> Am J Physiol Heart Circ Physiol. 291 (5), H2424-H2430 (2006).</li><li>Gomez-Arroyo, J. 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B., 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=Effects+of+6-mercaptopurine+in+pressure+overload+induced+right+heart+failure.">Effects of 6-mercaptopurine in pressure overload induced right heart failure.</a> PLoS One. 14 (11), e0225122 (2019).</li><li>Egemnazarov, B., 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=Pressure+overload+creates+right+ventricular+diastolic+dysfunction+in+a+mouse+model:+Assessment+by+echocardiography.">Pressure overload creates right ventricular diastolic dysfunction in a mouse model: Assessment by echocardiography.</a> J Am Soc Echocardiogr. 28 (7), 828-843 (2015).</li><li>Wang, Q., 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+right+ventricular+failure+by+pulmonary+artery+constriction+and+evaluation+of+right+ventricular+function+in+mice.">Induction of right ventricular failure by pulmonary artery constriction and evaluation of right ventricular function in mice.</a> J Vis Exp. (147), e59431 (2019).</li><li>Kojonazarov, B., 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=The+peroxisome+proliferator-activated+receptor+&#946;/&#948;+agonist+gw0742+has+direct+protective+effects+on+right+heart+hypertrophy.">The peroxisome proliferator-activated receptor &#946;/&#948; agonist gw0742 has direct protective effects on right heart hypertrophy.</a> Pulm Circ. 3 (4), 926-935 (2013).</li><li>Kojonazarov, B., 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=P38+MAPK+inhibition+improves+heart+function+in+pressure-loaded+right+ventricular+hypertrophy.">P38 MAPK inhibition improves heart function in pressure-loaded right ventricular hypertrophy.</a> Am J Respir Cell Mol Biol. 57 (5), 603-614 (2017).</li><li>Rai, N., 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=Effect+of+Riociguat+and+Sildenafil+on+right+heart+remodeling+and+function+in+pressure+overload+induced+model+of+pulmonary+arterial+banding.">Effect of Riociguat and Sildenafil on right heart remodeling and function in pressure overload induced model of pulmonary arterial banding.</a> Biomed Res Int. 2018, 3293584 (2018).</li><li>Sydykov, 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=Genetic+deficiency+and+pharmacological+stabilization+of+mast+cells+ameliorate+pressure+overload-induced+maladaptive+right+ventricular+remodeling+in+mice.">Genetic deficiency and pharmacological stabilization of mast cells ameliorate pressure overload-induced maladaptive right ventricular remodeling in mice.</a> Int J Mol Sci. 21 (23), 9099 (2020).</li><li>Andersen, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+combined+angiotensin+ii+receptor+antagonism+and+neprilysin+inhibition+in+experimental+pulmonary+hypertension+and+right+ventricular+failure.">Effects of combined angiotensin ii receptor antagonism and neprilysin inhibition in experimental pulmonary hypertension and right ventricular failure.</a> Int J Cardiol. 293, 203-210 (2019).</li><li>Andersen, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pressure+overload+induced+right+ventricular+remodeling+is+not+attenuated+by+the+anti-fibrotic+agent+pirfenidone.">Pressure overload induced right ventricular remodeling is not attenuated by the anti-fibrotic agent pirfenidone.</a> Pulm Circ. 9 (2), 2045894019848659 (2019).</li><li>Labazi, 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=Sex-dependent+changes+in+right+ventricular+gene+expression+in+response+to+pressure+overload+in+a+rat+model+of+pulmonary+trunk+banding.">Sex-dependent changes in right ventricular gene expression in response to pressure overload in a rat model of pulmonary trunk banding.</a> Biomedicines. 8 (10), 430 (2020).</li><li>Sun, X. Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Increased+mao-a+activity+promotes+progression+of+pulmonary+arterial+hypertension.">Increased mao-a activity promotes progression of pulmonary arterial hypertension.</a> Am J Respir Cell Mol Biol. 64 (3), 331-343 (2021).</li><li>Axelsen, J. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+Empagliflozin+on+right+ventricular+adaptation+to+pressure+overload.">Effects of Empagliflozin on right ventricular adaptation to pressure overload.</a> Front Cardiovasc Med. 10, 1302265 (2023).</li><li>Mamazhakypov, A., Veith, C., Schermuly, R. 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The authors have nothing to disclose.

