背景:小主动脉瓣环主动脉瓣置换是心外科手术的难点,治疗不当可能出现瓣膜与患者不匹配现象,使左室流出道狭窄、跨瓣压差增大,引起左室后负荷增加致心肌肥厚甚至充血性心力衰竭。目的:总结预防小主动脉瓣环瓣膜置换后发生人工心脏瓣膜...背景:小主动脉瓣环主动脉瓣置换是心外科手术的难点,治疗不当可能出现瓣膜与患者不匹配现象,使左室流出道狭窄、跨瓣压差增大,引起左室后负荷增加致心肌肥厚甚至充血性心力衰竭。目的:总结预防小主动脉瓣环瓣膜置换后发生人工心脏瓣膜与患者不匹配的治疗策略。方法:小主动脉瓣环均主动脉瓣置换患者85例。瓣口直径>17 mm,≤19 mm的患者,选19 mm SJM Regent瓣;对瓣口直径≤17 mm的患者,用牛心包补片加宽瓣环,再选19 mm SJM Regent瓣行瓣膜置换;对于瓣口直径>19 mm,≤21 mm,选21 mm Hancock II ultra生物瓣置换。治疗后应用超声心动图测量有效瓣口面积指数、左心室重量指数、室间隔厚度、左心室后壁厚度、跨瓣峰速、跨瓣压差和跨瓣平均压。出院后通过门诊对患者进行随访,定期复查超声心动图。结果与结论:治疗后早期无死亡病例,均治愈出院。随访时间为6个月-3年。主要并发症为低心排综合征2例、二次开胸止血1例、呼吸机依赖2例。所以患者均未出现脑栓塞或脑出血等脑部并发症。无瓣膜功能失调或卡瓣。未发现牛心包补片撕裂、瘤样膨出、钙化、血栓形成、免疫反应和感染等情况。81例获随访,随访率为95%(81/85)。NYHA心功能分级Ⅰ级65例,Ⅱ级16例。各不同瓣环直径患者治疗后跨主动脉瓣峰速和平均压差均明显降低,有效瓣口面积指数明显增加,左心室重量指数、室间隔厚度和左心室后壁厚度均明显降低,均未出现人工心脏瓣膜与患者不匹配。置换21 mm Hancock II ultra生物瓣和21 mm SJM Regent瓣组间的比较,前者获得了更好的跨瓣峰速和平均压差,以及更好的左心室重塑指标。19 mm Regent瓣患者治疗后体质量和体表面积较治疗前明显增加。结果提示对于小主动脉瓣环的患者应采取个体化的治疗策略预防主动脉瓣置换后瓣膜与患者不匹配的发生。展开更多
This paper aims to find the relationship between the structural parameters and the radial stiffness of the braided stent and to understand the stress distribution law of the wires. According to the equation of the spa...This paper aims to find the relationship between the structural parameters and the radial stiffness of the braided stent and to understand the stress distribution law of the wires. According to the equation of the space spiral curve, a three-dimensional parametrical geometrical model is constructed. The finite element model is built by using the beam-beam contact elements and 3D beam elements. The constituent nitinol wires are assumed to be linear elastic material. The finite element analysis figures out that the radial stiffness of the stent and the stress distribution of the wires are influenced by all the structural parameters. The helix pitch of the wires is the most important factor. Under the condition of the same load and other structural parameters remaining unchanged, when the number of wires is 24, the stress of the wire crosssection is at the minimum. A comparison between the vitro experimental results and the analytical results is conducted, and the data is consistent, which proves that the current finite element model can be used to appropriately predict the mechanical performance of the braided esophageal stents.展开更多
文摘背景:小主动脉瓣环主动脉瓣置换是心外科手术的难点,治疗不当可能出现瓣膜与患者不匹配现象,使左室流出道狭窄、跨瓣压差增大,引起左室后负荷增加致心肌肥厚甚至充血性心力衰竭。目的:总结预防小主动脉瓣环瓣膜置换后发生人工心脏瓣膜与患者不匹配的治疗策略。方法:小主动脉瓣环均主动脉瓣置换患者85例。瓣口直径>17 mm,≤19 mm的患者,选19 mm SJM Regent瓣;对瓣口直径≤17 mm的患者,用牛心包补片加宽瓣环,再选19 mm SJM Regent瓣行瓣膜置换;对于瓣口直径>19 mm,≤21 mm,选21 mm Hancock II ultra生物瓣置换。治疗后应用超声心动图测量有效瓣口面积指数、左心室重量指数、室间隔厚度、左心室后壁厚度、跨瓣峰速、跨瓣压差和跨瓣平均压。出院后通过门诊对患者进行随访,定期复查超声心动图。结果与结论:治疗后早期无死亡病例,均治愈出院。随访时间为6个月-3年。主要并发症为低心排综合征2例、二次开胸止血1例、呼吸机依赖2例。所以患者均未出现脑栓塞或脑出血等脑部并发症。无瓣膜功能失调或卡瓣。未发现牛心包补片撕裂、瘤样膨出、钙化、血栓形成、免疫反应和感染等情况。81例获随访,随访率为95%(81/85)。NYHA心功能分级Ⅰ级65例,Ⅱ级16例。各不同瓣环直径患者治疗后跨主动脉瓣峰速和平均压差均明显降低,有效瓣口面积指数明显增加,左心室重量指数、室间隔厚度和左心室后壁厚度均明显降低,均未出现人工心脏瓣膜与患者不匹配。置换21 mm Hancock II ultra生物瓣和21 mm SJM Regent瓣组间的比较,前者获得了更好的跨瓣峰速和平均压差,以及更好的左心室重塑指标。19 mm Regent瓣患者治疗后体质量和体表面积较治疗前明显增加。结果提示对于小主动脉瓣环的患者应采取个体化的治疗策略预防主动脉瓣置换后瓣膜与患者不匹配的发生。
基金The National Natural Science Foundation of China(No.51005124)the Opening Foundation of Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments(No.JS-NB-2009-1-1)
文摘This paper aims to find the relationship between the structural parameters and the radial stiffness of the braided stent and to understand the stress distribution law of the wires. According to the equation of the space spiral curve, a three-dimensional parametrical geometrical model is constructed. The finite element model is built by using the beam-beam contact elements and 3D beam elements. The constituent nitinol wires are assumed to be linear elastic material. The finite element analysis figures out that the radial stiffness of the stent and the stress distribution of the wires are influenced by all the structural parameters. The helix pitch of the wires is the most important factor. Under the condition of the same load and other structural parameters remaining unchanged, when the number of wires is 24, the stress of the wire crosssection is at the minimum. A comparison between the vitro experimental results and the analytical results is conducted, and the data is consistent, which proves that the current finite element model can be used to appropriately predict the mechanical performance of the braided esophageal stents.
