Modified heterotopic abdominal heart transplantation and a novel aortic regurgitation model in rats.Introduction. Although some experts can perform heterotopic abdominal heart transplantation in a very short time, it is difficult for beginners to achieve a high success rate. We demonstrate a reproducible method which beginners can perform with ease.
Additionally, we demonstrate the a AR model by using heterotropic abdominal heart transplantation and damaging the donor's aortic valve by a guidewire after harvesting the donor heart.Protocol. First, we explain heterotopic abdominal heart transplantation in rats. Donor heart harvest.
Before surgery, remove as much fur as possible with an electric shaver and depilatory cream. In addition, clean the operating area with iodine and 70%alcohol scrub three times. After administering heparin and making a midline abdominal incision, transect the abdominal aorta in order to unload the donor's heart.
Open the thoracic wall with a V-shaped incision. Initiate topical cooling with slushed ice. Tape the IVC with 5-0 silk.
Remove the thymus with scissors. Transect the brachiocephalic artery due to additional exsanguination. Administer cold cardioplegic solution into the IVC.
Ligate the IVC with 5-0 silk and divide it. Ligate the hilum of the right lung with 5-0 silk and divide it. Ligate the right SVC with 5-0 silk and divide it.
Divide the ascending aorta and PA en bloc with Potts scissors. Ligate the left SVC with 5-0 silk and divide it. Ligate the hilum of the left lung with 5-0 silk and divide it.
Ligate the base of the heart with 5-0 silk and divide it. Dissect the connective tissue between the ascending aorta and PA using micro tweezers. Perfuse cold cardioplegic solution into the coronary arteries.
Recipient preparation. Retract the small intestine towards the upper right side. Dissect the connective tissue between the small intestine and the colon.
Retract the colon to the left with two strip-like gauze pieces. Expose the abdominal aorta and IVC with cotton swabs. Heterotopic heart transplantation.
Clamp the abdominal aorta and IVC en bloc with side-biting clamp forceps. Puncture the abdominal aorta with a bent 23-gauge needle and extend the hole longitudinally with Potts scissors. Place the donor heart on a small plate, filled with slushed ice and cold, normal saline.
Tie the donor's ascending aorta to the recipient's abdominal aorta with two 9-0 nylon stay sutures at the six and 12 o'clock positions. Anastomose the left side of the recipient's abdominal aorta and the donor's ascending aorta with a running 9-0 nylon suture. Translocate the donor's heart to the left of the recipient's abdominal aorta and IVC.
Anastomose the right side of the recipient's abdominal aorta and the donor's ascending aorta with a running 9-0 nylon suture. Puncture the IVC with a bent 23-gauge needle and extend the hole longitudinally with Potts scissors. Tie the donor's PA to the recipient's IVC with a 9-0 nylon stay suture at the six o'clock position.
Anastomose the left side of the recipient's IVC and the donor's PA with a running 9-0 nylon suture. Tie the donor's PA to the recipient IVC with 9-0 nylon stay suture at the 12 o'clock position. Anastomose the right side of the recipient IVC and the donor's PA with a running 9-0 nylon suture.
Apply hemostatic agent to both anastomoses. Release the side-biting clamp forceps. The donor's heart recovered to sinus rhythm with a few minutes.
Second, we explain AR model using heterotopic abdominal heart transplantation in rats. Donor heart harvest. Harvest the donor's heart using a similar procedure as that of the normal transplant in rats, except for the ascending aorta and PA transection.
Remove the adipose tissue on the front of the ascending aorta and PA with Potts scissors. Dissect the connective tissue between the ascending aorta and PA with tweezers. After inserting one blade of Potts scissors into the transverse sinus, transect only the PA.Transect the aorta distally to the brachiocephalic artery.
Fix the donor's heart with pliers. Immobilize the ascending aorta with a vascular clip. Insert a stiff guidewire into the brachiocephalic artery and puncture the aortic valve.
Transect the aorta proximally to the brachiocephalic artery with Potts scissors. Recipient preparation. The recipient preparation procedure is similar to that of the normal transplant.
Heterotopic heart transplantation. The donor's heart transplantation procedure is similar to normal transplantation. Representative result.
Table one shows operative records of the normal model. Also, our transplantation procedure showed approximately 60 minute of ischemia time. All cases had good airway contraction after the clamping, owing to the strengthened myocardial protection.
Table two shows operative records of the AR model. The ischemia time in the AR model was only about five minutes longer than the normal model. Table three shows post-operative echocardiography data of the normal model and AR model.
The new AR model developed a significant larger LV dimension and thinner LV wall than the normal model. This is the normal model. This is the AR model.
LV dilatation was detected. Severe AR jet flow was detected. Figure four shows macroscopic findings of the AR model.
Macroscopic examination showed LV dilatation and endocardial thickening. Figure five shows Masson's trichrome-stained microphotographs of the AR model. Masson's trichrome-stained samples demonstrated fibrotic changes in the myocardium and endocardium.Discussion.
Key points of our modified transplantation procedure are as follows. First, transecting the donor's abdominal aorta before harvesting in order to unload the donor heart. Second, perfusing the donor's coronary arteries with cold cardioplegic solution.
Third, topical cooling of the donor's heart during the anastomosis procedure. Additionally, this novel AR model has some benefits. It is possible to puncture the aortic valve easily and in a shorter time compared to the traditional AR model.
Since this model does not contribute to the recipient circulation, the recipient can survive even when the donor heart showed severe AR.Conclusions. We believe that beginners can perform this study's procedure with ease and achieve a high success rate. Moreover, the novel AR model may contribute to studies on the pathomechanism of the myocardium and endocardium fibrosis and the evaluation of anti-fibrotic agents.
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