Wall Mechanics of the Stented Rabbit Aorta: Long-Term Study and Correlation with Histological Findings

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Abstract
Purpose: To evaluate long-term changes in arterial wall mechanics induced by stenting of the rabbit aorta. Methods: Eighteen New Zealand white rabbits had initial stent deployment (3×8 mm Multilink) at 110% of the pre-stenting abdominal aortic diameter. Group A (n=10) had no post-deployment stent expansion and group B (n=8) had 30% overdilation of the stent. A noninvasive B-mode ultrasound examination coupled with image processing allowed measurement of diameters at systole and diastole and the calculation of diameter compliance. Measurements were performed before stenting and compared to those recorded immediately after stenting and at 3 months at 3 locations: upstream from the stent, at the stent level, and downstream from the stent. Measurements were also compared among measurement sites. The pathological study included measurement of intimal thickening and calculation of an injury score. Results: At the stent level, diameter compliance was significantly lower after initial stenting and at 3 months than before stenting (group A: p<0.005; group B: p<0.001) and than downstream or upstream from the stent (group A: p<0.0001, group B: p<0.005). No significant difference in diameter compliance was found between groups A and B. In group B, intimal thickening and the injury score were greater than in group A (p<0.05 and p<0.0001, respectively). Conclusions: Endovascular stenting of the rabbit aorta impairs wall mechanics. Performing 30% overdilation of the stent does not worsen this impairment but induces greater in-stent intimal hyperplasia.