A Feasibility Study Of In-situ Modified Fenestrated Stent Grafts Technology

Background and Objective:Presently aortic aneurysms and aortic dissections with limited proximal neckare not suitable for endovascular repair. Thus we tried to verify the feasibility of theenvisaged of in situ modified fenestration after stent implantation, with the help of invitro simulation test.Method:In this study, we used the dog abdominal aorta to make pararenal aneurysmmodel after a series of processing, such as patch repair, balloon dilation, etc.Toestablish the in-vitro circulation, peristaltic pump and the flow rate valve had beenused to simulate the hemodynamic conditions during intervention operation.We applied different laser sources and the different parameters of the samekind of laser to irradiate the overlapping placement of the PTFE sheet and saphenousvein specimens in blood environment. By detecting and comparing the size of thecarbonized cavity, coagulative necrosis, and interstitial edema range of the vein, aswell as the hole of the PTFE sheet, to investigate the different thermal effect betweendifferent wave length and different parameters of the same laser. Then we explore thethermal character and verify the applicability, efficacy and safety between differentparameters and different laser.Result:9pararenal aneurysm models and1set of in-vitro circulation system had beenmade. Both of the Excimer laser and the Nd: YAG could be applied to make a hole onthe PTFE sheet in vitro instantly.But the former cannot go through the blood, thelatter caused a substantial larger range of the thermal damage on the vessel wall.Nd: YAG laser (wavelength1064nm) with a fixed total energy power, couldmake a hole on the PTFE sheet along with a carbonized cavity on the wall of vein,when the output rised above certain range. When increasing the output power thediameter of the hole kept the same, diameter of carbonized cavity and range ofcoagulative necrosis, and interstitial edema decreased, while the depth of carbonizedcavity the increases gradually.Conclusion:Nd: YAG laser could make a hole on the PTFE sheet in blood environment, aswell as a considerable thermal damage to surrounding vessels.The thermal effect on the walls of vessels and the PTFE sheet of theconsecutive Nd: YAG laser (1064nm) varies between different laser parameters, hascertain regularity.The method to prepare the pararenal aneurysm model is simple and effective.This so called ‘In-situ modified fenestrated stent grafts technology’, is feasiblein theory.