[Mathematical modeling of high-flow extra-intracranial bypass in the treatment of a complex cerebral aneurysm]. / Matematicheskoe modelirovanie obkhodnogo vysokopotochnogo ekstra-intrakranial'nogo shuntirovaniya pri lechenii slozhnoi tserebral'noi anevrizmy.

BACKGROUND: Intracranial aneurysms (IAs) pose a high risk of spontaneous subarachnoid hemorrhage. In the most complex cases, the only way to exclude the aneurysm from the circulation is to perform a high-flow extracranial-to-intracranial bypass, thus creating a new bloodstream. This avoids severe ischemic complications; however, it requires careful consideration of individual anatomy and hemodynamic parameters. Computational fluid dynamics (CFD) can be of great help in planning such a surgery by creating 3D patient-specific models of cerebral circulation. OBJECTIVE: Assessment of the perspectivity of high-flow extracranial-to-intracranial bypass planning using computational modeling. MATERIAL AND METHODS: In this research work, we have applied the CFD methods to a patient with a giant thrombosed IA of the internal carotid artery (ICA). Preoperative CTA images and Gamma Multivox workstation were used to create a 3D model with current geometry and three additional models: Normal anatomy (no IA), Occlusion (with ligated ICA), Virtual bypass (with bypass and ligated ICA). The postoperative data were also available. Boundary conditions were based on PC-MRI measurements. Calculation of hemodynamics was conducted with a finite element package ANSYS Workbench 19. RESULTS: The results demonstrated an increase in the blood flow on the affected side by more than 70% after the virtual surgery and uniformity of flow distribution between the affected and contralateral sides, indicating that the treatment is likely to be efficient. Later, postoperative data confirmed that. CONCLUSION: The study showed that virtual preoperative CFD modeling could significantly simplify and improve surgical planning.

[Analysis of local hemodynamics in complex aneurysms: an effect of the vessel arising from the dome or the neck]. / Issledovanie lokal'noi gemodinamiki v slozhnykh anevrizmakh: vliyanie sosuda, otkhodyashchego ot kupola ili sheiki.

BACKGROUND: Assessment of rupture risk for intracranial aneurysms (IA) is a particular challenge in cases of so-called complex aneurysms due to their variable morphometric characteristics. Arterial branch arising from the dome or the neck of IA is one of the least explored features of complex aneurysms. The methods of computational fluid dynamics may be valuable to determine the influence of arterial branches of IA on local hemodynamics. OBJECTIVE: To analyze local hemodynamics in IA with arterial branch arising from the cupola or the neck depending on the structure of the aneurysm and blood flow rate in the parent vessel. MATERIAL AND METHODS: CT angiography data of 4 patients with IA were estimated in this study. Modifications of the baseline 3D models of the aneurysms resulted 12 patient-specific models included into analysis. Hemodynamic calculations were made by using of ANSYS Workbench 19 software package. RESULTS: Wall shear stress (WSS) was characterized by the most significant variability, especially in case of sidewall aneurysms. Small cross-sectional area of additional branch in relation to the neck of IA was not followed by considerable changes of blood flow patterns inside IA after «virtual¼ removal of the vessel. Otherwise, the intensity of flows was drastically reduced. Simulation of high inlet flows demonstrated substantial variation of WSS in the area of jet. CONCLUSION: Additional arterial branch arising from the dome or the neck of IA significantly influences local hemodynamics. This influence depends on the localization of IA in relation to the parent vessel and the diameter of additional arterial branch.

[Vector mapping of deformation and blood flows in patients with ascending aortic aneurysm]. / Vektornoe kartirovanie deformatsii i potokov krovi u patsientov s anevrizmoi voskhodiashchei aorty.

The authors performed clinical studies based on modelling of an ascending aortic aneurysm in 37 patients and 10 apparently healthy subjects. Echocardiography was carried out in the B-mode using the Vivid E9 device (USA, GE). The linear dimensions of the aorta were assessed at three points - in the immediate vicinity of the valves, in the area of the maximum dilatation and in the area of decreased dilatation with registration of blood flow velocity in the aorta. The aortic walls were contoured with the division of equal intervals into 4 portions in order to obtain longitudinal shear deformation velocity during the cardiac cycle. We worked out a system of assessing the velocity vector fields with the help of transthoracic echocardiography in patients with an ascending aortic aneurysm, based on registration of blood flows, which made it possible to obtain the components of velocity. We also determined an optimal method of assessing turbulence in the aorta taking into account the direction of the vectors. Obtained were the numerical data of aortic wall deformation velocity in the longitudinal direction and calculation of the weighting function with the distinction between pathology and the norm. Based on the deformation, the distance between the registered points, and the movement of the vascular wall, we determined the reference values of blood flow velocity inside the aorta and immediately close to its walls.

