Evaluating the effect of non-Newtonian turbulent blood models within a double-stenosed artery

This article describes the numerical investigation of blood rheology within an artery that includes two narrowing areas via Computational Fluid Dynamics (CFD). Elliptic blending Reynolds stress model and two models of viscosity have been used in this investigation utilizing STAR-CCM+ 2021.2.1. The test model includes two elliptical stenosis with a 2mm distance between them, and the area of stenosis is 75%. Results of normalized axial velocity, turbulent kinetic energy (TKE) and turbulent viscosity ratio (TVR) were evaluated before, through and after the stenosis in order to predict and avoid the real problems that occur from changing the area of the artery. Furthermore, Fractional flow reserve (FFR) was employed to assess the level of risk of stenosis through the artery, which depends on pressure measurements. Corresponding to the author's observation, it was found that the recirculation regions in the area between the stenosis are larger than the area after the stenosis. Moreover, the results of TKE and TVR are almost identical through and downstream of the stenosis, whereas the TKE is slightly higher with the Carreau model than with the Newtonian flow at the upstream and through the first stenosis.

Evaluating the effect of non-Newtonian fluid turbulent flowing for blood within a double-stenosed artery

This article describes the numerical investigation of blood rheology within an artery that includes two narrowing areas via Computational Fluid Dynamics (CFD) to offer guidance to the community, especially surgeons, and help them to avoid the risk of stenosis. Elliptic blending Reynolds stress model and two models of viscosity have been used in this investigation utilizing STAR-CCM+ 2021.2.1. The test model includes two elliptical stenosis with a 2mm distance between them, and the area of stenosis is 75%. Results of normalized axial velocity, turbulent kinetic energy (TKE) and turbulent viscosity ratio (TVR) were evaluated before, through and after the stenosis in order to predict and avoid the real problems that occur from changing the area of the artery. Furthermore, Fractional flow reserve (FFR) was employed to assess the level of risk of stenosis through the artery, which depends on pressure measurements. Corresponding to the author's observation, it was found that the recirculation regions in the area between the stenosis are larger than the area after the stenosis. Moreover, the results of TKE and TVR are almost identical through and downstream of the stenosis, whereas the TKE is slightly higher with the Carreau model (arrive to 0.54 J/kg) than with the Newtonian flow (arrive to o.47 J/kg) at the upstream and through the first stenosis.

Retrospective analysis of cerebral neurological complications against background of seasonal respiratory viral infections and new coronavirus infection Covid‑19

Based on the example of seasonal epidemics of respiratory viral infections, it is partially possible to model the outcomes of neurological complications from Covid‑19, taking into account the pathogenetic features of the virus effect on the vascular wall and nerve cells. The accumulated experience of doctors of various specialties makes it possible to prevent such life-threatening complications as ACVA, PATE, intoxication, and sepsis. From the first days of the disease, it is necessary to conduct dynamic monitoring of blood rheology, the level of systemic oxygenation, use anticoagulants in preventive doses in patients at the early stages of the disease, conduct therapy aimed at reducing the risk of cytokine storm development.

Aggregation properties of mammalian erythrocytes and blood rheology.

Рассмотрены условия формирования агрегатов в сосудах. Представлена история изучения феномена обратимой агрегации эритроцитов. Дискутируется целесообразность терапевтической коррекции агрегации эритроцитов при патологии. This review contains the history of the reversible aggregation erythrocytes phenomenon study. The conditions of aggregates formation in vessels with low shear stress are discussed. The assumption is made on the feasibility of reducing еrythrocytes aggregation for correcting blood rheological behavior in the pathology.

Numerical modelling of blood rheology and platelet activation through a stenosed left coronary artery bifurcation

Coronary bifurcations are prone to atherosclerotic plaque growth, experiencing regions of reduced wall shear stress (WSS) and increased platelet adhesion. This study compares effects across different rheological approaches on hemodynamics, combined with a shear stress exposure history model of platelets within a stenosed porcine bifurcation. Simulations used both single/multiphase blood models to determine which approach best predicts phenomena associated with atherosclerosis and atherothrombosis. A novel Lagrangian platelet tracking model was used to evaluate residence time and shear history of platelets indicating likely regions of thrombus formation. Results show a decrease in area of regions with pathologically low time-averaged WSS with the use of multiphase models, particularly in a stenotic bifurcation. Significant non-Newtonian effects were observed due to low-shear and varying hematocrit levels found on the outer walls of the bifurcation and distal to the stenosis. Platelet residence time increased 11% in the stenosed artery, with exposure times to low-shear sufficient for red blood cell aggregation (>1.5 s). increasing the risk of thrombosis. This shows stenotic artery hemodynamics are inherently non-Newtonian and multiphase, with variations in hematocrit (0.163–0.617) and elevated vorticity distal to stenosis (+15%) impairing the function of the endothelium via reduced time-averaged WSS regions, rheological properties and platelet activation/adhesion.

