Compliance properties of conduits used in vascular reconstruction

Tai, Nigel; Salacinski, Henryk J.; Edwards, A. J.; Hamilton, George; Seifalian, AM

doi:10.1046/j.1365-2168.2000.01566.x

Cited by 232 publications

(187 citation statements)

References 28 publications

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“…2 Surgeons have therefore turned to the use of prosthetic materials like polyethylene terephthalate (Dacron), polytetrafluoroethylene, expanded polytetrafluoroethylene, and polyurethane. [2][3][4][5][6][7][8] However, the results obtained with these prosthetic materials prove to be inferior to those obtained with autologous conduits, especially when the blood vessel diameter is Ͻ5 mm. The problems that can arise when these types of materials are used include increased risk of thrombosis and infection, limited durability, lack of compliance both of the graft and around the anastomosis, 9 and failure as a result of restenosis.…”

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confidence: 99%

Tissue-Engineered Human Vascular Media With a Functional Endothelin System

et al. 2005

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Background-Cardiovascular diseases remain a major cause of death and disability in the Western world. Among the various approaches adopted to counteract the morbidity associated with these diseases, surgical procedures and cardiac and vascular xenotransplantations or allotransplantations are routinely performed. The suitable vascular graft would be as close as possible to the native and healthy vessel composed exclusively of human components provided by the patient and would adapt to the donor's hemodynamics. We have developed such a tissue-engineered human blood vessel reconstructed with human cells. Because endothelin is the most potent vasopressor known to date, we were interested in investigating the functionality of the endothelinergic system in our reconstructed human blood vessel. Methods and Results-Vasoconstriction studies were performed with nonselective and selective agonists and antagonists to demonstrate that ET A receptors were present and functional in tissue-engineered human vascular media constructed with the self-assembly method. Reverse-transcriptase polymerase chain reaction studies demonstrated that mRNA of the ET A but not the ET B receptor was present in these human tissue-engineered blood vessels. Furthermore, we demonstrated that the endothelin-converting enzyme, the main enzyme responsible for the formation of the biologically active endothelin peptides, was present and functional in these same bioengineered vascular media. Key Words: endothelin Ⅲ muscle contraction Ⅲ myocytes, smooth muscle C oronary artery disease is the most common cause of morbidity and mortality in Western countries. 1 Treatment options include drugs, balloon angioplasty, and CABG surgery. Most artery bypass graft surgery involves harvesting of the long saphenous vein or mammary artery. However, in about a third of patients, this surgery proves inadequate or unsuitable. 2 Surgeons have therefore turned to the use of prosthetic materials like polyethylene terephthalate (Dacron), polytetrafluoroethylene, expanded polytetrafluoroethylene, and polyurethane. [2][3][4][5][6][7][8] However, the results obtained with these prosthetic materials prove to be inferior to those obtained with autologous conduits, especially when the blood vessel diameter is Ͻ5 mm. The problems that can arise when these types of materials are used include increased risk of thrombosis and infection, limited durability, lack of compliance both of the graft and around the anastomosis, 9 and failure as a result of restenosis. These problems necessitate further interventions. 10 -12 One approach to the elaboration of a vascular prosthesis would be to construct one that would very closely resemble a natural healthy blood vessel in both composition and characteristics. This prosthesis would be composed of human cells only (devoid of exogenous synthetic material) and would have the capacity to contract and relax in response to vasoactive agents. We have recently developed a tissueengineering approach to produce a completely biological blood vessel from...

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confidence: 99%

Tissue-Engineered Human Vascular Media With a Functional Endothelin System

et al. 2005

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“…This reduced patency has been largely attributed to compliance mismatch between the AVG and the native artery to which it is grafted [18,232,233]. Veins are inherently less compliant than arteries [234] and become even less compliant upon abruptly exposed arterialization [235]. It appears as though change in AVG compliance is an important predictor of AVG failure.…”

Section: Changes In Mechanical Properties Of Vein Grafts Due To Artermentioning

confidence: 99%

“…Stiffness increases in abruptly exposed arterialized AVGs and could contribute to reduced clinical performance [234,235] …”

