Usefulness of polyurethane for small-caliber vascular prostheses in comparison with autologous vein graft

For long-term patency of small-caliber vascular prostheses, antithrombogenicity and microporous structure are very important. We have developed a new technique to give a microporous structure to a polyurethane vascular prosthesis that has favorable antithrombogenicity. A solution of tetrahydrofuran/dimethylformamide (1:1) containing 13 wt% of segmented polyurethane (PTMG + MDI) and calcium carbonate (mean particle size, 8μm) was dipcoated on a glass mandrel 3 mm in diameter and placed into distilled water. After the glass mandrel was removed, the polyurethane tube was placed into hydrochloric acid, and a microporous polyurethane vascular prosthesis was produced. Prostheses made in this fashion, and autologous jugular vein grafts were implanted into the femoral artery and the carotid artery of mongrel dogs. Patency was recognized on the arteriogram and duplex scanning (ultrasonography), and the removed grafts were inspected macroscopically and microscopically. This prosthesis was similar in elasticity to a vein graft. Patency was defined 8 weeks after implantation, and this prosthesis showed less intimal hyperplasia than the autologous vein graft. The new polyurethane prosthesis might be useful for small-caliber vascular reconstruction.