Name: shunt surgery, right heart catheterization, and vascular morphometry in a rat model for flow-induced pulmonary arterial hypertension
Uploaded: 2017-02-11T13:00:00
Description: Watch this Scientific Journal Video about Shunt Surgery, Right Heart Catheterization, and Vascular Morphometry in a Rat Model for Flow-induced Pulmonary Arterial Hypertension at JoVE.com

This study was supported by the Netherlands Cardiovascular Research Initiative, the Dutch Heart Foundation, the Dutch Federation of University Medical Centers, the Netherlands Organization for Health Research and Development, and the Royal Netherlands Academy of Sciences (CVON nr. 2012-08, PHAEDRA, The Sebald fund, Stichting Hartekind).

Procedures involving animal subjects have been approved by the Dutch Central Committee for Animal Experiments and the Animal Care Committee at University Medical Center Groningen (NL). Both Wistar and Lewis rats with weights between 180 and 300 g were used.
1. Housing and Acclimatization
<ol>
	<li>After arrival at the central animal facility, house rats in groups of 5 per cage. During a 7-day acclimatization period, accustom the rats to human handling, but do not perform any experimental pro...

<ol>
	<li>Hoeper, M. M., Bogaard, H. J., Condliffe, 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=Definitions+and+diagnosis+of+pulmonary+hypertension.">Definitions and diagnosis of pulmonary hypertension.</a> J Am Coll Cardiol. 62, D42-D50 (2013).</li><li>Stacher, E., Graham, B. B., Hunt, J. M., 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=Modern+age+pathology+of+pulmonary+arterial+hypertension.">Modern age pathology of pulmonary arterial hypertension.</a> Am J Respir Crit Care Med. 186 (3), 261-272 (2012).</li><li>Levy, M., Maurey, C., Celermajer, D. 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=Impaired+apoptosis+of+pulmonary+endothelial+cells+is+associated+with+intimal+proliferation+and+irreversibility+of+pulmonary+hypertension+in+congenital+heart+disease.">Impaired apoptosis of pulmonary endothelial cells is associated with intimal proliferation and irreversibility of pulmonary hypertension in congenital heart disease.</a> J Am Coll Cardiol. 49 (7), 803-810 (2007).</li><li>Sakao, S., Tatsumi, K., Voelkel, N. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversible+or+irreversible+remodeling+in+pulmonary+arterial+hypertension.">Reversible or irreversible remodeling in pulmonary arterial hypertension.</a> Am J Respir Cell Mol Biol. 43 (6), 629-634 (2010).</li><li>Gomez-Arroyo, J. G., Farkas, L., Alhussaini, A. 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=The+monocrotaline+model+of+pulmonary+hypertension+in+perspective.">The monocrotaline model of pulmonary hypertension in perspective.</a> Am J Physiol Lung Cell Mol Physiol. 302 (4), L363-L369 (2012).</li><li>Jones, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serial+noninvasive+assessment+of+progressive+pulmonary+hypertension+in+a+rat+model.">Serial noninvasive assessment of progressive pulmonary hypertension in a rat model.</a> Am J Physiol - Heart Circ Physiol. 283 (1), 364-371 (2002).</li><li>Hoffman, J. I., Rudolph, A. M., Heymann, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulmonary+vascular+disease+with+congenital+heart+lesions:+Pathologic+features+and+causes.">Pulmonary vascular disease with congenital heart lesions: Pathologic features and causes.</a> Circulation. 64 (5), 873-877 (1981).</li><li>van Albada, M. E., Berger, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulmonary+arterial+hypertension+in+congenital+cardiac+disease--the+need+for+refinement+of+the+evian-venice+classification.">Pulmonary arterial hypertension in congenital cardiac disease--the need for refinement of the evian-venice classification.</a> Cardiol Young. 18 (1), 10-17 (2008).</li><li>Dickinson, M. G., Bartelds, B., Borgdorff, M. A., Berger, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+disturbed+blood+flow+in+the+development+of+pulmonary+arterial+hypertension:+Lessons+from+preclinical+animal+models.">The role of disturbed blood flow in the development of pulmonary arterial hypertension: Lessons from preclinical animal models.</a> Am J Physiol Lung Cell Mol Physiol. 