Arterial Stenting and Overdilation: Does it Change Wall Mechanics in Small-Caliber Arteries?

PURPOSE: To evaluate changes in arterial wall mechanics induced by stent overdilation in the rabbit aorta. METHODS: Twenty New Zealand white rabbits had initial stent deployment (3-mm x 8-mm Multilink) at 10% overdilation. Group A (n=11) had no subsequent balloon expansion of the stent and Group B (n=9) had 30% overdilation of the stent. A noninvasive B-mode ultrasound examination coupled with image processing allowed the measurement of systolic and diastolic diameter and the calculation of diameter compliance (Cd) and distensibility coefficient (DC) as indexes of arterial wall biomechanics. Measurements were performed before stenting in the infrarenal aorta, after initial stenting, and after stent overdilation at 3 locations: upstream, at the stent level, and downstream from the stent. RESULTS: Cd was significantly lower in the stented aorta after initial stenting (p<0.0001) and after stent overdilation (p<0.0001) than before stenting. At the stent level, Cd and DC were significantly lower than downstream (p<0.0001) or upstream (p<0.0001) from the stent after initial stenting, as well as after stent overdilation. Downstream from the stent, Cd and DC were significantly lower after stent overdilation than before stenting (p<0.05). CONCLUSIONS: Endovascular stenting of the rabbit aorta produces a significant decrease in arterial wall compliance and distensibility. Stent overdilation is responsible for a slight additional decrease of compliance downstream from the stent.