The effect of heparin reversal after carotid endarterectomy in the dog

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Abstract
If total reversal of heparin immediately after carotid endarterectomy would have an adverse effect on the thrombogenicity of the endarterectomized vessel wall was studied. After systemic heparinization, unilateral common carotid endarterectomies were performed under the operating microscope on 14 dogs. Half of the animals were given protamine sulfate to reverse the heparin. Three hours after resumption of blood flow, these arteries, as well as contralateral vessels used as controls for fixation technique, were perfused with glutaraldehyde and prepared for scanning electron microscopy (SEM). Thrombin clotting times were measured throughout the experiments. Sections of the endarterectomized portions viewed by SEM showed nearly total coverage of the exposed collagen of the media with flattened platelets. There were scattered leukocytes, but few erythrocytes, little fibrin, and no true thrombus. There were no differences between the animals that received heparin reversal and those that did not. A group of 5 additional arteries underwent the same procedure except that no heparin was given. As expected, large amount of thrombus had formed within the lumina of these control vessels by 3 h. Since arterial thrombosis usually occurs within 3 h of endothelial injury, total reversal of heparin apparently does not increase thrombogenicity of the endarterectomized vessels. Heparin may be safely reversed in patients to help maintain postoperative hemostasis.