The effect of a bolus injection of unfractionated or low molecular weight heparin during aortobifemoral bypass grafting.
Eighteen patients undergoing aortobifemoral graft surgery for severe aortoiliac atherosclerotic disease received a bolus injection of 10,000 anti-Xa units of either unfractionated heparin (UFH) or low molecular weight heparin (LMWH) into the distal aorta as prophylaxis against thromboembolic complications related to clamping. Heparin activity was measured by factor Xa inhibition and by prolongation of the APTT. In both groups there was a delay before peak levels of heparin were observed. In the LMWH group, this amounted to 30 min. In the UFH group, APTT was prolonged by 46 s, 7 min after injection but only by 5 s at the end of the operation. In contrast, in the LMWH group, the prolongation in APTT 7 min after injection was less (34 s) but more sustained since a 12.5 s prolongation was still present at the end of the operation. During surgery, heparin activity exceeded 0.7 U/ml in the LMWH group, compared to significantly lower levels in the UFH group (less than or equal to 0.20 U/ml). By the end of the operation no heparin activity was detectable in the UFH group. Protein C antigen decreased after heparin injection and this fall was more pronounced in the UFH group. The level of C1q (a subcomponent of the first component of the complement system) was decreased in the UFH group (P less than 0.04), whereas in the LMWH group C1q levels increased. Platelet aggregation with collagen was inhibited to a significantly greater degree in the LMWH group than the UFH group (54% compared with 23%) (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Melissari
E
E
Thrombosis Research Unit, King's College School of Medicine & Dentistry, Denmark Hill, London, U.K.
Stringer
M D
MD
Kakkar
V V
VV
D000368:Aged; D001012:Aorta, Abdominal / Q000601:surgery*; D001807:Blood Vessel Prosthesis; D003166:Complement Activating Enzymes; D003172:Complement C1; D015922:Complement C1q; D005263:Femoral Artery / Q000601:surgery*; D006493:Heparin / Q000627:therapeutic use*; D006495:Heparin, Low-Molecular-Weight / Q000627:therapeutic use*; D006801:Humans; D007431:Intraoperative Complications / Q000517:prevention & control; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011486:Protein C / Q000037:antagonists & inhibitors; D013923:Thromboembolism / Q000517:prevention & control
D003172:Complement C1; D006495:Heparin, Low-Molecular-Weight; D010975:Platelet Aggregation Inhibitors; D011486:Protein C; D015922:Complement C1q; D006493:Heparin; D003166:Complement Activating Enzymes