In this paper, we present a murine model of pressure overload-induced RV hypertrophy and failure. We demonstrate that: (i) PTB in juvenile mice can induce varying degrees of RV pathology, ranging from mild RV hypertrophy to RV failure with extracardiac signs of decompensation and histologically confirmed RV fibrosis. (ii) Signs of RV dysfunction can be observed and quantified by echocardiography at 1&#160;and 3&#160;weeks after PTB surgery. (iii) The degree of RV hypertrophy is proportional to the severity of PTB and the...

Right ventricular (RV) failure is a clinical syndrome with symptoms of heart failure and signs of systemic congestion resulting from RV dysfunction1. RV dysfunction is strongly associated with morbidity and mortality in a number of cardiovascular and pulmonary diseases2. The etiology of RV dysfunction is complex, and its underlying signaling pathways and regulation remain inadequately elucidated.
Observations from current therapies show that improved RV function correlates closely to afterload reduction, suggesting pulmonary vasculature as the primary treatment target3. This indicates that current therapies only have a minimal direct effect on RV function, which can deteriorate even after the improvement of pulmonary vascular resistance3. Further research into improving RV function independently of afterload reduction is thus highly needed.
Robust and reproducible animal models are essential in the search for new therapeutic agents. In most models of chronic RV failure, the underlying cause is pulmonary hypertension induced by structural alteration of the pulmonary vasculature4,5,6. Well-characterized models include the chronic hypoxia model7,8, the Sugen-hypoxia model9,10,11, and the monocrotaline model12,13. Because the RV failure is secondary to pulmonary hypertension in these models, it is impossible to differentiate the effects of interventions on the pulmonary vasculature from the direct effects on the RV6.
To study the RV independently from the pulmonary vasculature, the pulmonary trunk banding (PTB) model has gained popularity and has been described in several animal species, including mice, rats, rabbits, dogs, sheep, and pigs6,14,15,16,17,18,19,20,21,22,23,24,25,26,27. In PTB models, constriction of the pulmonary trunk is achieved surgically, causing an increase in RV pressure6. Different approaches to the application of PTB exist, including constriction of the vessel with a ligature or with a metal ligating clip18,28. In models using ligatures, the pulmonary trunk is tied to a needle, and the needle is retracted, leaving the ligature in place. This results in a constriction&#160;of the vessel that depends on the needle size and the tension of the knot18,29. In models employing metal ligating clips, the degree of pulmonary trunk constriction may be more reproducible. Modified ligating clip appliers are used to close the ligating clips to a predefined and constant diameter. This makes the method operator-independent and reduces PTB-related variability in the disease phenotype15,27,28.
Murine PTB models have been shown to induce RV hypertrophy and failure18,28. One major challenge when using the PTB model is choosing the appropriate PTB diameter to achieve the desired degree of RV pathology. This is especially challenging when attempting to model decompensated RV failure. For this, the constriction needs to be tight enough to induce chronic RV failure without leading to acute RV failure and death shortly after surgery6. One approach to solving this challenge is to use weanlings or juvenile animals6,15. A PTB model has been used successfully to study different stages of RV failure using Wistar rat weanlings15,30. To achieve this, juvenile rats with remaining growth potential underwent PTB surgery with the application of titanium ligating clips. When the rats grew, the pulmonary stenosis gradually became more severe and resulted in RV hypertrophy or chronic RV failure, depending on the severity of PTB15,30. Inspired by this model, we hypothesized that different stages of RV pathology could be produced in a murine PTB model using juvenile mice. Studying a broad spectrum of RV pathology from mild to severe disease may help elucidate our understanding of disease progression and the transition from RV hypertrophy to RV failure.
Here, we present a murine model of RV pressure overload induced by PTB in juvenile mice. With this model, different degrees of RV pathology can be produced, ranging from RV hypertrophy to decompensated RV failure. This study includes detailed protocols for intubation, PTB surgery, and phenotyping by echocardiography.

