Experimental And Clinical Study Of Aneurysms And Arterio-Venous Fistula Treated With Intravascular Covered Stents Designed For Intracranial Vasculature

CHAPTER ONE THE CREATING OF LATERAL WIDE-NECK ANEURYSMS OF COMMON CAROTID ARTERY IN CANINE MODELSOBJECTIVE:Animal aneurysm models are required for the study of the treatments to intracranial aneurysms in humans with covered stents and so that experimental treatments can be tested prior to clinical trials.We are going to develope a canine model that consistently produces stable saccular wide-neck aneurysms similar in morphological features and hemodynamics to human intracranial aneurysms.METHODS:In 20 mongrel dogs,a harvested segment of the external jugular vein(EJV) was anastomosed to a common carotid artery(CCA) arteriotomy site to create a lateral wide-neck aneurysm.The end-to-side anastomosis was repeated on the contralateral side in each animal to form a second lateral wide-neck aneurysm.RESULTS:All animals survived the surgery uneventfully,and all 40 lateral wide-neck aneurysms were confirmed in 20 dogs by digital subtraction angiography (DSA) 2 to 4 weeks after surgery.There were some contrast material stagnation in the aneurysms cavity,but no spontaneous occlusion was found,nor obvious stenosis of the parent artery also.CONCLUSION:Lateral wide-neck aneurysms of sufficient size for endovascular access can be created in a reproducible fashion in mongrel dogs.This model is useful for studying complex endovascular procedures in aneurysms that mimic the human condition and for testing new devices and techniques. CHAPTER TWO EXPERIMENTAL STUDY OF COMMON CAROTID ARTERY ANEURYSMS TREATED WITH HOMEMADE COVERED STENTS DESIGNED FOR INTRACRANIAL VASCULATURE IN VIVO OF CANINE MODELSOBJECTIVE:To assess the effectiveness and biocompatibility of the covered stents in the treatment of experimental saccular aneurysms in canine models and to observe the occlusion of aneurysm with preservation of the parent vessel.METHODS:Ten healthy mongrel dogs were included in our study.20 experimental lateral wide-neck saccular aneurysms were created successfully using a microsurgical technique to produce end-to-side anastomosis from venous pouches of unilateral external jugular vein to the bilateral common arteries at a right angle.12 of 20 experimental aneurysms were treated with ePTFE covered stents,another 6 were treated with bare stents,and the other 2 were untreated to serve as bare controls. Altogether there were twelve ePTFE covered stents were implanted endovascularly in the common carotid arteries covering the orifice of the aneurysms.Control angiograpy was performed immediately after the procedure and 1,3,and 6 months, anticoagulant and antiplatelet therapy was performed.At each ending point,the aneurysm and its parent artery was removed,and fixed with paraformaldehyde(PFA) solution or 2%glutaraldehyde phosphate buffer for light microscopy or scanning electron microscopy.RESULTS:Pre-stenting angiography of the common carotid arteries showed lateral wide-neck saccular aneurysms and it's complex blood flow.The aneurysms were no longer visible and the parent arteries kept patent while control angiography was performed post stenting,the follow up angiography also showed the same result. All controlled aneurysms and their parent arteries kept patent within 6mon follow-up period.Histopathological analysis by light microscopy disclosed that all treated aneurysms were filled with thrombus,as well as with fibrotic reactive scar tissue. Stent wires were found to be embeded the vessel wall and encased by an extension of the tunica intima vasorum;Scanning electron microscopy indicated that the endothelialization began at 1 month,endothelialization began from stent woven wire mesh and extended to struts,and endothelium became mature at 3 months. CONCLUSION:The covered stent can exclude the aneurysms from circulation and promote thrombosis by changing hemodynamics within the aneurysm with patency of the parent artery.In this study,it was proved that the ePTFE covered stent may have a good prospect in clinical application with a good mechanical strength,compliance,physicochemical stability,and biocompatibility. It's an expedient,safe,and effective tool to treat some aneurysms.CHAPTER THREE EXPERIMENTAL STUDY OF COMMON CAROTID ARTERY LATERAL ANEURYSMS TREATED WITH SELF-MADE ENDOTHELIALIZED HEPARINIZED POLYURETHANE COVERED STENTS IN VIVO OF CANINE MODELSOBJECTIVE:To establish the method of making an endothelialized heparinized PUR covered stent and check the feasibility and effect of treatment in vivo for canine carotid artery lateral aneurysm models.METHODS:1.Establish the experimental CCA aneurysms in canine models, meanwhile dissect the external jugular vein from the canine models.Endothelial cells were isolated and cultured from the canine external jugular vein and identified in vitro. 