SACCULAR ANEURYSM INDUCTION BY ELASTASE DIGESTION OF THE ARTERIAL-WALL - A NEW ANIMAL-MODEL

OBJECTIVE: To develop a rabbit aneurysm model that is more realistic i n gross appearance and histological features than previous models and to enable the development of a larger animal model. METHODS: Ten rabbi ts received porcine pancreatic elastase, five at the right common caro tid artery bifurcation and five others at the right superior thyroid a rtery origin. One control animal received collagenase and another rece ived papaverine, each at the right superior thyroid artery origin. The agents were topically delivered to the arterial adventitia with a mic rosyringe after surgical exposure of the targeted arteries. The arteri es were monitored for aneurysm growth with a video camera for up to 3 hours and were then removed and processed for histology. RESULTS: Sacc ular aneurysms developed in one of five animals after elastase applica tion at the carotid bifurcation and in all five animals receiving elas tase at the superior thyroid artery origin. Among the six aneurysms, r ecurrent minor hemorrhages occurred in four, thrombosis of the aneurys m sac in three, and rupture causing severe bleeding in one. Histologic al sections revealed thin-walled aneurysms composed only of collagen f ibers and some cellular elements. No saccular dilation resulted from p apaverine application. Collagenase application resulted in a hemorrhag ic-thrombotic lesion in the arterial wall but no aneurysm formation. C ONCLUSION: Arterial saccular aneurysms were induced in rabbits by topi cal application of elastase with an easy and efficient method. These a neurysms are histologically similar to natural aneurysms, and their ar terial nature renders them more authentic than those of surgical model s. This aneurysm model may serve as a foundation for further aneurysm research.