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			<td>Biosyn 6-0, monofilament, absorbable suture</td>
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			<td>Dagrofil 1, braided, non-absorbable suture</td>
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			<td>C0842273</td>
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			<td>Depilatory cream&#160;</td>
			<td>Veet&#160;</td>
			<td>3132000</td>
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			<td>Mediq</td>
			<td>3340122</td>
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			<td>Disposable scalpels, size 11</td>
			<td>Swann-Morton</td>
			<td>11708353</td>
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			<td>Dr&#228;ger Vapor 2000 Sevoflurane</td>
			<td>Dr&#228;ger</td>
			<td>M35054</td>
			<td></td>
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			<td>Eye oinment neutral, &#34;Ophta&#34;</td>
			<td>Actavis</td>
			<td>MTnr.: 07586 Vnr: 53 96 68</td>
			<td></td>
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			<td>Horizon ligating clips</td>
			<td>Teleflex Medical</td>
			<td>5200 (IPN914931)</td>
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			<td>Horizon Open Ligating Clips applier, curved, 6&#34; (15 cm)</td>
			<td>Teleflex Medical</td>
			<td>537061</td>
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			<td>Kitchen roll holder</td>
			<td>n.a.</td>
			<td>n.a.</td>
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			<td>Metal wire of different thickness</td>
			<td>n.a.</td>
			<td>n.a.</td>
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			<td>Microsurgical instruments set</td>
			<td>Thompson</td>
			<td>n.a.</td>
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			<td>MiniVent Ventilator</td>
			<td>Hugo Sachs</td>
			<td>Type 845</td>
			<td></td>
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			<td>MS505S transducer&#160;</td>
			<td>Visual sonics</td>
			<td>n.a.</td>
			<td></td>
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			<td>Rimadyl Bovis vet. 50 mg/ml (Carprofen)</td>
			<td>Zoetis</td>
			<td>MTnr: 34547, Vnr: 10 27 99,</td>
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			<td>Sevoflurane Baxter 100 %</td>
			<td>Baxter Medical</td>
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			<td>Silicone tubing</td>
			<td>n.a.</td>
			<td>n.a.</td>
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			<td>Soft plastic sheet</td>
			<td>n.a.</td>
			<td>n.a.</td>
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			<td>Stereomicroscope, &#34;Opmi Pico&#34;</td>
			<td>Carl Zeiss Surgicals GmbH</td>
			<td>n.a.</td>
			<td></td>
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			<td>Ultrasonic probe holder/rail</td>
			<td>Visual Sonics</td>
			<td>11277</td>
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			<td>Varming plate&#160;</td>
			<td>Visual sonics</td>
			<td>11437</td>
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			<td>Venflon ProSafety, 22G, 0,9 x 25mm</td>
			<td>Becton Dickinson</td>
			<td>393222</td>
			<td></td>
		</tr>
	</tbody>
</table>

a murine model of pressure overload-induced right ventricular hypertrophy and failure by pulmonary trunk banding

Right ventricular (RV) failure caused by pressure overload is strongly associated with morbidity and mortality in a number of cardiovascular and pulmonary diseases. The pathogenesis of RV failure is complex and remains inadequately understood. To identify new therapeutic strategies for the treatment of RV failure, robust and reproducible animal models are essential. Models of pulmonary trunk banding (PTB) have gained popularity, as RV function can be assessed independently of changes in the pulmonary vasculature.
In this paper, we present a murine model of RV pressure overload induced by PTB in 5-week-old mice. The model can be used to induce different degrees of RV pathology, ranging from mild RV hypertrophy to decompensated RV failure. Detailed protocols for intubation, PTB surgery, and phenotyping by echocardiography are included in the paper. Furthermore, instructions for customizing instruments for intubation and PTB surgery are given, enabling fast and inexpensive reproduction of the PTB model.
Titanium ligating clips were used to constrict the pulmonary trunk, ensuring a highly reproducible and operator-independent degree of pulmonary trunk constriction. The severity of PTB was graded by using different inner ligating clip diameters (mild: 450 &#181;m and severe: 250 &#181;m). This resulted in RV pathology ranging from hypertrophy with preserved RV function to decompensated RV failure with reduced cardiac output and extracardiac manifestations. RV function was assessed by echocardiography at 1 week and 3 weeks after surgery. Examples of echocardiographic images and results are presented here. Furthermore, results from right heart catheterization and histological analyses of cardiac tissue are shown.

C57BL/6N mice (male, 5-week old, 17-20 g)&#160;were randomized to either severe PTB (sPTB, 250 &#181;m, n = 12), mild PTB (mPTB, 450 &#181;m, n = 9), or sham surgery (sham, n = 15). Evaluation of cardiac function was performed by echocardiography 1 week and 3 weeks after surgery. Right heart catheterization with subsequent euthanasia was performed 3 weeks post-surgery. Organs were weighed, and cardiac tissue was prepared for histological analyses.
Echocardiography 1 week after surgery revealed...

Author Spotlight: Investigating the Underlying Mechanisms of Right Ventricular Failure in Pulmonary Hypertension

We describe a murine model of right ventricular pressure overload-induced by pulmonary trunk banding. Detailed protocols for intubation, surgery, and phenotyping by echocardiography are included in the paper. Custom-made instruments are used for intubation and surgery, allowing for fast and inexpensive reproduction of the model.