305 (1), L1-L14 (2013).</li><li>Garcia, R., Diebold, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple,+rapid,+and+effective+method+of+producing+aortocaval+shunts+in+the+rat.">Simple, rapid, and effective method of producing aortocaval shunts in the rat.</a> Cardiovasc Res. 24 (5), 430-432 (1990).</li><li>Okada, K., Tanaka, Y., Bernstein, M., Zhang, W., Patterson, G. A., Botney, M. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pulmonary+hemodynamics+modify+the+rat+pulmonary+artery+response+to+injury.+A+neointimal+model+of+pulmonary+hypertension.">Pulmonary hemodynamics modify the rat pulmonary artery response to injury. A neointimal model of pulmonary hypertension.</a> Am J Pathol. 151 (4), 1019-1025 (1997).</li><li>van Albada, M. E., Schoemaker, R. G., Kemna, M. S., Cromme-Dijkhuis, A. H., van Veghel, R., Berger, R. 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G., Bartelds, B., Molema, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Egr-1+expression+during+neointimal+development+in+flow-associated+pulmonary+hypertension.">Egr-1 expression during neointimal development in flow-associated pulmonary hypertension.</a> Am J Pathol. 179 (5), 2199-2209 (2011).</li><li>Borgdorff, M. A., Bartelds, B., Dickinson, M. G., Steendijk, P., de Vroomen, M., Berger, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+loading+conditions+reveal+various+patterns+of+right+ventricular+adaptation.">Distinct loading conditions reveal various patterns of right ventricular adaptation.</a> Am J Physiol Heart Circ Physiol. 305 (3), H354-H364 (2013).</li><li>Ruiter, G., de Man, F. S., Schalij, I., 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=Reversibility+of+the+monocrotaline+pulmonary+hypertension+rat+model.">Reversibility of the monocrotaline pulmonary hypertension rat model.</a> Eur Respir J. 42 (2), 553-556 (2013).</li><li>van Albada, M. E., Bartelds, B., Wijnberg, 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=Gene+expression+profile+in+flow-associated+pulmonary+arterial+hypertension+with+neointimal+lesions.">Gene expression profile in flow-associated pulmonary arterial hypertension with neointimal lesions.</a> Am J Physiol Lung Cell Mol Physiol. 298 (4), L483-L491 (2010).</li><li>Dickinson, M. G., Kowalski, P. S., Bartelds, 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=A+critical+role+for+egr-1+during+vascular+remodelling+in+pulmonary+arterial+hypertension.">A critical role for egr-1 during vascular remodelling in pulmonary arterial hypertension.</a> Cardiovasc Res. 103 (4), 573-584 (2014).</li><li>van der Feen, D. E., Dickinson, M. G., Bartelds, M. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Egr-1+identifies+neointimal+remodeling+and+relates+to+progression+in+human+pulmonary+arterial+hypertension.">Egr-1 identifies neointimal remodeling and relates to progression in human pulmonary arterial hypertension.</a> Jheart lung transplant. 35 (4), 481-490 (2016).</li><li>Rungatscher, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+overcirculation-induced+pulmonary+arterial+hypertension+in+aorto-caval+shunt.">Chronic overcirculation-induced pulmonary arterial hypertension in aorto-caval shunt.</a> Microvasc Res. 94, 73-79 (2014).</li><li>O'Blenes, S. B., Fischer, S., McIntyre, B., Keshavjee, S., Rabinovitch, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemodynamic+unloading+leads+to+regression+of+pulmonary+vascular+disease+in+rats.">Hemodynamic unloading leads to regression of pulmonary vascular disease in rats.</a> J Thorac Cardiovasc Surg. 121 (2), 279-289 (2001).</li><li>Sakao, S., Taraseviciene-Stewart, L., Lee, J. D., Wood, K., Cool, C. D., Voelkel, N. 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This method describes the surgical procedure of an aorto-caval shunt in rats pre-treated with MCT to create flow-induced PAH and the techniques to assess the principle hemodynamic and histopathological end points that characterize PAH and this model.
Critical Steps within the Protocol and Troubleshooting
Surgery and post-surgery. During the aorto-caval shunt surgery, the most critical step is the dissection of the aorta and vena cava. The membranes that enclose the aor...

