Mark J. Kearns receives support from the UBC Clinician Investigator Program (awarded through the Royal College of Physicians and Surgeons of Canada), and the UBC 4YF Doctoral Fellowship.
John H. Boyd is a National Sanitorium Association and Michael Smith Foundation for Health Research Scholar. Funding through CIHR. The authors wish to thank Dr. M. Allard and Richard Wamboldt for their assistance with setup and maintenance of perfusion equipment.

All animals were housed and cared for in accordance with National and Institutional guidelines for the care and use of laboratory animals. Ethics approval for this protocol was granted by the University of British Columbia&#8217;s Animal Care Committee. Male, Sprague-Dawley rats weighing between 300 - 450 g were used for this protocol.
1. Donor Operation
<ol>
	<li>Have approximately 100 ml&#160;of cardioplegia (RT) in a cylindrical flask connected to long intravenous (IV) catheter tubing by ...

<ol>
	<li>Abbott, C. P., Lindsey, E. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+technique+for+heart+transplantation+in+the+rat.">A technique for heart transplantation in the rat.</a> Arch Surg. 89 (1964), 649-652 (1964).</li><li>Ma, Y., Wang, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+2+heterotopic+heart+transplant+techniques+in+rats:+cervical+and+abdominal+heart.">Comparison of 2 heterotopic heart transplant techniques in rats: cervical and abdominal heart.</a> Exp Clin Transplant. 9 (2), 128-133 (2011).</li><li>Wiedemann, D., Boesch, F., Schneeberger, S., Kocher, A., Laufer, G., Semsroth, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Graft+function+after+heterotopic+rat+heart+transplant+with+an+isolated+reperfused+working+heart:+a+methodic+consideration.">Graft function after heterotopic rat heart transplant with an isolated reperfused working heart: a methodic consideration.</a> Exp Clin Transplant. 10 (2), 154-157 (2012).</li><li>Chen, Z. H., Xia, S. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+technique+of+heterotopic+heart-lung+transplantation+in+the+rat.">The technique of heterotopic heart-lung transplantation in the rat.</a> J Tongji Med Univ. 6 (2), 67-70 (1986).</li><li>Ibrahim, M., Navaratnarajah, 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=Heterotopic+abdominal+heart+transplantation+in+rats+for+functional+studies+of+ventricular+unloading.">Heterotopic abdominal heart transplantation in rats for functional studies of ventricular unloading.</a> J Surg Res. 179 (1), e31-e39 (2013).</li><li>Asfour, B., Hare, 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=A+simple+new+model+of+physiologically+working+heterotopic+rat+heart+transplantation+provides+hemodynamic+performance+equivalent+to+that+of+an+orthotopic+heart.">A simple new model of physiologically working heterotopic rat heart transplantation provides hemodynamic performance equivalent to that of an orthotopic heart.</a> J Heart Lung Transplant. 18 (10), 927-936 (1999).</li><li>Figueiredo, J. -. L., Nahrendorf, M., Sosnovik, D. E., Weissleder, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MRI+of+a+novel+murine+working+heart+transplant+model.">MRI of a novel murine working heart transplant model.</a> Circ Heart Fail. 2 (3), 272-274 (2009).</li><li>Wen, P., Wang, X., 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+simple+technique+for+a+new+working+heterotopic+heart+transplantation+model+in+rats.">A simple technique for a new working heterotopic heart transplantation model in rats.</a> Transplant Proc. 45 (6), 2522-2526 (2013).</li><li>Didi&#233;, M., Biermann, D., 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=Preservation+of+left+ventricular+function+and+morphology+in+volume-loaded+versus+volume-unloaded+heterotopic+heart+transplants.">Preservation of left ventricular function and morphology in volume-loaded versus volume-unloaded heterotopic heart transplants.</a> A.Am J Physiol Heart Circ Physiol. 305 (4), H533-H541 (2013).</li><li>Gali&#241;anes, M., Zhai, X., Hearse, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+load+on+atrophy,+myosin+isoform+shifts+and+contractile+function:+studies+in+a+novel+rat+heart+transplant+preparation.">The effect of load on atrophy, myosin isoform shifts and contractile function: studies in a novel rat heart transplant preparation.</a> J Mol Cell Cardiol. 27 (1), 407-417 (1995).</li><li>Yokoyama, H., Ohmi, M., Murata, S., Nakame, T., Tabayashi, K., Mohri, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proposal+of+a+working+left+heart+model+with+a+heterotopic+transplantation+technique+in+rats.">Proposal of a working left heart model with a heterotopic transplantation technique in rats.</a> J Heart Lung Transplant. 14 (4), 706-712 (1995).</li><li>Maruyama, T., Swartz, M. T., McBride, L. R., Pennington, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Working+heart+model+of+heterotopic+heart-lung+transplantation+in+rats.">Working heart model of heterotopic heart-lung transplantation in rats.</a> J Thorac Cardiovasc Surg. 107 (1), 210-215 (1994).</li><li>Pacher, P., Nagayama, T., Mukhopadhyay, P., B&#225;tkai, S., Kass, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+cardiac+function+using+pressure-volume+conductance+catheter+technique+in+mice+and+rats.">Measurement of cardiac function using pressure-volume conductance catheter technique in mice and rats.</a> Nat Protoc. 3 (9), 1422-1434 (2008).</li><li>Jespersen, B., Knupp, L., Northcott, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femoral+arterial+and+venous+catheterization+for+blood+sampling,+drug+administration+and+conscious+blood+pressure+and+heart+rate+measurements.">Femoral arterial and venous catheterization for blood sampling, drug administration and conscious blood pressure and heart rate measurements.</a> J Vis Exp. (59), 3496-3410 (2012).</li><li>Habertheuer, A., Kocher, 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=Innovative,+simplified+orthotopic+lung+transplantation+in+rats).">Innovative, simplified orthotopic lung transplantation in rats).</a> J Surg Res. 185 (1), 419-425 (2013).</li></ol>

