Compensatory Blood Flow Research Articles

Understanding perioperative risk determinants in carotid endarterectomy: the impact of compromised circle of Willis morphology on inter-hemispheric blood flow indices based on intraoperative internal carotid artery stump pulse pressure and backflow patterns.

Carotid artery stenosis (CAS) often requires surgical intervention through carotid endarterectomy (CEA) to prevent stroke. Accurate cerebrovascular risk assessments are crucial in CEA, as poor collateral circulation can lead to insufficient interhemispheric blood flow compensation, resulting in ischemic complications. Therefore, understanding perioperative risk determinants is vital. This study aims to determine the impact of compromised circle of Willis (CoW) morphology on inter-hemispheric blood flow, focusing on indices based on intraoperative internal carotid artery stump pulse pressure and backflow patterns. In 80 CAS patients who underwent CEA, preoperative CT angiography for CoW was conducted. Patients were categorized into five subgroups based on their CoW anatomy and three additional groups based on intraoperative internal carotid artery (ICA) stump backflow patterns evaluated by the surgeon. Continuous blood pressure signals, including systolic, diastolic, mean, and pulse pressure values, were recorded during the procedure. The relationship between CoW anatomical variants and the systolic and diastolic segments of the averaged pressure waveforms, particularly diastolic pressure decay, was analyzed. The correlation between CoW anatomy and stump backflow intensity was also examined. Significant variability in ICA stump backflow and pressure values was evident across CoW variants. Patients with compromised CoW morphology exhibited weaker backflow patterns and lower ICA stump pulse pressure values, consistent with impaired interhemispheric blood flow. Notably, ICA stump diastolic pressure decay was consistent across most CoW variant groups, indicating developed collateral circulation in cases with CoW anomalies. Thus, impaired CoW integrity is associated with compromised interhemispheric blood flow indices based on intraoperative ICA stump pulse pressure and backflow patterns during CEA. Integrating intraoperative pulse waveform analysis with preoperative CT angiography provides a more detailed assessment of cerebrovascular risk, guiding the selective use of shunts. This combined approach may improve surgical outcomes and patient safety by identifying patients at increased risk of perioperative neurological events due to CoW anomalies.

Detectability of white matter cerebral blood flow using arterial spin labeling MRI in patients with sickle cell disease: Relevance of flow territory, bolus arrival time, and hematocrit.

Sickle cell disease (SCD) is the most common genetic blood disorder, characterized by red cell hemolysis, anemia, and corresponding increased compensatory cerebral blood flow (CBF). SCD patients are at high risk for cerebral infarcts and CBF quantification is likely critical to assess infarct risk. Infarcts primarily localize to white matter (WM), yet arterial spin labeling (ASL) MRI, the most common non-invasive CBF approach, has poor WM CBF sensitivity owing to low WM CBF and long WM bolus arrival time (BAT). We hypothesize that anemia, and associated cerebral hyperemia, in SCD leads to improved WM detection with ASL. We performed 3-Tesla multi-delay pulsed ASL in SCD (n = 35; age = 30.5 ± 8.3 years) and control (n = 15; age = 28.7 ± 4.5 years) participants and applied t-tests at each inversion time within different flow territories, and determined which regions were significantly above noise floor (criteria: one-sided p < 0.05). Total WM CBF-weighted signal was primarily detectable outside of borderzone regions in SCD (CBF = 17.7 [range = 12.9-25.0] mL/100 g/min), but was largely unphysiological in control (CBF = 8.1 [range = 7.6-9.9)] mL/100 g/min) participants. WM BAT was reduced in SCD versus control participants (ΔBAT = 37 [range = 46-70] ms) and BAT directly correlated with hematocrit (Spearman's-ρ = 0.62; p < 0.001). Findings support the feasibility of WM CBF quantification using ASL in SCD participants for appropriately parameterized protocols.

Quantification of Collateral Supply with Local-AIF Dynamic Susceptibility Contrast MRI Predicts Infarct Growth.

