高分子材料人造血管顺应性的研究

顺应性的匹配问题是高分子材料人造血管生物力学性能中的一个重要问题。作者概述了动、静脉血管顺应性的含义及人造血管顺应性的重要性。重点讨论了人造血管顺应性的力学表征及测试方法。人造血管的生物力学性能表征是指导开发新材料的基础和手段。     

小口径微孔聚氨酯人造血管生物力学性能研究

目的分析小口径聚氨酯人造血管的微观形态,探讨聚氨酯人造血管管壁厚度对其渗透性能和拉伸强度的影响。方法通过在直径为4mm玻璃棒模具上复合均匀厚度的聚氨酯膜,并加入一定量的致孔剂,研制出具有微观多孔结构的小口径聚氨酯人造血管。采用扫描电镜表征其微观多孔结构,根据ISO7198国际标准设计了一套人造血管渗透性能的测试装置来测试其水渗透性能,并通过INSTRON万能强力仪(型号:5566)测试其拉伸强度。结果小口径的聚氨酯人造血管的内、外表面以及截面均呈微孔结构,微孔的大小在100μm以下,大小和分布比较均匀,并且随着人造血管壁厚度的增加,其渗透性能逐渐减小,拉伸强度先增大后减小,实验测试结果均与国外研究在同一范围。结论用聚氨酯材料研制的小口径人造血管在部分生物力学性能方面能满足人体血管置换要求。     

经编人造血管顺应性的实验研究

对EP系列经编人造血管的径向顺应性和纵向顺应性进行了体外测试和研究,并分析了不同制备工艺对经编人造血管的径向顺应性的影响.实验结果表明,紧密化处理和波纹化热定性对人造血管的径向顺应性影响较大.测试压力段的选择对人造血管成品的纵向顺应性有较大的关系.     

小径微孔聚氨酯人工血管的顺应性

由激光测微器、压力传感器、A／D卡、微电脑和循环回路等组成的装置测定了小径人工血管的径向顺应性，由微注射器、压力传感器等组成的装置测定了体积顺应性，轴向顺应性由体积顺应性和径向顺应性计算出。体积顺应性，径向顺应性和轴向顺应性都随血管材料弹性的增大、盐／胶比的增加（孔隙率）和浸渍层数（血管壁厚度）的减小而增大。PU血管的外周模量与径向模量分别由径向顺应性。轴向顺应性计算，外周模量与径向模量之比值接近1，即两模量大小与变形方向无关。外周模量与径向模量随血管材料弹性和盐／胶比增加而变小。但管壁厚度对其的影响不大。通过合理选择更具弹性的PU材料（Chro佳，PCU1500次之），最佳盐／胶比例（6：1）以及控制浸渍层数（4～6层），可以制备出顺应性接近天然血管的小径人工血管。     

我国研制出小口径人造血管

“我们已经成功研制出直径小于6毫米的人造血管。这项技术填补了国际空白,有助于多种血管疾病的治疗。”人造血管项目负责人、北京理工大学材料学院副院长曹传宝教授在接受《生命时报》记者采访时骄傲地说。     

人造血管轴向拉伸性能测试装置的实验研究

介绍了一种新的人造血管纵向拉伸强度的测试方法,通过分析新旧两种方法的原理,论证了新方法更具合理性.     

聚氨酯涤纶复合人工血管顺应性研究

目的 分析不同应用环境对聚氨酯涤纶复合人工血管顺应性的影响。方法 通过改变测试中的频率和压力模拟人工血管不同应用环境,对3种不同直径的聚氨酯涤纶复合人工血管在恒定压力不同频率,以及恒定频率不同压力下的顺应性进行测试,使用t检验分析测试结果的差异性。结果 本研究中使用的3种直径的聚氨酯涤纶复合人工血管,在恒定压力不同频率的测试中,顺应性测试值均随着频率的增大而减小(P<0.05);在恒定频率不同压力的测试中,顺应性测试值随着压力的增大而减小(P<0.05)。结论 聚氨酯涤纶复合人工血管的顺应性结果明显受到应用环境的影响,并且这种影响呈规律性变化。在人工血管的生产、质控以及临床使用中应充分考虑预期使用部位的特性,以提高临床使用过程中人工血管与人体的适配性。     

