ABSTRACT
The quest for the ideal vascular prosthesis has been going on for more than a century. Carrel and Guthrie fi rst explored vascular replacement in the beginning of the 20th century when they successfully inserted a vein into the arterial circulation (Carrel and Guthrie 1906). They won the Nobel Prize in Medicine and Physiology in 1912. The fi rst synthetic vascular graft was hand sewn by Voorhees out of Vinyon-N cloth in 1952 and implanted into dogs (Voorhees et al. 1952). Many other textiles and materials were evaluated for vascular applications in the following years including kitted polyethylene terephthalate (Dacron) in 1958 by DeBakey (Debakey et al. 1958) and expanded polytetrafl uoroethylene (ePTFE) tubes in the early 1970s by Eiseman (Kelly and Eiseman 1982; Soyer et al. 1972), both of which proved very successful in the clinic and still remain the standard synthetic materials for revascularization procedures. The development of synthetic vascular prostheses was pivotal in the practice of vascular reconstruction, but while modern grafting materials have near excellent clinical results for large diameter arterial replacements, small diameter synthetic repairs (< 6 mm) are prone to failure. Small diameter arteries differ from larger diameters in terms of hemodynamics. Subject to lower blood fl ow velocities and lower wall shear stress, small diameter grafts are inclined to thrombosis, making inappropriate the synthetic ePTFE and Dacron grafts because of lack of endothelium (Berger et al. 1972). Autologous vessels such as the saphenous vein or the internal mammary artery remain the standard for small diameter revascularization procedures, but autologous material is not always available because of vascular disease or previous surgery. A new generation of man-made vascular grafts is therefore required to fi ll the clinical need for high-performing small diameter arterial prosthesis. The ideal small diameter vascular graft should mimic to the greatest extent the natural biological and physical properties of the artery it is meant to
replace. Two main strategies can be employed to create such grafts: using a biostable material with excellent blood biocompatibility or designing a transient scaffold aimed for degradation and remodelling to allow the artery to regenerate in the long term. Because of the unique mechanical and biological environment in arteries, there are several requirements that must be satisfi ed for clinically acceptable small diameter vascular grafts: they must have good hemocompatibility, tissue biocompatibility, infection resistance, durable mechanical strength, kink resistance, no blood leakage, and suture retention, and they must be appropriate for surgical handling.