In ischemic stroke, leptomeningeal collaterals can provide delayed and dispersed compensatory blood flow to tissue-at-risk despite an occlusion and can impact treatment response and infarct growth. The purpose of this work is to test the hypothesis that inclusion of this delayed and dispersed flow with an appropriately calculated Local Arterial Input Function (Local-AIF) is needed to quantify the degree of collateral blood supply in tissue distal to an occlusion. Seven experiments were conducted in a pre-clinical middle cerebral artery occlusion model. Dynamic susceptibility contrast MRI was imaged and post-processed to yield quantitative cerebral blood flow (qCBF) maps with both a traditionally chosen single arterial input function applied globally to the whole brain (i.e. "Global-AIF") and a delay and dispersion corrected AIF (i.e. "Local-AIF") that is sensitive to retrograde flow. Leptomeningeal collateral arterial recruitment was quantified with a pial collateral score from x-ray angiograms, and infarct growth calculated from serially acquired diffusion weighted MRI scans. The degree of collateralization at x-ray correlated more strongly with qCBF using the Local-AIF in the ischemic penumbra (R2=0.81) than traditionally chosen Global-AIF (R2=0.05). qCBF using a Local-AIF was negatively correlated (less infarct progression as perfusion increased) with infarct growth (R2 = 0.79) more strongly than a Global-AIF (R2=0.02). In acute stroke, qCBF calculated with a Local-AIF is more accurate for assessing tissue status and collateral supply than traditionally chosen Global-AIFs. These findings support use of a Local-AIF that corrects for delayed and dispersed retrograde flow in determining quantitative tissue perfusion with collateral supply in occlusive disease. MRI = magnetic resonance imaging; DSC = dynamic susceptibility contrast; PCS = pial collateral score; MCAO = middle cerebral artery occlusion; MCA = middle cerebral artery; AIF = arterial input function; rCBF = relative cerebral blood flow; qCBF = quantitative cerebral blood flow.

Analysis of the clinical characteristics of V4 segment steal blood in the vertebral artery

Objective: To explore the clinical characteristics of unilateral vertebral artery V4 segment occlusive lesions (severe stenosis or occlusion), where the contralateral vertebral artery can be compensated through blood flow and reverse supply to the posterior inferior cerebellarartery (PICA). Methods: This study is a retrospective case series of 66 patients with V4 segment occlusive lesions of unilateral vertebral artery diagnosed and treated from June 2020 to October 2022. Patient data were retrospectively collected, and their hemodynamic characteristics and imaging data were analyzed. Results: Of the 66 cases, 11 patients (16.7%) with V4 segment occlusive disease showed the blood flow of the vertebral artery on the opposite side of the lesion on the digital subtraction angiography (DSA), which can be reverse stolen to the posterior inferior cerebellar artery of the diseased side through the confluence point of the vertebrobasilar artery through the distal end of the ipsilateral vertebral artery V4. Owing to the lack of literature on this pathway and based on the characteristics of previous definitions of subclavian artery steal and carotid artery steal, we referred to this pathway as the vertebral artery V4 segment steal. In 6 patients (9.1%), transcranial Doppler ultrasound (TCD) and transcranial color Doppler ultrasound (TCCD) showed that the blood flow signal was not detected at the proximal end of the V4 segment of the affected side, rather the blood flow direction was reversed at the distal end of the V4 segment, resulting in compensatory acceleration of the blood flow velocity of the V4 segment of the contralateral vertebral artery. Conclusion: "V4 segment steal of vertebral artery" is a very rare route of vertebral artery steal. When V4 segment of the vertebral artery is occluded, clinicians should pay attention to observe the blood supply of PICA and whether there is such a steal route, to better evaluate the blood flow compensation and prognosis of patients.

Modeling cerebrovascular responses to assess the impact of the collateral circulation following middle cerebral artery occlusion.

An improved understanding of the role of the leptomeningeal collateral circulation in blood flow compensation following middle cerebral artery (MCA) occlusion can contribute to more effective treatment development for ischemic stroke. The present study introduces a model of the cerebral circulation to predict cerebral blood flow and tissue oxygenation following MCA occlusion. The model incorporates flow regulation mechanisms based on changes in pressure, shear stress, and metabolic demand. Oxygen saturation in cerebral vessels and tissue is calculated using a Krogh cylinder model. The model is used to assess the effects of changes in oxygen demand and arterial pressure on cerebral blood flow and oxygenation after MCA occlusion. An increase from five to 11 leptomeningeal collateral vessels was shown to increase the oxygen saturation in the region distal to the occlusion by nearly 100%. Post-occlusion, the model also predicted a loss of autoregulation and a decrease in flow to the ischemic territory as oxygen demand was increased; these results were consistent with data from experiments that induced cerebral ischemia. This study highlights the importance of leptomeningeal collaterals following MCA occlusion and reinforces the idea that lower oxygen demand and higher arterial pressure improve conditions of flow and oxygenation.

