Elastase-induced saccular aneurysms in rabbits: a dose-escalation study.

BACKGROUND AND PURPOSE Reproducible animal models facilitate preclinical assessment of aneurysm therapies. Our purpose was to determine if increased elastase doses enlarge aneurysms and parent arteries. METHODS Rabbit right common carotid artery (CCA) aneurysms were created with distal ligation and intraluminal elastase incubation. Groups were 1) sham (no elastase, n = 3), 2) 25% elastase (10 minutes, n = 9), 3) 50% elastase (10 minutes, n = 7), and 4) 50% elastase (20 minutes, n = 41). Angiography was performed after 14 days. Resultant aneurysm width and height and parent artery diameters were measured and compared with the Student t or Mann-Whitney (Wilcoxon rank sum) test. RESULTS Proximal segments were enlarged in all elastase subjects and no sham subjects. Mean measurements were significantly smaller in the sham group than in other groups. Aneurysm widths and heights, respectively, were 3.8 mm +/- 0.8 and 7.4 mm +/- 2.0 in the low-dose group; 3.9 mm +/- 1.3 and 8.5 mm +/- 3.8, medium-dose group; and 4.1 mm +/- 1.1 and 8.7 mm +/- 2.6, high-dose group. Differences were not significant. Parent artery widths were 3.5 mm +/- 0.7, 3.8 mm +/- 0.7, and 4.3 mm +/- 1.4 in the low-, medium-, and high-dose groups, respectively; the high-dose group had larger arteries (P =.07). CONCLUSION Aneurysms were reliably created and were sized similar to human intracranial aneurysms. Elastase concentration and incubation duration did not affect resultant size. Relatively short incubation (eg, 10 minutes) and 25% elastase can be used to create rabbit aneurysms, especially if dilatation of adjacent parent arteries is to be avoided.