Репозиторий Университета

© The Author(s) 2019. Responses of five rotary blood pumps, namely HeartAssist 5, HeartMate II, HeartWare, Sputnik 1, and Sputnik 2, were extensively assessed in six test cases using a mathematical model of the cardiovascular system. Data for the rotary pumps were derived from pressure–flow curves reported in the literature. The test cases were chosen to attempt to cover most common clinical conditions, such as partial or full support or transitions between different levels of ventricular support. The investigated parameters are collected in a table and presented in figures, such as pressure–volume loops, H-Q curves, pump flow, and aortic pressure waveforms. HeartAssist, Sputnik 1, and Sputnik 2 pumps provide comparable level of aortic pressure, pump flow pulsatility PI(QP), and aortic pressure pulsatility PI(AoP) due to the similarity of pressure–flow characteristic curves of these pumps. HeartMate II provides a minimal backflow among other investigated rotary blood pumps due to the maximum pressure head at zero flow. HeartWare provides minimal pulsation of flow, which is confirmed by a flow range from −2 to 7 L/min in case 1. At the same time, the greatest degree of unloading was demonstrated by the HeartWare due to the flatness of the pressure–flow curve shape. The conclusions were made based on the obtained results, including the influence of pressure–flow curve shape on the pump performance and occurrences of adverse events, such as backflow or suction. For example, the increase of the pressure head at zero flow decreases the likelihood of backflow through the pump, and with it, increasing the flow under minimal pressure head increases the likelihood of suction.

© 2019 The Authors International Journal for Numerical Methods in Biomedical Engineering Published by John Wiley  &  Sons Ltd Non-invasive coronary computed tomography (CT) angiography-derived fractional flow reserve (cFFR) is an emergent approach to determine the functional relevance of obstructive coronary lesions. Its feasibility and diagnostic performance has been reported in several studies. It is unclear if differences in sensitivity and specificity between these studies are due to study design, population, or "computational methodology." We evaluate the diagnostic performance of four different computational workflows for the prediction of cFFR using a limited data set of 10 patients, three based on reduced-order modelling and one based on a 3D rigid-wall model. The results for three of these methodologies yield similar accuracy of 6.5% to 10.5% mean absolute difference between computed and measured FFR. The main aspects of modelling which affected cFFR estimation were choice of inlet and outlet boundary conditions and estimation of flow distribution in the coronary network. One of the reduced-order models showed the lowest overall deviation from the clinical FFR measurements, indicating that reduced-order models are capable of a similar level of accuracy to a 3D model. In addition, this reduced-order model did not include a lumped pressure-drop model for a stenosis, which implies that the additional effort of isolating a stenosis and inserting a pressure-drop element in the spatial mesh may not be required for FFR estimation. The present benchmark study is the first of this kind, in which we attempt to homogenize the data required to compute FFR using mathematical models. The clinical data utilised in the cFFR workflows are made publicly available online.

© 2018 Elsevier Ltd The variation of blood flow waveform in the internal carotid artery (ICA) with age is a well-documented hemodynamic phenomenon, but little is known about how such variation affects the characteristics of blood flow in aneurysms present in the region. In the study, hemodynamic simulations were conducted for 26 ICA aneurysms, with flow waveforms measured in the ICAs of young and older adults being used respectively to set the inflow boundary conditions. Obtained results showed that replacing the young-adult flow waveform with the older-adult one led to little changes (<10%) in simulated time-averaged wall shear stress (WSS), transient maximum WSS, relative residence time and trans-aneurysm pressure loss coefficient, but resulted in a marked increase (32.36 ± 17.24%) in oscillatory shear index (OSI). Frequency-domain wave analysis revealed that the progressive enhancement of low-frequency harmonics dominated the observed flow waveform variation with age and was a major factor contributing to the increase in OSI. Cross-sectional comparisons among the aneurysms further revealed that the degree of increase in OSI correlated positively with some specific morphological features of aneurysm, such as aspect ratio and size ratio. In summary, the study demonstrates that the variation in flow waveform with age augments the oscillation of WSS in ICA aneurysms, which underlies the importance of setting patient-specific boundary conditions in hemodynamic studies on cerebral aneurysms, especially those involving long-term patient follow-up or cross-sectional comparison among patients of different ages.