Section: Clinical Performancementioning

confidence: 99%

In Situ Bioengineering of Arterial Vein Grafts

El-Kurdi

Morelli

Hong

et al. 2008

ASME 2008 Summer Bioengineering Conference, Parts a and B

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The autogenous saphenous vein remains the graft of choice for both coronary (500,000 annually in the US) and peripheral (80,000 annually) arterial bypass procedures. Failure of arterial vein grafts (AVGs) remains a major problem, and patients with failed grafts will die or require reoperation. Intimal hyperplasia (IH) accounts for 20% to 40% of all AVG failures. It is believed that this adverse pathological response by AVGs is largely due to their abrupt exposure to the significantly elevated circumferential wall stress (CWS) associated with the arterial system. We believe that if an AVG is given an ample opportunity to adapt and remodel to the stresses of its new environment, cellular injury may be reduced, thus limiting the initiating mechanisms of IH.The goal of this work was to develop a new mechanical conditioning paradigm, in the form of a peri-adventitially placed, biodegradable polymer wrap, to safely and functionally "arterialize" AVGs in situ. The polymer wrap was tuned so that as it degraded over a desired period of time, the mechanical support offered by it was reduced and the vein was exposed to gradually increasing levels of CWS in situ.To investigate the effects of mechanical conditioning on AVGs, we utilized both our well established, validated ex vivo vascular perfusion system (EVPS) as well as an appropriate preclinical animal model. The "engineering" component of this bioengineering study was to enhance our EVPS capabilities. Enhancements were made in the form of rigorous mathematical modeling, via subspace system identification, and automatic feedback control, via proportional iv integral and derivative control, of the arterial CWS and shear stress waveform generation capabilities of the EVPS. Pairs of freshly harvested porcine internal jugular veins (PIJVs) were perfused ex vivo under several biomechanical conditions. The acute hyperplastic response of PIJVs abruptly exposed to arterial hemodynamic conditions was compared to PIJVs perfused under normal venous conditions. In an attempt to attenuate this acute hyperplastic response, an ex vivo mechanical conditioning paradigm was imposed onto the PIJVs both via manual adjustment of EVPS parameters and via an adventitially placed tuned electrospun biodegradable polymer wrap. Early markers of IH were evaluated post-perfusion, and they included vascular smooth muscle cell apoptosis, proliferation, and phenotypic modulation. Quantification of these markers via immunohistochemical techniques provided the foundation for the final stage of this work. To assess the efficacy of the tuned electrospun biodegradable polymer wrap in attenuating the development of intimal hyperplasia in AVGs, a series of preclinical studies was performed in a pig model. PIJVs abruptly exposed to arterial levels of CWS showed a significant increase in apoptosis and in the number of synthetic smooth muscle cells, as well as a decrease in proliferation. Mechanical conditioning, via both manual adjustment of the EVPS parameters and placement of the biodegradable adventitial wra...

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“…28 This will lead to the formation of intimal hyperplasia (IH). [29][30][31] Thrombosis and IH are different processes; however few studies reported the existence of a relationship between thrombosis and the occurrence of IH, particularly after bypass surgery or angioplasty. 32,33 Thrombin is one of the vital proteins involved in the coagulation pathway: it converts fibrinogen …”

Section: Cardiovascular Graftsmentioning

confidence: 99%

Multifaceted prospects of nanocomposites for cardiovascular grafts and stents

Vellayappan¹,

Balaji²,

Subramanian³

et al. 2015

IJN

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Cardiovascular disease is the leading cause of death across the globe. The use of synthetic materials is indispensable in the treatment of cardiovascular disease. Major drawbacks related to the use of biomaterials are their mechanical properties and biocompatibility, and these have to be circumvented before promoting the material to the market or clinical setting. Revolutionary advancements in nanotechnology have introduced a novel class of materials called nanocomposites which have superior properties for biomedical applications. Recently, there has been a widespread recognition of the nanocomposites utilizing polyhedral oligomeric silsesquioxane, bacterial cellulose, silk fibroin, iron oxide magnetic nanoparticles, and carbon nanotubes in cardiovascular grafts and stents. The unique characteristics of these nanocomposites have led to the development of a wide range of nanostructured copolymers with appreciably enhanced properties, such as improved mechanical, chemical, and physical characteristics suitable for cardiovascular implants. The incorporation of advanced nanocomposite materials in cardiovascular grafts and stents improves hemocompatibility, enhances antithrombogenicity, improves mechanical and surface properties, and decreases the microbial response to the cardiovascular implants. A thorough attempt is made to summarize the various applications of nanocomposites for cardiovascular graft and stent applications. This review will highlight the recent advances in nanocomposites and also address the need of future research in promoting nanocomposites as plausible candidates in a campaign against cardiovascular disease.

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Compliance properties of conduits used in vascular reconstruction

Abstract: Compliant polyurethane grafts offer a greater degree of compliance match than either ePTFE or Dacron.

Cited by 232 publications

References 28 publications

Tissue-Engineered Human Vascular Media With a Functional Endothelin System

Tissue-Engineered Human Vascular Media With a Functional Endothelin System

In Situ Bioengineering of Arterial Vein Grafts

Multifaceted prospects of nanocomposites for cardiovascular grafts and stents

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