儿童心脏瓣膜置换手术技巧及效果

目的 总结1999年9月至2006年9月14例儿童心脏瓣膜置换术的经验。探讨儿童瓣膜置换的手术指征、辩膜选择、手术技术和术后抗凝治疗等问题。方法 全组14例中10例为先天性心脏瓣膜病变，3例风湿性病变，1例先天性室间隔缺损致心内膜炎、主动脉瓣膜菌栓。在中低温体外循环下手术，二尖瓣置换7例，主动脉瓣置换6例，二尖瓣置换＋主动脉瓣置换1例。均采用机械瓣。若合并其它先天性心脏畸形或三尖瓣关闭不全，同期矫治。术后常规应用华法林抗凝。结果 本组手术死亡1倒，12例心功能恢复至Ⅰ级，1例心功能Ⅱ级。发生1例感染性心内膜炎，治愈。均坚持采用华法林抗凝，无血栓栓塞及抗凝相关并发症发生，辩膜功能良好。结论 儿童心脏瓣膜置换术采用机械瓣效果较好；应用低强度的华法林进行抗凝治疗安全可靠。     

儿童心脏瓣膜置换手术技巧及效果

目的总结14例儿童心脏瓣膜置换术的经验,探讨儿童瓣膜置换的手术指征、瓣膜选择、手术技术和术后抗凝治疗等问题。方法全组14例中10例为先天性心脏瓣膜病变,3例风湿性病变,1例先天性室间隔缺损致心内膜炎、主动脉瓣膜菌栓。在中低温体外循环下手术,二尖瓣置换7例,主动脉瓣置换6例,二尖瓣置换 主动脉瓣置换1例。均采用机械瓣。若合并其它先天性心脏畸形或三尖瓣关闭不全,同期矫治。术后常规应用华法林抗凝。结果本组手术死亡1例,12例心功能恢复至I级,1例心功能II级。发生1例感染性心内膜炎,治愈。均坚持采用华法林抗凝,无血栓栓塞及抗凝相关并发症发生,瓣膜功能良好。结论儿童心脏瓣膜置换术采用机械瓣效果较好;应用低强度的华法林进行抗凝治疗安全可靠。     

心脏瓣膜替换术后抗凝治疗的监护

严重的风湿性心瓣膜疾病均需进行瓣膜替换手术。目前人工瓣膜均采用机械瓣膜。瓣膜替换术后，进行抗凝治疗时，如药量不足易出现血栓；药量过大可引起出血。这是抗凝治疗中最易出现的并发症。因此抗凝治疗期间病人的监护具有非常重要的意义。现将我院1999年8月至2004年2月行瓣膜替换术94例病人抗凝监护情况报告如下。     

组织工程心脏瓣膜细胞生物学研究进展

由于现有的机械瓣和生物瓣仍存在种种不足，如不具备生长性、需抗凝、易感染、不能生长和自我修复等。组织工程心脏瓣膜是一新兴的研究领域，涉及多门学科。构建组织工程心脏瓣膜应包括支架的制作、细胞的种植、瓣膜的体外培养和最终移植人人体。其中种植的细胞是组织工程心脏瓣膜的基本要素。就组织工程心脏瓣膜的细胞生物学研究进展做一综述。     

组织工程心脏瓣膜及干细胞应用前景

组织工程心脏瓣膜是一种具有活力、能够自我修复和增生的人工瓣膜。理想的组织工程心脏瓣膜由于具有优良的血流动力学特征,低或甚至无免疫反应,不需要长期抗凝治疗以及耐用性好等特性,能够很好地克服目前临床上使用的机械瓣和生物瓣的缺点。综述了近年来国外组织工程心脏瓣膜在生物材料、培养环境和种子细胞等方面的新进展,并展望了干细胞作为种子细胞的应用前景。     

C-LⅢ型短柱人工机械心脏瓣膜的研制

简述了C-LⅢ型短柱人工机械心脏瓣膜的设计依据、结构特点及关键材料与工艺特性，报道了强度和疲劳试验结果，研究和比较了C-LⅢ型短柱瓣、C-LI型标准瓣、Medtronic—Hall瓣体外流体动力学性能。结果表明，C-LⅢ型短柱人工机械心脏瓣膜结构简单、性能优良，是一种新型的有希望的国产人工心脏瓣膜。     

