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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. Severe acute respiratory syndrome coronavirus 2 infection-induced coagulopathy may be the underlying cause of acute limb ischemia, a sudden decrease in limb perfusion. The aim of this study was to present a case series of acute limb ischemia associated with severe acute respiratory syndrome coronavirus 2 infection. Material and Methods. This unicentric, observational cohort study evaluated the incidence, risk factors, clinical, laboratory and radiological findings, problems in diagnosis, treatment and outcome of patients with severe acute respiratory syndrome coronavirus 2 infection-induced acute limb ischemia. Results. The study included 14 patients with a diagnosis of severe acute respiratory syndrome coronavirus 2 infection-induced acute limb ischemia in a 20-month period. The majority of patients were male (78.6%), with a mean age of 67 years, body mass index > 30, and typical cardiovascular risk factors. Only 64.3% of acute limb ischemia patients with coronavirus disease 2019 underwent attempts of limb salvage; 14.3% required primary amputation; 21.4% were treated with systemic anticoagulant therapy alone. The mortality rate was high (42.9%). Revascularization was successful in 7 (50%) patients with acute limb ischemia. The overall amputation rate was 28.6%. Conclusion. The high incidence of acute limb ischemia associated with severe acute respiratory syndrome coronavirus 2 infection, even with thromboprophylaxis, high mortality rates and poor limb salvage outcomes, encourage clinicians to apply individually tailored diagnostic and therapeutic approaches. Prolonged systemic use of heparin may improve the effectiveness of surgical treatment, limb salvage, and overall survival.

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.

Introduction. Due to the ever-present lack of kidney transplant grafts, more and more organs obtained from the so-called ?marginal donors? group are accepted, which can provide suboptimal effect of transplantation, depending on their characteristics and/or implantation techniques. Case report. We presented a case with successful variation of kidney position with modified approach of kidney transplantation from an infant to an adult female patient with normal postoperative recovery. Urethral anastomosis was performed without antireflux procedure and this has not led to the development of reflux disease at an early stage. Conclusion. The position of a pair of kidneys proved to be satisfactory despite the growth of the kidney to the expected size and relatively small pelvis. There were no problems with venous stasis and kidney function from the very beginning was good.

We utilize historical sources of Sir Winston Churchill’s leadership during World War II (WWII) to provide insight into how leaders may leverage positive psychological resources (PsyCap) to lead oth...