Vascular implants for peripheral arterial bypass and aortic aneurysm repair - Biomaterials and Devices for the Circulatory System - page 216

have led to close appraisal of the cost-effectiveness of the management of
CLI, which has been the subject of much debate. In limbs that are not
irretrievably ischaemic, a policy of aggressive arterial reconstruction has
been shown to improve the patients' quality of life.
The bypass conduit is one of the most important factors determining
long-term patency, with autologous vein remaining the preferred choice
since its introduction by Kunlin in 1949. Vein, however, is absent or of insuf-
fi cient quality in up to one-third of patients necessitating the use of pros-
thetic material (e.g. ePTFE, Dacron) and biological prosthetic (e.g. modifi ed
human umbilical vein, HUV) (Tilanus et al. , 1985). A study by Kumar et al.
(1995) demonstrated no signifi cant difference in patency rates between
ePTFE and Dacron, but further randomised trials reported signifi cantly
higher patency rates in HUV grafts compared with ePTFE (Eickhof et al. ,
1987; McCollum et al. , 1991; Aalders and van Voonhoven, 1992; see Table
8.1). Long-term follow-up, however, revealed graft dilatation and aneurysm
formation in up to 30% of HUV bypasses and its popularity has diminished
subsequently (Aalders and van Voonhoven, 1992).
The superiority of vein over ePTFE has been established through ran-
domised trials summarised in Table 8.2 (Bergan et al. , 1982; Tilanus et al. ,
1985; Veith et al. , 1986; Kumar et al. , 1995). Tilanus et al. (1985) reported a
signifi cant difference in long-term patency rates between ePTFE, 37%, and
autologous vein, 70% ( p 0.001). The data reported by Bergan et al. (1982)

do not entirely corroborate with this, identifying a difference between the
two grafts only when anastomosed to infrapopliteal vessels. However, this

<

Table 8.1 Trials comparing the patency in HUV and ePTFE infrainguinal above-
knee (AK) and below-knee (BK) femoropopliteal bypass grafts

Primary
patency
(%)

Secondary
patency
(%)

￿ ￿ ￿ ￿ ￿

Distal
vessel

Bypass
material

Follow-up
(years) Author

Eickhoff et al.
(1987)*
( n

BK HUV 4 42**

BK ePTFE 22

= 105)

McCollum et al.
(1991)*
( n

AK HUV 3 57 66**

AK ePTFE 48 49

= 191)

Aalders and van
Voonhoven
(1992)*
( n

AK HUV 5 65 73**

AK ePTFE 32 41

= 85)

* Randomised controlled trial; ** statistical signifi cance p < 0.05.