生物主动脉瓣膜设计中的有限元分析模型

目的 为了更好地分析生物心脏瓣膜的应力分布及闭合性能,本研究提出一种新的有限元分析模型.方法 利用点点接触将瓣膜与支架的缝合点一一对应以模拟瓣膜实际缝制过程,建立将平面设计的瓣膜缝制到支架上的模型,从而形成缝制模型.而对照模型则直接建立瓣叶的理想三维几何结构.在两种模型的瓣叶上施加一定压力,进行有限元计算,将缝制模型与对照模型的应力分布情况进行对比,同时参照实际瓣膜的闭合情况对比上述两种模型的闭合形态.结果 缝制模型最大应力集中部位为瓣叶两翼,其瓣叶倾角及闭合形态分析均较可靠.结论有限元缝制模型可以为心脏瓣膜瓣叶性能分析提供比对照模型更精确的结果,从而为瓣叶形状的设计和优化提供指导依据.     

下肢深静脉瓣膜的形态和分布

解剖了成人成对的100侧下肢深静脉主干和36侧小腿深静脉的瓣膜。深静脉瓣膜可分为大、小二种类型。大瓣中以双叶瓣居多数(98.20%),单叶瓣和三叶瓣很少。静脉主干的瓣膜数平均7.23个,主要分布于股、腘静脉中(83.14%),以位于股深静脉口远侧处的一个最恒定,在离股深静脉口0～3cm范围内,89.00%肢体具有1～2个瓣膜。统计了静脉各段的瓣膜数,以及主干内各瓣膜至主要属支口的距离,以适应静脉造影时确定瓣膜位置的需要。双叶瓣可附着在静脉的前、后或左、右壁上,而以前者最多见(81.83%)。36侧小腿深静脉瓣膜数的平均值依次为:胫前静脉内侧支9.63个,外侧支8.97个:胫后静脉内侧支7.00个,外侧支6.86个;腓静脉内侧支6.23个,外侧支6.37个。下肢静脉瓣膜总数平均值为52.29个。     

股静脉瓣膜的临床应用解剖

目的:为原发性股静脉瓣膜功能不全的诊治和构建组织工程静脉瓣膜提供形态学基础.方法:26例(52侧)成人尸体的股静脉标本等分为远侧、中间、近侧1/3段,在手术显微镜下解剖观察和测量相关数据,并对股静脉瓣膜进行 Masson三色改良染色和 H-E染色.结果:股静脉瓣膜数为(3.81±1.44)个,瓣膜以半月形双叶瓣为主,瓣膜方位除近段以前后位为主外,其余两段无显著性差异.瓣膜腔面和窦面均覆着一层内皮细胞,在两层内皮细胞之间为大量的胶原纤维,腔面内皮下覆着一弹力纤维带.结论:在临床行静脉瓣膜成形术时,应保证瓣叶的形态规则和闭合严密,以维持其正常的血流动力学;在构建组织工程瓣膜时,半月形双叶瓣或三叶瓣为最佳形态.     

下肢深静脉瓣膜的应用解剖

在30具成人尸体上,对60侧股静脉,胸静脉、股深静脉、胫前静脉,56侧胫后静脉,58侧腓静脉的瓣膜进行了观察,深入研究了各段静脉瓣膜的出现率、数目、形态、分布和位置。单侧下肢深静脉瓣膜总数平均值为48.61个。绝大多数瓣膜为双叶瓣(99.34%±0.14%),极少数为单叶瓣(0.61±0.14%),三叶瓣罕见(0.03±0.03%)。双叶瓣大部分位于静脉的前、后壁(88.78±0.58%),少部分位于静脉的左、右壁(11.21±0.58%);单叶瓣位于静脉的后壁;三叶瓣位于静脉的右、后、右壁。     

