ABSTRACT
The technique of plasma coating emerged in the seventies as a novel and versatile approach to modifying the surface chemistry of a wide range of materials. Chawla developed plasma polymerized silicone coatings and Garfinkle and Hoffman demonstrated that polyester vascular prostheses treated with tetrafluoroethylene plasma yield dramatic improvements in the resistance to thrombus formation and emboli.
Atrium Medical Corporation has produced a Plasma TFE® tubular woven polyester blood conduit, whose internal surface has been treated with fluoropolymer. The absence of crimps and the inclusion of a helically wound external support suggests that this device heralds a new generation of woven polyester vascular prostheses. This study reports the results of an in vitro evaluation of this new product.
A unique feature of the Plasma TFE® graft is that it contains texturized yarns in the warp direction and flat multifilament yarns in the weft direction. Such a mixture is not usually found in commercial prostheses, and results in the graft’s unique characteristic of expanding at low pressures of less than 50mm Hg, and then exhibiting minimal increases in diameter at internal pressures above 80 mm Hg. Because of the absence of crimps, the elongation of this graft is about half the value for the Woven DeBakey Soft, the least extensible commercial woven control. While the bursting strength is comparable to other woven prostheses, the average water permeability value of 180 ml/cm2/min/120 mm Hg is considerably higher than the value of 100 quoted in the manufacturer’s literature. The suture retention strength results highlight the high frequency of prosthesis rather than the suture breaks and indicate that the suture retention performance can be improved by cutting with a cautery instead of scissors. Surface analysis by ESCA, solvent extraction and differential dyeing demonstrate that the flow surface of the prosthesis contains a non-uniform plasma coating and a high level of extractable contaminants.