The authors have nothing to disclose.

Success with the technique described here will be predicated on several factors. Key among them will be ensuring stability of both donor and recipient animals, adopting meticulous operative technique that is safe and associated with minimal blood loss, ensuring complete cardioplegic arrest with uniform graft cooling, minimizing total ischemic time, and adequately de-airing the graft. As acknowledged above, the technique&#8217;s technical complexity is its chief limitation.
We have advanced pre...

The first rodent model of heterotopic abdominal heart transplantation (HAHT) was described by Abbott and colleagues in 19641. This technique, and subsequent modifications have been widely applied to characterize transplant graft function and immunologic status. The majority of HAHT techniques described involve a non-volume loaded heart2,3. Models of HAHT involving volume-loaded ventricles have been described, but they are frequently limited in one or more respects.
Heterotopic abdominal heart-lung transplantation (HAHLT) with a volume-loaded left ventricle (LV) has been described previously. Chen and colleagues4, and subsequently Ibrahim and colleagues5 described HAHLT with a single aorto-aortic (donor ascending to recipient abdominal aorta) anastomosis. The only volume load presented to the ventricle in this circulation is the coronary venous return. Asfour and colleagues described a HAHT technique in which the lung circuit was eliminated by anastomosing donor pulmonary artery (PA) to donor left atrium (LA)6. In this circulation, venous inflow to right ventricle (RV) occurs via a donor SVC to recipient IVC anastomosis, and the subsequent LV load is ejected into the aorto-aortic anastomosis. Cardiac function was partially assessed in vivo, and also in vitro using a Langendorff rig. Figueiredo and colleagues described a HAHLT model similar to our own7, but in mice. Venous inflow to the RV occurs via donor SVC to recipient IVC anastomosis. Blood subsequently passes through the single lung circulation and LV load is ejected into the aorto-aortic anastomosis. Cardiac function in their study was assessed by magnetic resonance imaging (MRI). Wen and colleagues described a unique HAHT technique in which the LV is loaded by means of a recipient aorta to donor LA anastomosis8. The LV, therefore, fills at systemic pressures. Cardiac function, and whether LV stroke volume is ejected antegradely in their model was not assessed.
Many of the techniques referenced above involve non-physiologic LV loading conditions, including the techniques whose partial LV load is represented only by coronary venous return. On the other hand, many techniques do approach physiologic LV loading. The majority of these techniques, as with the technique of Asfour and colleagues, omit the pulmonary circulation and utilize a donor PA to donor LA anastomosis6,9. The circulation described by Galinanes and colleagues10 employs a direct recipient cava to donor LA anastomosis, omitting the pulmonary circulation and the right heart. Yokoyama and colleagues achieve the same effect by ligating the donor PA and creating an interatrial communication in the donor heart (omitting donor lung and right heart circulations)11. The circulation of Maruyama and colleagues12 involves an anastomosis between donor left PA and recipient Ao, which permits LV filling via the pulmonary circulation as a conduit, but effectively excludes the right heart.
In cases where near physiologic loading conditions were met, we advance the technique of HAHLT in 2 major respects. First, to our knowledge, the exact configuration we report has not been described in rats. It is possibly the most versatile circulation for investigators wishing to study the physiology, structure, and immunology of the transplanted heart-lung graft. Second, we describe how the function of the transplant graft can be directly characterized in vivo. For this application, pressure-volume conductance catheters can be introduced directly into the LV apex of the transplant graft, which allows for complete cardiac functional characterization. 
The technique described here can be applied to both acute and chronic studies of transplant graft function, while the functional assessment may be performed either in vivo or in vitro. We present a model in which the loading conditions can be near physiologic, however the degree of ventricular loading may be manipulated both acutely and chronically by diverting venous return towards or away from the graft. Afterload conditions can also be manipulated. Because the lung and its airway are retained in this transplant configuration, investigators can re-ventilate the donor lung acutely. Uniquely, lung re-ventilation changes the composition of blood perfusing the transplant coronary arteries. Under non-ventilated conditions, blood ejected from the donor aorta is deoxygenated, and mixes with oxygenated blood in the recipient aorta. Under acutely ventilated conditions, ejected blood becomes oxygenated. Thus, transplant graft function can be compared under ventilated and non-ventilated conditions, and also under variably loaded conditions.
The protocol below describes important modifications to previously described HAHLT donor and recipient operations. It also describes an optimal technique for protecting the transplant graft throughout the period of ischemia (time between donor explant and recipient implant). Advantages of this technique include physiologic conditions potentially approaching that of an orthotopically transplanted graft, and a wide range of investigative applications. An important limitation is its technical complexity. With adequate mentoring and practice, the advantages of this technique will likely outweigh the challenges in adopting it.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Material/Equipment</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Celsior Cardioplegic Soution</td>
			<td>Genzyme</td>
			<td></td>
			<td>The solution is kept on ice throughout the procedure. We prepare our own solution, with slight modifications.</td>
		</tr>
		<tr>
			<td>Rodent Ventilator</td>
			<td>Harvard Apparatus</td>
			<td>Model 683</td>
			<td></td>
		</tr>
		<tr>
			<td>Vital Sign Monitor</td>
			<td>Nonin</td>
			<td>Model 9847V</td>
			<td>Displays SpO2 and heart rate.</td>
		</tr>
		<tr>
			<td>IV Cannulae</td>
			<td>Jelco</td>
			<td>3063</td>
			<td>24-26G x 3/4&#34; cannulae.</td>
		</tr>
		<tr>
			<td>IV Tubing</td>
			<td>CareFusion</td>
			<td>MP9259-C</td>
			<td>Short-length connector tubing (18cm).</td>
		</tr>
		<tr>
			<td>Surgical Clips</td>
			<td>Teleflex Medical</td>
			<td>001204</td>
			<td>Horizon titanium ligating clips.</td>
		</tr>
		<tr>
			<td>Sutures</td>
			<td>Ethicon, Sharpoint</td>
			<td>LA54G, AK-0107</td>
			<td>3-0 silk reel, and 9-0 prolene suture (single-armed, DR5 needle).</td>
		</tr>
		<tr>
			<td>Surgical Instruments</td>
			<td>Not Applicable</td>
			<td>Not Applicable</td>
			<td>The instruments used are generic, and can be purchased from any surgical supply company.</td>
		</tr>
	</tbody>
</table>

