[Experimental study on the influence of porosity on the development of the neointima in E-PTFE grafts]

The influence of the porosity on the fate of the neointima of E-PTFE grafts implanted to the canine abdominal aorta was experimentally investigated. E-PTFE grafts (each 7 cm X 8 mm) which were pretreated with multiple regular small perforations using a needle were divided into 4 groups according to the mode of the perforation; in Group A perforations were made at regular 2 mm interval with 21 gauge needle, in Group B at 2 mm interval with 25 gauge needle and in Group C at 4 mm interval with 25 gauge needle, in Group D at 4 mm interval with 27 gauge needle, respectively. The grafts in Groups A and B revealed the infiltration of the fibroblasts and development of vasa vasorum from outside to inside through the perforated holes 14 days after implantation, and then the neointimatization of the grafts was completed 180 days after implantation. The grafts in Groups C and D demonstrated incomplete healing of the central luminal portion of the graft even 180 days after implantation. In contrast, Untreated E-PTFE grafts showed little neointimatization and luminal surface of the graft was mostly covered with mural thrombi 180 days after implantation. The study demonstrated that the porosity of E-PTFE graft is insufficient in early neointimatization, while increasing the porosity with multiple small perforations plays a significant role in early development of neointima.