The goal of this method is to create a reproducible model for severe, flow-induced pulmonary arterial hypertension in rats and to measure its principle hemodynamic and histopathological end points.
Pulmonary arterial hypertension (PAH) is a clinical syndrome that encompasses a progressive increase in pulmonary vascular resistance leading to right ventricular failure and death. Within the superordinate disease spectrum of pulmonary hypertensive diseases (PH), PAH is the most severe form and one that remains without a cure1. The underlying arteriopathy in PAH is characterized by a typical form of vascular remodeling that occludes the vessel lumen. Muscularization of normal non-muscularized vessels and hypertrophy of the medial vessel layer are regarded as early disease phenomena in PAH, are also seen in other forms of PH2, and are thought to be reversible3. As PAH advances, the intimal layer begins to remodel, eventually forming characteristic neointimal lesions2. Neointimal-type pulmonary vascular remodeling is exclusive to PAH and is currently regarded to be irreversible4.
As PAH is a rare disease, advances in its pathobiological comprehension and development of novel therapies have relied heavily on animal models. The monocrotalin (MCT) model in rats is a simple single hit model that has been, and still is, used frequently. MCT is a toxin that causes injury to the pulmonary arterioles and regional inflammation5. 60 mg/kg MCT leads to an increase in the mean pulmonary artery pressure (mPAP), pulmonary vascular resistance (PVR), and right ventricular hypertrophy (RVH) after 3 - 4 weeks6. The histomorphology is characterized by isolated medial hypertrophy without neointimal lesions5. The MCT rat model thus represents a moderate form of PH, and not PAH, although it is commonly presented as the latter.
In children with PAH associated with a congenital left-to-right shunt (PAH-CHD), increased pulmonary blood flow is regarded as the essential trigger for the development of neointimal lesions7,8,9. In rats, increased pulmonary blood flow can be induced by the creation of a shunt between the abdominal aorta and the vena cava, a technique first described in 199010. Alternatives to create increased pulmonary flow are by unilateral pneumonectomy or by subclavian to pulmonary artery anastomosis11. Conceptual disadvantages of these models consist of potential compensatory growth of the remaining lung and adaptive pathway activation induced by the pneumonectomy, or of iatrogenic injury of the pulmonary vasculature due to pulmonary artery anastomosis, both confounding the effects of increased pulmonary blood flow.
When an aorto-caval shunt is created and increased pulmonary blood flow is induced as a second hit in MCT-treated rats, characteristic neointimal lesions occur, and a severe form of PAH and associated right ventricular failure (RVF) develop 3 weeks after the increased flow12. The hemodynamic progression of PAH in this model can be assessed in vivo by echocardiography and right heart catheterization. The vascular histomorphology, vessel wall thickness, degree of arteriolar occlusion, and parameters for right ventricular failure form the pillars of the ex vivo characterization of PAH.
This method describes detailed protocols for the aorto-caval shunt (AC-shunt) surgery, right heart catheterization, and qualitative and quantitative assessment of vascular histomorphology.