Assessment of cerebral autoregulatory function and inter-hemispheric blood flow in older adults with internal carotid artery stenosis using transcranial Doppler sonography-based measurement of transient hyperemic response after carotid artery compression

Unhealthy vascular aging promotes atherogenesis, which may lead to significant internal carotid artery stenosis (CAS) in 5 to 7.5% of older adults. The pathogenic factors that promote accelerated vascular aging and CAS also affect the downstream portion of the cerebral microcirculation in these patients. Primary treatments of significant CAS are eversion endarterectomy or endarterectomy with patch plasty. Factors that determine adequate hemodynamic compensation and thereby the clinical consequences of CAS as well as medical and surgical complications of carotid reconstruction surgery likely involve the anatomy of the circle of Willis (CoW), the magnitude of compensatory inter-hemispheric blood flow, and the effectiveness of cerebral microcirculatory blood flow autoregulation. This study aimed to test two hypotheses based on this theory. First, we hypothesized that patients with symptomatic and asymptomatic CAS would exhibit differences in autoregulatory function and inter-hemispheric blood flow. Second, we predicted that anatomically compromised CoW would associate with impaired inter-hemispheric blood flow compensation. We enrolled older adults with symptomatic or asymptomatic internal CAS (>70% NASCET criteria; n = 46) and assessed CoW integrity by CT angiography. We evaluated transient hyperemic responses in the middle cerebral arteries (MCA) after common carotid artery compression (CCC; 10 s) by transcranial Doppler sonography (TCD). We compared parameters reflecting autoregulatory function (e.g., transient hyperemic response ratio [THRR], return to baseline time [RTB], changes of vascular resistance) and inter-hemispheric blood flow (residual blood flow velocity). Our findings revealed that CAS was associated with impaired cerebral vascular reactivity. However, we did not observe significant differences in autoregulatory function or inter-hemispheric blood flow between patients with symptomatic and asymptomatic CAS. Moreover, anatomically compromised CoW did not significantly affect these parameters. Notably, we observed an inverse correlation between RTB and THRR, and 49% of CAS patients exhibited a delayed THRR, which associated with decreased inter-hemispheric blood flow. Future studies should investigate how TCD-based evaluation of autoregulatory function and inter-hemispheric blood flow can be used to optimize surgical techniques and patient selection for internal carotid artery revascularization.

CHANGES IN THE CEREBRAL CORTEX NEURON ULTRASTRUCTURE IN RATS WITH PARTIAL CEREBRAL ISCHEMIA

The ultrastructural characteristics of neuronal organelles are significant indicators of brain damage under ischemic exposure, which necessitates the study of changes in the ultrastructure of brain neurons.&#x0D; The aim of the study was to examine the disorders of brain neurons under its partial ischemia at the ultrastructural level using an experimental model.&#x0D; Materials and Methods. The experimental group included 12 male rats weighing 260±20 g, the control group consisted of 6 falsely operated male rats of the same weight. Partial cerebral ischemia (PCI) was modeled by right common carotid artery ligation. The material was taken 1 hour after the operation.&#x0D; Results. The study showed that the size and shape of the mitochondria of neurons of the parietal cortex and the hippocampus in PCI rats did not differ from those of the control group (p&gt;0.05), except for a smaller number of cristae per unit area in the mitochondria of parietal cortex neurons (by 18 %, p&lt;0.05).&#x0D; The size and shape of the Golgi complex and lysosomes did not differ in the groups either. However, there was an increase in the number of free ribosomes in the cytoplasm of neurons in the parietal cortex and hippocampus of PCI rats, by 58 % and 54 %, respectively (p&lt;0.05).&#x0D; The ratio of fixed and free ribosomes in control rats decreased from 3.4 to 0.8 in the parietal cortex (p&lt;0.05) and from 2.33 to 0.7 in the hippocampus (p&lt;0.05).&#x0D; Conclusions. In general, the neuron ultrastructure in PCI rats was similar to that in the control group, which might be due to blood flow compensation in the circle of Willis. An increase in the number of free ribosomes is a sign of deranged protein biosynthesis in neurons. A decrease in the number of mitochondrial cristae in neurons in the parietal cortex indicates energy deficiency.

