Platelet activation during carotid endarterectomy and the antiplatelet effect of Dextran 40.
OBJECTIVE
To determine changes in platelet activation during carotid endarterectomy (CEA) and the antiplatelet effect of Dextran 40.


METHODS
Prospective study in 40 patients undergoing CEA. Platelet activity was measured by whole blood flow cytometry and platelet aggregometry during CEA. The expression of P-selectin and the PAC-1 antigen were used as markers of platelet activation and aggregation. Patients received aspirin (75-300 mg) preoperatively and 5,000 units unfractionated heparin during surgery. High intensity transient signals (HITS) in the ipsilateral middle cerebral artery were monitored using transcranial Doppler (TCD) perioperatively.


RESULTS
P-selectin expression increased after carotid clamping (P < 0.01) and clamp release (P < 0.05). There was higher expression of PAC-1 after carotid clamping (p < 0.05). Spontaneous and ADP-induced platelet aggregation increased after carotid clamping (P< 0.01) and release (P < 0.01). TCD monitoring showed an increased HITS count from preoperative levels, after clamp release (P < 0.01) and during recovery (P < 0.01). After the operation, patients with more than 50 HITS per 30 min were started on an infusion of dextran 40 (n = 6). P-selectin expression decreased 24 h after dextran 40 (P < 0.01).


CONCLUSIONS
Significant platelet activation and aggregation occurs during CEA despite the current use of antiplatelet treatment. Dextran 40 had an antiplatelet effect after CEA providing further evidence that it may contribute to reducing thromboembolic complications.
Academic Surgical Unit, Imperial College School of Medicine, St Mary's Hospital, Praed St, London W2 1NY, UK.
P A
PA
Robless
T J
TJ
Tegos
D
D
Okonko
A O
AO
Mansfield
A N
AN
Nicolaides
D P
DP
Mikhailidis
G
G
Stansby
D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage / Q000494:pharmacology*; D003911:Dextrans / Q000008:administration & dosage / Q000494:pharmacology*; D004341:Drug Evaluation; D016894:Endarterectomy, Carotid / Q000009:adverse effects*; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D020766:Intracranial Embolism / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D019007:P-Selectin / Q000097:blood; D015539:Platelet Activation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D010979:Platelet Function Tests; D011446:Prospective Studies; D013923:Thromboembolism / Q000209:etiology / Q000517:prevention & control; D017585:Ultrasonography, Doppler, Transcranial
D000925:Anticoagulants; D003911:Dextrans; D019007:P-Selectin; D010975:Platelet Aggregation Inhibitors