Evaluation of aspirin resistance and the presence of unstable carotid plaque in patients undergoing carotid endarterectomy.

BACKGROUND: Antiplatelet therapy using low dose acetylsalicylic acid (ASA) is routinely recommended in patients undergoing surgical or endovascular treatment of carotid artery disease. Despite this treatment, a significant proportion of postoperative complications may result from inadequate response to antiplatelet therapy which may contribute to the development of unstable plaques. AIM: Assessment of correlation between ASA resistance and the presence of unstable carotid plaque in patients after carotid endarterectomy. METHODS: We studied 66 patients (27 women and 39 men) aged 41-80 years who were operated for carotid stenosis. All patients received ASA (75 mg once daily) in the pre- and perioperative period. Measurements of platelet reactivity were performed using the PFA-100 platelet analyser at the second day after the operation. Plaque stability was evaluated using a computer analysis system based on the greyscale median method. The patients were divided into two groups, showing good response to ASA or ASA-resistant. RESULTS: ASA resistance was identified in 19 (32%) patients. In multivariate logistic regression analysis, unstable plaque showed a borderline correlation with ASA resistance (p = 0.051). CONCLUSIONS: 1. Prevalence of increased platelet reactivity despite ASA treatment (ASA resistance) in patients treated surgically for carotid artery disease is high, suggesting a possibility of ineffective antiplatelet therapy. 2. A modest correlation between abnormal platelet response during treatment with ASA and the presence of unstable plaques suggests that these two phenomena may coexist but we were unable to show a clear association between them.

Elasticity of the carotid artery walls as a prognostic factor for the occurrence of restenosis after a surgery for internal carotid artery stenosis.

BACKGROUND: Restoration of carotid artery patency is one of the most frequently performed operations in vascular surgery. One of the most important problems that occur both short- and long-term after carotid endarterectomy is recurrent stenosis. Despite advances in imaging studies and better knowledge of the mechanisms of atherogenesis, the mechanism of restenosis remains unclear. Patients with internal carotid artery atherosclerosis experience decreased elasticity of the intima-media complex, resulting in increased vessel wall stiffness. In the future, measurement of carotid artery elasticity may become a marker for the development of post-surgical stenosis occurring after endarterectomy of both the carotid artery and other peripheral vessels. AIM: To assess the elasticity of carotid artery walls as a prognostic factor for the occurrence of restenosis after a surgery for common carotid artery stenosis. METHODS: Classic carotid artery endarterectomy was performed in 180 patients selected on the basis of standard, ultrasound- based recommendations. The phenomenon of restenosis was examined using ultrasound techniques at 3, 6, 9 and 12 months after the surgery. Measurements of carotid artery elasticity were performed using a Vascular Echo Doppler device, and patients were divided into two groups depending on the occurrence (or non-occurrence) of restenosis. RESULTS: Group I (without restenosis) included 156 (86.6%) patients, and Group II (with restenosis) included 24 (13.4%) patients. At 3 and 6 months after the surgery, an increase of the elasticity of vessel walls (coefficient a) was observed in both groups, but the differences in the elasticity of the carotid arteries were not significant. At 12 months after the surgery, all patients in Group II (with restenosis) had significantly increased coefficient a values as compared to Group I patients (p < 0.05). CONCLUSIONS: A decrease in carotid artery wall elasticity as measured using coefficient a may be associated with the process leading to the occurrence of restenosis after the surgery. Further research is required in order to confirm the conclusions presented in this paper and to explain potential mechanisms of this phenomenon.

Application of a time-resolved optical brain imager for monitoring cerebral oxygenation during carotid surgery.

Recent studies have shown that time-resolved optical measurements of the head can estimate changes in the absorption coefficient with depth discrimination. Thus, changes in tissue oxygenation, which are specific to intracranial tissues, can be assessed using this advanced technique, and this method allows us to avoid the influence of changes to extracerebral tissue oxygenation on the measured signals. We report the results of time-resolved optical imaging that was carried out during carotid endarterectomy. This surgery remains the "gold standard" treatment for carotid stenosis, and intraoperative brain oxygenation monitoring may improve the safety of this procedure. A time-resolved optical imager was utilized within the operating theater. This instrument allows for the simultaneous acquisition of 32 distributions of the time-of-flight of photons at two wavelengths on both hemispheres. Analysis of the statistical moments of the measured distributions of the time-of-flight of photons was applied for estimating changes in the absorption coefficient as a function of depth. Time courses of changes in oxy- and deoxyhemoglobin of the extra- and intracerebral compartments during cross-clamping of the carotid arteries were obtained. A decrease in the oxyhemoglobin concentration and an increase in the deoxyhemoglobin concentrations were observed in a large area of the head. Large changes were observed in the hemisphere ipsilateral to the site of clamped carotid arteries. Smaller amplitude changes were noted at the contralateral site. We also found that changes in the hemoglobin signals, as estimated from intracerebral tissue, are very sensitive to clamping of the internal carotid artery, whereas its sensitivity to clamping of the external carotid artery is limited. We concluded that intraoperative multichannel measurements allow for imaging of brain tissue hemodynamics. However, when monitoring the brain during carotid surgery, a single-channel measurement may be sufficient.

[Chlamydia pneumoniae infection in patients with advanced carotid atherosclerosis]. / Zakazenia Chlamydia pneumoniae u chorych z zaawansowana miadyca tetnic szyjnych.

Despite the growing number of scientific reports showing different markers of infection caused by Chlamydia pneumoniae in patients with advanced atherosclerosis, there is still no clear confirmation of a pathogenetic link between this infection and atherogenesis. The aim of the present study was to investigate the presence C. pneumoniae DNA in peripheral blood mononuclear cells and carotid endarterectomy samples obtained from patients with advanced atherosclerosis according to the presence specific antibodies against C. pneumoniae in serum. The levels of IgG, IgM and IgA antibodies to C. pneumoniae were determined by enzyme immunoassay (EIA) in sera of 36 patients with advanced atherosclerosis undergoing carotid endarterectomy. The presence of C. pneumoniae DNA in the carotid samples and in peripheral blood mononuclear cells was investigated by a nested polymerase chain reaction (PCR). We have not confirm the presence of C. pneumoniae DNA either in the carotid endarterectomy samples or in peripheral blood mononuclear cells, both in patients having the specific antibodies against C. pneumoniae and in seronegative patients. In the studied group of patients with advanced carotid atherosclerosis there was no correlation between the presence of specific antibodies against C. pneumoniae and the presence of C. pneumoniae DNA in endarterectomy samples and peripheral blood mononuclear cells.