Modified Heterotopic Abdominal Heart Transplantation and a Novel Aortic Regurgitation Model in Rats

Summary

This study demonstrates a reproducible heterotopic abdominal heart transplantation technique in rats that beginners can learn and perform. Additionally, a novel aortic regurgitation model in rats is generated by performing heterotopic abdominal heart transplantation and damaging the donor's aortic valve using a guidewire after harvesting.

Abstract

Over the past 50 years, many researchers have reported heterotopic abdominal heart transplantation in mice and rats, with some variations in the surgical technique. Modifying the transplantation procedure to strengthen the myocardial protection could prolong the ischemia time while preserving the donor's cardiac function. This technique's key points are as follows: transecting the donor's abdominal aorta before harvesting to unload the donor's heart; perfusing the donor's coronary arteries with a cold cardioplegic solution; and topical cooling of the donor's heart during the anastomosis procedure. Consequently, since this procedure prolongs the acceptable ischemia time, beginners can easily perform it and achieve a high success rate.

Moreover, a new aortic regurgitation (AR) model was established in this work using a technique different from the existing one, which is created by inserting a catheter from the right carotid artery and puncturing the native aortic valve under continuous echocardiographic guidance. A heterotopic abdominal heart transplantation was performed using the novel AR model. In the protocol, after the donor's heart is harvested, a stiff guidewire is inserted into the donor's brachiocephalic artery and advanced toward the aortic root. The aortic valve is punctured by pushing the guidewire further even after the resistance is felt, thus inducing AR. It is easier to damage the aortic valve using this method than with the procedure described in the conventional AR model. Additionally, this novel AR model does not contribute to the recipient's circulation; therefore, this method is expected to produce a more severe AR model than the conventional procedure.

Introduction

Heterotopic abdominal heart transplantation in rats was first reported in 1964 by Abbott et al.¹and has been used to study acute and chronic allograft rejection, cardiac allograft vasculopathy, ischemia-reperfusion injury, and cardiac remodeling^{2,3,4,5,6,7,8,9,10,11}. Some modifications have been added to the pro....

Protocol

All the animal procedures were conducted in accordance with "An Outline of the Act on Welfare and Management of Animals" and "Standards Relating to the Care and Keeping and Reducing Pain of Laboratory Animals" by the Ministry of the Environment, Government of Japan and the "Guidelines for Proper Conduct of Animal Experiment" by the Science Council of Japan^16,17,18. The animal protocols were reviewed and approved by the Institutional Animal Care and Use Committee of the University of Tokyo (M-P19-065).

1. Heterotopic ab....

Results

Regarding the normal model, good LV contraction was successfully established after de-clamping. The ischemia time of the transplanted heart and the recipient's anesthesia time were approximately 60 min and 130 min, respectively (Table 1).

Good LV contraction was also obtained after de-clamping in the new AR model. The ischemic time of the transplanted heart and the recipient's anesthesia time in the AR model were approximately 5 min and 10 min longer than the times of the norm.......

Discussion

Key steps were discovered to prevent the donor heart from stiffening during implantation. First, it is vital to transect the donor's abdominal aorta before harvesting to unload the donor's heart^4,7. If the donor's surgical procedure is performed without endotracheal intubation, breathing ceases after the thoracotomy, which obstructs the donor's pulmonary circulation. Consequently, the donor's heart becomes overloaded, preventing good contracti.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Antisedan (atipamezole)	Nippon Zenyaku Kogyo Co., Ltd.
Domitor (medetomidine)	Nippon Zenyaku Kogyo Co., Ltd.
Dormicum (midazolam)	Maruishi Pharmaceutical Co., Ltd.
heparin	AY Pharmaceuticals Co.,Ltd.
Jcl:Wistar rats	CLEA Japan, Inc.
microscope	Orinpas Co., Ltd.	SZ61
modified Krebs-Henseleit cardioplegic solution	Merck KGaA
sevoflurane	FUJIFILM Wako Pure Chemical Corporation
SURGICEL FIBRILLAR	Johnson & Johnson K.K.
Vetorphale (butorphanol)	Meiji Animal Health Co., Ltd.