High porosity PTFE improves endothelialization of arterial grafts without increasing early thrombogenicity

High porosity (HP) (90 micron internodal distance) PTFE grafts were implanted into the carotid and femoral arteries of dogs to investigate early thrombogenicity, patency, and endothelialization.

Standard PTFE (STD) grafts (30 micron internodal distance) were used as controls. 12 HP and 12 STD grafts were implanted into 6 dogs. Indium-111 labeled platelets were infused intravenously after graft implantation. A graft platelet accumulation index (GPAI) was calculated as the ratio of radioactive emission from the PTFE grafts excised at 48 hours to the emission from a native arterial segment. Another 12 HP and 12 STD grafts were implanted into femoral and carotid arteries to assess patency and endothelialization at 4 and 18 weeks.

There was no significant difference in the GPAI of the HP and STD grafts at either the carotid (HP = 31.5 +/- 9.7, STD = 30.6 +/- 11.8; p > 0.05) or femoral (HP = 34.0 +/- 5.0, STD = 31.5 +/- 7.9; p > 0.05) positions. Combined data (carotid and femoral HP vs. carotid and femoral STD) also did not demonstrate a difference in GPAI (HP = 32.8 +/- 7.5, STD = 31.1 +/- 9.6; p > 0.05). Patency rates were the same at 4 weeks (75%), but greater in the HP grafts at 18 weeks (HP = 75%, STD = 37%; p > 0.05). No difference was noted in the percentage of graft endothelialization at 4 weeks (HP = 5.2 +/- 5.8, STD = 5.0 +/- 4.0; p > 0.05), however, at 18 weeks the HP graft had significantly more endothelial coverage compared to STD grafts (HP = 75.2 +/- 13.9, STD = 22.6 +/- 9.5; p < 0.01).

Given that HP PTFE is no more thrombogenic than STD PTFE, and that it provides superior endothelialization, HP grafts should continue to be developed and studied for potential clinical use.