[Establishment of experimental abdominal aortic aneurysm model in rats].

Objective: To establish a new reliable experimental abdominal aortic aneurysm (AAA) rat model that simulates human aneurysms and has high survival rate.

Methods: Twenty-four SD rats were randomly divided equally into two groups (male: female=1: 1). Intraluminal saline infusion was given to rats in group A. Rats in group B were given intraluminal elastase infusion and extraluminal calcium chloride application. The diameter of abdominal aorta was measured and eventually harvested at 4 weeks. Successful AAA formation was defined as a dilation ratio )50%. HE stain was applied to evaluate the histology changes of aorta.

Results: Group A had a survival rate, technical success rate and AAA formation rate of 83. 3%, 91. 67%, and 0% respectively, compared with 91. 67%, 100%, and 90. 91% in group B. The AAA formation rate in group B was significantly higher than that in group A (P<0. 05). The dilation ratio during infusion was 50. 82% ±4. 11% in group A and 48. 19% ± 3. 89% in group B. The dilation ratio after infusion was 29. 55% ± 4. 69% in group A and 27. 89% + 4. 28% in group B. The difference of dilation ratio between the two groups was not significant. The post-surgery (28 d) dilation ratio was 27. 89% ± 4. 28%0 in group A and 88. 98% ± 42. 33% in group B (P< 0. 05). Fusiform aneurysms, local adhesion and calcification were found in group B. Rats in group B also had thickening intimal, degenerated matrix in media, loss of elastin fiber, apoptosis of vascular smooth muscle cells and transmural inflammation, none of which was observed in group A.

Conclusion: With improved operative procedure, intraluminal elastase infusion and extraluminal calcium chloride application can create reliable AAA rat model.