Verification of blood flow path reconstruction mechanism in distal sigmoid colon and rectal cancer after high IMA ligation through preoperative and postoperative comparison by manual subtraction CTA

IntroductionWe aimed to investigate manual subtraction computed tomography angiography (MS-CTA) to further confirm the distribution and classification of LCA (left colic artery) ascending/descending branches, then observe the postoperative blood flow path to illustrate how the above branches evolved to postoperative blood path. Material and methods89 patients with distal sigmoid and rectal cancer were referred in our observation and underwent MS-CTA between June 2020 and March 2022. We classified the distribution of LCA and confirmed whether there exists AMCA (accessory middle colic artery). Then we planned blood flow path based on the classification of LCA branches before operation. High ligation was applied in regular radical surgery. During operation, we carefully protect the bifurcation of ascending and descending LCA. Then we compared the planned blood flow path with the actual postoperative blood flow path to verify the mechanism we proposed previously. ResultsOf 89 patients, 82 cases met our criteria, we summarized 6 distribution pattens of LCA ascending and descending branches. These preoperative pattens are consistent with the inspection during operation. The postoperative blood flow path of 6 pattens is evolved from the above adjacent anastomotic branches and is consistent with the planned blood flow path. We also found 2 cases with IMA stenosis and 1 case with SMA stenosis under pathological condition, and their compensatory blood flow path is in accordance with our theory. The rate of the anastomotic leakage in our study group is relatively low (7.3%). ConclusionMS-CTA could confirm the distribution of LCA and AMCA, display accurate postoperative blood reconstruction path after IMA high ligation, and it further verified the mechanism we proposed previously, which is the proximal anastomotic branches forming new blood flow path from high-pressure area to the low-pressure area. This mechanism might be helpful for performing accurate laparoscopic sigmoid and rectal cancer surgery.

Impact of placental sharing and large bidirectional anastomoses on birthweight discordance in monochorionic twins: a retrospective cohort study in 449 cases

In monochorionic twin pregnancies, the fetuses share a single placenta. When this placenta is unequally shared, a discordant antenatal growth pattern ensues resulting in high rates of perinatal morbidity and mortality. Understanding placental pathophysiology is paramount in devising feasible antenatal management strategies. Unequal placental sharing is not the sole determinant of birthweight discordance as there is no one-to-one relationship with placental share discordance. Placental angioarchitecture, especially the presence of large bidirectional anastomoses, is thought to affect this relationship by allowing for a compensatory intertwin blood flow. This study aimed to assess whether placental angioarchitecture can affect birthweight discordance in live-born monochorionic twins, the aim of our study was 2-fold: (1) to assess the relationship between birthweight discordance and placental share discordance and (2) to examine to what extent large bidirectional anastomoses can compensate for the effect of unequal placental sharing on birthweight discordance, with a subgroup analysis for umbilical artery Doppler flow patterns in cases with a birthweight discordance of ≥20%. This was a retrospective cohort study that included monochorionic twin pregnancies observed in our center between March 2002 and June 2021, in which twins with a birthweight discordance of ≥20% were classified according to umbilical artery Doppler flow patterns of the smaller twin. We excluded cases with twin-twin transfusion syndrome and twin anemia polycythemia sequence. Monochorionic placentas of live-born twins were injected with dye, and images were saved for computer measurements of placental sharing and the diameter of anastomoses. Univariate linear regressions of the relationship between placental share discordance and birthweight discordance (both calculated as weight or share larger twin-weight or share smaller twin/weight or share larger twin×100%) and the relationship between arterioarterial and venovenous diameters and birthweight ratio/placental territory ratio were performed. A total of 449 placentas were included in the analysis. Placental share discordance was positively correlated with birthweight discordance (β coefficient, 0.325; 95% confidence interval, 0.254-0.397; P<.0001). The arterioarterial diameter was negatively correlated with birthweight ratio/placental territory ratio (β coefficient,-0.041; 95% confidence interval,-0.059 to-0.023; P<.0001), meaning that an increase in arterioarterial diameter leads to less birthweight discordance than expected for the amount of placental share discordance. There was no relationship between venovenous diameter and birthweight ratio/placental territory ratio (β coefficient,-0.007; 95% confidence interval,-0.027 to 0.012; P=.473). Birthweight discordance in monochorionic twins was strongly associated with placental share discordance. Large arterioarterial anastomoses can mitigate the effect of unequal placental sharing.

