A Feasibility Experiment Of Ascending Aortic Aneurysm Filling Stent-graft System

Background Dating back from1994, thoracic endovascular aortic repair (TEVAR) haswitnessed great development over the past20years. With lower morbidity and mortality,TEVAR has been regarded as a safe treatment option for thoracic aortic diseases not suitablefor open surgery. The standard open surgery treatment for ascending aortic aneurysm (AAA)is Bentall procedure. In the endovascular era, vascular surgeons endeavored to applyendovascular techniques to the management of ascending aortic diseases, with the progress ofendovascular repair of ascending aortic dissection, ascending aortic pseudo aneurysm,ascending aortic rupture and so on. In order to add endovascular treatment to the first choicesof the AAA repair procedures, the design of the stent graft is of the first priority. The biggestchallenge of the design is faced with the particular anatomic characters of the ascending aorta,which makes it very difficult for the fixation of the stent graft. The generally accepted stentgraft depends on the distal and proximal fixation zones in the vessel to perform the repair.Present endoluminal aortic aneurysm repairs suffer form a number a number limitations.Laving the aneurysm sac untreated might increase the risk of postoperative endoleak, stentgraft migration, growing aneurysms to name a few.In search of new endografts with new design, we contrived a filling stent graft. Utilizingconventional TEVAR devices, we used a double-walled sac fixed outside the stent graft toperform polymer injection for steadier fixation and better prevention of endoleak. Thepurposes of the research are:1Bring forward a new conception of AAA repair device.2contrive and manufacture the device.3synthesize a kind of thermo-sensitive gel, and detectits properties.4perform a tentative experiment in the37-Celsius degree water pool to checkthe feasibility of the system.Purpose Measure the dimensions of the ascending aorta, design a filling stent graft for AAAendovascular repair.2. Synthesize a kind of thermo-sensitive copolymer as filling material.3.Perform a tentative experiment.Methods1.154healthy people were involved in the research for the ascending aortamorphology study by three-dimensional reconstruction and measurements of the aorta.2.Contrive and manufacture a new device for endovascular reaire of AAA. Utilize aGORE-TAG stent graft and manufacture a double walled sac by PET material as fillingstructure.3. Synthesize a kind of copolymer PLGA-PEG-PLGA by materials such as lactide,glycolide, and polyethylene glyco with infrared absorption spectrum and nuclear magnetic resonance tests, and measure itsmolecular weight.4. In the37-Celsius degrees water pool, a preliminary experiment isperformed with releasing of the stent graft and injecting the copolymer to test thefeasibility of the endovascular repair system.Results1. Sinus-tube junction to the brachiocephalic artery distance is82.2±9.80mm,diameter at sinus-tube junction is28.07±2.96mm, at middle of the ascending aorta is31.32±3.11mm, at proximal brachiocephalic artery segment is28.60±2.45mm.2. The PETmade filling structure were attached onto the GORE-TAG31mm*10cm stent graft withmodified ethyl glue, forming the filling stent graft, which can hold up105ml of water,0.3atm pressure with the size of10cm length,30mm inner lumen, and45mm maximumdiameter.3. Synthesize a kind of copolymer PLGA-PEG-PLGA by materials such aslactide, glycolide, and polyethylene glycol. Infrared absorption spectrum and nuclearmagnetic resonance tests showed the existence of characteristic segments, with a totalmolecular weight of5478. The gel solution phase transition tempreture is36.8-Celsiusdegrees.4. An average injection pressure of3atm was used to perform the injectionprocedure within85seconds, completing the volume of90ml gel solution injection. Thegel solution completed the total phase transition after injection. Pressure monitoring of thefilling structure witnessed a drop of final pressure after the phase transition.Conclusions1. Raise a new conception of AAA graft design, providing a possible optionfor AAA grafts manufacturing.2. Synthesize a thermo-sensitive copolymer, whose watersolution will maintain fluid status, but transform to gel status at the human bodytemperature. This PLGA-PEG-PLGA copolymer can be used as the filling material in thepreliminary experiment of the AAA graft system.3. The tentative experiment in the poolconfirmed the feasibility of the filling stent graft system, but its relatively low qualityneeds further study and technical refinement.