Physical properties of polytetrafluoroethylene bypass material after balloon dilation

PURPOSE: To evaluate the performance characteristics of 3-mm and 6-mm polytetrafluoroethylene (PTFE) grafts after radial dilation comparable to their use in endovascular applications. MATERIALS AND METHODS: PTFE conduits with 3- and 6-mm internal diameters were radially expanded three, four, and five times the original diameter with angioplasty balloons. Internal diameter, outer diameter, wall thickness, radial and longitudinal shortening, internodal distance, radial and longitudinal tensile strength, water entry pressure, and suture retention strength were measured and compared with nondilated samples. RESULTS: After dilation, the diameter of the 3- and 6-mm PTFE conduits recoiled approximately 23%, and the length shortened insignificantly. The wall thickness decreased to approximately half, and the internodal distance did not change. Porosity decreased as evidenced by a slight increase in the water entry pressure. Longitudinal and radial tensile strength, as well as suture retention strength, were decreased. CONCLUSIONS: Dilation of PTFE graft, as used in endovascular applications, by three to five times results in moderate elastic recoil. This needs to be taken into consideration if the material is used without a supporting inner stent. Because of the absence of significant change in porosity, perigraft fluid collections are not likely to occur. Significant decrease in suture retention strength after dilation poses a risk of localized tear and potential procedure failure.