2.Establish the heparinized PUR covered stent.3.The vascular endothelial cells were adhered to the internal surface of the stent covered with heparinized polyurethane,and an endothelialized heparinized PUR covered stent was established.4.The covered stent was compressed on a balloon catheter,and deployed to the aneurismal orifice site in CCA of the canine model with neurovascular interventional technique.5.After deployment the follow up was performed via CTA or DSA in 1,3,and 6 months,and the histopathological assay was also carried out. RESULTS:The endothelialized heparinized PUR covered stent was established successfully.Four experimental CCA aneurysms were treated with the endothelialized heparinized PUR covered stents.It was confirmed that all aneurysms were cured,without endoleak or recanalization.The EC(Endothelial Cell) developed good over the whole internal surface of the covered stents.No obviously stenosis was found,otherwise,the parent arteries of controlled aneurysms treated with an ordinary PUR covered stent,had been found occluded spontaneously at 1 and 3 months.CONCLUSION:Canine vascular endothelial cells can adhere to the surface of the stent covered with heparinized polyurethane to form an endothelialized heparinized polyurethane covered stent with the capability of anti-washout to the blood flow.From this study,we can see that the treatment effect to the experimental CCA lateral aneurysms in canine models was good.CHAPTER FOUR CLINICAL STUDY OF INTRACRANIAL COMPLICATED ANEURYSMS TREATED WITH WILLIS COVERED STENT DESIGNED FOR INTRACRANIAL VASCULATUREOBJECTIVE:The study was to evaluate the endovascular treatment efficacy of a home-made Willis covered stent specially designed for the intracranial vasculature in the management of complicated intracranial aneurysms of the cranial internal carotid artery(CICA) and vertebral artery(VA).METHODS:From October 2006 to September 2007,Willis intracranial covered stents were used to treat complicated intracranial aneurysms in seven patients aged from 37 to 56 years.Three complicated aneurysms at cavernous segment of the internal carotid artery(ICA-Cav);one at ophthalmic segment of the internal carotid artery(ICA-Oph);one recurrent complicated aneurysm at posterior communicating segment of the internal carotid artery(ICA-Pcom);and two at subdural segment of the vertebral artery(VA-Sub).All these aneurysms cannot be treated via coiling technique in the aneurysmal sac directly,neither can through surgical clipping easily,so be presumed as complicated intractable intracranial aneurysms.Antiplatelet therapy was adopted post stent deployment within six months,clinical and angiography follow up was performed within 12 months.RESULTS:Nine covered stents were used in this study,and eight covered stents were successfully deployed in the parent arteries in all seven cases,obtained total obliteration of the aneurysms with the parent arteries kept patent and favorable clinical outcomes in six cases.There was an endoleak in a vertebral giant fusiform dissecting aneurysm when two covered stent had been deployed.The distal end angiorrhexis lead to a cerebral hematoma in one caes,which was evacuated by a craniotomy and gained a good result.One covered stent slipped away from the balloon,and been captured by a micro guide wire.No other procedure-related complications occurred.Follow up angiograms were performed five to twelve months after covered stent deployment in all seven cases,showed no recanalization of the aneurysms and normal patency of the parent arteries.CONCLUSION:The Willis covered stent system was a useful tool for the endovascular treatment of the complicated intracranial aneurysms.Further research and deployment should be performed to optimize the covered stent technique for the cerebrovascular system(CVS). CHAPTER FIVE CLINICAL STUDY OF CAROTID CAVERNOUS FISTULA TREATED WITH HOMEMADE WILLIS COVERED STENTS DESIGNED FOR INTRACRANIAL VASCULATUREOBJECTIVE:The study was to evaluate the endovascular treatment of carotid cavernous fistula with Home-made Willis Intracranial Covered Stent.METHODS:From November 2006 to June 2007,Home-made Willis Intracranial Covered Stents were used to treat carotid cavernous fistula in seven patients aged from 33 to 68 years.Six of them were traumatic carotid cavernous fistula because of traffic accident,presented with protruding eye,conjunctival congestion,ocular movement disorder and intracranial souffle.The other one was a spontaneous carotid cavernous fistula without traumatic history,presented with progressive encephalalgia and intracranial bruit.RESULTS:The covered stents were successfully deployed at fistula site in the parent arteries in all seven cases,leading to total obliteration of the fistula with the parent arteries kept patent and favorable clinical outcomes in four cases.There was a slight endoleak at the fistula of the spontaneous CCF,and obtained relief of the symptom.The covered stents shifting occurred in two patients,when the balloons withdrawn,and result in reopening of the fistula,and then the fistula and parent arteries had to be occluded with detachable ballons.No other procedure-related complications occurred.Follow up angiograms were performed four to eight months after covered stent deployment in four cases,showed no recanalization of the fistula and normal patency of the parent arteries.No radiology data were obtained in other three patients,and clinical follow up verified that the symptom had been improved.CONCLUSION:The Home-made Willis covered stent system was a useful tool for the endovascular treatment of the carotid cavernous fistula.Further research and deployment should be performed to optimize the covered stent technique for the cerebrovascular system(CVS).