A NEW ANIMAL-MODEL OF CONTROLLED CORONARY-ARTERY OCCLUSION IN CONSCIOUS RABBITS

Objective: The aim was to develop a method for installing a pneumatic occluder on the coronary artery of a rabbit, and to see whether repetitive coronary occlusions could induce collateral development as in dogs. Methods: A superficial branch of the left coronary artery was encircled with a balloon occluder, and a catheter was inserted into the left atrial appendage of New Zealand White rabbits, with a survival rate of 89.5%. Baseline collateral flow was measured 5-7 d after surgery with radioactive microspheres while the artery was occluded. According to a predetermined schedule animals were assigned to control and experimental groups. In the latter the balloon was inflated for 2 min once every 15 min for 8 h per d, 5 d per week. Collateral flow measurements were repeated after 100 and 300 occlusions. In control animals repeat flow measurements were made approximately 4 and 14 d after the first determination. Results: Inflation of the balloon occluder reliably resulted in marked S-T segment elevation which quickly resolved after balloon deflation. These changes were nearly identical after two weeks of observation. Average baseline collateral flows in both groups were less than 5% of normal myocardial flow. There was no appreciable change during the two week period of observation in either control rabbits or those receiving at least 300 2 min coronary occlusions. Conclusions: The rabbit tolerates implantation of a pneumatic coronary occluder without noticeable problem and can successfully serve as a small animal model of repetitive or chronic myocardial ischaemia. The surgical preparation is not difficult, and ischaemia can be reproducibly created and relieved for at least three weeks following surgery. Coronary collaterals are sparse in the rabbit, and repetitive occlusions can be instituted without the complication of collateral development.