rat heterotopic abdominal heart/single-lung transplantation in a volume-loaded configuration

Herein, we describe a novel technique for heterotopic abdominal heart-lung transplantation (HAHLT) in rats. The configuration of the transplant graft involves anastomosis of donor inferior vena cava (IVC) to recipient IVC, and donor ascending aorta (Ao) to recipient abdominal Ao. The right upper and middle lung lobes are preserved and function as conduits for blood flow from right heart to left heart.
There are several advantages to using this technique, and it lends itself to a broad range of applications. Because the graft is transplanted in a configuration that allows for dyamic volume-loading, cardiac function may be directly assessed in vivo. The use of pressure-volume conductance catheters permits characterization of load-dependent and load-independent hemodynamic parameters. The graft may be converted to a loaded configuration by applying a clamp to the recipient&#8217;s infra-hepatic IVC. We describe modified surgical techniques for both donor and recipient operations, and an ideal myocardial protection strategy. Depending on the experimental aim, this model may be adapted for use in both acute and chronic studies of graft function, immunologic status, and variable ventricular loading conditions. The conducting airways to the transplanted lung are preserved, and allow for acute lung re-ventilation. This facilitates analysis of the effects of the mixed venous and arterial blood providing coronary perfusion to the graft.
A limitation of this model is its technical complexity. There is a significant learning curve for new operators, who should ideally be mentored in the technique. A surgical training background is advantageous for those wishing to apply this model. Despite its complexity, we aim to present the model in a clear and easily applicable format. Because of the physiologic similarity of this model to orthotopic transplantation, and its broad range of study applications, the effort invested in learning the technique is likely to be worthwhile.

The HAHLT technique described above is highly technical and requires close attention to detail. Table 1 highlights some of the key factors associated with successful versus unsuccessful procedures, and can be used as a guide for troubleshooting technical difficulties.
After the recipient aorta is unclamped, the graft coronary arteries should be seen to fill with oxygenated blood. Accordingly, the myocardium should become pink and well perfused. In technically successful experi...

Watch this Scientific Journal Video about Rat Heterotopic Abdominal Heart/Single-lung Transplantation in a Volume-loaded Configuration at JoVE.com

Rat Heterotopic Abdominal Heart/Single-lung Transplantation in a Volume-loaded Configuration

We describe a novel technique for heterotopic abdominal heart-lung transplantation (HAHLT) in rats. The transplant configuration results in a partially loaded graft circulation, allowing direct functional assessment. This model may be employed for acute or chronic studies of function and immunologic status of the transplanted graft.

Herein, we describe a novel technique for heterotopic abdominal heart-lung transplantation (HAHLT) in rats. The configuration of the transplant graft ...

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8.2K ビュー.  UBC James Hogg Research Center, St. Paul's Hospital. We describe a novel technique for heterotopic abdominal heart-lung transplantation (HAHLT) in rats. The transplant configuration results in a partially loaded graft circulation, allowing direct functional assessment. This model may be employed for acute or chronic studies of function and immunologic status of the transplanted graft.