A large animal model with a continuous expanding infrarenal aortic aneurysm gives access to a more realistic AAA model with anatomy and physiology similar to humans, and thus allows for new experimental research in the natural history and treatment options of the disease.
10 pigs (group A) underwent infrarenal aortic dissection, balloon dilatation, infusion of elastase into the lumen and placement of a stenosing cuff around the aorta. 10 control pigs (group B) underwent a sham procedure. The subsequent 28 days the AP-diameters of the aneurysms were measured using ultrasound, hereafter the pigs were euthanized for inspection and AAA wall sampling for histological analysis.
In group A, all pigs developed continuous expanding AAA's with a mean increase in AP-diameter to 16.26 ± 0.93 mm equivalent to a 57% increase. In group B the AP-diameters increased to 11.33 ± 0.13 mm equivalent to 9.3% which was significantly less than in group A ( p < 0.001). In group A, a significant negative association between the preoperative weight and the resulting AP-diameters was found. Histology shoved more or less complete resolution of the elastic tissue in the tunica media in group A. The most frequent complication was a neurological deficit in the lower limbs.
In pigs it's possible to induce continuous expanding AAA's based upon proteolytic degradation and pathological flow, resembling the real life dynamics of human aneurysms. Because the lumbars are preserved, it's also a potential model for further studies of novel endovascular devices and their complications.