A Murine Model of Pressure Overload-Induced Right Ventricular Hypertrophy and Failure by Pulmonary Trunk Banding

Right ventricular (RV) failure caused by pressure overload is strongly associated with morbidity and mortality in a number of cardiovascular and pulmonary ...

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568 Views.  Aarhus University. We describe a murine model of right ventricular pressure overload-induced by pulmonary trunk banding. Detailed protocols for intubation, surgery, and phenotyping by echocardiography are included in the paper. Custom-made instruments are used for intubation and surgery, allowing for fast and inexpensive reproduction of the model. 

Video: Author Spotlight: Investigating the Underlying Mechanisms of Right Ventricular Failure in Pulmonary Hypertension

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, ...

Chronic Thromboembolic Pulmonary Hypertension and Assessment of Right Ventricular Function in the Piglet

An original piglet model of Chronic Thromboembolic Pulmonary Hypertension (CTEPH) associated with chronic Right Ventricular (RV) dysfunction is described. Pulmonary Hypertension (PH) was induced in 3-week-old piglets by a progressive obstruction of the pulmonary vascular bed. A ligation of the left Pulmonary Artery (PA) was performed first through a mini-thoracotomy. Second, weekly embolizations of the right lower pulmonary lobe were done under fluoroscopic guidance with n-butyl-2-cyanoacrylate during 5 weeks. Mean Pulmonary Arterial Pressure (mPAP) measured by ritght heart catheterism, increased progressively, as well as Right Atrial pressure and Pulmonary Vascular Resistances (PVR) after 5 weeks compared to sham animals. Right Ventricular (RV) structural and functional remodeling were assessed by transthoracic echocardiography (RV diameters, RV wall thickness, RV systolic function). RV elastance and RV-pulmonary coupling were assessed by Pressure-Volume Loops (PVL) analysis with conductance method. Histologic study of the lung and the right ventricle were also performed. Molecular analyses on RV fresh tissues could be performed through repeated transcutaneous endomyocardial biopsies. Pulmonary microvascular disease in obstructed and unobstructed territories was studied from lung biopsies using molecular analyses and pathology. Furthermore, the reliability and the reproducibility was associated with a range of PH severity in animals. Most aspects of the human CTEPH disease were reproduced in this model, which allows new perspectives for the understanding of the underlying mechanisms (mitochondria, inflammation) and new therapeutic approaches (targeted, cellular or gene therapies) of the overloaded right ventricle but also pulmonary microvascular disease.

Chronic Thromboembolic Pulmonary Hypertension (CTEPH) and Right Ventricular (RV) dysfunction were induced in piglets by progressive obstruction of the pulmonary arteries. Consequences were remarkably similar to those observed in CTEPH patients. This animal model would be a very useful tool for pathophysiology and therapeutic experiments on CTEPH and RV failure.

An original piglet model of Chronic Thromboembolic Pulmonary Hypertension (CTEPH) associated with chronic Right Ventricular (RV) dysfunction is described. ...

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 ...

Echocardiographic Measurement of Right Ventricular Diastolic Parameters in Mouse

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling associated with conditions of pressure overload. However, the RV diastolic function is rarely quantified in experimental studies. This might be due to technical difficulties in the visualization of the RV in the apical four-chamber view in rodents. Here we describe two positions facilitating the visualization of the apical four-chamber view in mice to assess the RV diastolic function.
The apical four-chamber view is enabled by tilting the mouse fixation platform to the left and caudally (LeCa) or to the right and cranially (RiCr). Both positions provide images of comparable quality. The results of the RV diastolic function obtained from two positions are not significantly different. Both positions are comparably easy to perform. This protocol can be incorporated into published protocols and enables detailed investigations of the RV function.

Here we describe and compare two positions for obtaining the apical four-chamber view in mice. These positions enable the quantification of the right ventricular function, provide comparable results, and can be used interchangeably.

Diastolic dysfunction is a prominent feature of right ventricular (RV) remodeling associated with conditions of pressure overload. However, the RV ...

A Pulmonary Trunk Banding Model of Pressure Overload Induced Right Ventricular Hypertrophy and Failure

Right ventricular (RV) failure induced by sustained pressure overload is a major contributor to morbidity and mortality in several cardiopulmonary disorders. Reliable and reproducible animal models of RV failure are therefore warranted in order to investigate disease mechanisms and effects of potential therapeutic strategies. Banding of the pulmonary trunk is a common method to induce isolated RV hypertrophy but in general, previously described models have not succeeded in creating a stable model of RV hypertrophy and failure.
We present a rat model of pressure overload induced RV hypertrophy caused by pulmonary trunk banding (PTB) that enables different phenotypes of RV hypertrophy with and without RV failure. We use a modified ligating clip applier to compress a titanium clip around the pulmonary trunk to a pre-set inner diameter. We use different clip diameters to induce different stages of disease progression from mild RV hypertrophy to decompensated RV failure.
RV hypertrophy develops consistently in rats subjected to the PTB procedure and depending on the diameter of the applied banding clip, we can accurately reproduce different disease severities ranging from compensated hypertrophy to severe decompensated RV failure with extra-cardiac manifestations.
The presented PTB model is a valid and robust model of pressure overload induced RV hypertrophy and failure that has several advantages to other banding models including high reproducibility and the possibility of inducing severe and decompensated RV failure.