人造血管在治疗四肢大血管损伤中的初步应用

目的作者自1995-2002年采用人造血管移植修复四肢大血管损伤23例，进行回顾性研究人造血管在治疗四肢大血管损伤中的应用。方法23例中男19例，女4例。年龄：21～47岁，平均34．7岁。手术清创和探查后，针对不同的情况选择人造血管移植修复方法。结果采用人造血管移植23例，肢体全部保存，肢体功能恢复较佳。结论四肢大血管损伤救治应快速诊断、快速救治，采用人造血管移植修复四肢主要血管损伤是一种快捷有效的方法。     

维持血液透析患者人造血管的护理

目的 探讨人造血管在维持血液透析患者中的应用和护理方法.方法 使用非生物性材料四氟乙烯人造血管(PTFE),将PTFE血管连接于上肢动脉与静脉之间,则可以建立一种透析所需的长期血管通路,采用U型搭桥术.结果 解决了内瘘闭塞或自体血管缺陷难以造瘘带来的困难.结论 PTFE血管的应用,提高了长期维持血透患者的生命质量.     

Fabrication of small-diameter polyurethane vascular grafts with microporous structure

 Microporous polyurethane vascular grafts with a diameter of 3 mm were fabricated by a spray phase inversion technique (SPIT). The microporous structure and hydraulic permeability of the grafts were regulated by changing the fabrication conditions. The maximum hydraulic permeability of 26 ml/min/cm², which was obtained in this series of grafts, satisfied the target value of about 10–40 ml/min/cm², which our previous studies suggested would lead to satisfactory graft patency. Further investigation is, however, needed to optimize the microporous structure and hydraulic permeability of the grafts. Received: October 10, 2000 / Accepted: February 4, 2002     

Usefulness of polyurethane for small-caliber vascular prostheses in comparison with autologous vein graft

 For long-term patency of small-caliber vascular prostheses, antithrombogenicity and microporous structure are very important. We have developed a new technique to give a microporous structure to a polyurethane vascular prosthesis that has favorable antithrombogenicity. A solution of tetrahydrofuran/dimethylformamide (1 : 1) containing 13 wt% of segmented polyurethane (PTMG + MDI) and calcium carbonate (mean particle size, 8 μm) was dipcoated on a glass mandrel 3 mm in diameter and placed into distilled water. After the glass mandrel was removed, the polyurethane tube was placed into hydrochloric acid, and a microporous polyurethane vascular prosthesis was produced. Prostheses made in this fashion, and autologous jugular vein grafts were implanted into the femoral artery and the carotid artery of mongrel dogs. Patency was recognized on the arteriogram and duplex scanning (ultrasonography), and the removed grafts were inspected macroscopically and microscopically. This prosthesis was similar in elasticity to a vein graft. Patency was defined 8 weeks after implantation, and this prosthesis showed less intimal hyperplasia than the autologous vein graft. The new polyurethane prosthesis might be useful for small-caliber vascular reconstruction. Received: December 18, 2000 / Accepted: January 28, 2002     

Non-invasive studies of peripheral vascular compliance using a non-occluding photoplethysmographic method

A non-invasive technique is implemented to measure a peripheral vascular compliance index C_index, using an infrared photoplethysmographic waveform as an indicator of intravascular volume change and a continuous blood pressure monitor to measure the blood pressure during each heart-beat. The non-linear behaviour of C_index with pressure and the effect of age on C_index are studied in 62 males (15–73 years). Repeatability tests and the effect of ice-water exposure of a portion of a limb are studied in 10 and 14 subjects, respectively. For each individual, C_index measurements are taken at discrete values of local mean arterial pressure (P_mean), and a C_index against P_mean plot is obtained. There is a statistically significant difference (p<0.05) in C_index for the lower values of P_mean (60–100 mmHg) between two age groups formed (15–52 and 58–73 years). The cold-pressor test (CPT) shows a 68% median decrease in C_index, with an inter-quartile range of 60–77%, in a matter of seconds. The results suggest that C_index may be a useful noninvasive indicator of peripheral vascular compliance in humans.     