康复手册结合播放录像在心脏瓣膜置换者健康教育中的应用

目的探讨康复手册结合播放录像在心脏瓣膜置换者健康教育中应用效果和实用性,为进一步提高护理工作质量提供依据。方法将104例心脏瓣膜置换者随机分为对照组和实验组,对照组54例,实验组50例,对照组按传统的方法进行健康教育,实验组采用发放康复手册结合播放录像的方式进行健康教育。对照两组患者的健康知识答题正确率、预防并发症的方法、抗凝治疗依从性、对教育的满意度进行评价,比较两种教育方法的效果。结果实验组患者康复知识回答正确率为97.13%,对照组为73.10%,实验组显著高于对照组（P〈0.01）;实验组中对预防术后并发症的掌握率、抗凝治疗的依从性、对教育的满意度高于对照组（P〈0.05）。结论在心脏瓣膜置换患者中应用康复手册结合播放录像进行健康教育能明显提高健康教育效果和质量,是一种有效的教育方式。     

康复手册结合播放录像在心脏瓣膜置换者健康教育中的应用

目的 探讨康复手册结合播放录像在心脏瓣膜置换者健康教育中应用效果和实用性,为进一步提高护理工作质量提供依据.方法 将104例心脏瓣膜置换者随机分为对照组和实验组,对照组54例,实验组50例,对照组按传统的方法进行健康教育,实验组采用发放康复手册结合播放录像的方式进行健康教育.对照两组患者的健康知识答题正确率、预防并发症的方法、抗凝治疗依从性、对教育的满意度进行评价,比较两种教育方法的效果.结果 实验组患者康复知识回答正确率为97.13%,对照组为73.10%,实验组显著高于对照组(P＜0.01);实验组中对预防术后并发症的掌握率、抗凝治疗的依从性、对教育的满意度高于对照组(P＜0.05).结论 在心脏瓣膜置换患者中应用康复手册结合播放录像进行健康教育能明显提高健康教育效果和质量,是一种有效的教育方式.     

组织工程化静脉瓣研究的现状及展望

原发性瓣膜功能不全、血栓形成完全再通后的瓣膜破坏以及先天性瓣膜缺乏等形成的深静脉功能不全,静脉瓣移植常常是最后的选择。但是,自体静脉瓣移植除来源有限、损伤较大外,尚有瓣膜强度不足和带瓣静脉的管径难以符合要求等问题。而异体瓣膜和人工瓣膜必须终身抗凝,极易发生血栓、栓塞和抗凝相关出血等严重并发症,影响患者生存和生活质量。近年来,心血管组织工程技术的发展为构建组织工程化静脉瓣提供了可能。研究证明,虽然每条深静脉的瓣膜有多对,但只要移植一对有功能的瓣膜就能明显改善血液逆流的问题。理想的组织工程化静脉瓣应该具有类似天然瓣膜的三层结构,有较强的力学性能,能够承受跨壁压力和血流对瓣膜的切应力;表面应该完全内皮化,有较好的抗血栓形     

组织工程心脏瓣膜细胞生物学研究进展

由于现有的机械瓣和生物瓣仍存在种种不足,如不具备生长性、需抗凝、易感染、不能生长和自我修复等。组织工程心脏瓣膜是一新兴的研究领域,涉及多门学科。构建组织工程心脏瓣膜应包括支架的制作、细胞的种植、瓣膜的体外培养和最终移植入人体。其中种植的细胞是组织工程心脏瓣膜的基本要素。就组织工程心脏瓣膜的细胞生物学研究进展做一综述。     

Daily transient discontinuation of extracorporeal LVAD to prevent thromboembolism of mechanical aortic valve prosthesis

Patients with mechanical aortic valves are generally contraindicated for left ventricular assist device (LVAD) insertion because the prosthetic valve often becomes fixed in closed position. A 41-year-old woman with mechanical aortic valve prosthesis experienced sudden chest pain and developed cardiogenic shock. A paracorporeal pulsatile LVAD and a monopivot centrifugal pump as a right VAD (RVAD) were implanted. The mechanical aortic valve was intentionally left in place. Soon after the operation, LVAD support was discontinued daily for few seconds to allow the mechanical aortic valve to open and to avoid thrombus formation. The patient was successfully weaned off RVAD and received anticoagulation therapy with warfarin. On postoperative day 141, she was transferred to a university hospital where a HeartMate II LVAD was implanted, and the aortic valve was successfully replaced with a bioprosthetic valve. The patient is currently awaiting heart transplantation.     

Observations on Cardiac Output in Animal Experiments and Clinical Application of Jiuling Bileaflet Mechanical Valve Prosthesis

Objective:To observe the cardiac output(CO)in animals and patients undergone valve replacement with Jiuling bileaflet mechanical valve prosthesis.Methods: 1.Animal experiments:6 sheep that subjected to mitral replacement with a 21-mm-valve prosthesis were measured by open cardiac catheterization intraoperatively. Echocardiographic and open cardiac catheterization under dobutamine stress were performed on 2 sheep survival for 30 months post-operation.2.Patient measurements:CO of 14 cases of aortic valve and 10 cases of mitral valve was measured by open cardiac catheterization,and after 12 months,it was measured by echocardiography.Results:1. Animal experiments:The mean CO of 6 sheep was 2.5 L/min intraoperatively by catheterization,and that of 2 sheep survival for 30 months post-implant was 3.0 L/min by echocardiography and 2.9 L/min by catheterization,respectively.2.Patient measurements: The mean cardiac index of 4 patients with 21 mm valve replacement was(2.55±0.27) L/min/m2by catheterization,and was(2.84±0.13)L/min/m2 by echocardiography after 12 months.Conclusion:This study demonstrates that cardiac function on animals and patients return to normal activity after undergone the valve replacement,and the newly valve prosthesis shows excellent hemodynamic performance.     