Internal Carotid Artery Constriction with or without Superficial Temporal Artery–Middle Cerebral Artery Bypass for Patients with Giant Internal Carotid Aneurysms

The optimal management of giant internal carotid aneurysms (GICAs) is disputed owing to their low incidence. The aim of this study was to describe the use of internal carotid artery (ICA) constriction as therapeutic management of GICAs. This retrospective cohort study analyzed data from medical histories and follow-up of 14 patients with GICAs. Before surgery, the patients underwent balloon test occlusion and magnetic resonance perfusion evaluation. ICA constriction was considered only for patients with negative balloon test occlusion. A transverse incision of about 50% of the initial part of the ICA was done, and the free margins on both sides were sutured, causing 70%-90% stenosis. ICA constriction alone was selected (11 cases) if both anterior communicating artery and posterior communicating artery compensatory blood flow existed and magnetic resonance perfusion was ≤II1 on the affected side. If there was only 1 compensatory vessel from the anterior communicating artery and posterior communicating artery, and/or magnetic resonance perfusion was >II1, ICA constriction was combined with low-flow bypass (3 cases). The mean follow-up time of the 14 patients was 43.5 months (interquartile range: 38.8-51.3 months). Of these 14 patients, 5 achieved O'Kelly-Marotta grades C and D. Clinical improvement occurred in 12 of 14 patients. No patients experienced new-onset stroke. ICA constriction exhibits a perforator protective effect. This procedure could be a promising alternative to ICA ligation in patients with GICAs and negative balloon test occlusion.

Study on the correlation between the circle of Willis structure and collateral circulation in bilateral carotid artery occlusion

Background and purposeBilateral carotid artery occlusion (CAO) is a rare condition and the collateral circulation is more complicated than in unilateral CAO. The circle of Willis (CoW) is the most important collateral circulation compensation pathway in CAO. However, the specific role of CoW in the collateral circulation compensation pathway of CAO has not been fully elucidated. The purpose of this study is to investigate the role of CoW in the collateral circulation compensation pathway of CAO.Materials and methodsClinical, imaging, and hemodynamic data of 30 patients with bilateral CAO were collected to analyze the collateral blood flow compensation pathway and its characteristics, and to examine the correlation between the structure of the CoW and the collateral circulation of bilateral CAO.ResultsThis paper summarized 30 patients with bilateral CAO. There were 0 cases of the CoW complete type, 18 cases of the partially complete type (60%), and 12 cases of the incomplete type (40%). For the partially complete type cases, there were 14 complete anterior circulation cases (46.7%). The collateral circulation collateral circulation pathway included 14 cases with anterior communicating artery(ACoA), 7 cases with posterior cerebral artery (PCA)-middle cerebral artery (MCA) leptomeningeal anastomosis (LMA), 5 cases with ophthalmic artery(OA), 3 cases with lateral posterior communicating artery(PCoA), 1 case with internal carotid artery (ICA) stealing, 1 case with new Moyamoya vessels, and 4 cases of other types. There were four cases (13.3%) with complete posterior circulation, including four cases with bilateral PCoA, three cases with PCA-MCA LMA, and two cases with OA. There were 12 cases (40%) with incomplete CoW, including 8 cases with PCA-MCA LMA, 3 cases with lateral PCoA, 1 case with anterior cerebral artery (ACA)-MCA LMA, 4 cases with OA, and 1 other case.ConclusionThe collateral circulation pathway differs among patients with different CoW structure types. When the CoW is partially complete, it mainly provides blood flow compensation to the ischemic area through primary collateral circulation. When the CoW is incomplete, it mainly provides blood flow compensation to the ischemic area through secondary collateral circulation.

Study of the kidney function remaining in kidney donors and its related factors in transplant center of Imam Khomeini hospital, Urmia

Introduction: Concerns about the occurrence of premature kidney failure have been expressed a few years after the kidney donation in the donor due to increase in compensatory blood flow in the remaining kidney nephrons. Objectives: This study aimed to study the kidney function remaining in living kidney donors and its related factors. Patients and Methods: Data were collected from 30 kidney donors in Imam Khomeini hospital in Urmia and evaluated using SPSS-22 software. Results: The mean duration of nephrectomy was 36.36 ± 6.22 years. The mean serum creatinine was significantly increased at the time of examination than before donation, and the glomerular filtration rate (GFR) decreased significantly (P&lt;0.001). Male donors (P=0.025) and donors who did not have relative relationship with the recipient (P=0.44) had better kidney function. The renal function at the time of examination was 74.86% amount before donation. The glucose tolerance test (mg/dL 2 hours) of the donors increased significantly at the time of the study compared to the time before donation (P=0.049). Conclusion: The remaining kidney function of the donors has decreased significantly seven years after donation. It seems that kidney donors need more time to excrete excess glucose, so they are far from being over-carbohydrate.