<table border="0" cellpadding="0" cellspacing="0" width="835">
	<tbody>
		<tr height="25">
			<td height="25" style="height:25px;width:307px;">
			Shunt Surgery
			</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td style="width:196px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Sterile surgical gloves</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Duratears Eye ointment</td>
			<td style="width:151px;">Alcon</td>
			<td style="width:183px;">10380</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Chloride-Hexidine</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Cotton swabs</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Histoacryllic tissue glue</td>
			<td style="width:151px;">B. Braun Medical</td>
			<td>1050052</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Silkam 5-0 sutures black non-resorbable</td>
			<td style="width:151px;">B. Braun Medical</td>
			<td>F1134027</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Safil 4-0 sutures violet resorbable</td>
			<td style="width:151px;">B. Braun Medical</td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">18 G needle&#160;</td>
			<td style="width:151px;">Luer</td>
			<td>NN1838R BD</td>
			<td>tip bent in 45 degrees orifice to the outside</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Gauzes 10x10 cm</td>
			<td>Paul Hartmann</td>
			<td>407825</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Temgesic Buprenorphine</td>
			<td style="width:151px;">RB Pharmaceuticals</td>
			<td style="width:183px;">5429</td>
			<td>subcutaneous injection</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Sodium Chloride 0.9 %</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Ventilation mask Rat</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Scalple blade</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Biemer clamp 18 mm, 5 mm opening&#160;</td>
			<td><a href="https://www.google.nl/url?sa=i&amp;rct=j&amp;q=&amp;esrc=s&amp;source=images&amp;cd=&amp;cad=rja&amp;uact=8&amp;ved=0ahUKEwitqICpkITNAhWiL8AKHe6iCC8QjhwIBQ&amp;url=http%3A%2F%2Fwww.agnthos.se%2Fquote%2Fquote%2Fcaturl%2Fid%2F242%2FBiemer&amp;psig=AFQjCNEnfRXuMQ6Doi4_-2KMYu3qeRovMA&amp;ust=1464777707579746">AgnTho</a></td>
			<td>64-562</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Heat mat</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Kocher Clamp</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Shaving machine</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Microscope</td>
			<td style="width:151px;">Leica</td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:307px;">
			Right Heart Catheterization
			</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Name</td>
			<td style="width:151px;">Company</td>
			<td style="width:183px;">Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Sterile surgical gloves</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Eye ointment</td>
			<td style="width:151px;">Duratears</td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Chloride-Hexidine</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Cotton swabs</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Gauzes 10x10 cm</td>
			<td>Paul Hartmann</td>
			<td>407825</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Silkam 5-0 sutures black non-resorbable</td>
			<td style="width:151px;">B. Braun Medical</td>
			<td>F1134027</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Needle 20 G</td>
			<td style="width:151px;">Luer</td>
			<td style="width:183px;"></td>
			<td>Tip slightly bent to the inside</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Cannula 20 G</td>
			<td style="width:151px;">Luer</td>
			<td style="width:183px;"></td>
			<td>to introduce catheter, tip pre-formed in 20 degrees</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Silastic Catheter 15 cm long</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td>0.5 mm ball 2 mm from tip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Pressure transducer</td>
			<td style="width:151px;">Ailtech</td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Bedside monitor Cardiocap/5</td>
			<td style="width:151px;">Datex-Ohmeda</td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Shaving machine</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">10mL Syringe</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Sodium Chloride 0.9 %</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td>for flushing</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:307px;">
			Vascular Morphology
			</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Name</td>
			<td style="width:151px;">Company</td>
			<td style="width:183px;">Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">50ml Syringe</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">4 % Formaldehyde</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">18 G cannula with tube</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Verhoef staining kit</td>
			<td style="width:151px;">Sigma-Aldrich</td>
			<td><a href="http://www.sigmaaldrich.com/catalog/product/sigma/ht254?lang=en&amp;region=NL">HT254</a></td>
			<td>http://www.sigmaaldrich.com/catalog/product/sigma/ht254?lang=en&#38;region=US</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Digital slide scanner</td>
			<td style="width:151px;">Hamamatsu</td>
			<td style="width:183px;">C9600</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Image-J</td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;">Elastic (Connective Tissue Stain)&#160;</td>
			<td style="width:151px;">Abcam</td>
			<td style="width:183px;">ab150667</td>
			<td>http://www.abcam.com/elastic-connective-tissue-stain-ab150667.html</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:307px;"></td>
			<td style="width:151px;"></td>
			<td style="width:183px;"></td>
			<td>http://www.abcam.com/ps/products/150/ab150667/documents/ab150667-Elastic%20Stain%20Kit%20(website).pdf</td>
		</tr>
	</tbody>
</table>

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.

Representative results are presented in Figure 4. The presented results show characteristics of MCT+FLOW in Lewis rats in the following groups: Control (n = 3), MF8 (n = 5), MF14 (n = 5), MF28 (n = 5), and MF-RVF (n = 10). Statistical analyses were performed using the one-way ANOVA with Bonferroni correction.
60 mg/kg MCT and increased pulmonary blood flow lead to a mean rise in systolic right ventricular pressu...

Watch this Scientific Journal Video about Shunt Surgery, Right Heart Catheterization, and Vascular Morphometry in a Rat Model for Flow-induced Pulmonary Arterial Hypertension at JoVE.com

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

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 ...

