Placement of a fenestrated Palmaz stent across the renal arteries. Feasibility and outcome in an animal study

Objectives: to investigate the feasibility of placing stents across renal a rteries. Design: we have studied in pigs: (i) the feasibility of accurately placing fenestrated stent in front of one renal ostium; (ii) the short-term effects on renal arteries and function after the placement of such a fenestrated s tent. Materials and methods: eight fenestrated Palmaz stents were placed over pig s' renal ostia under fluoroscopy. Five weeks later, angiograms were perform ed and the animals were sacrificed. Proliferation of the healing tissues ov er the ostia was measured and analysed by microscopy. Serum creatinine was measured prior to all angiograms and at 5 weeks. Results: all eight stents were correctly placed. One stent later migrated a nd was excluded from the study. One pig died at day 1. Gross examination co nfirmed the correct placement of the fenestrations in four pigs out of seve n (57%). In the six remaining pigs, at 5 weeks, there was no angiographic e vidence of stent misplacement and all the kidneys were fully perfused. Nine renal ostia were covered by struts and neointima with a mean area of cover age of 38 +/- 5% altogether. No tissue proliferation was observed over the three renal ostia located in front of the fenestration. Serum creatinine di d not significantly increase at 5 weeks. Conclusion: creating a fenestration in a stent for renal arteries may be wo rth while in order to avoid neointimal covering of the renal ostia. However , accurate placement of such a fenestrated stent remains a difficult task.