去细胞组织工程心脏瓣膜研究现状与展望

当前临床应用的所有生物瓣,包括无支架生物瓣共同致命弱点是易钙化、衰败,不具有生长活性。而随着组织工程技术的发展,组织工程心脏瓣膜的研究逐渐成为心脏外科领域的研究热点之一。在去细胞同种、异种瓣膜支架的基础上构建的组织工程瓣膜,以其具有低免疫原性、无细胞毒性、植入体内后宿主细胞再细胞化程度高、较好的仿生性、耐久性和机械强度,尤其具有生长功能等多方面的优势,而成为未来组织工程心脏瓣膜研究发展的一个重要方向。本文对近年来去细胞组织工程心脏瓣膜的研究进展进行综述,并指出目前研究中所存在的问题。     

组织工程心脏瓣膜

在心脏外科领域中,人工心脏瓣膜置换术是治疗心脏瓣膜性病变的主要外科治疗手段,然而,临床上可以使用的人工心脏瓣膜存在不同程度的缺陷。随着组织工程技术的发展,组织工程心脏瓣膜被认为是一种潜在的理想的人造瓣膜,具有非常重要的临床应用前景,是目前心脏瓣膜外科领域研究热点之一。本文对近年来组织细胞来源和种植、瓣膜支架材料、体外预适应和动物试验等方面的内容进行了综述,并指出目前研究中所存在的问题。     

异种生物瓣材料防钙化抗衰坏研究新进展

人工心脏瓣膜广泛应用于临床。机械瓣耐用，但是需终身抗凝，血栓栓塞率较高，存在与抗凝有关的合并症。生物瓣具有中央血流，跨瓣压差小，血栓栓塞率低，不需终身抗凝等优点，与瓣膜有关的合并症明显低于机械瓣。但是生物瓣的耐久性欠佳影响其临床使用。而钙化是导致生物瓣衰坏最主要的原因。近年来随着对瓣膜设计及瓣膜材料鞣制方法的改进，特别是组织工程技术的发展，生物瓣防钙化研究有了大的发展前景。现综述如下。     

组织工程心脏瓣膜研究进展（综述）

心脏瓣膜置换术是外科治疗瓣膜性心脏病的主要方法,临床应用的人工心脏瓣膜存在着需要终身抗凝或瓣膜容易衰败等缺点。随着组织工程学的发展,心脏瓣膜方面的研究已取得初步进展。该文综述近年来组织工程心脏瓣膜在种植材料、种子细胞、动物实验和基础研究方面取得的进展,并探讨组织工程心脏瓣膜的优越性和可行性。     

抗凝人工机械心脏瓣膜

人工心脏瓣膜直接暴露于连续的血流中。人工瓣膜的金属部分通常刺激血液使其凝固,对许多脏器(包括脑)的血管有引起血栓的潜在危险,因此病人必须服用抗凝药。而服用抗凝药后,当病人受伤时有引起出血致死的可能,所以同样有危险。适用于动物或人体组织的瓣膜特别强调克服血凝问题,但目前尚不能提供这样的机械瓣膜。许多不同类型的人工瓣膜已应用多年,但不管机械瓣的设计如何,其瓣环均用涤纶或特氟隆织物包裹,以利外科医生迅速地缝     

以带蒂筋膜瓣为引导骨再生膜包裹非细胞型组织工程骨修复超临界骨缺损研究进展

由创伤、肿瘤、感染、先天性畸形等造成的骨缺损临床治疗非常棘手,且由骨缺损导致的骨不愈合发生率很高。美国每年约600万骨折患者中,5％～10％因骨缺损导致骨折无法愈合[1]。骨缺损的治疗措施多种多样,自体骨移植是目前临床上治疗骨缺损的主要方法。但该方法存在缺陷,并可带来一些并发症,不利于其在临床中的广泛使用[2-3]。用带蒂筋膜瓣为膜材料应用引导性骨再生(guided bone regeneration,GBR)技术包裹非细胞型组织工程骨修复骨缺损是近年来研究的热点。现就应用带蒂筋膜瓣GBR技术包裹非细胞型组织工程骨修复超临界骨缺损的研究进展综述如下。     

无支架瓣膜研究进展

无支架瓣膜于 196 5年开始临床应用 ,由于手术难度大、术后瓣膜关闭不全发生率高 ,加上当时心肌保护技术尚不完善 ,瓣膜制作、保存方面存在大量问题 ,临床进展缓慢[1] 。伴随体外循环心肌保护技术的发展成熟 ,瓣膜外科手术经验的积累 ,生物瓣处理技术的初步完善 ,近十年这一领域的临床研究进展十分迅速 ,出现了多种品牌的无支架瓣膜 ,其中以MedtronicFreestyle[3～ 9] 、St.JudeTorontoSPV[10 ,11] 两种瓣膜使用较多 ,此外CryolifeO′Brien、BaxterPrima、Shelhigh及Biocor等无支架瓣膜亦有报道。临床应用显示 ,无支架瓣膜具有以下优…     

人工心脏瓣膜置换术前、术后病人的护理与健康宣教

在后天心血管疾病当中瓣膜性心脏病是成人主要的后天性心脏病之一,而人工心脏瓣膜置换术是通过置换受损的瓣膜,恢复瓣膜启闭功能,改善心功能,提高生活质量.临床主要用于治疗风湿性心脏病、部分感染性心内膜炎等所致的心脏瓣膜病变[1].我科自2005年12月～2007年3月共开展心脏瓣膜置换术18例,其中换机械瓣10例,生物瓣8例,现将术前、术后的护理与健康教育报告如下.     

