Name: a pulmonary trunk banding model of pressure overload induced right ventricular hypertrophy and failure
Uploaded: 2018-11-29T13:30:00
Description: Watch this Scientific Journal Video about A Pulmonary Trunk Banding Model of Pressure Overload Induced Right Ventricular Hypertrophy and Failure at JoVE.com

This work was supported by The Danish Council for Independent Research [11e108410], the Danish Heart Foundation [12e04-R90-A3852 and 12e04-R90-A3907], and The Novo Nordisk Foundation [NNF16OC0023244].

All rats were treated according to Danish national guidelines&#160;described in the Danish law on animal experiments and Ministerial order on animal experiments. All experiments were approved by the Institutional Ethics Review Board and conducted in accordance with the Danish law for animal research (authorization number 2012-15-2934-00384, Danish Ministry of Justice).
1. Adjustment of the Ligating Clip Applier
NOTE: The banding of the pulmonary trunk...

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We describe an accessible and highly reproducible method of pulmonary trunk banding using a modified ligating clip applier to compress a titanium clip around the pulmonary trunk. By adjusting the applier to compress the clip to different inner diameters, distinct phenotypes of RV hypertrophy and failure can be induced including severe RV failure with extra-cardiac manifestation of decompensation.
Although simple, the protocol contains a few critical steps. Importantly, the rats cannot be too b...

The right ventricle (RV) can adapt to a persistent pressure overload. In time, however, adaptive mechanisms fail to sustain cardiac output, the RV dilates and eventually the RV fails. RV function is the main prognostic factor of several cardiopulmonary disorders including pulmonary arterial hypertension (PAH), thromboembolic pulmonary hypertension (CTEPH), and various forms of congenital heart disease with a pressure (or volume) overload of the RV. Despite intense treatment, RV failure remains a predominant cause of death in these conditions.
As a consequence of the unique properties1,2 and embryological development3 of the RV, knowledge derived from left heart failure cannot simply be extrapolated to right heart failure. Animal models of right heart failure are therefore needed in order to investigate the mechanisms of RV failure and potential pharmacological treatment strategies.
There are experimental models of pulmonary hypertension induced by SU5416 combined with hypoxia (SuHx)4 or monocrotaline (MCT)5, which induce RV failure secondary to disease in the pulmonary vasculature. These models are used to evaluate therapeutic effects of drugs that target the pulmonary vasculature. Both the SuHx and the MCT model are non-fixed afterload models of RV failure. Consequently, it is not possible to conclude if an improvement in RV function after an intervention is secondary to afterload reducing pulmonary vascular effects or if it is caused by direct effects on the RV. In addition, the MCT model has several extra-cardiac effects.
In experimental pulmonary trunk banding models, the afterload of the RV is fixed due to a mechanical constriction of the pulmonary trunk. This allows for the investigation of direct cardiac effects of an intervention on the RV independent from any pulmonary vascular effects6,7,8,9. Usually, the banding is performed by placing a needle along the pulmonary trunk. Then a ligature is placed around the needle and the pulmonary trunk and tied with a knot, and the needle is removed leaving the suture around the pulmonary trunk. Depending on the gauge of the needle, different degrees of constrictions can be applied, but despite this approach being widely used, it has some disadvantages. First, the diameter of the banding is not exactly the same as the outer diameter of the needle as the ligature is tied around both the needle and the pulmonary trunk. Second, there may be significant variation to how tightly the knot is tied making it difficult to reproduce a certain degree of banding. This will lead to a variation in banding diameter and thereby a larger dispersion. Finally, the knot may come loose over time.
One study applies a half-closed tantalum clip around the pulmonary trunk10. They compressed the clip around the pulmonary trunk to an inner area of 1.10 mm2 and compared it to rats subjected to banding with a suture using an 18 G needle. Overall, banding with the clip was associated with less peri-surgical complications and data variance.
Based on the principles described by Schou et al.11, we further developed and characterized the pulmonary trunk banding (PTB) model of RV hypertrophy and failure. Here, we present our experience using this model based on results from previous studies12,13. For this model, a titanium clip is compressed around the pulmonary trunk to an exact preset inner diameter, which may be adjusted in order to induce distinct RV failure phenotypes.

