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Introduction/Objective. Circle of Willis (CoW) provides the most significant collateral flow in the presence of significant stenosis or occlusion of internal carotid artery. In terms of collateral flow ?incomplete? type and ?complete? type of CoW can be recognized. Patients with carotid artery disease with incomplete CoW have lower cerebrovascular reactivity and higher risk for stroke. Cerebrovascular reactivity refers to the residual capacity of dilatation of cerebral blood vessels in the condition of insufficient blood flow. In this study we analyzed changes in cerebrovascular reactivity after carotid endarterectomy in asymptomatic patients with respect to complete and incomplete CoW morphology. Methods. In this study in 97 patients with asymptomatic carotid artery disease we measured cerebrovascular reactivity before and after carotid endarterectomy by using method of ?apnea test? and ?breathholding index? (BHI). Patients were divided into two following groups: patients with ?complete? CoW and ?incomplete? CoW based on non-contrast magnetic resonance angio performed previously to the operation. Descriptive statistics, univariate analysis, and ANOVA for comparison of BHI values between groups were used. Results. The results showed significant increase in cerebrovascular reactivity at the side of stenosis in both groups of patients with complete CoW (BHI value increased from 0.897 to 1.090; F (1.65) = 30.788, p < 0.0005, parc. ?2 = 0.321) and incomplete CoW (BHI value increased from 0.690 to 1.010; F (1.27) = 62.318, p < 0.0005, parc. ?2 = 0.698) and the more significant increase in the group of incomplete CoW compared to the group with complete CoW (F (1.92) = 4.557, p = 0.035, parc. ?2 = 0.047) Conclusion. In most asymptomatic patients, cerebrovascular reactivity restores to normal following carotid endarterectomy. Parameters of cerebrovascular reactivity are lower in patients with incomplete CoW and the increase after carotid endarterectomy is more significant in such patients.

Introduction. Endovascular revascularization is a peripheral artery disease therapy used to improve blood flow in blood vessels. The objective of this study was to analyze the types and prevalence of comorbidities in patients with indications for carotid artery revascularization, as well as early results of endovascular carotid artery revascularization in relation to periprocedural complications. Material and Methods. This retrospective study was conducted from October 2014 to October 2019 and included 96 patients. Descriptive and comparative statistical analysis was performed in all patients, male and female, and those with both symptomatic and asymptomatic carotid diseases. Results. The study included 96 patients, of whom 69.8% were male and 30.2% were female. A successful endovascular procedure was performed in 89.6% of patients, while in 10.4% of patients the procedure failed. The distribution of patients by sex, age and the duration of procedure, showed a statistically significant difference (p < 0.05) in the age (p = 0.0003) and duration of the procedure (p = 0.022). The comparison of two groups of patients, with symptomatic and asymptomatic carotid atherosclerotic disease, hyperlipoproteinemia (p = 0.015) showed a statistically significant difference (p < 0.05) between the two groups. Conclusion. Endovascular revascularization has a high success rate in the treatment of atherosclerotic disease of the carotid arteries as well as low periprocedural morbidity and mortality. The analysis of gender-related differences, we concluded that endovascular revascularization lasts significantly longer in female patients, and that the average age is significantly higher in male patients compared to females. We also concluded that hyperlipoproteinemia is a major risk factor for carotid artery disease.

Introduction. Carotid endarterectomy is an efficient surgical procedure of primary and secondary prevention of ischemic stroke in asymptomatic and symptomatic patients with extracranial carotid artery disease. Material and Methods. In this paper we analyzed incidence, risk factors, potential causes and preventive measures for early stroke after carotid endarterectomy in patients (809) who underwent surgery for carotid artery stenosis at the Clinic of Vascular and Endovascular Surgery of the Clinical Center of Vojvodina in Novi Sad during a five year period (April 2013 - March 2018). Results and Discussion. Early operative stroke was registered in 12 patients with no significant difference between symptomatic (2.8%) and asymptomatic (1.1%) patients (odds ratio - 2,56, 95% confidence interval - 0.8063 to 8.1770 standard deviation 1,596; p = 0,11). Contralateral carotid occlusion (odds ratio - 3.1154, 95% confidence interval - 1.1620 to 8.3522, p = 0.0239) and no dual antiplatelet therapy (odds ratio - 3.1154, 95% confidence interval - 1.8537 to 526.4871; p = 0.0169) were pointed out as risk factors for operative stroke. Most of the perioperative and early postoperative strokes after carotid endarterectomy were due to arterial-arterial thromboembolism, intracerebral hemorrhage and acute carotid occlusion that developed rarely and were associated with severe neurological deficit. Conclusion. Even though our results are in agreement with the literature data, additional measures for surgical quality control would further decrease the incidence of operative stroke.

