The overall goal of this procedure is to hetero topically transplant a heart and single lung graft in a configuration that permits volume loading. This is accomplished by first harvesting the donor heart lung graft. Next, the recipient is prepared and then the donor tissue is implanted.
Finally, the donor graft tissue is de aired and reperfused. Ultimately, a pressure volume conductance catheter can be used to assess the function of the graft in real time. The main advantage of this technique over existing methods like heterotopic abdominal heart transplantation, is that the addition of the lung graft allows for antegrade blood flow through a native circuit, facilitating dynamic volume loading of the heart lung graft, as well as cardiovascular assessment post-transplant.
To prepare the inferior vena cava or IVC or subsequent anastomosis begin by dissecting away the peric caval fat of the donor animal, starting at the cavo atrial junction and proceeding inferiorly to the diaphragm. Next, using a sharp lower circumferentially, free the superior vena cava or SVC and encircle it with a four zero silk tie. Dissect the left vena cava free from surrounding structures and ligate it proximally and distally.
Then resect the intervening portion of the cava, exposing the left subclavian artery circumferentially, free the innominate and left common carotid arteries, applying proximal and distal clips to the innominate artery. Then divide the section of the artery between the clips using a 26 gauge intravenous catheter, cannulate the SVC and secure it in place with a preexisting four zero silk tie. Then to harvest the heart lung graft, divide the IVC immediately superior to the diaphragm and the SVC superior to the cannulation site, taking care to avoid injuring the trachea.
Then transect the trachea proximally. Grasp it with forceps and use gentle traction and sharp dissection to separate the trachea from the underlying esophagus. Remove the heart and lung tissue on block.
Then placing the anterior surface of the heart face down. Cannulate the descending aorta with a blunt tipped 16 gauge cannula, and infuse the tissue with five to 10 milliliters of cardioplegia using a sharp lower. Next, expose the left main stem bronchus, ligate it with a four zero silk tie, and divide the bronchus distal to the ligature.
Then remove all but the right upper and middle lobes of the lung and place the graft in an appropriate receptacle until the implantation to implant the donor tissue. Circumferentially free the IVC and aorta of the recipient proximally and distally. Then encircle each site with four zero silk ties, leaving approximately two to three centimeters of space between the clamp sites.
When the vessels are clear, apply a single curved clamp to the IVC and aorta, ensuring that enough of each vessel is free for anastomosis. Next, using a 25 gauge needle attached to a saline filled one milliliter syringe, make a ven otomy in the anterior wall of the IVC. Then use pot scissors to extend the incision to match the length of the donor IVC orifice and secure the ends of the anastomosis with a nine zero nylon suture, leaving a short end of suture free at each anchor point or tying down the anastomosis in running fashion.
Complete one half of the suture line and tie it to the opposing short suture arm. Then complete and tie down the other half of the suture. Begin the aortic anastomosis by anchoring the superior aspect of the AOR autotomy with a nine zero nylon suture.
Then in running fashion, start a suture line on the medial side and finish with the lateral side of the anastomosis. Tie the line to the remaining short arm of suture and then ligate the SVC with a surgical clip. Now slowly and carefully, release the curved vessel clamp and allow the aorta to bleed from the carotid artery.
After a few seconds, ligate the carotid artery with a surgical clip and observe the graft for hemostasis, a successful reperfusion and a return of spontaneous cardiac activity. Here, representative in vitro baseline pressure volume data from an in vitro working heart assessment of cardiac function After heterotopic abdominal heart and lung transplantation is shown as illustrated in the figure preload occlusion. Pressure volume data can be derived acutely with this method as well, providing investigators with a variety of cardiac output data Following this procedure other downstream, such as investigation of the effects of acute and chronic alterations.
In loading conditions on in vivo graft function can be performed.
