Biomedical Engineering Reference
In-Depth Information
1
Tissue responses to implanted materials
I. DIMARAKIS and S. M. REHMAN, University
Hospital of South Manchester, UK and
G. ASIMAKOPOULOS, University Hospitals Bristol
NHS Foundation Trust, UK
Abstract
: Advances in cardiovascular procedures would have not been
possible without the concomitant developments in biotechnology.
Materials and devices used for the restoration of anatomical and
physiological circulatory properties are associated with risks and
potential complication. This chapter discusses the commonest forms of
tissue response to implanted biomaterials.
Key words
: cardiovascular procedures, implanted biomaterials, tissue
responses.
1.1
Introduction
Advances in cardiovascular procedures would have not been possible
without the concomitant developments in biotechnology. The application
of biomaterials spans from prosthetic heart valves, ventricular assist devices,
cardiac pacemakers and endovascular implants, to suture material and bio-
adhesives. Materials and devices used for the restoration of anatomical and
physiological circulatory properties are not without associated risks and
potential complication, both in the immediate as well as the long-term
period, following implantation within the recipient.
Implant building blocks vary from an array of metals and their alloys,
polymers and ceramics. Naturally occurring materials such as collagen, hyal-
uronan and dextran are commonly used. Synthetic polymers used for the
construction of implantable devices include polylactic acid, polylactic-co-
glycolic acid, polyvinyl alcohol and others (Onuki
et al.
, 2008). The majority
of implanted devices are composed of more than one type of material and
are referred to as complex composition implants. Although these materials
have been used extensively with good functional results, there are issues of
biocompatibility. The need to surpass physical limitations and improve the
biomechanical profi le of metals has led to the development of novel metal
alloys. In addition to superior physical and chemical properties regarding
strength, durability and resistance to corrosion, certain alloys have very
unique properties. An example is nickel-titanium (nitinol) alloys that
exhibit shape memory and superelasticity, making it one of the most widely
used materials in medical prostheses.
