Experimental microaneurysms in rats: I. Model for induction☆

Abstract Background Small aneurysms (lesser than 2 mm) in humans called sessile, baby aneurysms, or microaneurysms, generally are not able to be clipped or to be coil-packed through endovascular route. Among the modalities of treatment that have been used for treating microaneurysms, bipolar coagulation and wrapping of the lesion are outstanding. Nevertheless, demonstration of the efficacy of these treatments is difficult because most reported experimental models for inducting aneurysms are complex and difficult to be reproduced. This study aimed to develop a simple and reproducible model for inducing microaneurysms. Methods Microaneurysms were induced using a mechanical lesion of the bifurcation of the aorta in 72 rats. Three groups of 10 animals were sacrificed 7, 14, and 21 days after the lesion and 2 groups (35 and 7 animals) after 30 days. The aortic bifurcation was macro/microscopically analyzed in the first 4 groups and a resistance test was applied in the fifth group. Results Microaneurysms occurred in 77.8% of cases. Microscopically, degenerative changes were observed in the intima, media, and adventitia and in the internal elastic lamina. The bursting pressure ranged from 368 to 1,472 mm Hg during the resistance test in the fifth group. Conclusions The presented model of experimental microaneurysm induction is simple, reproducible and gives a high rate of positivity.