Biomedical Engineering Reference
In-Depth Information
8
Vascular implants for peripheral arterial
bypass and aortic aneurysm repair
T. V. H O W, University of Liverpool, UK, R. K. FISHER
and S. R. VALLABHANENI, Royal Liverpool
and Broadgreen University Hospitals NHS Trust,
UK, and C. K. CHONG, University of Sheffi eld, UK
Abstract
: Prosthetic vascular grafts have been used to treat occlusive
arterial disease for over six decades with good results for large diameter
arterial reconstructions. Less invasive endovascular procedures in the
form of angioplasty and stenting are considered when the pattern of
disease is suitable. For the treatment of aortic aneurysms, endovascular
repair with a remotely introduced stent-graft is fi rmly established. This
chapter describes the prosthetic grafts, the modifi cations made to
improve their patency as well as newly developed tissue engineered
small diameter artery analogs. The principles of aortic aneurysm repair,
the developments in device design and their clinical performance are
also discussed.
Key words
: vascular grafts, Dacron grafts, expanded
polytetrafl uoroethylene (PTFE) grafts, intimal hyperplasia, tissue
engineered vascular grafts, endovascular procedures, stent-grafts.
8.1 Introduction
Vascular implants are widely used to treat both occlusive and aneurysmal
diseases. Arterial occlusive disease is mainly associated with atherosclerosis
producing symptomatic stenotic lesions and reduced perfusion of distal
tissues. Restoration of blood fl ow is achieved through several methods,
ranging from minimally invasive endovascular procedures, such as angio-
plasty and stenting, through to major surgical arterial reconstruction using
bypass grafts. The success of surgical intervention relies on maintaining
graft patency, and numerous parameters and adjuvant techniques have been
explored to optimise patency.
An aneurysm or a localised dilatation of a segment of artery may result
in rupture, haemorrhage and death if untreated. The majority of aneurysms
occur in the abdominal aorta below the renal arteries. Conventional treat-
ment involves replacement of the affected aorta with a prosthetic graft
segment. This major open abdominal surgery is associated with signifi cant
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