Evaluation and embolization strategy by ASITN/SIR grade for injured internal carotid artery of nasopharyngeal carcinoma

Objective: To study the strategy of endovascular treatment for patients with the risks of internal carotid artery (ICA) rupture and bleeding during the treatment of nasopharyngeal carcinoma (NPC) based on American Society of Intervention and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) grade of collateral circulation. Methods: A total of 56 patients (45 males and 11 females, aged from 28 to 76 years old) diagnosed with nasopharyngeal carcinoma and admitted to the Department of Neurosurgery, the Third Affiliated Hospital of Southern Medical University from July 2018 to January 2020 were retrospectively analyzed. There were 15 cases of ASITN/SIR grade 4, 24 cases of ASITN/SIR grade 3, 5 cases of ASITN/SIR grade 2, 5 cases of ASITN/SIR grade 1, and 7 cases of ASITN/SIR grade 0. The events of stroke and death were analyzed statistically. Results: ALL patients with ASITN/SIR grade 4 or 3 and some of patients with ASITN/SIR grades 2-0 passed balloon occlusion test and electrophysiological monitoring. ICA pseudoaneurysm was found in 35 patients, and one-stage ICA embolization was performed in 29 patients after evaluation. Among them, 8 cases of ASITN/SIR grade 4 and 10 cases of ASITN/SIR grade 3 with obvious posterior circulation compensation obtained successful one-stage ICA embolization without cerebral ischemia; cerebral ischemic events occurred in 5 (55.6%) of 9 patients with ASITN/SIR grade 3 and in 1(50.0%) of 2 patients with ASITN/SIR grade 2. The total incidence of ischemic events was 20.7% (6/29) and 1 case was disabled (1/29, 3.4%). Among patients with ASITN/SIR 3, there were statistically significant differences in stroke event rate between patients with obvious posterior circulation compensation and patients with slight or without posterior circulation compensation (0/10 vs. 5/9, χ(2)=4.95, P=0.026). Follow-up time was 10.1±7.8 months, and 46 patients were survival (46/56, 82.1%) and 10 patients died (10/56, 17.9%) with a mean survival time of 2.6±1.4 months. Conclusions: For NPC patients with ICA invasion, ASITN/SIR based on DSA can simplify the assessment process of cerebral blood flow compensation. ICA can be embolized directly in patients with ASITN/SIR 4 or 3 with obvious posterior communicating compensation.

Ablation of Vitamin D Signaling Compromises Cerebrovascular Adaptation to Carotid Artery Occlusion in Mice.

Vitamin D insufficiency has been associated with increased incidence and severity of cerebrovascular disorders. We analyzed the impact of impaired vitamin D signaling on the anatomical and functional aspects of cerebrovascular adaptation to unilateral carotid artery occlusion (CAO), a common consequence of atherosclerosis and cause of ischemic stroke. Cerebrocortical blood flow (CoBF) showed a significantly increased drop and delayed recovery after CAO in mice carrying a functionally inactive vitamin D receptor (VDR) with the most sustained perfusion deficit in the temporal cortex. To identify the cause(s) for this altered adaptation, the extent of compensatory blood flow increase in the contralateral carotid artery and the morphology of pial collaterals between the anterior and middle cerebral arteries were determined. Whereas VDR deficiency had no significant influence on the contralateral carotid arterial blood flow increase, it was associated with decreased number and increased tortuosity of pial anastomoses resulting in unfavorable changes of the intracranial collateral circulation. These results indicate that VDR deficiency compromises the cerebrovascular adaptation to CAO with the most sustained consequences in the temporal cortex. The dysregulation can be attributed to the altered development and function of pial collateral circulation whereas extracranial vessels may not be impaired.

