PURPOSE: To compare two stent-grafts with a polyurethane-carbonate (PUC) po
lymer lining of different pore size and water permeability in the iliac art
eries of sheep.
MATERIALS AND METHODS: Two stent-grafts with an inner PUC-lining of normal
and low water permeability (normal, 1,200 mL/min/cm(2); low, 280 mL/min/cm(
2); pressure gradient, 20 mm Hg) were implanted in each of 16 sheep, Hoop s
trength was two times higher in low-permeable than in normal-permeable sten
t-grafts. Patency was monitored with use of angiography and intravascular u
ltrasound (IVUS) after 1, 3, and 6 months. The sheep were killed after 1 or
6 months. Specimens were studied histologically. IVUS and histologic data
were analyzed statistically.
RESULTS: IVUS measurements showed a wider patent lumen of the low- compared
to the normal-permeable prostheses at all time points (P < .03), This is l
ikely due to the greater hoop strength of the low-permeable stent graft. Af
ter 1 month, both types of prostheses demonstrated complete transprosthetic
tissue penetration and were covered with neointima and endothelium, The ne
ointimal area was greater in low- than in normal-permeable stent-grafts (1
month, P < .005; 6 months, P < .03),
CONCLUSIONS: Presumably, the higher permeability of the normal-permeable st
ent grafts led to the reduced neointimal area by improving transprosthetic
capillary ingrowth and endothelialization.