SMALL-CALIBER POLYURETHANE AND POLYTETRAFLUOROETHYLENE GRAFTS - A COMPARATIVE-STUDY IN A CANINE AORTOILIAC MODEL

In vivo stability of a new small‐caliber polyurethane graft (n8) was assessed in a canine aortoiliac model and compared to that of a conventional expended polytetrafluoroethylene (ePTFE) graft (n8). Six months following implantation, marked aneurysmal dilatation to 230 ± 80% (x ± SD) of the original diameter occurred in polyurethane grafts, while dilatation to 110 ± 8% of the original diameter occurred in ePTFE grafts (p < 0.005). Interval patency was 75% for each graft type. Luminal thrombus affected 59% of polyurethane graft surfaces compared to 22% of ePTFE graft surfaces (p < 0.01). Qualitative examination of representative sections of polyurethane conduits demonstrated thick inner capsules with numerous small islands of graft material surrounded by macrophages and bands of mature fibrous tissue, in contrast to the thinner neointima and limited anastomotic pannus ingrowth observed in ePTFE grafts. Copyright © 1990 John Wiley & Sons, Inc.