Novel "biomechanical" polymeric valve prostheses with special design for aortic and mitral position: a future option for pediatric patients?

In children, systemic heart valve replacement with bioprostheses is associated with accelerated valve degeneration, and mechanical prostheses require permanent anticoagulation. Novel "biomechanical" polymeric valve prostheses ("bio" = flexible, "mechanical" = synthetic), solely made of polycarbonate urethane (PCU), were tested in vitro and in a growing animal (calf) model with the aim of improved durability without permanent anticoagulation. The trileaflet aortic prosthesis has diminished pressure loss and reduced stress and strain peaks. The asymmetric bileaflet mitral valve mimics natural nonaxial inflow. The valves underwent long-term in vitro testing and in vivo testing in growing calves for 20 weeks [mitral (7), aortic (7)] with comparison to different commercial bioprostheses [mitral (7), aortic (2)]. In vitro durability of PCU valves was proved up to 20 years. Survival of PCU valves versus bioprostheses was 7 versus 2 mitral and 5 versus 0 aortic valves, respectively. Two animals with PCU aortic valves died of pannus overgrowth causing left ventricular outflow tract obstruction. Degeneration and calcification were mild (mitral) and moderate (aortic) in PCU valves but were severe in biological valves. There was no increased thrombogenicity of the PCU valves compared to bioprostheses. The novel polymeric valve prostheses revealed superior durability compared to current bioprostheses in growing animal model without permanent anticoagulation and thus, may be a future option for pediatric patients.     

Blood compatibility of a newly developed trileaflet mechanical heart valve

An ideal heart valve prosthesis, which has both the flow dynamic properties and blood compatibility of a tissue valve prosthesis and the durability of a mechanical prosthesis, does not exist. The Triflo trileaflet mechanical heart valve (MHV; Triflo Medical Inc., Irvine, CA) is a newly developed MHV prosthesis with the following design goals: central flow, minimal flow disturbance and stasis around the hinge region, and durability. The current study was conducted to evaluate the blood compatibility of a 29 mm Triflo MHV in the mitral position of eight calves for 5 months without any postoperative anticoagulation. Whole blood platelet aggregometry and the Xylum Clot Signature Analyzer (Xylum Corporation, Scarsdale, NY) were used to evaluate the postoperative changes in platelet and coagulation functions. Full autopsies, histological examinations of major internal organs, and scanning electron microscopy analyses of the explants were performed. Early termination occurred in two cases; one was because of valve thrombosis on the 25th day, and the other was killed because of a nonvalvular complication on the 105th day. The valve thrombosis was attributed to prolonged ventricular fibrillation at the time of valve replacement surgery. Whole blood platelet aggregometry and clot signature analyzer parameters did not show any sign of activation of platelets or the coagulation system. No hemolysis was observed. There was no macroscopic valve thrombosis or embolism observed in the remaining seven cases. Scanning electron microscopy analyses showed clean leaflet and valve ring surfaces, with only occasional minute platelet aggregations. Excellent blood compatibility of the Triflo MHV was demonstrated in this study.     

Bioreactors for Development of Tissue Engineered Heart Valves

Millions of people worldwide are diagnosed each year with valvular heart disease, resulting in hundreds of thousands of valve replacement operations. Prosthetic valve replacements are designed to correct narrowing or backflow through the valvular orifice. Although commonly used, these therapies have serious disadvantages including morbidity associated with long-term anticoagulation and limited durability necessitating repeat operations. The ideal substitute would be widely available and technically implantable for most cardiac surgeons, have normal hemodynamic performance, low risk for structural degeneration, thrombo-embolism and endocarditis, and growth potential for pediatric patients. Tissue engineered heart valves hold promise as a viable substitute to outperform existing valve replacements. An essential component to the development of tissue engineered heart valves is a bioreactor. It is inside the bioreactor that the scaffold and cells are gradually conditioned to the biochemical and mechanical environment of the valve to be replaced.     

