Pharmacological control of intimal hyperplasia in small diameter polytetrafluoroethylene grafts. An experimental study.

OBJECTIVE: The efficacy of a postoperative treatment with Low molecular weight heparin (LMWH) vs Ticlopidine in controlling early thrombosis, intimal hyperplasia and growth of true endothelial cells in small prosthetic expanded polytetrafluoroethylene (ePTFE) grafts (4 mm) interposed in the carotid artery of sheep has been evaluated. EXPERIMENTAL DESIGN: Thirty animals were randomized into three different groups: control group (CTRL); ticlopidine hydrochloride (TICL) 250 mg/b.d. by month for 4 weeks from day 1; LMWH 3,085 IU AXa s.c. preoperatively and once a day for the same period. RESULTS: Complete thrombosis of the graft occurred in 7 sheep in the CTRL group and 5 in the TICL group while 2 partial thrombosis were observed in the LMWH group (n.s.). In all the evaluable cases, hyperplasia was observed in both anastomotic areas and did not involve the middle portion of the graft. The mean +/- SD intimal thickness was 603 +/- 20 micron in the CTRL group, 356 +/- 10 in the TICL group and 152 +/- 17 in the LMWH group (p < 0.001) compared to the 60 +/- 12 of the normal intima. True endothlial cells were found mainly in the LMWH group close to the arterial anastomosis. CONCLUSIONS: The postoperative use of LMWH seems to inhibit intimal hyperplasia, with interesting results also on patency and cellular coverage. Further studies are necessary to support this promising trend.