Effect of surgical manipulation of polytetrafluoroethylene grafts on microstructural properties and healing characteristics

The effects of graft healing of alterations in the microstructure of polytetrafluoroethylene (PTFE) grafts induced by surgical instruments have not been fully elucidated. This study evaluates changes in the structural and physical properties of PTFE grafts resulting from the intentional application of commonly used surgical instruments and the influence of these changes on cellular ingrowth. The extent of cellular ingrowth into intact (10, 30, and 60 μm unreinforced and 30 μm reinforced [R]) and structurally compromised PTFE grafts (30 reinforced and 60 μm nonreinforced) implanted subcutaneously in Sprague-Dawley (n=14) rats was evaluated at 7 and 21 days. The thrombogenicity of 10-, 30-, 60-, and 80-μm intact graft segments was determined gravimetrically after suspension in the internal jugular vein of dogs for 90 minutes. Cellular ingrowth consisting of fibroblasts, macrophages, and microvessels was directly related to porosity and was most extensive in 60-μm uncompromised graft segments, being 7-, 17-, and 20-fold greater than was observed in 60- and 30R-μm compromised grafts and undamaged 10-μm grafts, respectively. There was a direct relationship between porosity and thrombogenicity of intact graft segments suspended in the jugular vein. The amount of thrombus adherent to 80-μm graft segments was eightfold greater compared with 10-μm grafts. Manipulation of PTFE with surgical instruments significantly impairs healing and may be a possible etiologic factor in the poor long-term performance of these grafts.