Application of artificial palpation in vascular surgeries for detection of peripheral arterial stenosis

Palpation is one of the applied methods that surgeons usually use during surgery in order to verify the health condition of a tissue/organ. In fact, most of surgical assessments are based on analysis of the force feedback received from tissue/organ via palpation. Although palpation has a key role in efficient progress of surgery operations, it depends very much on the experience and skill of the surgeons. This limits the application of this technique in some cases to a large extent. In this regard, an artificial tactile sensing approach is an innovative technology that tries to make tactile data more available for surgeons, especially in situations where doing the palpation is not possible or is too difficult. In this paper, having considered the present problems of artery bypass surgery in peripheral arterial occlusive disease (PAOD), applicability of a new tactile sensory system capable of detecting arterial stenosis during surgery was evaluated. Presenting the modelling and numerical solution of the problem, it was demonstrated that the artificial tactile sensing approach is not only capable of detecting the presence of an arterial stenosis in an artery, but also its type. Furthermore, it was shown that the new tactile sensory system (previously designed, fabricated and tested in laboratory) is efficiently capable of detecting the simulated artery in the simulated biological tissue as well as diagnosis of the stenosis occurred inside it.     

人工肌肉临床应用前景

有临床应用前景的人工肌肉材料大致有两类。传导电子做驱动力的材料靠电场力作用,如场致电收缩式聚合物、电场反应式弹性体及压电铁电型塑料,应用电压很高。传导离子的材料有pH响应式水凝胶、电容驱动式碳纳米管、电化学式导电聚合物及离子塑料金属复合物,应用电压低。还有电解相变式收缩材料、磁敏式收缩材料、光致敏液晶收缩材料及分子致动塑料等。这些可望在检验标本移取、眼外肌、假肢和人工心脏的开发上获得应用。     

Mechanical property characterization of electrospun recombinant human tropoelastin for vascular graft biomaterials

The development of vascular grafts has focused on finding a biomaterial that is non-thrombogenic, minimizes intimal hyperplasia, matches the mechanical properties of native vessels and allows for regeneration of arterial tissue. In this study, the structural and mechanical properties and the vascular cell compatibility of electrospun recombinant human tropoelastin (rTE) were evaluated as a potential vascular graft support matrix. Disuccinimidyl suberate (DSS) was used to cross-link electrospun rTE fibers to produce a polymeric recombinant tropoelastin (prTE) matrix that is stable in aqueous environments. Tubular 1 cm diameter prTE samples were constructed for uniaxial tensile testing and 4 mm small-diameter prTE tubular scaffolds were produced for burst pressure and cell compatibility evaluations from 15 wt.% rTE solutions. Uniaxial tensile tests demonstrated an average ultimate tensile strength (UTS) of 0.36 ± 0.05 MPa and elastic moduli of 0.15 ± 0.04 and 0.91 ± 0.16 MPa, which were comparable to extracted native elastin. Burst pressures of 485 ± 25 mm Hg were obtained from 4 mm internal diameter scaffolds with 453 ± 74 μm average wall thickness. prTE supported endothelial cell growth with typical endothelial cell cobblestone morphology after 48 h in culture. Cross-linked electrospun rTE has promising properties for utilization as a vascular graft biomaterial with customizable dimensions, a compliant matrix and vascular cell compatibility.     

The input impedance of the peripheral vascular termination in skeletal muscle

In order to investigate the dynamic behaviour of the peripheral vessels of the arterial system, simultaneous pressure-flow measurements were made in the deep femoral artery of the rabbit at the same site. The input impedance calculated from the recorded pulses was regarded as representing the peripheral vascular termination in skeletal muscle and was expressed in terms of modulus and phase. The modulus decreases monotonously with increasing frequency while the phase angle is about –45° in the low frequency range and becomes less negative with increasing frequency. This behaviour can be simulated by a model in which the inert mass of the pulsating blood, the elastic compliance of the blood vessels, and the frictional resistance to blood flow are taken into account. An essential result is that the model is provided with a considerable degree of elastic compliance, which means that the peripheral vessels as a whole possess an important compliance and do not behave like pure frictional resistances.To Prof. Dr. Erik Wetterer on the occasion of his 75th birthday