The overall goals of these procedures are to create a model for flow-induced pulmonary arterial hypertension in rats, and to analyze its principle hemodynamic and histological endpoints by right heart catheterization and vascular morphometry. We present the creation of a rat model for flow-associated pulmonary hypertension that is characterized by a new intimal-type vascular remodeling similar to the human pulmonary arterial hypertension, and that is induced by a clinically well-recognized trigger, namely increased pulmonary blood flow. These characteristics will enhance the translation of the findings in this model to the human disease.We also show standardized methods for hemodynamic evaluation and characterization of histopathology using quantitative morphometry. The implications of these techniques extend toward the discovery and evaluation of novel treatment strategies and allow the assessment of the specific effects on pulmonary hemodynamics and vascular morphology. Demonstrating the procedures will be Annemieke Smit-Van Oosten and Michel Weij, microsurgeons from this laboratory.Before beginning the surgery, scrub the skin of an anesthetized rat with chloride hexadene for disinfection and inject buprenorphine subcutaneously for post-operative analgesia. Next, use scissors to make a midline incision along the abdomen, starting one centimeter below the diaphragm, extending to just above the genitalia. Transfer the intestines onto a sterile gauze wet with 0.9%saline to the left side of the animal and cover the organ with more wet, sterile gauze.Use new swabs to separate the membranes that attach the abdominal aorta and the vena cava inferior to the surrounding tissues. Under a dissecting microscope, use splinter forceps to remove the perivascular aortic fat just above the bifurcation on the right side of the aorta where the needle will be inserted. Then, separate the aorta and vena cava from two millimeters superior of the site, the needle insertion site, to create space for a beamer clamp.Now place a loose 5-O suture around the aorta and place a Kocher clamp on the suture to create tension on the ligature superior to the incision. Place the beamer clamp just superior to the suture, and use a new swap to compress the vena cava as distally as possible to obstruct the flow. Next, bend an 18 gauge needle to a 45 degree angle with the bevel placing outwards, and holding the needle 90 degrees to the animal, insert the needle tip into the aorta just above the bifurcation with the bevel facing to the left.Dissect the membranes enclosing the aorta and the vena cava just enough to create good visibility of the insertion area for the shunt, as over-dissection will cause the shunt to leak. Manipulate the tip of the needle to the left and insert the needle into the vena cava until it can be observed within the vessel. To prevent thrombosis, use a new cotton swab to push the remaining blood out of the aorta through the insertion site and use a sterile gauze to dry the area around the shunt.Remove the needle and immediately apply a drop of tissue glue onto the puncture site. Then remove the clamp from the aorta and manually release the ligature on the aorta promixal to the shunt. The vena cava distal to the shunt should become bright red and create turbulence at the shunt site.After verifying the shunt, return the intestines to the abdominal cavity and use resorbable 4-0 sutures to close the muscle and skin layers. Then ventilate the animal with 100%oxygen for anesthesia recovery. For right heart catheterization, disinfect the neck with chloride hexadene and use a number 10 scalpel blade to make a 1.5 centimeter incision in the right ventral side of the neck from the right collar bone to the mandibular bone.Under the dissecting microscope, use scissors to spread the tissue, then use tweezers to gently pull the tissue apart until the jugular vein appears. Dissect the membranes around the jugular vein using splinter forceps. Then place a loose 5-O suture around the vessel and tape the ligature to the ventilation mask to increase the tension on the vein.Downstream of the insertion site, place a loose ligature around the vessel. Next, use the forceps handles to slightly bend the tip of a 20 gauge needle with the bevel facing inward and introduce the tip of the needle into the vein. Quickly place a cannula containing a catheter inside the vessel and remove the needle, closing the downstream ligature around the cannula to secure the cannula into place.Now conduct the cannula and the catheter into the jugular vein, maneuvering the cannula under the collar bone to enter the right atrium. Point the tip of the cannula towards the heart to enter the right ventricle. A right ventricle pressure curve should appear on the bedside monitor.When the right ventricle pressure curve is constant, record the systolic and diastolic right ventricular pressure one, and manipulate the tip of the cannula to the left and upwards. Advance the catheter within the cannula, then advance the catheter into the main pulmonary artery. When the pulmonary artery pressure curve is constant, record the systolic, diastolic, and mean pulmonary artery pressure ones.Then advance the catheter within the cannula until the ball at the tip of the catheter becomes wedged in a pulmonary artery. The drop in the pressure curve should be observed on the bedside monitor. When the wedge pressure curve is constant, record the systolic, diastolic, and mean wedge pressures.Then slowly pull back the catheter and, guided by the curves on the bedside monitor, record the respective values for PA and RV pressure. When the catheter reaches the right ventricle, slightly pull the cannula and catheter back and measure the mean right atrial pressure. In this representative experiment, 28 days after MCT administration and an increased pulmonary blood flow, a mean rise in the systolic right ventricular, systolic pulmonary artery, and mean pulmonary artery pressures are observed.The right ventricular to left ventricular and septal weight ratios increase significantly from day 14 post-treatment until the right ventricular failure stage, indicating right ventricle hypertrophy. The wet to dry ratio of the liver is also significantly increased at the right ventricular failure stage, indicating edema of the liver, as well as congestive right ventricular failure. Muscularization of the inter-acinar vessels increases progressively during pulmonary artery hypertension progression with almost half of the vessels exhibiting total muscular media by day 14 post-treatment in nearly all of the arterioles muscularized by the end stage of the disease.Further, neo-intimal lesions are first observed at day 21 with approximately 65%of all the arterioles exhibiting a neo-intimal layer by the end of the disease progression. This results in progressive vascular occlusion with up to 60%of the lumen occluded in the end stage of the disease. Once mastered, these techniques can be complete in 20 minutes per technique.Following this procedure, other methods like echo-cardiography or pressure volume looping can be performed to answer additional questions about right ventricular function. After its development, this technique paves the way for researchers in the field of pulmonary arterial hypertension to explore the effects of increased blood flow on the pulmonary vasculature. After watching this video, you should have a good understanding of how to create a model for flow-induced pulmonary arterial hypertension in rats, and how to analyze its principle hemodynamic and histological endpoints.

