Vascular implants for peripheral arterial bypass and aortic aneurysm repair - Biomaterials and Devices for the Circulatory System - page 217

Table 8.2 Trials of vein vs. ePTFE/Dacron grafts for infrainguinal bypass

Primary
patency
(%)

Secondary
patency
(%)

Distal
vessel

Bypass
material

Follow-up
(years) Author n

Bergan et al.
(1982)

AK pop Vein 41 2.5 70

AK pop ePTFE 33 72

BK pop Vein 50 76

BK pop ePTFE 46 62

Infra pop Vein 57 50**

Infra pop ePTFE 58 20

Tilanus et
al. (1985)

Fempop Vein 85 5 70**

Fempop ePTFE 91 37

Veith et al.
(1986)

AK pop Vein 85 4 61

AK pop ePTFE 91 38

BK pop Vein 62 76**

BK pop ePTFE 80 54

Combined
pop

Vein 147 68**

Combined
pop

ePTFE 171 38

Infrapop Vein 106 49**

Infrapop ePTFE 98 12

Kumar et al.
(1995)

AK pop Vein 50 4 73 90**

AK pop ePTFE 49 47 47

** Statistically signifi cant results ( p 0.05).

pop: popliteal; fempop: femoropopliteal.

<

study only reported patency rates up to 30 months follow-up, whereas the
benefi t of vein grafts becomes more evident with time. It is generally
accepted that autologous vein achieves the optimum patency, particularly
in bypass to crural vessels performed for critical limb ischaemia, and that
ePTFE should be reserved for arterial reconstruction only in the absence
of vein.

￿ ￿ ￿ ￿ ￿

8.3.2 Expanded polytetrafl uoroethylene

Expanded PTFE grafts are made by extrusion of PTFE resin mixed with a
lubricant. The microporous structure of ePTFE is obtained by a process that
involves rapid stretching of the extruded tube at high temperature. The
structure is characterised by circumferentially arranged nodes, about
5-10 μ m wide by 5-100 μ m long, interconnected by longitudinal fi brils of

less than 0.5 m in diameter. Porosity is an important factor that determines

the healing and incorporation of a prosthetic graft to the surrounding tissue.

μ