Displaying all 9 publications

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  1. Lim KO
    Med J Malaysia, 1991 Jun;46(2):136-43.
    PMID: 1839417
    Even though artificial heart valve implants have a history of some 30 years, there is to this day no ideal valve substitute. Each of the categories of substitutes used has its own advantages as well as problems. Since my last review on the subject, that appeared in this journal, was some 13 years ago (Lim, 1977), it is perhaps appropriate to provide an update on the status of cardiac valve replacement for the general local readership.
    Matched MeSH terms: Bioprosthesis/trends
  2. Fallahiarezoudar E, Ahmadipourroudposht M, Idris A, Mohd Yusof N
    Mater Sci Eng C Mater Biol Appl, 2015 Mar;48:556-65.
    PMID: 25579957 DOI: 10.1016/j.msec.2014.12.016
    The four heart valves represented in the mammalian hearts are responsible for maintaining unidirectional, non-hinder blood flow. The heart valve leaflets synchronically open and close approximately 4 million times a year and more than 3 billion times during the life. Valvular heart dysfunction is a significant cause of morbidity and mortality around the world. When one of the valves malfunctions, the medical choice is may be to replace the original valves with an artificial one. Currently, the mechanical and biological artificial valves are clinically used with some drawbacks. Tissue engineering heart valve concept represents a new technique to enhance the current model. In tissue engineering method, a three-dimensional scaffold is fabricated as the template for neo-tissue development. Appropriate cells are seeded to the matrix in vitro. Various approaches have been investigated either in scaffold biomaterials and fabrication techniques or cell source and cultivation methods. The available results of ongoing experiments indicate a promising future in this area (particularly in combination of bone marrow stem cells with synthetic scaffold), which can eliminate the need for lifelong anti-coagulation medication, durability and reoperation problems.
    Matched MeSH terms: Bioprosthesis*
  3. Ooi, Ching Sheng, Lim, Meng Hee, Lee, Kee Quen, Kang, Hooi Siang, Mohd Salman Leong
    MyJurnal
    Previous studies have indicated that the pipe-surface-mounted helical strakes effectively reduce vortex-induced vibration (VIV) under a uniform flow application, particularly during the lock-in region. Since VIV experiments are time-consuming, observation is generated with an interval helical strakes parameter in pitch and height to lessen tedious procedures and repetitive post-processing analyses. The aforementioned result subset is insufficient for helical strakes design optimisation because the trade-off between the helical strakes dimension, lock-in region and flow velocity are non-trivial. Thus, a parametric model based on an improved recursive least squares (RLS) parameter estimation technique is proposed to define the statistical relationship between input, or strakes and pipe dimension, and output, or VIV amplitude ratio. As results suggested, revised RLS estimated VIV model demonstrated an optimal prediction with the highest coefficient of determination and lowest Integral Absolute Error. The feasibility of VIV parametric model was validated by embed into Genetic Algorithm (GA) as the fitness function to acquire a desirable helical strakes dimension with minimum VIV amplitude. The rapid generation of optimal helical strakes dimension which returned the highest VIV suppression implied a superior simulation method compared to the experimental outcome.
    Matched MeSH terms: Bioprosthesis
  4. Kakavand M, Yazdanpanah G, Ahmadiani A, Niknejad H
    J Tissue Eng Regen Med, 2017 06;11(6):1701-1709.
    PMID: 26190586 DOI: 10.1002/term.2064
    Amniotic membrane (AM), a placenta-derived natural biomaterial, has several characteristics which make it a potential substitute for blood vessels. However, there are no reports on the effects of the AM on blood components. The aim of this study was to evaluate the blood compatibility of the epithelial and mesenchymal surfaces of the amnion for potential use in vascular tissue engineering. The activation of intrinsic and extrinsic pathways of the clotting system, haemolysis and platelet adhesion were studied and the results were compared with heparin-coated expanded polytetrafluoroethylene (ePTFE) as a standard synthetic vascular graft. Prothrombin time (PT), activated partial thromboplastin time (aPTT), clotting time (CT) and haemolysis (%) tests showed that both the epithelial and mesenchymal sides of the AM are haemocompatible. Platelet aggregation and P-selectin production from the platelets showed that the epithelial surface of the AM has less induction of platelet activation than ePTFE. The results of scanning electron microscopy (SEM) demonstrated that platelets in contact with ePTFE had a higher rate of adhesion than with the epithelial and mesenchymal surfaces of the AM. Moreover, the morphological distribution of the platelets showed that the majority of platelets were round, while a large number of cells on ePTFE were dendritic. These results suggest that the AM which contains epithelial and mesenchymal stem cells has appropriate haemocompatibility to be employed in vascular tissue engineering, especially as a vein substitute. Copyright © 2015 John Wiley & Sons, Ltd.