shunt-surgery-right-heart-catheterization-vascular-morphometry-rat

Research

JoVE Journal

Medicine

Femoral Arterial and Venous Catheterization for Blood Sampling, Drug Administration and Conscious Blood Pressure and Heart Rate Measurements

In multiple fields of study, access to the circulatory system in laboratory studies is necessary. Pharmacological studies in rats using chronically implanted catheters permit a researcher to effectively and humanely administer substances, perform repeated blood sampling and assists in conscious direct measurements of blood pressure and heart rate. Once the catheter is implanted long-term sampling is possible. Patency and catheter life depends on multiple factors including the lock solution used, flushing regimen and catheter material. This video will demonstrate the methodology of femoral artery and venous catheterization of the rat. In addition the video will demonstrate the use of the femoral venous and arterial catheters for blood sampling, drug administration and use of the arterial catheter in taking measurements of blood pressure and heart rate in a conscious freely-moving rat. A tether and harness attached to a swivel system will allow the animal to be housed and have samples taken by the researcher with minimal disruption to the animal. To maintain patency of the catheter, careful daily maintenance of the catheter is required using lock solution (100 U/ml heparinized saline), machine-ground blunt tip syringe needles and the use of syringe filters to minimize potential contamination. With careful aseptic surgical techniques, proper catheter materials and careful catheter maintenance techniques, it is possible to sustain patent catheters and healthy animals for long periods of time (several weeks).

Chronic catheterization of blood vessels in the rat is often required for administration of substances, obtain blood sample over a period of time or for direct conscious blood pressure measurements. Femoral arterial catheterization of the rat and corresponding measurements of blood pressure in the conscious animal will be demonstrated.

In multiple fields of study, access to the circulatory system in laboratory studies is necessary. Pharmacological studies in rats using chronically ...

Surgical Procedures for a Rat Model of Partial Orthotopic Liver Transplantation with Hepatic Arterial Reconstruction

Orthotopic liver transplantation (OLT) in rats using a whole or partial graft is an indispensable experimental model for transplantation research, such as studies on graft preservation and ischemia-reperfusion injury 1,2, immunological responses 3,4, hemodynamics 5,6, and small-for-size syndrome 7. The rat OLT is among the most difficult animal models in experimental surgery and demands advanced microsurgical skills that take a long time to learn. Consequently, the use of this model has been limited. Since the reliability and reproducibility of results are key components of the experiments in which such complex animal models are used, it is essential for surgeons who are involved in rat OLT to be trained in well-standardized and sophisticated procedures for this model.
While various techniques and modifications of OLT in rats have been reported 8 since the first model was described by Lee et al. 9 in 1973, the elimination of the hepatic arterial reconstruction 10 and the introduction of the cuff anastomosis technique by Kamada et al. 11 were a major advancement in this model, because they simplified the reconstruction procedures to a great degree. In the model by Kamada et al., the hepatic rearterialization was also eliminated. Since rats could survive without hepatic arterial flow after liver transplantation, there was considerable controversy over the value of hepatic arterialization. However, the physiological superiority of the arterialized model has been increasingly acknowledged, especially in terms of preserving the bile duct system 8,12 and the liver integrity 8,13,14.
In this article, we present detailed surgical procedures for a rat model of OLT with hepatic arterial reconstruction using a 50% partial graft after ex vivo liver resection. The reconstruction procedures for each vessel and the bile duct are performed by the following methods: a 7-0 polypropylene continuous suture for the supra- and infrahepatic vena cava; a cuff technique for the portal vein; and a stent technique for the hepatic artery and the bile duct.