Optimized mouse model of embolic MCAO: From cerebral blood flow to neurological outcomes

The embolic middle cerebral artery occlusion (eMCAO) model mimics ischemic stroke due to large vessel occlusion in humans and is amenable to thrombolytic therapy with rtPA. However, two major obstacles, the difficulty of the eMCAO surgery and unpredictable occurrence of clot autolysis, had impeded its application in mice. In this study, we modified catheters to produce suitable fibrin-rich embolus and optimized the eMCAO model using cerebral blood flow (CBF) monitored by both laser Doppler flowmetry (LDF) and 2D laser speckle contrast imaging (LSCI) to confirm occlusion of MCA. The results showed that longer embolus resulted in higher mortality. There was a compensatory increase in MCA territory perfusion after eMCAO associated with decreased infarct volume; however, this was only partly dependent on recanalization as clot autolysis was only observed in ∼30% of mice. Cortical CBF monitoring with LSCI showed that the size of peri-core area at 3 h displayed the best correlation with infarct volume that is attributed to compensatory collateral blood flow. The peri-core area best predicted functional outcome after eMCAO. In summary, we developed a reliable eMCAO mouse model that better mimics embolic ischemic stroke in humans, which will increase the potential for successful translation of stroke neuroprotective therapies.

The effect of preset intraoperative intraocular pressure during phacoemulsification on the blood flow velocity in the central retinal artery

Aim. To evaluate the effect of preset elevated intraocular pressure (IOP) level during phacoemulsification on central retina artery and central retinal vein hemodynamics and to determine possible compensatory mechanisms of the ocular blood flow autoregulation in response to intraoperational IOP jump.&#x0D; Methods. This prospective study included 23 cataract patients without concomitant ocular vascular conditions (15 women and 8 men) aged from 62 to 83 years. The mean age was 72.5 5.7 years. In all patients, an intraoperational color duplex scanning in the regimens of color Doppler imaging and pulsed wave velocity imaging using ultrasound scanner Logiq S8 (GE). The blood flow was estimated in retrobulbar vessels: central retinal artery, central retinal vein with maximal systolic velocity, end-diastolic velocity of the blood flow, and resistance index (RI). The investigation was performed under IOP control, which was measured using Icare Pro tonometer, and under blood pressure control using patient monitoring system Draeger Vista 120. In the operating room, ocular blood flow was examined three times: immediately before surgery, straight after the surgical incision sealing at preset intraoperational IOP level, and after IOP normalization and repeated sealing of the corneal tunnel.&#x0D; Results. Under preset intraoperational IOP maintenance on 58.01 8.10 mm Hg level, there was a clinically significant (p 0.05) decrease of blood flow velocity in the central retinal artery. In 30.4% of cases, the blood flow velocity in the central retinal artery during diastolic phase was not registered. The flow velocity in central retinal vein did not change significantly, and did not depend on IOP level (p 0.05).&#x0D; Conclusions. At the 5560 mm Hg IOP level, in humans, compensatory blood flow autoregulation mechanisms in response to intraoperational IOP jumps are absent, up to complete blood flow stop in the central retinal artery at the diastolic phase, and this could be a risk factor for retinal ischemia.

Influence of operative treatment of variсocele on the development of arterial hypertension

Purpose of the research. To assess the incidence of arterial hypertension in men with varicocele and to identify the relationship between increased blood pressure and surgical treatment of varicocele.&#x0D; Material and methods. A survey of 412 men receiving treatment for arterial hypertension, 482 men previously operated on for varicocele and 68 patients with varicocele who had no surgical treatment was conducted.&#x0D; Results. Varicose veins of the spermatic cord in patients with arterial hypertension were detected in 44.6% of cases, which exceeds the incidence of varicocele occurrence in men of a comparable age category by 1.52 times. Surgical treatment of the left spermatic cord varicocele is combined with the development of arterial hypertension in 51.2% of patients, which is three times higher than the incidence of hypertension in men who didnt undergo surgical treatment for varicocele and twice the frequency of hypertension in the general population of men of comparable age. The more frequent occurrence of renal arterial hypertension in patients who underwent surgical treatment for varicocele may indicate an adverse effect of occlusion of the internal spermatic vein on the state of renal venous hemodynamics.&#x0D; Conclusion. Varicocele should be considered as a compensatory process for renal venous hypertension due to obstruction of blood flow through the renal vein, and elimination of compensatory blood flow can lead to renal venous hypertension, hypoxia and the development of arterial hypertension.

Bilateral internal carotid artery occlusion with compensatory perfusion in a HIV-infected patient

HIV infection occlusive arteriopathies may result in neurological symptoms. We report a case of bilateral complete occlusion of the extracranial portions of the internal carotid arteries in a HIV+ve patient who presented with a syncopal episode due to intraventricular haemorrhage. Compensatory blood flow from the posterior cerebral circulation via the circle of Willis resulted in small telangiectatic vessels arising from the posterior cerebral circulation which probably accounted for this rare haemorrhagic complication of an occlusive arteriopathy.