OZONE FEATURES IN THE CONTEXT OF ADVANCING COVID-19 PANDEMIC

Coronavirus disease 2019 represents a serious challenge for modern society worldwide because of the considerable and unfavourable consequences of the pandemic in terms of human health, economics and social life. In the present survey, some essential peculiarities of ozone as an air pollutant and powerful oxidant under the conditions of the COVID-19 pandemic as reflected in the recent literature are described. The understanding of ozone chemistry during COVID-19 lockdown can improve ozone parameterization in models of chemical transport. Ozone peroxides such as ozonides, aldehydes, hydrogen peroxides, and organic peroxide serve as messengers to modulate the human immune system and improve blood rheology.

Effects of preformed physical factors on blood rheology in patients with chronic post-embolic pulmonary hypertension

Введение. Основу взаимодействия физических факторов и организма составляют электрические и биоэнергетические процессы, вызывающие изменения показателей центральной и периферической гемодинамики, обменных процессов, трофики, дыхания, реактивности и сопротивляемости организма. К таким физическим факторам, в частности, относятся электромагнитные колебания оптического излучения или фототерапия. Цель исследования - оценка эффективности воздействия коротковолнового излучения (фотогемотерапии, ФГТ) и ультрафиолетового (УФ) облучения крови на ее реологические свойства в комплексной терапии больных хронической постэмболической легочной гипертензией (ХПЛГ). Методика. Проведено комплексное клинико-лабораторное обследование 64 пациентов (30 женщин и 34 мужчины), поступивших в клинику с симптомами хронической легочной недостаточности, развившейся после перенесенной тромбоэмболии легочной артерии. Больные ХПЛГ были распределены в 3 группы: 1-ю (контрольную) группу составили 15 пациентов, получавшие только базисное лечение; 2-ю (экспериментальную) группу - 26 больных, получавшие базисную терапию в комплексе с ФГТ; 3-ю (экспериментальную) группу - 23 пациента, которые получали базисную терапию в сочетании с воздействием на кровь УФ облучения. Для ФГТ синим светом и УФ воздействия на кровь применяли аппараты АФС-Соларис (Россия) со светодиодами, излучающими синий свет с длиной волны 450 ± 10 нм, и УФ лучи с длиной волны 365 ± 10 нм. Исследовали вязкость крови на ротационном вискозиметре RotoVisco-100 (Нааке GmbH, Германия) в диапазоне скоростей сдвига от 1 до 150 с-1, агрегацию эритроцитов на колориметре-нефелометре ФЭК-56 М (Россия), показатель гематокрита на гематокритной центрифуге (Autocrit, США). Результаты. У больных 1-й группы после базисного медикаментозного лечения отсутствовали статистически значимые изменения вязкости крови, агрегации эритроцитов и показателя гематокрита. У пациентов как 2-й, так и 3-й группы выявлены статистически значимые изменения реологических свойств крови: снижение вязкости крови, агрегации эритроцитов, показателя гематокрита. Заключение. Оптическое излучение синего света имеет выраженное физиологическое воздействие: вызывает медленный, но пролонгированный положительный эффект на реологические свойства крови. УФ облучение при воздействии на кровь также способствует улучшению гемореологии и циркуляции крови и активирует рудиментарные механизмы, запускающие адаптационные системы организма, ранее не функционирующие. Introduction. Electrical and bioenergetic processes that cause changes in central and peripheral hemodynamics, metabolic processes, trophism, respiration, reactivity, and body resistance are the basis of interaction between physical factors and the body. Such physical factors include, in particular, electromagnetic oscillations of the optical radiation or phototherapy. Aim: to assess the effectiveness of short-wave radiation (photohemotherapy, PHT) and ultraviolet (UV) irradiation of blood on its rheology in the complex treatment of chronic post-embolic pulmonary hypertension (CPPH). Methods. 64 patients (30 women and 34 men) with symptoms of chronic pulmonary insufficiency secondary to pulmonary embolism underwent a comprehensive clinical and laboratory examination. CPPH patients were divided into 3 groups: the 1st (control) group consisting of 15 patients who received only a basic treatment; the 2nd (experimental) group including 26 patients who received a basic therapy combined with PHT; and the 3rd (experimental) group consisting of 23 patients who received a basic therapy combined with UV irradiation of blood. AFS-Solaris devices (Russia) producing light-emitting diode-derived blue light with a wavelength of 450 ± 10 nm were used for FGT, and UV rays with a wavelength of 365 ± 10 nm were used for the UV exposure of blood. Blood viscosity was measured on a RotoVisco-100 (Нааке GmbH, Germany) rotational viscometer at shear rates ranging from 1 to 150 s-1; erythrocyte aggregation was studied with a FEK-56 M (Russia) colorimeter-nephelometer; and hematocrit was measured with a hematocrit centrifuge (Autocrit, USA). Results. There were no statistically significant changes in blood viscosity, erythrocyte aggregation, or hematocrit values in the 1st group after the basic treatment. Statistically significant changes in blood rheology parameters observed in both the 2nd and 3rd groups included decreases in blood viscosity, erythrocyte aggregation, and hematocrit values. Conclusion. Optical irradiation with blue light exerted a pronounced physiological effect evident as a slow but long-standing positive influence on blood rheology parameters. The UV irradiation of blood also improved hemorheology and blood circulation and activated rudimentary mechanisms triggering previously non-functional adaptive systems.