Orthotopic liver transplantation in rats is an indispensable experimental model for biomedical research. Here we present our surgical procedures for orthotopic rat liver transplantation with hepatic arterial reconstruction using a 50% partial graft.

Orthotopic liver transplantation (OLT) in rats using a whole or partial graft is an indispensable experimental model for transplantation research, such as ...

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 ...

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. ...

Hemodynamic Characterization of Rodent Models of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare disease of the pulmonary vasculature characterized by endothelial cell apoptosis, smooth muscle proliferation and obliteration of pulmonary arterioles. This in turn results in right ventricular (RV) failure, with significant morbidity and mortality. Rodent models of PAH, in the mouse and the rat, are important for understanding the pathophysiology underlying this rare disease. Notably, different models of PAH may be associated with different degrees of pulmonary hypertension, RV hypertrophy and RV failure. Therefore, a complete hemodynamic characterization of mice and rats with PAH is critical in determining the effects of drugs or genetic modifications on the disease. 
Here we demonstrate standard procedures for assessment of right ventricular function and hemodynamics in both rat and mouse PAH models. Echocardiography is useful in determining RV function in rats, although obtaining standard views of the right ventricle is challenging in the awake mouse. Access for right heart catheterization is obtained by the internal jugular vein in closed-chest mice and rats. Pressures can be measured using polyethylene tubing with a fluid pressure transducer or a miniature micromanometer pressure catheter. Pressure-volume loop analysis can be performed in the open chest. After obtaining hemodynamics, the rodent is euthanized. The heart can be dissected to separate the RV free wall from the left ventricle (LV) and septum, allowing an assessment of RV hypertrophy using the Fulton index (RV/(LV+S)). Then samples can be harvested from the heart, lungs and other tissues as needed.

Pulmonary arterial hypertension (PAH) is a disease of pulmonary arterioles that leads to their obliteration and the development of right ventricular failure. Rodent models of PAH are critical in understanding the pathophysiology of PAH. Here we demonstrate hemodynamic characterization, with right heart catheterization and echocardiography, in the mouse and rat.

Pulmonary arterial hypertension (PAH) is a rare disease of the pulmonary vasculature characterized by endothelial cell apoptosis, smooth muscle ...

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 ...

Left Atrial Stenosis Induced Pulmonary Venous Arterialization and Group 2 Pulmonary Hypertension in Rat

The mechanism of mitral stenosis-induced pulmonary venous arterialization and group 2 pulmonary hypertension (PH) is unclear. There is no rodent model of group 2 PH, due to mitral stenosis (MS), to facilitate the investigation of disease mechanisms and potential therapeutic strategies. We present a novel rat model of pulmonary venous congestion-induced pulmonary venous arterialization and group 2 PH caused by left atrial stenosis (LAS). LAS is achieved by constricting the left atrium using a half-closed titanium clip. After the LAS surgery, a rat model with a transmitral inflow velocity greater than or equal to 2.0 m/s on echocardiography gradually develops pulmonary venous arterialization and group 2 PH over an 8- to 10-week period. In this protocol, we provide the step-by-step procedure of how to perform the LAS surgery. The presented LAS rat model mimics MS in humans and is useful for studying the underlying molecular mechanism of pulmonary venous arterialization and for the preclinical evaluation of therapies for group 2 PH.

Left atrial stenosis (LAS) is a novel surgical technique used for studying group 2 pulmonary hypertension (PH) and mechanisms underlying pulmonary venous arterialization. Here, we present a protocol to constrict the left atrium using a titanium clip to cause pulmonary venous arterialization and moderate PH in a rat.

The mechanism of mitral stenosis-induced pulmonary venous arterialization and group 2 pulmonary hypertension (PH) is unclear. There is no rodent model of ...

