Optimal dose and duration of heparin for inhibition of intimal hyperplasia.
BACKGROUND
A Dacron patch graft was placed in the common carotid artery of sheep to assess the effect of three different doses of unfractionated heparin administered for periods of one to four weeks.


METHODS
Animals were divided into a control group (n=6) in which animals received a patch graft but no heparin and three main treatment groups on the basis of the dose of heparin received. Group 1 animals (n=24) received 140 units per kg daily in two divided doses. Group 2 (n=24) received 280 units per kg daily and Group 3 (n=24) received 420 units per kg daily. Each treatment group was further divided into four subgroups on the basis of the duration of treatment. Groups 1(i), 2(i), 3(i) had treatment for one week. Groups 1(ii), 2(ii), 3(ii) had treatment for two weeks. Groups 1(iii), 2(iii), 3(iii) had treatment for three weeks. Groups 1(iv), 2(iv), 3(iv) had treatment for four weeks. There were six animals in each subgroup giving a total of 72 treated sheep. Animals were sacrificed at four weeks and an intimal measurement in pm was obtained under light microscopy from a transverse sectioned segment of artery containing the patch graft using an eyepiece graticule.


RESULTS
There were no haemorrhagic complications. Control animals had a mean intimal thickness of 176 pm. All treatment groups had significantly less IH--Group 1 131.9 (p<0.01), Group 2 138.5 (p<0.05), Group 3 117.8 (p<0.01). There were no significant differences between the treatment groups. There was significantly less IH in animals treated for four weeks (106.3) compared to one week (140.2, p<0.05).


CONCLUSIONS
This study indicates that inhibition of IH can be achieved by heparin with optimal effect from a four week treatment period.
Ao
P Y
PY
Department of Surgery, The University of Sydney Westmead Hospital, NSW, Australia.
Hawthorne
W J
WJ
Taylor
D A
DA
Fletcher
J P
JP
D000818:Animals; D001807:Blood Vessel Prosthesis; D017536:Carotid Artery, Common / Q000187:drug effects / Q000473:pathology* / Q000601:surgery; D004334:Drug Administration Schedule; D006493:Heparin / Q000008:administration & dosage* / Q000494:pharmacology; D006965:Hyperplasia / Q000517:prevention & control; D011093:Polyethylene Terephthalates; D012756:Sheep; D013997:Time Factors; D017539:Tunica Intima / Q000187:drug effects / Q000473:pathology*
D011093:Polyethylene Terephthalates; D006493:Heparin