Outcome of common iliac arteries after aortoaortic graft placement during elective repair of infrarenal abdominal aortic aneurysms

HYPOTHESIS: Supplemental oxygen can reduce intimal hyperplasia (IH) after stent deployment in a rabbit model. BACKGROUND: Endovascular stent placement is technically feasible, but long-term durability in vessels outside the aortoiliac system is compromised with postinterventional IH, which causes restenosis and failure of the arterial conduit. METHODS: Groups (n = 4 to 6) of female New Zealand white rabbits underwent placement of a 3-mm intraaortic stent with laparotomy and were placed in either normoxic (21% inspired oxygen concentration) or supplemental-oxygen (40% inspired oxygen concentration) environments for 0, 7, 14, and 28 days. The transarterial wall oxygen gradient was measured at 0, 7, and 28 days with an oxygen microelectrode. 5-Bromo-2'deoxyuridine (BrdU) was injected into the peritoneum before death to assess cellular proliferation. Aortic specimens were harvested en bloc and sectioned for analysis of cellular proliferation and intimal thickness. RESULTS: Intraaortic stent placement significantly decreased the transarterial wall oxygen gradient in the outer 70% of the vessel wall and was easily reversed at 7, 14, and 28 days with application of supplemental oxygen. Cellular proliferation was significantly decreased at 14 days (0.5% +/- 0.001% versus 2.3% +/- 0.002%; P <.001) and 28 days (0.4% +/- 0.001% versus 1.0% +/- 0.001%; P <.025) as measured with count of nuclei staining for 5-Bromo-2'deoxyuridine in the intima and media. Intimal thickness was significantly decreased at 28 days in oxygen-supplemented rabbits (intimal area/medial area = 0.50 +/- 0.07) as compared with controls (intimal area/medial area = 0.89 +/- 0.11; P <.025). CONCLUSION: This study shows the ability of supplemental oxygen to reverse arterial wall hypoxia, decrease cellular proliferation, and control IH at the deployment site of an intraarterial stent in a rabbit model. Forty-percent supplemental oxygen suppresses IH by 44% at 28 days as compared with normoxic control values. Cellular proliferation is reduced four-fold at 14 days and two-fold at 28 days in oxygen-supplemented rabbits as compared with control media after deployment. The clinical implications of these findings are significant, especially as the role of endovascular interventions continues to expand.