[Phenomenological Regularities of Assessment of Left Ventricle Function in Mitral Valve Insufficiency].

OBJECTIVE: to examine relationship between anatomical changes of the left ventricle (LV), dynamics of velocity of its volume modification, and blood flows in the LV in patients with mitral regurgitation (MR) before and after surgical treatment. MATERIALS AND METHODS: We included into this study 58 patients with severe 3-4 degree MR (38 men, 20 women aged 24-69 [mean age 51±9] years) in sinus rhythm (96 %) or atrial fibrillation (4 %). The control group included 86 healthy volunteers, mean age 39±7 years. Transthoracic echocardiographic studies were performed in both groups by standard technique at rest using a high-quality echocardiograph Vivid E9, equipped with a 3.5-4.6 MHz multi frequency transducer (in patients before and after surgical repair - mitral valve [MV] replacement and MV reconstruction with annuloplasty ring). The analysis of files recorded was performed off-line by vector analysis technique including estimation of myocardial deformation velocities and dynamics of LV volume modification, construction of "flow-volume" diagram, calculation of the expended kinetic energy, and registration of intraventricular blood flows. RESULTS: End diastolic volume (EDV), end systolic volume (ESV) and total stroke volume (TSV) (effective + retrograde) were significantly increased in patients with severe LV volume overload before surgery in comparison with the control group (p.

[ASSESSMENT OF EXTRAVASCULAR LUNG WATER BY QUANTITATIVE COMPUTER IMAGE ANALYSIS IN PATIENTS WITH ACUTE RESPIRATORY DISTRESS SYNDROME].

PURPOSE: To evaluate the possibility of quantitative computed tomography (CT) of the lungs in patients with acute respiratory distress syndrome (ARDS) for assessment of the severity of the condition and the effectiveness of treatment. MATERIALS AND METHODS: The study included 29 patients with ARDS and 22 with no signs of lung disease (control group). We measured extravascular lung water (EVLW) by transpulmonary thermodilution (TTD) and analysed CT of the lungs in patients with ARDS. Patients in the control group underwent CT of the lungs only. CT images were processed using the "Gamma Multivoks". RESULTS: According to CT poorly ventilated lung areas accounted for 2% of the total in the control group. Normally ventilated and hyper-ventilated lung areas prevailed in these patients. In the group of ARDS hyper-ventilated areas almost were not identified and normality and poorly ventilated areas we found. In patients with ARDS total lung volume was 1.5 times less than in the control group (median volume of 3393 and 4955 mL respectively). Pulmonary weight in ARDS group was bigger than in controls (median weight of the lungs 1233 and 812 g respectively). Effects of treatment according to quantitative CT evaluated in 14 survived patients. Notes the increase in lung volume (median 4656.5 ml) (p = 0.0001) and a decrease in lung weight (median 862 g) (p = 0.0012). The weight and volume of the lungs, the ratio of hyper, normal and poorly ventilated areas of the lung in patients with acute respiratoy distress syndrome after treatment did not differ from those in the control group. CONCLUSIONS: Quantitative analysis of CT reveals changes in the mass and volume of the lungs and can be used to diagnose and evaluate the effectiveness of the treatment. Pulmonary weight calculated by CT correlates with EVLW determined by TTD.

[PREDICTORS OF RISK OF SURGERIES IN PATIENTS WITH FAILURE OF THE CORONARY CIRCULATION].

The paper analyzes the study of the myocardium in patients with coronary artery disease to identify new predictors of reduction of myocardial contractility. Research carried out on the basis of transthoracic echocardiography and transesophageal on Vivid 7 unit and Vivid-E9 with multifrequency array sensor (3.5-5.5 MHz) by method with the obligatory registration ofstandard ECG. All studies in the form of static and moving images (3-5 cardiocycles Cine-loop) is stored in workstation memory Echopac 7 (GE Vingmed Ultrasound, USA). To assess the functional state of left ventricular myocardium was measured geometry of the cavities of the heart and determines the main central hemodynamics: end-diastolic and end-systolic volume qf the left ventricle, the si:e of the left atrium, the rate of displacement of the myocardium ofivector analysis, stroke vohne, duration of the phases ofthe cardiac cycle, the pressure in the pulmonary circulation. In patients with low reserves, changes are observed during the period of contraction and relaxation. The maximum rate peaks do not coincide, and are significantly reduced compared with the outcome. Acceleration, velocity of bloodflow in the left ventricular cavity shows changing the direction of blood flow--this is nothing other than the power characteristic, which reflects energy during the contraction. Determination of the eddy currents and the velocity characterizes the acceleration of change in the direction of blood flow

[Assessment of velocity of deformation of abdominal aorta wall with the help of the multivox working station].