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			<td height="40" style="height:40px;width:217px;">17G IV Venflon Cannula</td>
			<td style="width:189px;">Becton Dickinson, US</td>
			<td style="width:108px;">393228</td>
			<td style="width:291px;">Distal 2 mm of the needle have been cut off</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">1 mL syringe + 26G needle&#160;</td>
			<td>Becton Dickinson, US</td>
			<td>303172 &#38; 303800</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">4-0 absorbable multifilament suture</td>
			<td>Covidien, US</td>
			<td>GL-46-MG</td>
			<td>Polysorb, violet, 5x18&#34;</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">4-0 multifilament ligature</td>
			<td>Covidien, US</td>
			<td>LL-221</td>
			<td>Polysorb, violet, 98&#34;</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Buprenorphine</td>
			<td>Indivior UK Limited</td>
			<td></td>
			<td>Local procurement, Temgesic 0.3 mg/mL</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Carprofene</td>
			<td>ScanVet, DK</td>
			<td>27693</td>
			<td>Norodyl 50 mg/mL</td>
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		<tr height="40">
			<td height="40" style="height:40px;">Chlorhexidine</td>
			<td>Faaborg Pharma, DK</td>
			<td></td>
			<td>Local procurement</td>
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		<tr height="40">
			<td height="40" style="height:40px;">Contractor</td>
			<td>Aesculap, Germany</td>
			<td>BV010R</td>
			<td>Blunt, self retaining, 70 mm</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Ear Hooklet</td>
			<td>Lawton, Germany</td>
			<td>66-0261</td>
			<td>Small, 14 cm, tip modified to an angle of 85&#176;</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Eye gel</td>
			<td>Decra, UK</td>
			<td></td>
			<td>Lubrithal, Local procurement</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Forceps, Delicate Tissue&#160;</td>
			<td>Lawton, Germany</td>
			<td>09-0020</td>
			<td></td>
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		<tr height="40">
			<td height="40" style="height:40px;">Forceps, Dissecting&#160;</td>
			<td>Lawton, Germany</td>
			<td>09-0013</td>
			<td>1 regular, 1 with tip modified to an angle of 100&#176;</td>
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		<tr height="40">
			<td height="40" style="height:40px;">Gas Anesthesia System</td>
			<td>Penlon Limited, UK</td>
			<td>SD0217SL</td>
			<td>Sigma Delta Vaporizer</td>
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		<tr height="40">
			<td height="40" style="height:40px;">Hair trimmer</td>
			<td>Oster</td>
			<td>76998-320-051</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Horizon Open Ligating Clip Applier</td>
			<td>Teleflex, US</td>
			<td>137085</td>
			<td>Modified with adjustable stop mechanism</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Horizon Titanium Clips</td>
			<td>Teleflex, US</td>
			<td>001200</td>
			<td>Small</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Induction chamber</td>
			<td>N/A</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Iris Scissor</td>
			<td>Lawton, Germany</td>
			<td>05-1450</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Iris Scissor&#160;</td>
			<td>Aesculap, Germany</td>
			<td>BC060R</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Mechanical ventilator</td>
			<td>Ugo Basile, Italy</td>
			<td>7025</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Microscissor</td>
			<td>Lawton, Germany</td>
			<td>63-1406</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Microscope</td>
			<td>Carl Zeiss, Germany</td>
			<td>303294-9903</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Needle Holder</td>
			<td>Lawton, Germany</td>
			<td>08-0011</td>
			<td>&#160;TITEGRIP</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Pean</td>
			<td>Lawton, Germany</td>
			<td>06-0100</td>
			<td>Halsted-Mosquito, straight</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Pro-Optha</td>
			<td>Lohmann &#38; Rauscher, Germany</td>
			<td>16515</td>
			<td>Tampon</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Saline 9 mg/mL</td>
			<td>Fresenius Kabi, DK</td>
			<td>209319</td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Sevoflurane</td>
			<td>AbbVie, US</td>
			<td></td>
			<td>Sevorane, Local procurement</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Surgical hook</td>
			<td>Lawton, Germany</td>
			<td>51-0665</td>
			<td>Cushing, 19 cm, tip modified to an angle of 90&#176;</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Surgical Tape</td>
			<td>3M, US</td>
			<td>1530-0</td>
			<td>Micropore</td>
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			<td height="40" style="height:40px;">Temperature Controller</td>
			<td>CMA Microdialysis; Sweden</td>
			<td>8003760</td>
			<td>CMA 450&#160;</td>
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		<tr height="40">
			<td height="40" style="height:40px;">Weighing machine</td>
			<td>VWR, US</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;width:217px;">Wistar rat weanlings</td>
			<td>Janvier Labs, France</td>
			<td style="width:108px;"></td>
			<td>RjHan:WI, 100-120 g</td>
		</tr>
	</tbody>
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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.

Using the described PTB procedure in previous studies from our group12,13, we induced RV hypertrophy (PTB mild) by banding with a 1.0 mm clip, a moderate degree of RV failure (PTB moderate) by banding with a 0.6 mm clip and a severe degree of RV failure (PTB severe) by banding with a 0.5 mm clip. The rats subjected to the severe banding developed extra-cardiac manifestations of RV failure including liver failure and ascites (<stro...