婴幼儿罗叶泵聚氨酯瓣膜的制作及功能测试

背景：现有成人罗叶泵使用机械瓣,但机械瓣膜的尺寸较大,对血液破坏较大,不适于婴幼儿心室辅助泵,故设计和制作尺寸小、血栓形成低的高分子瓣膜是目前研究的热点。 目的：设计和制作20 mL婴幼儿罗叶泵的瓣膜,并进行基本功能测试和疲劳测试 方法：通过MASTERCAM软件设计瓣膜尺寸和形状,通过制作瓣膜模具和注塑获得聚氨酯瓣膜;根据ISO5840的要求测试聚氨酯瓣膜的静止泄露、跨瓣压差和耐疲劳性能。 结果与结论：制作了聚氨酯三叶瓣膜,但注塑失败率较高;所制作的三叶瓣膜的基本功能基本符合ISO 5840的要求;聚氨酯瓣膜在连续运行1.0×107次后,20 mL罗叶泵的搏出量的变化率为5.2%。两个聚氨酯瓣膜保持完整,瓣叶无变化。说明设计并成功制作了聚氨酯三叶瓣膜;所制备的聚氨酯瓣膜能满足20 mL罗叶泵的需要,已具备了临床试验的能力。     

个体化治疗预防小主动脉瓣环瓣膜置换后瓣膜与患者的不匹配

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。 中国组织工程研究杂志出版内容重点：肾移植;肝移植;移植;心脏移植;组织移植;皮肤移植;皮瓣移植;血管移植;器官移植;组织工程全文链接：     

瓣膜高度对移植主动脉瓣开闭性能的影响

临床上治疗主动脉瓣膜关闭不全的的手术多采用瓣膜移植,但术后患者重建的主动脉根部存在扩张现象,因此瓣膜高度的不足会致使主动脉瓣膜再次关闭不全。本文研究不同主动脉瓣膜高度设计对瓣膜开闭性能的影响,通过体外数值模拟,获取最佳手术方案,提供技术支持和理论依据。本文以根部直径26.0 mm、瓣膜高度14.0 mm为参照,建立瓣膜高度增量为±0.5 mm的六组三维几何模型。通过对模型最大应力、瓣口面积和接触力等参数的结构力学计算和分析,获得合理的几何尺寸。研究发现,六组模型的最大应力值范围在640～690 kPa之间,与文献的结果相符合;瓣膜高度分别为13.5、14.0、14.5 mm的三组模型的瓣口面积在合理范围内;六组瓣叶接触力随瓣膜高度增加呈增大趋势。研究表明主动脉瓣膜的高度对主动脉瓣膜关闭性能存在影响,太小或太大的瓣膜高度会减小主动脉收缩期的瓣口面积,影响主动脉开闭功能。     

一种新型干性生物瓣膜耐久性能体外测试及评价

随着生物技术的发展,近年来出现了通过覆盖钙结合位点的牛心包处理技术,并以此为瓣叶材料制备出干性生物瓣膜。由于干性生物瓣膜临床应用时间短,尚缺少长期耐久性数据。本研究采用体外加速方法,对一种干性生物瓣膜耐久性能进行测试及评价。选取23和32 mm这两个规格干性生物瓣膜进行体外耐久性能测试。通过瓣膜脉动流实验、瓣叶热力学分析和显微镜下胶原纤维观察,对其耐久性能进行评价。经过2亿次循环(模拟临床使用5年),干性生物瓣膜流体力学性能无明显变化,其中23 mm规格干性生物瓣膜平均跨瓣压差有所升高,但仍处于同规格生物瓣膜较低水平;32 mm规格干性生物瓣膜平均跨瓣压差几乎没有变化。有效瓣口面积基本一致,返流百分比无明显变化,说明干性生物瓣膜未发生明显的狭窄和返流,能量损失无明显变化,说明瓣膜的效能无明显降低。瓣叶材料的热力学变性温度由96.6℃降至91.2℃;在双光子共聚焦显微镜下观察,同样测试条件下亮度变暗,但胶原纤维形状未发生变化,仍是卷曲的立体结构,说明胶原纤维含量降低,化学键部分丢失,与热变性温度表现一致。干性生物瓣膜耐久性能实验后,微观结构发生一定变化,但仍具有良好的流体力学性能。     