    Matched MeSH terms: Bioprosthesis*
  5. Lim KO, Cheong KC
    Med Eng Phys, 1994 Nov;16(6):526-30.
    PMID: 7858787
    In the fabrication of a bioprosthetic heart valve from bovine pericardial tissues, the tissues are subjected to suturing. The stress-strain response of sutured as well as unsutured strips of this tissue were examined. The stress-strain response was determined using a tensile-testing machine. It was found that suturing weakens the tissue in that sutured strips are more extensible, exhibit a lower stress at rupture and a lower final elastic modulus. In addition, it was also found that the bigger the suture/needle size used the greater the decrease in tissue strength. In all, tissue strength was observed to decrease by 22 to 59% in this study. The weakening of the tissue is attributed to the puncture holes created by the surgeon's needle which create regions of weakness. This response of bovine pericardial tissue to suturing should be given due consideration in the fabrication of a bioprosthetic heart valve using this tissue.
    Matched MeSH terms: Bioprosthesis/standards*
  6. Morales DL, Herrington C, Bacha EA, Morell VO, Prodán Z, Mroczek T, et al.
    Front Cardiovasc Med, 2020;7:583360.
    PMID: 33748192 DOI: 10.3389/fcvm.2020.583360
    Objectives: We report the first use of a biorestorative valved conduit (Xeltis pulmonary valve-XPV) in children. Based on early follow-up data the valve design was modified; we report on the comparative performance of the two designs at 12 months post-implantation. Methods: Twelve children (six male) median age 5 (2 to 12) years and weight 17 (10 to 43) kg, had implantation of the first XPV valve design (XPV-1, group 1; 16 mm (n = 5), and 18 mm (n = 7). All had had previous surgery. Based on XPV performance at 12 months, the leaflet design was modified and an additional six children (five male) with complex malformations, median age 5 (3 to 9) years, and weight 21 (14 to 29) kg underwent implantation of the new XPV (XPV-2, group 2; 18 mm in all). For both subgroups, the 12 month clinical and echocardiographic outcomes were compared. Results: All patients in both groups have completed 12 months of follow-up. All are in NYHA functional class I. Seventeen of the 18 conduits have shown no evidence of progressive stenosis, dilation or aneurysm formation. Residual gradients of >40 mm Hg were observed in three patients in group 1 due to kinking of the conduit (n = 1), and peripheral stenosis of the branch pulmonary arteries (n = 2). In group 2, one patient developed rapidly progressive stenosis of the proximal conduit anastomosis, requiring conduit replacement. Five patients in group 1 developed severe pulmonary valve regurgitation (PI) due to prolapse of valve leaflet. In contrast, only one patient in group 2 developed more than mild PI at 12 months, which was not related to leaflet prolapse. Conclusions: The XPV, a biorestorative valved conduit, demonstrated promising early clinical outcomes in humans with 17 of 18 patients being free of reintervention at 1 year. Early onset PI seen in the XPV-1 version seems to have been corrected in the XPV-2, which has led to the approval of an FDA clinical trial. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT02700100 and NCT03022708.
    Matched MeSH terms: Bioprosthesis
  7. Ruszymah BH, Chua K, Latif MA, Hussein FN, Saim AB
    Int J Pediatr Otorhinolaryngol, 2005 Nov;69(11):1489-95.
    PMID: 15941595
    Treatment and management of congenital as well as post-traumatic trachea stenosis remains a challenge in pediatric surgery. The aim of this study was to reconstruct a trachea with human nasal septum chondrocytes by using the combination of biodegradable hydrogel and non-biodegradable high-density polyethylene (HDP) as the internal predetermined shape scaffold.
    Matched MeSH terms: Bioprosthesis*
  8. Riahi M, Ang HL, Jones M, Prachasilchai P, Baruteau AE, Promphan W, et al.
    Circ Cardiovasc Interv, 2018 04;11(4):e005923.
    PMID: 29618579 DOI: 10.1161/CIRCINTERVENTIONS.117.005923
    Matched MeSH terms: Bioprosthesis*
  9. Dillon J, Yakub MA, Nordin MN, Pau KK, Krishna Moorthy PS
    Eur J Cardiothorac Surg, 2013 Oct;44(4):682-9.
    PMID: 23407161 DOI: 10.1093/ejcts/ezt035
    Type IIIa mitral regurgitation (MR) due to rheumatic leaflet restriction often renders valve repair challenging and may predict a less successful repair. However, the utilization of leaflet mobilization and extension with the pericardium to increase the surface of coaptation may achieve satisfactory results. We reviewed our experience with leaflet extension in rheumatic mitral repair with emphasis on the technique and mid-term results.
    Matched MeSH terms: Bioprosthesis
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