Modified technique of abdominal heart transplantation in the rat

Background: A rapid, reproducible screening model is essential for evaluati on of novel preservation regimens. This study describes a modification of t he abdominal rat heart transplantation model reducing anastomosis time and allowing quantitative assessment for 7 days. Methods: Hearts, obtained from inbred Dark Agouti rats, were arrested and s tored in cold colloid-free University of Wisconsin solution until transplan tation. The Dark Agouti recipient underwent a left nephrectomy. The donor l eft common carotid artery was anastomosed to the recipient left renal arter y with a "sleeve" anastomosis. The "cuffed" donor left pulmonary artery was inserted into the left renal vein. Study I examined continuing viability b y daily palpation and morphologic study by examination of hematoxylin and e osin-stained sections on days 4 or 90. Study 2 examined quantitative assess ment of cardiac function in the anesthetized recipient. The model was furth er modified by introducing an externalized, fluid-filled, balloon-tipped ca theter into the left ventricle. Results: The new technique allowed vascular anastomoses to be completed in 5 to 12 minutes, minimizing rewarming of the graft. Most (25 of 28) grafts beat for 90 days, and 80% of these showed normal, structure. There was evid ence of myocyte damage or arteriosclerosis in 5 of 25 at 90 days and in 4 o f 17 at 4 days. Cardiac function parameters were similar in consecutive run s and did not change between days 1 and 7. Conclusion: This abdominal rat heart transplant model is quick and easy to perform, minimizes warm ischemia, and is suitable for both short- and long- term studies. Quantitative parameters, assessed by use of an in situ intrav entricular balloon-tipped catheter, are reproducible and maintained for 7 d ays.