Evaluation of the risks of using an oversized balloon catheter in the human infrarenal abdominal aorta

Objectives: To evaluate the effects on the aortic wall of balloon dilatation as utilised in deployment of stent-graft devices during endoluminal repair of infrarenal abdominal aortic aneurysm. Methods: Large dilatation balloons were expanded within the aorta of 41 cadavers. Testing was done to evaluate the effect of differing degrees of balloon oversizing, at pressures in the range of 0.15-2.5 atm. The aorta was then open for macroscopic inspection. Results: In group 1 (mild atherosclerosis) no macroscopic abnormalities were detected with up to 6 mm oversized balloon. In group 2 (moderate atherosclerosis) fracture of atherosclerotic plaque occurred in seven of 14 aortas (50%) with 2.5 mm-4 mm oversized balloon. In group 3 (severe atherosclerosis) fracture of atherosclerotic plaque occurred in six of seven (85%) with 2.5 mm to 4 mm oversized balloon and rupture of the aorta occurred at 6 mm oversizing. Conclusions: This study suggests that balloon overdilatation by the aorta by 2 mm, at pressures less than 2 atmospheres, allows safe deployment even in the presence of severe atheroma. Larger amounts of overdilatation are relatively safe in mildly atherosclerotic aorta. Aortic rupture is unlikely with overdilatation up to 6 mm, especially in less calcified vessels.