The effect of low-molecular-weight heparin on microvenous thrombosis in a rat model.
OBJECTIVE
To assess the impact of a low-molecular-weight heparin sodium, dalteparin sodium, on a thrombogenic microvenous anastomosis, using a randomized, blinded animal model.


METHODS
Using male Sprague-Dawley rats, 70 IU/kg of dalteparin sodium (for the treatment group) or isotonic sodium chloride solution (for the control group) were administered subcutaneously in a blinded randomized fashion. Using microsurgical techniques, the femoral venous pedicle was isolated bilaterally. A tuck anastomosis was then performed on each side. Vessel patency was assessed periodically for 3 hours using a strip and refill test. Patency or thrombosis was confirmed by cutting the vessel proximal to the anastomosis and examining the lumen for thrombus.


RESULTS
A total of 58 venous tuck anastomoses were performed. There was no difference in bleeding complications between the treatment and control groups. The control group had a thrombosis rate of 50%, and the treatment group had a thrombosis rate of 60%. The chi2 analysis does not indicate a statistical difference between these 2 groups (P = .59).


CONCLUSIONS
Low-molecular-weight heparin, at standard therapeutic dosing, may not provide an adequate antithrombotic effect to prevent anastomotic thrombosis in free tissue transfer.
Emerick
Kevin S
KS
Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA 02114, USA.
Deschler
Daniel G
DG
D000714:Anastomosis, Surgical / Q000379:methods*; D000818:Animals; D016009:Chi-Square Distribution; D006495:Heparin, Low-Molecular-Weight / Q000494:pharmacology*; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D020246:Venous Thrombosis / Q000188:drug therapy*
D006495:Heparin, Low-Molecular-Weight