Inhibition of intimal hyperplasia and occlusion in Dacron graft with heparin and low molecular weight heparin.
OBJECTIVE
Intimal hyperplasia (IH) is a significant cause of late prosthetic graft occlusion. The influence of heparin and low molecular weight heparin (LMWH) on IH was studied in a sheep model.


METHODS
A gelatin sealed Dacron (Gelsoft) interposition vascular graft was placed end to end in sheep carotid artery. Standard heparin (SH) was administered in a dose of 7,500 units twice daily subcutaneously (n = 6). LMWH (enoxaparin) was administered in two dosages, a "low dose" of 2 mg/kg (n = 6) and a "high dose" of 5 mg/kg (n = 6) subcutaneously daily. A control group received a graft but no heparin (n = 6). At one month the animals were sacrificed and the grafts sectioned. An intimal measurement was obtained under light microscopy using an eyepiece graticule from a longitudinally sectioned graft.


RESULTS
Controls occluded five grafts of six and recorded a mean intimal thickness of 2,510 micrometres, SH sheep occluded two with a mean thickness of 83 (p < 0.05), low dose enoxaparin sheep had no occlusions with a mean thickness of 73 (p < 0.001) and high dose enoxaparin sheep occluded one with a mean thickness of 225 (p < 0.01). The reduced occlusion rates were significant for the LMWH groups (p = 0.007 for low dose, p = 0.04 for high dose) but not for SH. There were no significant differences between treatment groups with respect to IH.


CONCLUSIONS
In this sheep animal study, each of SH and two LMWH dose regimens resulted in a reduction in Dacron vascular graft occlusion rate and the development of IH, with the greatest effect seen in the low dose LMWH group.
Taylor
A
A
Department of Surgery, University of Sydney, New South Wales, Australia.
Ao
P
P
Fletcher
J
J
D000818:Animals; D000925:Anticoagulants / Q000008:administration & dosage / Q000627:therapeutic use*; D002339:Carotid Arteries / Q000187:drug effects / Q000601:surgery; D002455:Cell Division / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006083:Graft Occlusion, Vascular / Q000517:prevention & control*; D006493:Heparin / Q000008:administration & dosage / Q000627:therapeutic use*; D006495:Heparin, Low-Molecular-Weight / Q000008:administration & dosage / Q000627:therapeutic use*; D006965:Hyperplasia / Q000473:pathology / Q000517:prevention & control; D007262:Infusions, Intravenous; D012756:Sheep; D013918:Thrombin Time; D017539:Tunica Intima / Q000187:drug effects* / Q000473:pathology
D000925:Anticoagulants; D006495:Heparin, Low-Molecular-Weight; D006493:Heparin