保留二尖瓣瓣下结构的瓣膜置换可促进瓣膜有效愈合

背景:保留全瓣瓣下结构在瓣膜置换手术中争议不断,对于瓣膜疾病术式的选择尚无统一且可靠标准。目的:探讨分析保留二尖瓣瓣下结构的瓣膜置换促进瓣膜有效愈合的效果。方法:选取2018年1-12月十堰市太和医院收治的因二尖瓣关闭不全为主要病变合并或不合并主动脉瓣疾病,行保留二尖瓣瓣下结构二尖瓣膜置换、二尖瓣及主动脉瓣双瓣置换的患者68例,其中保留全瓣瓣下结构11例、保留后瓣瓣下结构35例、二尖瓣及瓣下腱索全切22例。术后6个月进行超声心动图复查,比较3组患者左房舒张期末前后径、左室舒张期末横径、左室射血分数、左室短轴缩短率等心功能指标,以及左室流入道及流出道、各瓣膜功能、瓣周愈合情况;并记录术后3年内患者并发症情况。结果与结论:(1)保留全瓣瓣下结构组和保留后瓣瓣下结构组患者体外循环时间、阻断时间、ICU停留时间、术后住院时间均低于二尖瓣及瓣下腱索全切组(P <0.05);(2)3组患者左房舒张期末前后径、左室舒张期末横径、左室射血分数、左室短轴缩短率等心功能指标水平差异无显著性意义(P> 0.05),但保留全瓣瓣下结构组左房舒张期末前后径和左室舒张期末横径低于保留后瓣瓣下结构组和二...     

人体主动脉瓣膜钙化组织的力学性质

目的采用纳米压痕测试方法,测量人体主动脉瓣取出物的钙化组织的材料力学性能。方法采集5名主动脉瓣狭窄患者的瓣叶取出物,选取钙化瓣叶进行纳米压痕测试,获得钙化组织弹性模量、硬度等材料力学参数。结果瓣叶钙化组织的弹性模量为(15.69±3.89) GPa,硬度为(0.59±0.15) GPa。结论通过纳米压痕测试方法得到瓣叶钙化组织的弹性模量和硬度,为瓣膜的生物力学研究提供实验数据参考。     

Development of a prosthetic venous valve

The pathology of thrombophlebitis primarily results from the obliteration of venous valves in the lower extremities. The objective of this study was to develop a prosthetic venous valve that could be implanted in the human femoral system to ameliorate the deleterious effects of thrombophlebitis. Prosthetic venous valves were produced from two materials: Pellethane valves were fabricated from a dip-casting process; umbilical vein valves were produced by a fixation process. The valves were evaluated as implants within the external jugular veins of 10 research dogs. Each animal was implanted with one Pellethane valve in one external jugular vein and one umbilical vein venous valve in the contralateral jugular vein. Each valve was positioned over a stainless-steel cylinder that had been implanted into the jugular veins in such a manner that there existed no blood-cylinder interaction. Patency of the valves was determined by X-ray venography at 24, 48, and 72 h and at 5 and 8 days postoperatively. All of the umbilical vein venous valves were occluded by the end of 48 h, whereas two of the Pellethane venous valves remained patent for at least 5 days but were occluded at 8 days. The results of this study suggest the possibility of success of Pellethane valve implants in the venous circulation and indicate future directions for study.     

Fluid dynamics of venous valve closure

In vitro experiment was performed on a stended bovine jugular vein valve (VV, 14 mm I.D.×2 cm long) and a stentless bovine jugular vein valve conduit (10 mm I.D.×6 cm long) in a hydraulic flow loop with a downstream oscillatory pressure source to mimic respiratory changes. Simultaneous measurements were made on the valve opening area, conduit and sinus diameter changes using a specially designed laser optic system. Visualization of flow fields both proximal and distal to the venous valve, and the valve opening area were simultaneously recorded by using two video cameras. Laser Doppler anemometer surveys were made at three cross sections: the valve inlet, the valve exist, and 2 cm downstream of the venous valve to quantity flow reflux at valve closure. The experiment confirmed that the VV is a pressure-operated rather than a flowdriven device and that little or no reflux is needed to close the valve completely. The experiment further demonstrated that the VV sinus expands rapidly against back pressure, a critical character to consider in venous prosthesis design.     