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 Rodent Model of The Ross Operation: Syngeneic Pulmonary Artery Graft Implantation in A Systemic Position

The Ross operation for aortic valve disease has regained new interest due to its outstanding long-term results. Nonetheless, when employed as freestanding root replacement, the possible dilation of the pulmonary autograft and subsequent aortic regurgitation is described. Several animal models have been proposed. However, these are usually limited to ex-vivo models or in-vivo experiments with relatively expensive large animal models. In this study, we sought to establish a rodent model of pulmonary artery graft (PAG) implantation in a systemic position. A total of 39 adult Lewis rats were included. Immediately after euthanasia, the pulmonary root was harvested from a donor animal (n=17). Syngeneic recipient (n=17) and sham-operated (n=5) rats were sedated and ventilated. In the recipient group, the PAG was implanted with an end-to-end anastomosis in infra-renal abdominal aortic position. Sham-operated rats underwent only transection and re-anastomosis of the aorta. Animals were followed with serial ultrasound studies for two months and post-mortem histological analysis. The median PAG diameter in the native position was 3.20 mm (IQR=3.18-3.23). At follow-up, the median diameter of the PAG was 4.03 mm (IQR=3.74-4.13) at 1 week, 4.07 mm (IQR=3.80-4.28) at 1 month, and 4.27 mm (IQR=3.90-4.35) at 2 months (p&lt;0.01). Peak systolic velocity was 220.07 mm/s (IQR=210.43-246.41) at 1 week, 430.88 mm/s (IQR=375.28-495.56) at 1 month, and 373.68 mm/s (IQR=305.78-429.81) at 2 months (p=0.02) and did not differ from the sham-operated group at the end of the experiment (p=0.5). Histological analysis did not show any sign of endothelial thrombosis. This study showed that rodent models may allow for the evaluation of the long-term adaptation of the pulmonary root to a high-pressure system. A systemically placed syngeneic PAG implantation represents a simple and feasible platform for the development and evaluation of novel surgical techniques and drug therapies to further improve the outcomes of the Ross operation.

We demonstrate how to establish a murine model of pulmonary root implantation into the descending aorta to simulate the Ross procedure. This model enables the medium/long-term evaluation of pulmonary autograft remodeling in a systemic position, representing the basis of developing therapeutic strategies to promote its adaptation.

The Ross operation for aortic valve disease has regained new interest due to its outstanding long-term results. Nonetheless, when employed as freestanding ...

A Model of Reverse Vascular Remodeling in Pulmonary Hypertension Due to Left Heart Disease by Aortic Debanding in Rats

Pulmonary hypertension due to left heart disease (PH-LHD) is the most common form of PH, yet its pathophysiology is poorly characterized than pulmonary arterial hypertension (PAH). As a result, approved therapeutic interventions for the treatment or prevention of PH-LHD are missing. Medications used to treat PH in PAH patients are not recommended for treatment of PH-LHD, as reduced pulmonary vascular resistance (PVR) and increased pulmonary blood flow in the presence of increased left-sided filling pressures may cause left heart decompensation and pulmonary edema. New strategies need to be developed to reverse PH in LHD patients. In contrast to PAH, PH-LHD develops due to increased mechanical load caused by congestion of blood into the lung circulation during left heart failure. Clinically, mechanical unloading of the left ventricle (LV) by aortic valve replacement in aortic stenosis patients or by implantation of LV assist devices in end-stage heart failure patients normalizes not only pulmonary arterial and right ventricular (RV) pressures but also PVR, thus providing indirect evidence for reverse remodeling in the pulmonary vasculature. Using an established rat model of PH-LHD due to left heart failure triggered by pressure overload with subsequent development of PH, a model is developed to study the molecular and cellular mechanisms of this physiological reverse remodeling process. Specifically, an aortic debanding surgery was performed, which resulted in reverse remodeling of the LV myocardium and its unloading. In parallel, complete normalization of RV systolic pressure and significant but incomplete reversal of RV hypertrophy was detectable. This model may present a valuable tool to study the mechanisms of physiological reverse remodeling in the pulmonary circulation and the RV, aiming to develop therapeutic strategies for treating PH-LHD and other forms of PH.

The present protocol describes a surgical procedure to remove ascending-aortic banding in a rat model of pulmonary hypertension due to left heart disease. This technique studies endogenous mechanisms of reverse remodeling in the pulmonary circulation and the right heart, thus informing strategies to reverse pulmonary hypertension and/or right ventricular dysfunction.

Pulmonary hypertension due to left heart disease (PH-LHD) is the most common form of PH, yet its pathophysiology is poorly characterized than pulmonary ...