Copyright © 2018 by the MediaSphere. Diabetes mellitus (DM) is a genetically heterogeneous disease, and some cases of type 1 diabetes mellitus (T1DM) are caused by a mutation of one gene. The child has suffered from brittle diabetes since the age of 1 year and received insulin. The HbA1c level is 9.9-11.4%. The patient was examined at the age of 14 years; the disease duration is 13 years. The daily dose of insulin is 1.15-1.35 U/kg. DM complications include initial manifestations of distal diabetic polyneuropathy as well as cheiropathy. The mother (39 years) and grandmother (74 years) have T1DM with multiple complications. A genetic study revealed that all three family members had a heterozygous substitution p.P274 in the PTF1A gene with an unknown pathological significance. At present, it can not be asserted that the identified mutation is the etiologic factor of diabetes in the described case. We can not exclude T1DM in this child because specific antibodies have not been tested. However, the mutation is detected in all three members of the same family with diabetes, which does not exclude the discovery of a new form of MODY, not described earlier.

Copyright © 2018 by the MediaSphere. MODY3 is one of the most common subtypes of MODY. Obesity in MODY3 patients modifies the disease course and complicates diagnostics at the clinical stage. A proband was diagnosed with type 2 diabetes mellitus (T2DM) at the age of 12 years; metformin therapy was used. A family history of DM involves three generations: The mother, aunt, and maternal grandfather have suffered from insulin-dependent DM since the age of 23, 22, and 40 years, respectively. The patient was examined at the age of 14 years. Obesity was present (SDS BMI 2.3). The insulin and C-peptide levels were 4.4 μU/mL and 1.5 ng/mL, respectively. The HbA1c level was 7.3%. Under glucose load, glycemia reached diabetic values; hyperinsulinemia and insulin resistance were not detected. Specific pancreatic antibodies were absent. Metformin was discontinued, and a sulfonylurea (SU) drug was prescribed, which had a positive effect. The heterozygous mutation p.P291fs was identified in the HNF1A gene. Therefore, MODY3 was verified. The presence of concomitant obesity in the patient significantly complicates the differential diagnosis, and only a careful comprehensive analysis of clinical and laboratory parameters and a family history makes it possible to suspect the diagnosis of MODY3 (requiring subsequent molecular genetic verification) and prescribe pathogenetic therapy.

© 2018 Sergey S. Simakov. The study of the physiological and pathophysiological processes in the cardiovascular system is one of the important contemporary issues, which is addressed in many works. In this work, several approaches to the mathematical modelling of the blood flow are considered. They are based on the spatial order reduction and/or use a steady-state approach. Attention is paid to the discussion of the assumptions and suggestions, which are limiting the scope of such models. Some typical mathematical formulations are considered together with the brief review of their numerical implementation. In the first part, we discuss the models, which are based on the full spatial order reduction and/or use a steady-state approach. One of the most popular approaches exploits the analogy between the flow of the viscous fluid in the elastic tubes and the current in the electrical circuit. Such models can be used as an individual tool. They also used for the formulation of the boundary conditions in the models using one dimensional (1D) and three dimensional (3D) spatial coordinates. The use of the dynamical compartment models allows describing haemodynamics over an extended period (by order of tens of cardiac cycles and more). Then, the steady-state models are considered. They may use either total spatial reduction or two dimensional (2D) spatial coordinates. This approach is used for simulation the blood flow in the region of microcirculation. In the second part, we discuss the models, which are based on the spatial order reduction to the 1D coordinate. The models of this type require relatively small computational power relative to the 3D models. Within the scope of this approach, it is also possible to include all large vessels of the organism. The 1D models allow simulation of the haemodynamic parameters in every vessel, which is included in the model network. The structure and the parameters of such a network can be set according to the literature data. It also exists methods of medical data segmentation. The 1D models may be derived from the 3D Navier - Stokes equations either by asymptotic analysis or by integrating them over a volume. The major assumptions are symmetric flow and constant shape of the velocity profile over a cross-section. These assumptions are somewhat restrictive and arguable. Some of the current works paying attention to the 1D model's validation, to the comparing different 1D models and the comparing 1D models with clinical data. The obtained results reveal acceptable accuracy. It allows concluding, that the 1D approach can be used in medical applications. 1D models allow describing several dynamical processes, such as pulse wave propagation, Korotkov's tones. Some physiological conditions may be included in the 1D models: gravity force, muscles contraction force, regulation and autoregulation.