Cardiac valve replacement: a bioengineering approach

The second most common major heart operation in the western world is valve replacement. Any one of the four heart valves may become either so stenotic or regurgitant that it needs to be replaced in order to restore normal heart function. Although replacement surgery of dysfunctional heart valves has a very high success rate, it can provide the surgeon with a difficult decision regarding the choice of a suitable prosthesis for the individual patient. Over the years many different types of artificial heart valves have been devised. Surgeons typically deal with a heart valve replacement by installing a mechanical prosthesis or by using a bioprosthetic valve, hand-crafted from animal tissue. Least commonly, valves can be taken from human organ donors. Mechanical valve substitutes have a long fatigue life but the central flow occluders often induce blood cell trauma. Tissue substitutes have an unimpeded central orifice when open, cause minimal cell damage but have a relatively short fatigue life, especially in children where calcification may be a major problem. More recently alternative materials, such as polyurethane, have been used in artificial heart valve design while the new concept of tissue-engineering has enhanced the prospects towards an ideal cardiac valve replacement. Today's artificial valves are designed with a better understanding of the cardiovascular system with the aid of computers. Advances in computer software have allowed simulations of fluid flows through valve substitutes, both in cardiac flow simulators and the heart itself.     

In Vitro Study of Influence of Mimic Cardiac Rate on Hydrodynamics of the Different Mechanical Cardiac Valve Prostheses

To assess the influence of mimic cardiac rate on hydrodynamics of the different mechanical prosthetic cardiac valves. Methods. US-made CarboMedics bileaflet valve and China-made Jiuling bileaflet valve and C-L tilting disc valve have been tested in a pulsatile flow simulator in the aortic position. The testing condition was set at the mimic cardiac rate of 55 beats/min,75 beats/min,100beats/min and a constant mimic cardiac output of 4L/min. The mean pressure differences (△P),leakage volumes (LEV) and closing volumes(CLV) across each valve,and the effective orifice areas(EOA) have been analyzed. Results.Within the range of physiology,the AP,LEV and CLV were falling as the increasing of mimic cardiac rate,and the extent of variance was larger. The EOA was increasing with the increase of the mimic cardiac rate. It is a different response as the altering of the cardiac rate for the different type of the mechanical prosthetic cardiac valves.Conclusions.The change of the mimic cardiac rate can affect the hydrodynamics of the mechanical prosthetic cardiac valves. The hydrodynamics of the bileaflet valve prosthesis is better than the tilting disc valve.     

Long-term results of mitral valve replacement: biological xenograft versus mechanical valves

 We studied 279 patients who underwent mitral valve replacement at the Department of Thoracic and Cardiovascular Surgery, Hyogo College of Medicine, between November 1973 and December 1998. The patients were divided into two groups based on the type of replacement valve (154 patients in the biological xenograft group and 125 patients in the mechanical valve group), and the long-term results were compared. Clinically satisfactory results were obtained in both the biological xenograft group and the mechanical valve group according to the surgical results, long-term survival, and incidence of prosthetic valve endocarditis. At 15 years, fewer patients in the mechanical valve group than in the biological xenograft group were free of bleeding events (92.5 ± 3.7% vs 100% P < 0.05). At 15 years, the biological xenograft group was lower than the mechanical valve group with respect to freedom from thromboembolism (72.2 ± 4.6% vs 93.5 ± 3.6% P < 0.01), freedom from valve failure (22.0 ± 5.2% vs 87.0 ± 4.1% P < 0.005) and freedom from cardiac events (16.5 ± 3.9% vs 47.2 ± 14.5% P < 0.01). Though it has previously been suggested that biological xenografts used in mitral valve replacement do not need anticoagulation, the current study suggests the need for anticoagulation with the use of biological xenografts. Mechanical valves require close monitoring of anticoagulation, but their use has decreased the incidence of valve failure and thromboembolism, as compared with the use of biological xenografts. Therefore, mechanical valves are currently the preferred choice for mitral valve replacement. We believe that biological xenografts are indicated only for the older patient (≧65 years). Received: August 1, 2002 / Accepted: October 28, 2002 Correspondence to:H. Yao     

Thrombolytic treatment of thrombosis on the aortic valvular prosthesis complicated by brain embolism

The authors present a case of thrombosis on the St. Jude Medical 19 aortic valve prosthesis. The diagnosis was confirmed by transthoracic and transoesofageal echocardiography, cardiac fluoroscopy revealed restricted movement of the aortic valve prosthesis leaflet. Thrombolytic therapy was complicated with brain embolism that was successfully percutaneously removed from the cerebral artery by the mechanical device. The patient has fully recovered without any neurological residual symptoms. This case report should be instructive to other clinicians who encounter the same complications after thrombolytic treatment.     

Twenty-two years without anticoagulation with metallic heart valve

Anticoagulation is essential and vital for mechanical heart valves to prevent lethal complications such as valve thrombosis and systemic embolism. Herein, we reported the third longest survived case with a metallic aortic valve without anticoagulation and reviewed the role of anticoagulation in mechanical heart valves.