奇妙的心音——心脏瓣膜替换术

当人体患了风湿性心脏病并累及到瓣膜,比如二尖瓣、主动脉瓣等,日久天长,心脏瓣膜便失去了它开启、关闭的功能,人的生命也就受到威胁。这时,就需要做心脏瓣膜替换术。就是取下患病的瓣膜,用人工制作的生物瓣或机械瓣取而代之。1960年首次应用瓣膜替换术成功后,揭示了治疗严重心脏瓣膜     

术中经食管超声心动图对心脏瓣膜置换术后即刻评估的价值研究

目的:研究术中经食管超声心动图对心脏瓣膜置换术(HVR)后即刻评估的价值。方法:选取168例行心脏瓣膜置换术患者,均在术中行经食管超声心电图检查,记录主动脉瓣环内径及钙化斑块情况,计算主动脉瓣内直径;观察并记录心脏收缩功能情况,血管内血栓、钙化及钙化斑块大小情况;术后观察人工瓣膜是否成功,重点分析心脏收缩、血容量及瓣膜闭合等情况。比较所有患者手术前后的瓣膜及心功能情况,分析术中经食管超声心动图对HVR术后即刻评估的价值。结果:经食管超声心动图三维检查检测的主动脉瓣环内径及钙化检出情况与手术病理结果相比,差异无统计学意义。在术中行经食管超声心动图发现,2例患者存在生物瓣瓣叶脱垂及缝线勒住生物瓣瓣脚情况,为在机体应力状态下人工瓣膜对合不良影响瓣叶功能,遂均更换相同型号瓣膜,更换后瓣环内反流消失。168例患者术后主动脉平均跨膜压差明显低于术前水平,左室射血分数及有效瓣口面积指数水平明显高于术前,差异有统计学意义(t=20.352,t=32.784,t=22.583;P<0.001)。所有患者均完成HVR,其中6例患者(生物瓣瓣叶脱垂1例、缝线勒住生物瓣瓣脚1例、拆除后离体检测碟片运动无异常的主动脉瓣机械瓣关闭不全1例、机械瓣碟片启闭不灵活且经调整碟片方向仍无改善的二尖瓣3例)更换新的人工瓣膜。所有患者术后恢复顺利,未发生院内死亡。结论:经食管超声心动图应用于HVR术中的临床价值较高,可及时确定人工瓣膜功能异常,协助判断内源性因素并给予及时补救,有助于为提高手术有效保障,对临床治疗效果进行真实性评估,有效提高HVR成功率。     

A method of determining the feedback resistance of artificial heart valves

Methods to check the back-feed resistivity of the artificial heart valve in static mode have been worked out. These methods allow one to check the resistivity of the closed valve to the revert liquid flow or liquid leakage through it when the new prostheses are tested. The comparative tests of two biovalves and eight mechanical prostheses were carried out. It was stated that among the mechanical valves, which are most widely used in the hospitals (disk, ball and triaflet) the highest resistance when closed has the silicon ball aortic valve AKCh-4-0.6 (Sh).     

人工机械心脏瓣膜的发展及其设计制造的优化

人工心瓣经过几代的发展，经临床验证，取得了很好的效果，但还不完善。而新兴的组织工程心瓣和高分子材料在人工心瓣领域的应用还处于起步阶段，一定时期内人工心瓣的需求依旧是机械心瓣占大多数。本文通过对四代人工机械心脏瓣膜发展和改进的研究，分析了人工机械心脏瓣膜优化设计及制造的几个关键环节。     

Surgery of the mitral valve--in the work of József Kudász

The author described his results of surgical treatment of mitral valve disease. Of 57 patients, the isolated mitral procedure was performed in 72%, and the combined (valve and coronary) in 28% of the cases. In 75% of the patients valve repair, and in 25% valve replacement were performed. There were 2 cases (3.5%) of early mortality after combined surgery where patients had also ischaemic heart disease. All the replaced valve prostheses and 84% of repaired mitral valve had a normal function. The mitral regurgitation was moderate in 14%, of cases and mild in 2% of cases at the follow up, but no reoperation was needed. After the surgery 85% of patients had sinus rhythm, 13% had atrial arrhythmia and in 2% the pacemaker was needed. Attempt of valve repair had to be made in all patients with mitral valve disease which can be performed in almost every case of degenerative valve prolapse and the rupture of chordae tendineae.     