Most frequent cause of abnormalities of elastic properties of walls of abdominal aorta is development of atherosclerosis resulting in replacement of elastin by simpler fibrillar proteins and collagen. This subsequently leads to dilation of the aorta and formation of aneurism. Increase of collagen content in the aortic wall correlates with growth of aneurism dimensions. Main method of treatment of aneurisms is implantation of abdominal aortic prosthesis. Detailed preoperative assessment of functional state of the aortic wall is necessary in preoperative period but none of modern imaging instrumental methods including ultrasound study allows to realize this assessment. In this article we present first experience of assessment of aortic wall deformation velocity analyzing results of ultrasound study with the help of the Multivox working station in 36 patients 16 of whom were operated because of aneurism of abdominal aorta.

[Myocardial biomechanics in patients with coronary circulatory insufficiency].

The paper analyzes a new approach to evaluating myocardial systolic and diastolic function, which is based on recording of the rate of myocardial displacement in different phases of a cardiac cycle. Changes in the rate of vector movements in a period of isovolumic contraction and relaxation are shown on ample clinical materials in both healthy individuals and patients with coronary heart disease. There is evidence for a significant difference in the performance of a stress test by healthy individuals and patients with a low coronary circulatory reserve.

[Modeling of hemodynamic changes in the aneurysm of the middle cerebral artery depending on the pathology of the parent artery].

OBJECTIVE: To examine the influence of the parent artery pathology on the local hemodynamics on the level of aneurysm. MATERIAL AND METHODS: Mathematical models of the arteriovenous malformation (AVM) were built on the CT-angiography data of real patients. To simulate the thrombosis, the parent artery and its branches were sequentially turned off in the model 1. In the model 2, the simulation of embolization of AVM was achieved by cutting off the exactly section of the parent artery that was involved in the arteriovenous formation. RESULTS AND CONCLUSION: Model 1 showed that the flow redistribution did not significantly impact on the risk of rupture after the parent artery was turned off and blood pressure was increased in both aneurysms by 3 mm Hg. Model 2, in which the aneurysms were combined with a direct arteriovenous drainage with low peripheral resistance, showed that turning off the parent artery and pathological drainage led to the serious reduction in the venous drainage flow and it's increasing in the parent artery by about 60% that significantly increased the risk of rupture.

[Problems in emergency care for concomitant injury in the Saratov region].

The paper deals with the topical problem in emergency care delivered to patients with severe concomitant injury at its all stages (prehospital, hospital, and interhospital transportation ones). The authors analyze the activities of anesthesiological-and-resuscitative units of therapeutic-and-prophylactic facilities in Saratov and its region from 1993 to 2003. The paper presents principal schemes of delivering emergency care in severe concomitant injury and considers the problems (material, logistic, professional, and organizational) hampering the delivery of emergency care, interhospital transportation, and the rendering of various medical aids at different-leveled hospitals. The authors propose possible ways of their solution, which may ensure the timeliness of medical aid delivered to patients with severe concomitant injury, improve its quality, reduce mortality and disability rates in the patients.

[Levels in the structural organization of Escherichia coli promoter DNA]. / Urovni strukturnoi organizatsii promotornoi DNK.

A number of additional structural elements were identified by statistic analysis of nucleotide sequences in promoters recognized by Escherichia coli RNA polymerase. Together with canonical hexanucleotides, these elements characterize different levels in the structural organization of promoter DNA. Sequence motifs exhibiting the highest statistical significance, which dominate in the contact regions with RNA polymerase alpha and sigma subunits, are considered as targets for specific interaction with RNA polymerase. A typical feature of these elements is the presence of easily deformable dinucleotides (TG, CA and TA) or tracts containing only A/T base pairs. Thus, we noticed that the frequency of occurrence of TA in the promoter DNA is essentially higher than the average value for the genome. Besides the regions of specific interaction with RNA polymerase, these dinucleotides are often located in the number of other sites periodically distributed along the promoter DNA. This preferred disposition suggests that deformable elements participate in the adaptive conformational transitions of the promoter DNA favoring optimal configuration of the transcription complex. Probably, the most important feature of promoter DNA revealed by statistic analysis is the presence of A/T-tracts regularly distributed in the wide range from -160 up to +75 relative to the transcription start point. Both of these spatially distributed elements (TA dinucleotides and A/T-tracts) are linked with canonical regions and, therefore, may contribute to the conformational or dynamic features of the transcription machinery. Having high statistic significance, these elements might be considered as additional factors discriminating the promoter DNA on the background of other nucleotide sequences in the genome.