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Publication Detail
A novel aortic valve prosthesis made of a new nanocomposite polymer: hydrodynamic assessment.
  • Publication Type:
    Journal article
  • Publication Sub Type:
    Article
  • Authors:
    Rahmani, B , Tzamtzis S, Ghanbari H, Burriesci G, Seifalian AM
  • Publication date:
    2012
  • Pagination:
    132, 133
  • Journal:
    Cardiology
  • Volume:
    121
  • Issue:
    2
  • Status:
    Published
Abstract
Background: Synthetic flexible-leaflet heart valves have been widely studied as possible alternatives to mechanical and bioprosthetic valves. However, they have not yet become a valid cardiac valve replacement (CVR) option, mainly due to their suboptimal material design. Nevertheless, the emergence of nanotechnology and novel biomaterials has provided new solutions to overcome the limitations of synthetic valves. Methods: The present study introduces an innovative low-profile semi-stented aortic valve (SSAV) made of a novel nanocomposite polyurethane with a polycarbonate soft segment (PCU) and polyhedral oligomeric silsesquioxane (POSS) nanoparticles covalently bonded as pendant chain functional groups to the hard segment. POSS-PCU has shown excellent in-vivobiostability, hemocompatibility, physiochemical properties, and resistance to thrombogenicity and calcification. It is successfully implanted in human in forms of small calibre vascular bypass graft, lacrimal duct, and more recently the world’s first synthetictrachea. The SSAVs of three leaflet thicknesses (100, 150 and 200μm) and 21mm internal diameter were 0.0 0.2 0.4 0.6 0.8 0.5 1.0 1.5 2.0 2.5 3.0 LOX grade Type I Type I Type III Type III Normal Normal 50 μm 50 μm Myxomatous mitral valve Myxomatous mitral valve LOX + DAPI merge LOX + DAPI merge (r 3 = 0.855; p = 0.0001) Collagen I density Myxomatous valve Normal valve Fig. 1.Abstracts Cardiology 2012;121:87–148 133 produced by an automated dip-coating procedure and assessed invitro for their hydrodynamic function under a physiological range of pulsatile conditions (increasing cardiac output of 2–7 l/min). Result: Compared to commercially available bioprosthetic valve of equivalent size (SJM Epic™), the SSAVs showed significantly improved forward flow characteristics. The mean pressure gradient across the SSAV did not exceed 10 mmHg where as it reached 24 mmHg for the control. The SSAV achieved an effective orifice area of up to 3.14 cm2 , which was considerably wider than that of the control (1.52 cm2 ). The polymeric valves were also characterised by a lower systolic energy loss, especially at high cardiac outputs. The diastolic characteristics of the SSAV were comparable to that of the bioprostheses. The SSAV of 100 μm leaflet thickness demonstrated a total regurgitant volume of less than 5.5 ml which was significantly lower than the thicker SSVAs and control (P<0.05). The thinner leaflets were found to improve the hydrodynamic function of the valves. Conclusion: The SSAV offers potential improvements to the clinical outcome of CVR therapy owing to its excellent hydrodynamic performance and the unique characteristics of POSS-PCU nanocomposite.
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UCL Authors
Dept of Mechanical Engineering
Research Department of General Surgery
Dept of Mechanical Engineering
University College London - Gower Street - London - WC1E 6BT Tel:+44 (0)20 7679 2000

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