A rabbit model of abdominal aortic aneurysms (AAA)

Abstract

Abstract Introduction: The rat elastase model of AAA is well established and useful for studying the early events in AAA formation. Development of a physiologic large animal model that reliably produces AAA expansion will allow in vivo testing of endovascular devices. Methods: Adult male New Zealand white rabbits (3.0–3.5 kg) were anesthetized and the terminal aorta exposed through a midline incision. Nine animals were divided into three groups: (I) saline controls, (II) elastase (100u/ml), or (III) elastase (100 μ/mL) and collagenase (50 μ/mL). A 2 cm segment of infrarenal aorta was isolated and was infused with one of the solutions for 5 minutes. Peak pressures were maintained between 300–400 mmHg. The aortic diameter was measured directly and by angiography before infusion, after infusion and at 8 weeks, when the animals were humanly killed. Results: Both treatment groups had significant increases in the size of the aorta at the end of the experiment compared to controls (p = 0.013). Animals treated with elastase and collagenase had a significantly greater change in mean aortic diameter, 2.7mm increased to 6.1mm, at 8-weeks compared to elastase alone, 2.8mm increased to 4.3 mm (p = 0.018). Conclusions: Infusion of an isolated segment of rabbit aorta with elastase and collagenase may provide a reproducible large animal model of AAA. Further work is required to determine if this could lead to a physiologic model with reproducible rupture that will allow in vivo testing of endovascular devices.