An Aortic Model for the Physiological Assessment of Endovascular Stent-Grafts

Background: The aim of this study was to manufacture a new aortic model with physiological properties, which could be used for long-term durability testing of endovascular stent-grafts, as per the recommendations of the Food and Drug Administration. Methods: Porcine abdominal aortas were acquired to establish values for compliance. The aortic model was manufactured using a nanocomposite polymer. Latex mock aorta was used for comparison. A pulsatile flow phantom perfused the aortas and synthetic tubes at physiological pulse pressure and flow. Diametrical compliance and stiffness index were calculated over mean pressures from 30 to 120 mm Hg. Data were analyzed using one-way analysis of variance and Bonferroni's test. Results: Flow circuit hemodynamic values were similar for porcine aorta and synthetic tubes. Compliance of aorta ranged from 2.97 +/- 0.72 (mean +/- SD) to 1.42 +/- 0.37%/mm Hg x 10(-2). The polymer model showed significantly better compliance (range, 3.66 +/- 1.05-2.72 +/- 0.28%/mm Hg x 10(-2); p < 0.05), with no significant difference in elastic stiffness index (range, 101.6 +/- 28.9-51.3 +/- 10.7 for aorta and 39.8 +/- 8.5-34.2 +/- 3.8 for polymer model; p > 0.05). It also showed anisotropic behavior similar to the aorta. Latex tubes showed compliance that was lower than that in aorta (range, 0.87 +/- 0.24-0.86 +/- 0.2%/mm Hg x 10(-2)) and failed by a significant distension on increase in pressure from mean of 90 mm Hg. Conclusions: We have developed physiologically relevant aortic model showing compatible anatomy, compliance, and viscoelasticity, which could be used for long-term fatigue analysis of vascular stents and grafts. The latex mock aortas can fail at physiological pressures.