下肢股段主要静脉及其瓣膜的解剖及临床意义

目的通过对103侧成人尸体下肢股段主要静脉及其瓣膜的观测,为临床血管疾病的外科及介入诊疗提供形态学依据。方法在103侧成人尸体下肢股段中观测主要静脉瓣膜的数量及形状、静脉特别点外径、静脉特别点的体表位置。结果大隐静脉股段瓣膜均为双瓣型,隐股点处外径(真径)为(5.18±1.25)mm,隐股点至腹股沟韧带的距离为(3.92±0.71)cm;股浅静脉第一对瓣膜多为双瓣型,瓣膜附着缘静脉外径(压扁径)为(1.06±0.17)cm,其位置较恒定,距股深静脉入口下缘(1.16±0.66)cm,到隐股点距离为(6.16±1.69)cm;股深静脉注入点下缘至隐股点下缘的距离为(5.00±1.57)cm,至腹股沟韧带的距离为(7.84±1.89)cm。结论以上观测结果为临床血管外科手术及介入治疗提供解剖学基础。     

Number and location of venous valves within the popliteal and femoral veins: a review of the literature

Although deep venous insufficiency is common and important, the anatomy of deep vein valves is poorly understood. The aim of this study was to investigate the location, number and consistency of venous valves in the femoral and popliteal veins in normal subjects. A detailed literature search of PubMed was performed. Abstracts and selected full text articles were scrutinised and relevant studies published between 1949 and 2010 reporting anatomical details of deep vein valves were included. From 7470 articles identified by the initial search strategy, nine studies with a total of 476 legs were included in this review. All studies were cadaveric and subjects ranged from stillborn fetuses to 103 years of age. Studies suggested that femoral veins contain between one and six valves, and popliteal veins contain between zero and four valves. Deep vein valves were consistently located in the common femoral vein (within 5 cm of the inguinal ligament), the femoral vein (within 3 cm of the deep femoral vein tributary) and in the popliteal vein near the adductor hiatus. Valves are consistently located at specific locations in the deep veins of the leg, although there is often significant variability between subjects. Further anatomical and functional studies using new imaging modalities available should target these areas to identify whether certain valves play a more important role in venous disease. This may guide us in the development of new treatment options for patients with deep venous disease.     

髂静脉压迫综合征的造影表现

目的：探讨髂静脉压迫综合征的造影方法及表现。方法：对79例髂静脉压迫综合征患者行血管造影检查，其中单纯下肢深静脉顺行造影17例，另62例加做股静脉插管造影。结果：79例患者髂静脉均有不同程度的狭窄，左侧72例，右侧6例，双侧1例；其中髂静脉病变部位近端增宽、密度减低25例，局部狭窄23例，充盈缺损14例，正位造影正常、侧位造影明显狭窄14例，髂静脉闭塞3例。所有患者显示不同程度的股静脉瓣膜返流。结论：血管造影是诊断髂静脉压迫综合征最确切和实用的方法。     

下肢静脉血栓的彩色多普勒超声诊断

目的 探讨下肢静脉血栓的彩色多普勒超声声像图特点。方法 回顾性分析71例下肢静脉血栓形成患者的彩色多普勒声像图特点。结果 左下肢的发病率明显高于右下肢，常累及股静脉、股浅静脉、股深静脉、月国静脉等。声像图特点为管腔内探及实性高或低回声团块CDFI血流信号变细或无血流信号；脉冲多普勒血流速度减慢且不受呼吸影响。结论 彩色多普勒超声诊断下肢静脉血栓具有直观性、可靠性。     