Watch this Scientific Journal Video about A Pulmonary Trunk Banding Model of Pressure Overload Induced Right Ventricular Hypertrophy and Failure at JoVE.com

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

This method can help answer key questions about underlying mechanisms and treatment of right ventricular failure. The main advantage of this technique is that it allows a precise and reproducible afterload increase that induces right ventricular hypertrophy and failure. The implications of this technique extend toward the the therapy of right ventricular failure, because it eliminates effects secondary to pulmonary vasodilation.Before beginning the trunk isolation procedure select an appropriate diameter for the banding and adjust the ligating clip applier until the distance between the jaws is one millimeter when the clip is fully compressed leaving a lumen of 6 millimeters. Next, confirm a lack of response in toe pinch in an anesthetized 100 to 120-gram Wistar rat weanling and make a two-centimeter skin incision along the midline of the sternum. Under a dissecting microscope cut the major pectoral muscle at its sternal attachment and identify the second, third, and fourth costae.Use a pair of scissors to cut the fourth, third, and second costae close to the sternum and carefully dissect the intercostal muscles until a complete left thoracotomy has been performed. When performing the left lateral thoracotomy you should be very careful as the left internal mammorial artery is just bellow the ribcage, so be very careful. Insert a retractor between the sternum and the costae and open the jaws until the thymus is visible at the top of the viewing field.Use the peen forceps to carefully flip the thymus to expose the aorta and the pulmonary trunk and guide the tip of a small surgical hooklet, bent to an 85 degree angle, through the reverse paracardial sinus behind the left atrial appendage. Pull the hooklet halfway back through the sinus and guide the tip of the ear hook upward until it appears between the ascending aorta, and the pulmonary trunk. When placing the ear hook make sure you have the right angle.you shouldn't use any force it might be a bit difficult initially but you can master it with practice. Use iris scissors to remove any connective tissue covering the tip to separate the pulmonary trunk from the ascending aorta. Use angled foreceps to guide a 10 centimeter piece of 4/0 multifilimant ligature around the pulmonary trunk through the passage made by the hook.Seize the end of the ligature with another forceps. The pulmonary trunk should now be separated from the ascending aorta and can be controlled by the ligature around it. When the pulmonary trunk has been secured, use a clip to load the adjusting ligating clip applier.Carefully guide one jaw and one leg of the clip through the passage around the pulmonary trunk using the ligature to gently pull the pulmonary trunk up and into the fork of the clip. When the pulmonary trunk is in the fork, and the two tips of the clip are free of any connective tissue, compress the clip to apply the banding removing the ligature as soon as the right ventricle dilates in response to the banding. When the trunk has been banded remove the peen forceps from the thymus and return the tissue to it's natural position.Remove the retractor, and use absorbable 4/0 multifiliment sutures to close the thorax in three layers. Then subcutaneously inject 2 milliliters of saline to replace any fluid lost during the surgery and monitor the animal until full recumbency. Selecting different diameters of the clip it is possible to induce different stages of disease severity, as evident here by an increasing degree of right ventricular hypertrophy.Only severe banding causes extra cardiac manifestations including liver failure. Differences in moderate versus severe pulminary trunk banding are evident by increasing right ventricular pressure and cause moderate versus severe right ventricular failure as revealed by a stepwise decrease in cardiac output and tricuspid annular plane systolic excursion as the severity of the banding increases. Pulmonary trunk banding procedure induced right ventricle dilation is evident by an increase in both right ventricular end diastolic volume and in systolic volume in the moderate pulmonary trunk banded rats compared to sham-operated animals, and in the severe pulmonary trunk banded rats compared to both the moderate and sham animals.A stepwise decrease in right ventricular ejection fraction is also observed. Right ventricular hypertrophy is further indicated by an increase in cardiomyocyte cross sectional area in pulmonary trunk banded rats, compared to sham-operated animals as well as other morphological changes to the right ventricle associated with right ventricle failure, including right ventricle fibrosis. Once mastered this technique can be performed in 30 minutes if it's performed properly.While attempting this procedure it's important to obtain consistent results with the model before initiating experimental research. After its development this technique paved the way for researchers in the field of right heart failure to explore pharmacologic interventions and basic mechanisms. After watching this video you should have a good understanding on how to perform pulmonary trunk banding.

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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 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. ...