We present a surgical method to induce right ventricular hypertrophy and failure in rats.

Right ventricular (RV) failure induced by sustained pressure overload is a major contributor to morbidity and mortality in several cardiopulmonary ...

Induction and Phenotyping of Acute Right Heart Failure in a Large Animal Model of Chronic Thromboembolic Pulmonary Hypertension

The development of acute right heart failure (ARHF) in the context of chronic pulmonary hypertension (PH) is associated with poor short-term outcomes. The morphological and functional phenotyping of the right ventricle is of particular importance in the context of hemodynamic compromise in patients with ARHF. Here, we describe a method to induce ARHF in a previously described large animal model of chronic PH, and to phenotype, dynamically, right ventricular function using the gold standard method (i.e., pressure-volume PV loops) and with a non-invasive clinically available method (i.e., echocardiography). Chronic PH is first induced in pigs by left pulmonary artery ligation and right lower lobe embolism with biological glue once a week for 5 weeks. After 16 weeks, ARHF is induced by successive volume loading using saline followed by iterative pulmonary embolism until the ratio of the systolic pulmonary pressure over systemic pressure reaches 0.9 or until the systolic systemic pressure decreases below 90 mmHg. Hemodynamics are restored with dobutamine infusion (from 2.5 &#181;g/kg/min to 7.5 &#181;g/kg/min). PV-loops and echocardiography are performed during each condition. Each condition requires around 40 minutes for induction, hemodynamic stabilization and data acquisition. Out of 9 animals, 2 died immediately after pulmonary embolism and 7 completed the protocol, which illustrates the learning curve of the model. The model induced a 3-fold increase in mean pulmonary artery pressure. The PV-loop analysis showed that ventriculo-arterial coupling was preserved after volume loading, decreased after acute pulmonary embolism and was restored with dobutamine. Echocardiographic acquisitions allowed to quantify right ventricular parameters of morphology and function with good quality. We identified right ventricular ischemic lesions in the model. The model can be used to compare different treatments or to validate non-invasive parameters of right ventricular morphology and function in the context of ARHF.

We present a protocol to induce and phenotype an acute right heart failure in a large animal model with chronic pulmonary hypertension. This model can be used to test therapeutic interventions, to develop right heart metrics&#160;or to improve the understanding of acute right heart failure pathophysiology.

The development of acute right heart failure (ARHF) in the context of chronic pulmonary hypertension (PH) is associated with poor short-term outcomes. The ...

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 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.

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 ...

Generation and Characterization of Right Ventricular Myocardial Infarction Induced by Permanent Ligation of the Right Coronary Artery in Mice

Right ventricular infarction (RVI) is a common presentation in clinical practice. Severe RVI can lead to fatal hemodynamic dysfunction and arrhythmia. In contrast to the extensively used mouse myocardial infarction (MI) model generated by left coronary artery ligation, the RVI mouse model is rarely employed due to the difficulty associated with model generation. Research on the mechanisms and treatment of RVI-induced RV remodeling and dysfunction requires animal models to mimic the pathophysiology of RVI in patients. This study introduces a feasible procedure for RVI model generation in C57BL/6J mice. Further, this model was characterized based on the following: infarct size evaluation at 24 h after MI, assessment of cardiac remodeling and function with echocardiography, RV hemodynamics assessment, and histology of the infarct zone at 4 weeks after RVI. In addition, a coronary vasculature cast was performed to observe the coronary arterial arrangement in RV. This mouse model of RVI would facilitate the research on mechanisms of right heart failure and seek new therapeutic targets of RV remodeling.

There are several differences between the right and left ventricles. However, the pathophysiology of right ventricular infarction (RVI) has not been clarified. In the present protocol, a reproducible method for RVI mouse model generation is introduced, which may provide a means to explain the mechanism of RVI.

Right ventricular infarction (RVI) is a common presentation in clinical practice. Severe RVI can lead to fatal hemodynamic dysfunction and arrhythmia. In ...