Ab. Lumsden et al., NONPOROUS EXPANDED POLYTETRAFLUOROETHYLENE GRAFTS REDUCES GRAFT NEOINTIMAL HYPERPLASIA IN DOG AND BABOON MODELS, Journal of vascular surgery, 24(5), 1996, pp. 825-833
Purpose: Neointimal hyperplasia frequently develops after placement of
prosthetic vascular grafts and is a major cause of graft failure. Thi
s study was an attempt to prevent vascular lesion formation by coating
the graft luminal surface with a thin layer of nonporous silicone pol
ymer, and subsequently with an ultrathin layer of vapor phase (plasma
gas)-deposited fluoropolymer, thereby providing a smooth and chemicall
y uniform surface that was postulated to limit pannus tissue ingrowth
across the graft anastomoses. Methods: Bilateral femoral arteriovenous
(AV) conduits were constructed in four dogs using expanded polytetraf
luoroethylene graft materials (ePTFE; 6-mm inside diameter, 2.5-cm lon
g). In each animal, one femoral AV shunt was constructed from a graft
whose luminal surface was entirely coated with polymer. On the contral
ateral side, an uncoated graft served as a control. Bilateral aortoili
ac grafts were placed in three baboons using 5-cm segments of ePTFE (4
-mm inside diameter). One end (1 cm) of each graft had been coated wit
h polymer In each animal, the coated end of one graft was placed proxi
mally and the coated end of the second graft was placed distally in th
e contralateral vessels. Results: All grafts were patent at 30 days. I
n the dog model, there was a significant reduction in graft neointimal
area at the venous anastomoses for the coated grafts compared with th
e uncoated grafts (0.03 +/- 0.02 mm(2) and 1.11 +/- 0.54 mm2, respecti
vely; p < 0.05). In the baboon model, the silicone coating significant
ly reduced the graft neointimal thickness (0.003 +/- 0.003 mm vs 0.21
+/- 0.05 mm; P < 0.05) and neointimal area (0.05 +/- 0.08 mm2 vs 0.82
+/- 0.58 mm2; p < 0.05). Conclusions: These data demonstrate that heal
ing of ePTFE grafts can be effectively modified by altering the physic
al properties of the graft surface. Neointimal hyperplasia within ePTF
E grafts is significantly reduced by the local application of a fluoro
carbon-coated, silicone-based polymer. The resulting graft now surface
effectively prevents tissue ingrowth from the adjacent native vessel,
thereby preserving the anastomosis luminal area. This approach could
represent a new strategy for limiting graft surface anastomotic neoint
imal hyperplasia.