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. 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+increased+pulmonary+blood+flow+in+pulmonary+arterial+hypertension.">The role of increased pulmonary blood flow in pulmonary arterial hypertension.</a> Eur Respir J. 26 (3), 487-493 (2005).</li><li>Brittain, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Echocardiographic+assessment+of+the+right+heart+in+mice.">Echocardiographic assessment of the right heart in mice.</a> JVis Exp. (e81), (2013).</li><li>Dickinson, M. 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>
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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.

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JoVE Journal

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16.6K ビュー.  University Medical Center Groningen, University of Groningen. 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 tr...