Background Cerebral hyperperfusion syndrome is a rare but potentially severe complication of carotid artery revascularisation that develops under conditions of resistant postoperative hypertension and impaired cerebrovascular autoregulation. Objective Was to determine which preoperative and operative factors affect the development of cerebral hyperperfusion syndrome after carotid endarterectomy. Methods This prospective observational study enrolled 93 asymptomatic patients who underwent carotid endarterectomy. Cerebral hyperperfusion was registered in patients who had 100% postoperative increase in mean flow in middle cerebral artery registered by Transcranial Doppler ultrasound. Cerebral hyperperfusion syndrome was diagnosed in patients with cerebral hyperperfusion who postoperatively developed at least one of the symptoms. Pre-operative and operative risk factors for cerebral hyperperfusion syndrome were analysed by multivariate binary logistic regression. Results Out of 93 operated patients, cerebral hyperperfusion was registered in 23 and cerebral hyperperfusion syndrome in 18 patients. Risk factors for cerebral hyperperfusion syndrome were included in the binary logistic regression model. Incomplete Circle of Willis morphology on 3D TOF magnetic resonance image (p = 0.002), Breath holding index below the 0.69 cut-off (p = 0.006), positive criteria for insufficient collateral flow through circle of Willis registered by TCD (p = 0.03), and poorly controlled hypertension (p = 0.023) showed statistically significant independent predictive value for cerebral hyperperfusion syndrome. The model was statistically significant (p = 0.012) and correctly classified 90.3 % of patients. Conclusions Incomplete circle of Willis and insufficient collateral flow, low cerebrovascular reserve, and poorly regulated hypertension are significant predictors of post- carotid endarterectomy hyperperfusion development.

Introduction. This research has been aimed at determining whether incomplete Circle of Willis in patients with significant extracranial carotid stenosis is associated with a higher incidence of neurological symptomatology and/or ischemic cerebral lesions. Material and Methods. The research was conducted as a prospective study which comprised 211 patients who underwent surgical treatment of extracranial carotid disease at the Department of Vascular Surgery in Novi Sad and 102 patients in the control group. Each patient underwent preoperative magnetic resonance imaging and magnetic resonance angiography with visualization of cerebral parenchyma, extracranial and intracranial cerebral circulation. Assessment of Circle of Willis morphology was performed by 3D time-of-flight magnetic resonance angiogram sequence analysis. The patients were divided into two groups: group I - the patients with complete Circle of Willis and group II - the patients with incomplete Circle of Willis i.e. with the disruption of anterior and/or ipsilateral posterior circulation - regarding the side of significant carotid stenosis. Results. Out of 211 patients who were operated during a two-year period, 133 had the complete Circle of Willis, while 78 patients had the incomplete Circle of Willis. Out of 111 patients with symptomatic carotid disease or silent cerebral infarction, 52.5% (58) had the complete Circle of Willis and 47.5% (53) had the incomplete Circle of Willis. It was shown to be statistically different (P = 0.0146) in relation with the asymptomatic group of patients (100), where the frequency of the complete Circle of Willis was 75% (75) while the insufficiency of anterior or ipsilateral posterior collateralization was found in 25% (25). In the control group there were significantly fewer cases of developed collateral flow and the complete Circle of Willis (41%) compared to the operated patients with extracranial carotid stenosis (63%) (P = 0.0003). Conclusion. Incompleteness of Circle of Willis is associated with more frequent occurrence of neurological symptomatology or ischemic lesions of brain parenchyma in operated patients with significant extracranial carotid stenosis. The control group without extracranial carotid stenosis had less developed collaterals of Circle of Willis compared to extracranial carotid patients.