Shunt Surgery, Right Heart Catheterization, and Vascular Morphometry in a Rat Model for Flow-induced Pulmonary Arterial Hypertension

In this protocol, PAH is induced by combining a 60 mg/kg monocrotalin (MCT) injection with increased pulmonary blood flow through an aorto-caval shunt (MCT+Flow). The shunt is created by inserting an 18-G needle from the abdominal aorta into the adjacent caval vein. Increased pulmonary flow has been demonstrated as an essential trigger for a severe form of PAH with distinct phases of disease progression, characterized by early medial hypertrophy followed by neointimal lesions and the progressive occlusion of the small pulmonary vessels. To measure the right heart and pulmonary hemodynamics in this model, right heart catheterization is performed by inserting a rigid cannula containing a flexible ball-tip catheter via the right jugular vein into the right ventricle. The catheter is then advanced into the main and the more distal pulmonary arteries. The histopathology of the pulmonary vasculature is assessed qualitatively, by scoring the pre- and intra-acinar vessels on the degree of muscularization and the presence of a neointima, and quantitatively, by measuring the wall thickness, the wall-lumen ratios, and the occlusion score.

This protocol describes a surgical procedure to create a model for flow-induced pulmonary arterial hypertension (PAH) in rats and the procedures to analyze the principle hemodynamic and histological end-points in this model.

In this protocol, PAH is induced by combining a 60 mg/kg monocrotalin (MCT) injection with increased pulmonary blood flow through an aorto-caval shunt ...

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 ...

O-Ring Aortic Banding Versus Traditional Transverse Aortic Constriction for Modeling Pressure Overload-Induced Cardiac Hypertrophy

Aortic banding in mice is one of the most commonly used experimental models for cardiac pressure overload-induced cardiac hypertrophy and the induction of heart failure. The previously used technique is based on a threaded suture around the aortic arch tied over a blunted 27 G needle to create stenosis. This method depends on the surgeon manually tightening the thread and, thus, leads to high variance in the diameter size. A newly refined method described by Melleby et al. promises less variance and more reproducibility after surgery. The new technique, o-ring- aortic banding (ORAB), uses a non-slip rubber ring instead of a suture with a thread, resulting in reduced variation in pressure overload and reproducible phenotypes of cardiac hypertrophy. During surgery, the o-ring is placed between the brachiocephalic and left carotid arteries. Successful constriction is confirmed by echocardiography. After 1 day, correct placement of the ring results in an increased flow velocity in the transverse aorta over the o-ring-induced stenosis. After 2 weeks, impaired cardiac function is proven by decreased ejection fraction and increased wall thickness. Importantly, besides less variance in the diameter size, ORAB is associated with lower intra- and post-operative mortality rates compared with transverse aortic constriction (TAC). Thus, ORAB represents a superior method to the commonly used TAC surgery, resulting in more reproducible results and a possible reduction in the number of animals needed.

The present protocol describes a new technique of aortic banding in mice to induce pressure overload cardiac hypertrophy. For banding, a rubber ring with a fixed inner diameter is used. This new technique promises less variance and more reproducible data for future experiments.

Aortic banding in mice is one of the most commonly used experimental models for cardiac pressure overload-induced cardiac hypertrophy and the induction of ...

Chronic Ovine Model of Right Ventricular Failure and Functional Tricuspid Regurgitation

The pathophysiology of severe functional tricuspid regurgitation (FTR) associated with right ventricular dysfunction is poorly understood, leading to suboptimal clinical results. We set out to establish a chronic ovine model of FTR and right heart failure to investigate the mechanisms of FTR. Twenty adult male sheep (6-12 months old, 62 &#177; 7 kg) underwent a left thoracotomy and baseline echocardiography. A pulmonary artery band (PAB) was placed and cinched around the main pulmonary artery (PA) to at least double the systolic pulmonary artery pressure (SPAP), inducing right ventricular (RV) pressure overload and signs of RV dilatation. PAB acutely increased the SPAP from 21 &#177; 2 mmHg to 62 &#177; 2 mmHg. The animals were followed for 8 weeks, symptoms of heart failure were treated with diuretics, and surveillance echocardiography was used to assess for pleural and abdominal fluid collection. Three animals died during the follow-up period due to stroke, hemorrhage, and acute heart failure. After 2 months, a median sternotomy and epicardial echocardiography were performed. Of the surviving 17 animals, 3 developed mild tricuspid regurgitation, 3 developed moderate tricuspid regurgitation, and 11 developed severe tricuspid regurgitation. Eight weeks of pulmonary artery banding resulted in a stable chronic ovine model of right ventricular dysfunction and significant FTR. This large animal platform can be used to further investigate the structural and molecular basis of RV failure and functional tricuspid regurgitation.

Right ventricular failure and functional tricuspid regurgitation are associated with left-sided heart disease and pulmonary hypertension, which contribute significantly to morbidity and mortality in patients. Establishing a chronic ovine model to study right ventricular failure and functional tricuspid regurgitation will help in understanding their mechanisms, progression, and possible treatments.

The pathophysiology of severe functional tricuspid regurgitation (FTR) associated with right ventricular dysfunction is poorly understood, leading to ...