Economic Evaluation of the Combined Use of Warfarin and Low-dose Aspirin Versus Warfarin Alone in Mechanical Valve Prostheses

Background

The use of combined therapy of antiplatelet and anticoagulant versus anticoagulant alone to reduce instances of thromboembolic events in patients with heart valve prostheses is an established standard of care in many countries but not in Egypt. A previous Markov model cost-effectiveness study on Egyptian patients aged 50–60 years demonstrated that the combined therapy reduces the overall treatment cost. However, due to the lack of actual real-world data on cost-effectiveness and the limitation of the Markov model study to 50- to 60-year-old patients, the Egyptian medical community is still questioning whether the added benefit is worth the cost.

Objective

To assess, from the perspective of the Egyptian health sector, the cost-effectiveness of the combined use of warfarin and low-dose aspirin (75 mg) versus that of warfarin alone in patients with mechanical heart valve prostheses who began therapy between the age of 15 and 50 years.

Methods

An economic evaluation was conducted alongside a randomized, controlled trial to assess the cost-effectiveness of the combined therapy in patients with mechanical valve prostheses. A total of 316 patients aged between 15 and 50 years were included in the study and randomly assigned to a group treated with both warfarin and aspirin or a group treated with warfarin alone.

Results

The patients in the combined therapy group exhibited a significantly longer duration of protection against the first event. Fewer primary events were observed in the patients treated with warfarin plus aspirin than in those treated with warfarin alone (1.4 %/year, vs. 4.8 %/year), and a higher mean quality-adjusted life-years (QALYs) value over 4 years was obtained for the group treated with warfarin plus aspirin (difference 0.058; 95 % CI 0.013–0.118), although this difference did not reach a conventional level of statistical significance. The total costs over a 4-year period were lower with the combined therapy (difference ?US$244; 95 % CI ?US$483.1 to ?US$3.8), which yielded an incremental cost-effectiveness ratio of ?US$4206 per QALY gained. Thus, the combined therapy was dominant. All costs were reported in US dollars (USD) for the financial year 2014.

Conclusions

The results of this analysis indicate that from the perspective of the Egyptian health sector, the addition of aspirin to the typical warfarin therapy is more effective and less costly for patients with mechanical valve prostheses than treatment with warfarin alone. This combined strategy could be adopted to prevent the complications of mechanical valve prostheses. Our study adds to the body of evidence supporting the option of warfarin-plus-aspirin therapy for patients with mechanical valve prostheses.

     

Effect of healing on small internal diameter arterial graft compliance

Porosity is an essential component for long term function of small internal diameter synthetic vascular prostheses. Theoretically, porosity is required for healing by providing a scaffold for ingrowth of periprosthetic tissues. Porosity may be required for transfer of fluids and ions in prostheses even if tissue ingrowth does not occur. Increased permeability of vascular grafts has been shown to enhance tissue incorporation. Implants with pore sizes greater than 10 microns but less than 45 microns become ingrown with fibrohistiocytic tissue and capillaries. Implants with pore sizes greater than 45 microns are ingrown with organized fibrous tissue and minimal histiocytic response. The phenomenon of differential ingrowth may have important functional significance. Prostheses which heal with organized fibrous tissue have the potential for long term contracture, strangulation of vascularity and calcification. Fibrohistiocytic tissue has low mechanical strength and does not appear to contract or calcify. Elastomeric microporous vascular prostheses which are minimally ingrown or ingrown with fibrohistiocytic tissue maintain compliance after months of implantation. This study was designated to determine the effects of healing on the compliance of small internal diameter vascular replacements and to correlate the compliance to patency rates.     

Breast reconstruction with expander prostheses

Breast reconstruction with tissue expanders is a technique that has been known to clinical practice since 1978. The authors present their clinical experience in the Plastic and Reconstructive Surgery Service of the Virgen del Camino Hospital from 1980 to 2005. They describe breast reconstruction using tissue expanders and the evolution towards immediate breast reconstruction with durable expanders prostheses, which resemble conventional breast prostheses and try to emulate the extirpated breast. They provide an historical review of the repercussion of mastectomy and breast reconstructive surgery in the different professional and social areas, as well as the change in mentality of society and health professionals that has benefited patients. The characteristics of post-mastectomy breast reconstruction, using expanders prostheses, are set out, as well as its advantages and drawbacks.     

Herzgewebe aus embryonalen Stammzellen

Embryonic stem cells can give rise to all somatic cells, making them an attractive cell source for tissue engineering applications. The propensity of cells to form tissue-like structures in a culture dish has been well documented. We and others made use of this intrinsic property to generate bioartificial heart muscle. First proof-of-concept studies involved immature heart cells mainly from fetal chicken, neonatal rats and mice. They eventually provided evidence that force-generating heart muscle can be engineered in vitro. Recently, the focus shifted to the application of stem cells to eventually enable the generation of human heart muscle and reach following long-term goals: (1) development of a simplified in vitro model of heart muscle development; (2) generation of a human test-bed for drug screening and development; (3) allocation of surrogate heart tissue to myocardial repair applications. This overview will provide the background for cell-based myocardial repair, introduce the main myocardial tissue engineering concepts, discuss the use of embryonic and non-embryonic stem cells, and lays out the potential direct and indirect therapeutic use of human tissue engineered myocardium.