© Russian Journal of Cardiology.  Aim. Evaluation of clinical specifics, predictors of repeat hospitalizations and mortality in chronic obstructive pulmonary disease (COPD) patients according to pulmonary hypertension (PH) severity grade. Material and methods. To the study, 288 COPD patients included (II-IV severity grade, GOLD 2016; males 276, females 12; mean age 59,5±9,27 y. o., smoking 23,1±11,42 pack/years; 2,4±0,89 exacerbations annually, body mass index (BMI) 27,2±12,06 kg/m 2 ). According to the presence and grade of systolic pressure increase in pulmonary artery (SPPA) the patients were selected to three groups: 1st — with no PH (SPPA <40 mmHg, n=168), 2nd — with moderate PH (SPPA 40-55 mmHg, n=101), 3rd — with severe PH (SPPA >55 mmHg, n=19). Results. Increase of SPPA was found in 120 (41,7%) patients: moderate PA — in 101 (35,1%), severe PH — 19 (6,6%). It was shown that the presence and severity of PH do increase the severity of clinical signs of COPD, hemodynamic disorders, increase the rate of repeat hospitalizations and mortality rate. The predictors of repeat hospitalizations in COPD patients are increased SPPA and C-reactive protein concentration (CRP); mortality predictors are severity of symptoms by CAT, Borg dyspnea, number of exacerbations during one year, size of the right atrium, grade of SPPA increase, CRP concentration, fibrinogen, N-terminal precursors of C-natriuretic peptide (NT-proCNP) and brain peptide (NT-proBNP) in the blood. Conclusion. PH in COPD patients in most cases is moderate, and it worsens the clinical picture, hemodynamic disorders, shows only moderate correlation with breathing disorders, increases the rate of rehospitalizations and mortality risk. The survival rate of COPD and PH patients depends on the severity.

AIM: To study the state of cerebral hemodynamics and platelet hemostasis in patients with carotid stenosis (CS). MATERIAL AND METHODS: The prospective study included 123 patients with atherosclerotic CS. The 1st group included 53 patients (mean age 52±12.5 yrs) who underwent carotid endarterectomy (CEA); the 2nd group - 70 patients who were treated conservatively (mean age 58.5±15.9 yrs). The state of blood flow through the main arteries of the head (Doppler flowmetry), platelet aggregation induced by adrenaline, the frequency of acute cardiovascular events that occurred during 12 months were evaluated. RESULTS AND CONCLUSION: The severity of neurological deficits and cognitive impairment increased with increasing of the degree of CS. CEA leads to an improvement of cerebral hemodynamics and stabilization of cognitive functions. The adverse course of the disease occurred in 23.6% of patients (stroke/heart attack during the year in 5.7%, progression of cerebral ischemia in 20%, restenosis within 5 years after CEA in 15%). Hyperaggregation of platelets induced by ADP and epinephrine and decreased aggregation of platelets induced by collagen in patients receiving ASA were identified in 53% of the operated and in 60% of non-operated patients. The use of combined antiplatelet therapy normalize the platelet hemostasis and reduce the frequency of acute cardiovascular events.