Results of superior vena cava resection in patients with lung and mediastinal tumors

Background: Thoracic tumors involving the superior vena cava (SVC) are common in the practice of a thoracic surgeon treating cancer patients. Extended combined procedures that allow for complete removal of the tumor improves overall and disease-free survival and as such are justified from an oncologist’s perspective. In some patients, due to a long-standing SVC syndrome, the development of venous collaterals would increase the early postoperative risk of thrombus formation in the prosthesis. In such a case, it is possible to perform circular SVC resection without subsequent prosthetic replacement. Aim: To evaluate the short-term results of SVC resection in patients with chest tumors, to develop an algorithm and to identify the patient group in whom circular SVC without prosthetic replacement is feasible. Materials and methods: Twenty eight (28) patients were included into the study (22 men and 6 women, with the mean age of 55 [range, 21 to 70 years]; all of them had undergone SVC resection within the intervention for a lung or mediastinal malignancy for 10 years (from 2008 to 2018) in the Department of Thoracic Surgery, Moscow Research Institute of Oncology named after P.A. Herzen. We analyzed their short-term results of the procedures, the postoperative course, and technical particulars of the procedures. Results: Locally advanced lung cancer was diagnosed in 19 (67%) of the patients, thymoma in 3 (10%), lung metastatic disease in 2 (7%), germ-cell mediastinal tumors in 2 (7%), thymus cancer in 1 (3%), and residual lymphoma in 1 (3%) patient. In the majority of the patients (15 cases, 53%), the complicated clinical course had been diagnosed before surgery. In 4 patients with protracted SVC syndrome, we performed circular resection without any prosthetic replacement. In 22 patients (78%), the postoperative course was uneventful. Postoperative mortality was 7%. Conclusion: SVC resection can be safely performed in patients with primary mediastinal and lung tumors. With a long-standing SVC syndrome, the newly developed cava-caval anastomoses can provide significant functional support; in such patients with compensatory collateral blood flow, the circular SVC resection without prosthetic replacement is relatively safe.

Comparative assessment of fetal blood flow and cardiac system status of pregnant women with mitral valve pathology

Annotation. The aim of this work is to analyze the course of pregnancy in women with mitral pathology, the task is to identify preclinical criteria for worsening cardiovascular pathology that can lead to the development of complications of pregnancy and functioning of the fetal CVS, to evaluate the effectiveness of preventive measures. The article presents the analysis of changes in ultrasound characteristics of fetoplacental blood flow in women with mitral valve prolapse and mitral valve insufficiency, as well as cardiovascular status in these women. Statistical processing was performed by calculating Student coefficients (+) using the Microsoft Excel PC program. Doppler examination of fetal umbilical cord blood flow during pregnancy was studied. The correlation between the level of maternal blood flow compensation and pathological changes in the fetoplacental complex was established. As a result of our work, the prevalence of the disease was estimated. As of 2018, it was found that of the total number of extragenital pathology in 1676 pregnant women with CVSD; respectively for 2017 — 1699, for 2016 — 1925, 2015 — 1857 in the region. Of these, 331 (2018), 313 (2017), 326 (2016), 306 (2015) had mitral valve defects, including prolapse. A retrospective assessment of pregnancy and childbirth indicates the possibility of complications of pregnancy and childbirth. In the group of patients with mitral valve prolapse and mitral valve insufficiency, compared to the control group, they did not show significant changes in the dynamics of the Doppler metrics of cardiovascular pathology, which indicates the compensation of the cardiovascular system against the background of changes in the valve. At the same time, the tendency to decrease of CF in women with mitral valve prolapse and insufficiency of the mitral valve against the background of increasing pregnancy is revealed, indicates a violation of CVD adaptation to changes inherent in pregnancy, which provoke hemic and hemodynamic changes in the body, which will cause pregnancy and fetal status. FPC status in women with mitral valve prolapse and mitral valve insufficiency worsens in the third trimester of pregnancy, especially indicators such as the ratio of systolic volume ratio (SVR) to diastolic volume ratio (DVR) and IR. The administration of 40 mg of ƅ-blockers for a 2-week period improved the FPC, was safe and effective.