| Popis: |
Introduction: Carotid endarterectomy (CEA) for patients with a significant (>70%) carotid stenosis reduces their risk of stroke over the subsequent years of follow up. This benefit is ameliorated by post-operative strokes and deaths. If the post-operative complication rate can be reduced then it is possible that patients with lesser stenoses may also benefit from CEA. This body of work has concentrated on identifying factors related to the development of strokes secondary to carotid thrombosis following CEA. The number of microembolic signals detected by transcranial Doppler ultrasound arising from the endarterectomised vessel wall has been shown in a number of publications to correlate with risk of post-operative carotid thrombosis. Methods and Results: 1)Patients who undergo two carotid endarterectomies at separate time points have a significant correlation between the number of post-operative emboli seen at the first and second procedures (p=0.038). 2) A randomised controlled trial of 274 patients undergoing closure of the arteriotomy site with either a prosthetic Dacron patch or a vein patch was performed. This showed that whilst the vein patch had fewer emboli overall (median of 3 vs 5, p=0.028), the number of people having high levels of sustained embolisation or needing post-operative Dextran-40 therapy (to prevent carotid thrombosis) was not different between the 2 groups (p=0.62). 3) Laboratory platelet function studies (flow cytometry and aggregometry) showed that patients at increased risk of post-operative carotid thrombosis had platelets that were significantly more responsive to the physiological agonist, ADP (pO.OOOl for flow cytometry and p=0.0012 for aggregometry). The degree of inhibition by aspirin did not have a significant effect. 4) Dextran-40, an effective drug for the prevention of carotid thrombosis, was found to bind to the surface of platelets in a dose dependent manner (p=0.006). Unexpectedly, Dextran-40 increased the rate at which platelets aggregated together following stimulation with ADP (p=0.047). Activated platelets bound significantly more Dextran-40 than resting platelets (p |
