Inhibition of fibro-intimal hyperplasia in a polytetrafluoroethylene vascular graft with standard heparin and low molecular weight heparin.
BACKGROUND
Fibro-intimal hyperplasia is a significant cause of late prosthetic vascular graft failure. The influence of standard unfractionated sodium heparin (SH) and low molecular weight heparin (LMWH) on intimal hyperplasia was studied in a sheep polytetrafluoroethylene (PTFE) end-to-side carotid artery vascular graft model.


METHODS
Sodium heparin was administered subcutaneously in a dose of 7250 units twice daily (n = 6). Enoxaparin, an LMWH, was administered subcutaneously in two different dose regimens of 2 mg/kg (n = 6) and 5 mg/kg (n = 6) daily. At 1 month the animals were killed and the grafts sectioned. An intima to media ratio was obtained under light microscopy, using an eyepiece graticule, from measurements taken from the floor of the native artery. Results were analysed with a rank-sum correlation test.


RESULTS
Control sheep had a median ratio of 0.104, an SH level of 0.021, a low-dose LMWH level of 0.035 and a high-dose LMWH level of 0.017. There was a significant difference between control and SH (P < 0.001), control and high-dose LMWH (P < 0.05), and SH and low-dose LMWH (P < 0.05), but there were no differences between SH and high-dose LMWH or between the two LMWH groups. Both LMWH groups recorded high anti-Xa levels but only slight prolongation of thrombin time.


CONCLUSIONS
Low molecular weight heparin has a similar effect to SH on the inhibition of fibro-intimal hyperplasia in this animal model but is safer, with less bleeding potential, and is more convenient to administer as a once-daily dose.
Taylor
A
A
Department of Surgery, University of Sydney, New South Wales, Australia.
Fletcher
J P
JP
Ao
P Y
PY
D000818:Animals; D001807:Blood Vessel Prosthesis; D002339:Carotid Arteries / Q000601:surgery; D002341:Carotid Artery Thrombosis / Q000517:prevention & control; D006083:Graft Occlusion, Vascular / Q000517:prevention & control*; D006493:Heparin / Q000008:administration & dosage*; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage*; D006965:Hyperplasia / Q000209:etiology; D011138:Polytetrafluoroethylene; D012756:Sheep; D017539:Tunica Intima / Q000473:pathology; D014654:Vascular Patency
D006495:Heparin, Low-Molecular-Weight; D011138:Polytetrafluoroethylene; D006493:Heparin