A Novel Pressure Difference Induced-perforation Aortic Stent-grafts System: An Experimental Study

Background:Thoracic endovascular aortic repair (TEVAR) has been developed as a safe andeffective treatment modality in many types of diseases of the descending thoracic aorta,such as aneurysms and dissections.1However, a large number of patients have beenexcluded from it because of an inadequate proximal neck.2For example, approximately40%of patients undergoing TEVAR have the stented aortic lesion that extends near the leftsubclavian artery (LSA).³To ensure an adequate seal zone, landing zones have been extended to reach proximalto the origin of the LSA, thereby covering this arch vessel. However, LSA coveragewithout revascularization might lead to an increased prevalence of left arm ischemia,stroke, paraplegia and death.^4-7Furthermore, several feasible options that can be used tomanage the LSA including scallops, fenestrations, and branches, must be customized,requiring extensive preoperative assessment and planning, which may not be possible inthe emergency setting,⁸and the routine but indispensable preoperative assessmentequipment, such as computed tomographic angiography (CTA) and magnetic resonanceangiography (MRA), might not be available in many hospital. Our vision, therefore, was todesign a novel, non-customized stent-graft system so as to increase the accessibility ofendovascular techniques to a greater number of patientsAs we know, there exists pressure difference (PD) between LSA and aorta when LSAwas covered by stent-graft in human.⁹Thus, if we could design a kind of fabric whoseyarns may generate sliding and deformation with help of the PD while the origin of LSA isbeing covered, we might develop a novel stent graft system that would allow in situ"fenestration" by blood itself and would allow more accurate fenestration placement, withless reliance on preoperative imaging. The aims of this study are1) to explore the meanpressure drop after the left subclavian artery was covered by stent-graft in pig aortic arch.2)to develop a new pressure-gated stent-graft device for aortic arch reconstitution, fabric ofwhich can maintain blood flow to the left subclavian artery while the aortic arch is beingcovered by the stent graft.3) to evaluate the ability to create in vitro fenestrations usingliquid pressure difference between the aortic arch and left subclavian artery of aorticmodel.Methods:1. Twelve domestic pigs weighing40.42±2.21kg were selected to measure the blood pressure difference before and after the left subclavian artery was covered bystent-graft, the blood pressure was measured by connecting the4F catheter to a pressuretransducer (MPA-2000bio-signal analysis system).2. Select two structures of polyestermonofilament and multifilament as a raw material to develop the pressure-induced leakagestent-graft device for aortic arch reconstitution by multiple textiles molding technology.3.The pressure-induced aortic prosthesis was composed of a tubular component and specialfabric that can be pressure-induced deformation and leakage. Delivery and deploymentcharacteristics, in vivo flexibility of the stent, and side branch accessibility were evaluatedin aortic model device.Results:1. Before the left subclavian artery was covered by stent-graft, there was nodifference between aortic arch and left subclavian artery in blood pressure (P=0.262); afterthe left subclavian artery was covered, the mean pressure drop42.78±5.17mmHg(P<0.001)in left subclavian artery. On the14thday after procedure, the mean bloodpressure in aortic arch was still higher than that in the left subclavian artery(P=0.004).2.The device was evaluated in vitro experimental models of aortic arch; the device can beused easily and quickly in concavity arch.3. Three samples (30%) test failed; the rest ofthe sample stent-grafts were deployed at the intended target locations. Mean deformationleakage pressure difference was39.72±1.81mmHg.Conclusions: For the first time, we proposed the design of pressure differenceinduced-perforation aortic stent-grafts system and verified that pressure difference of42.78±5.17mmHg is high enough to allow in situ "fenestration" by stent graft made bymulti-dimensional and multiple textiles forming technology. Further studies on durabilityand safety of the stent grafts system in vivo are expected.