下肢深静脉血栓形成药物治疗150例疗效分析

目的探讨下肢深静脉血栓形成药物治疗的方法、疗效。方法回顾分析2005年5月至2010年7月对150例LDVT患者药物治疗资料，发病时间1d～1个月，均为单肢发病，周围型60例，髂股型85例，混合型5例，全部病例经下肢血管彩超及静脉造影检查证实。治疗期间均未置放下腔静脉滤器，予抗凝、溶栓等治疗，时间10～14d。结果130例患者治疗期间患者水肿完全消退，2周后复查Doppler超声基本全程通畅；20例患者患肢轻度肿胀，Doppler超声复查存在髂股静脉短段闭塞，给予华法林维持治疗及弹力袜保护治疗6个月至1年。所有病例均获随访12-18个月，患肢肿胀明显消退，均无肺栓塞并发症。结论下肢深静脉血栓形成药物治疗安全、效果肯定。     

Non satellite veins in the pelvic limb of the llama (Lama glama)

The objective of this study was to determine the major differences in the venous system of the pelvic limb of the llama (Lama glama) and that of other mammals, including humans. Eight adult llamas, preserved by means of 6% formalin solution at 0°C, were dissected. The venous system was perfused with a solution of 17% coloured industrial gelatin. Two venous systems are recognised, superficial and deep. The veins of the deep system follow the same course as the arteries, except for two important veins located in the femoral, popliteal and crural regions. A more voluminous vein than the femoral originates in a venous tripod in the proximal part of the femoral canal and forms an anastomosis with the femoral vein distally. The popliteal vein gives off an expansion located along the popliteal region. In the leg, it continues with a vein that accompanies the tibial nerve and forms an anastomosis distally with the medial saphenous vein. The described venous distribution represents an interesting complement to the medial saphenous, popliteal and femoral veins, being more important than the last one for its volume. In the thigh it would correspond to the deep femoral vein as in humans and dogs; the homology in the popliteal and leg regions is too difficult because it probably corresponds to the caudal tibial vein of the human, the caudal branch of the medial saphenous vein, and the satellite vein of the tibial nerve in the horse. Anat Rec 256:99–103, 1999. © 1999 Wiley‐Liss, Inc.     

Morphological changes in femoral vein wall structure in presence of persistent vertical reflux

The article contains an analysis of different mechanisms of persistent chronic venous insufficiency formation and its impact on the condition of lower extremity magistral vein wall. The authors studied autopsy samples of femoral vein segments from 86 patients aged 56 to 64 years, who had died of non-cardiovascular diseases. The investigation revealed significant changes in the vein wall structure, associated with persistent overload caused by valvular insufficiency and continuous persistent vertical reflux. At the same time, valve cusp structure remodels. Histological studies show that the overload of the system of deep femoral vein segment primarily increases the bulk of longitudinal smooth muscle cells, which fulfill the main contractile function in contrast to circular smooth muscle cells, performing the tonic function. Further overload of all vein wall structures results in structural alterations, smooth muscle cell hypertrophy, forming of longitudinal smooth muscle cell fascicle, and finally, their dystrophic changes. These processes bring about clinical presentations of chronic venous insufficiency.     

DKA, CVL and DVT. Increased risk of deep venous thrombosis in children with diabetic ketoacidosis and femoral central venous lines

Incidence of type 1 diabetes mellitus is continuing to rise in children. The presentation of diabetic ketoacidosis (DKA) in children with newly diagnosed diabetes is significantly higher in those less than 5 years old. Critically ill patients admitted to Paediatric Intensive Care Units (PICU), would have a central venous line (CVL) inserted as part of their ongoing management. There are associations linking with the development of deep venous thrombosis (DVT) in DKA/CVL patients. An 18-month-old boy presented with a short history of polydypsia, polyuria and weight loss. The initial blood sugar was 27.0 mmol/L and a venous blood gas showed severe metabolic acidosis. He was diagnosed and treated for DKA. He was transferred to the regional PICU for further management. There, a central venous line (CVL) was inserted in his left femoral vein. This was removed on Day 4. Subsequently, he developed a swelling on his left leg, with significant discrepancy in leg circumference. Doppler ultrasound confirmed a deep venous thrombosis. Conclusion Diabetes has a propensity for hypercoagulability and DKA promotes a prothrombotic state. Retrospective studies have shown younger patients with DKA and a femoral CVL are at higher risk of developing DVT. A central femoral line should avoided in such patients. DVT prophylaxis and Doppler follow up should also be considered.