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1

Impact of lower limb movements on iliac vein stenting in iliac vein compression syndrome patients: insights from computational modeling

Lu Jian, Fan Zhenmin, Ye Xia, Deng Xiaoyan, Feng Hai, Liu Mingyuan

Acta of Bioengineering and Biomechanics

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2024

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Vol. 26, no. 1

23--35

EN

Iliac vein stenting is the primary treatment for patients with iliac vein compression syndrome (IVCS). However, post-stent placement, patients often experience in-stent restenosis and thrombosis. Despite this, the role of lower limb movements in the functioning of stents and veins in IVCS patients remains unclear. This study aimed to address this knowledge gap by developing a computational model using medical imaging techniques to simulate IVCS after stent placement. Methods: This research used a patient-specific model to analyze the effects of lower extremity exercises on hemodynamics post-stent placement. We conducted a comprehensive analysis to evaluate the impact of specific lower limb movements, including hip flexion, ankle movement and pneumatic compression on the hemodynamic characteristics within the treated vein. The analysis assessed parameters such as wall shear stress (WSS), oscillatory shear index (OSI), and residence time (RRT). Results: The results demonstrated that hip flexion significantly disrupts blood flow dynamics at the iliac vein bifurcation after stenting. Bilateral and left hip flexion were associated with pronounced regions of low WSS and high OSI at the iliac-vena junction and the stent segment. Additionally, active ankle exercise (AAE) and intermittent pump compression (IPC) therapy were found to enhance the occurrence of low WSS regions along the venous wall, potentially reducing the risk of thrombosis poststent placement. Consequently, both active joint movements (hip and ankle) and passive movements have the potential to influence the local blood flow environment within the iliac vein after stenting. Conclusions: The exploration of the impact of lower limb movements on hemodynamics provides valuable insights for mitigating adverse effects associated with lower limb movements post iliac-stenting. Bilateral and left hip flexions negatively impacted blood flow, increasing thrombosis risk. However, active ankle exercise and intermittent pump compression therapies effectively improve the patency.

2

Fluid–structure interaction simulation for studying hemodynamics and rupture risk of patient-specific intracranial aneurysms

Chang Ruan, Qi Yu, Jingyuan Zhou, Xinying Ou, Yi Liu, Yu Chen

Acta of Bioengineering and Biomechanics

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2023

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Vol. 25, no. 3

EN

The role of regional hemodynamics in intracranial aneurysms (IAs) hemodynamics and rupture risk has been widely discussed based on numerical models over the past decades. The aim of this paper is to investigate hemodynamics and rupture risk with a complicated IA model. Fluid-structure interaction (FSI) simulations were performed to quantify the hemodynamic characteristics of the established IA models. Hemodynamic parameters, including wall shear stress (WSS), flow velocity, and flow pattern, were calculated and analyzed. In this paper, the risk assessment of intracranial aneurysms focuses on the mechanical properties of blood flow and blood vessel walls. Vortex flow and concentrated impact field during blood flow play a decisive role in the rupture and development of aneurysms. The uneven distribution of wall shear stress on the vessel wall has a great influence on growth and rupture. By observing the simulation results of rigid walls, risks can be predicted efficiently and accurately. This paper focuses on the relationship between hemodynamics and rupture risk with a double intracranial aneurysms disease mode and provides a new perspective on the treatment of intracranial aneurysms.

3

Segmentary strategy in modeling of cardiovascular system with blood supply to regional skin

Li Zhongyou, Jiang Wentao, Diao Junjie, Chen Chong, Xu Kairen, Fan Haidong, Yan Fei

Biocybernetics and Biomedical Engineering

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2021

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Vol. 41, no. 4

1505--1517

EN

Objective: The focus of this study is to model the cardiovascular system (CS) involving regional skin blood flow (SBF) to gain new insights into the skin-CS relationship. Methods: A lumped parameter model with a series of electrical components was developed to model the CS involving SBF. Four parts were considered: the heart, arterial circulation, microcirculation (including the skin and other tissues), and the venous system. The model was validated based on previous publications. Additionally, the body surface was divided into seven blocks replaced by lumped resistances in this model, including the head, upper limbs and neck, chest and back, anterolateral abdomen, posterior abdomen, lower limbs, and buttocks. The SBF of each block was described using a weighted average method (relative ratio of cutaneous blood perfusion and regional body surface area) Results: Cardiodynamics characterized the properties of cardiac cycles, including isovolumic contraction, accelerated ejection, decelerated ejection, isovolumic diastole, and filling phases. Blood flow and pulse pressure in the arterial trunk declined and increased, respectively, from the aorta root to the distal portion, exhibiting normal cardiovascular properties. Accordingly, the blood pressure of the arterial branches attached to the arterial trunk also satisfied normal physiological characteristics; the blood flow of all the arterial branches exhibited good agreement with previous studies. Additionally, the modeled SBF of each region was consistent with the data from the weighted average method. Conclusion: This model effectively demonstrates the normal properties of the CS that involves regional SBF and may be promising in the prediction of the skin-CS relationship.

4

Numerical study on flow topology and hemodynamics in tortuous coronary artery with symmetrical and asymmetrical stenosis

Song Jianfei, Kouidri Smaine, Bakir Farid

Biocybernetics and Biomedical Engineering

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2021

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Vol. 41, no. 1

142--155

EN

Tortuosity in coronary artery has been found to be greatly related to the potential sites of stenosis in these last years. Many investigations have been carried out based on the tool of Computational Fluid Dynamics (CFD) mainly focusing on the influences of curved artery in blood flow. Within the limited investigations of coupling between stenosis and tortuosity, the stenosis has been considered to be located at the tortuous segment. However, with recent clinical studies, the case of stenosis occurred at non-tortuous segment before tortuosities has been confirmed which has not been paid enough attention yet. Therefore, the present study aims to investigate the disturbed streamlines and hemodynamics in curved and spiral artery considering symmetrical and asymmetrical stenosis upstream these tortuosities. Different stenosis severities, pulse rates and distances between stenosis and tortuosity as controlling parameters have been studied. The distribution of time averaged wall shear stress (TAWSS) and streamlines through tortuous segment have been displayed in order to determine the potential disease sites. Artery surface of TAWSS below critical value has been quantified as well to evaluate the risks of atherosclerosis. The results reveal that larger artery surface of TAWSS below critical value generally goes with smaller pulse rate, larger stenosis severity and distance between stenosis and tortuosity both for curved and spiral artery. However, exceptions were found in the cases of distance of 6 mm in curved artery with symmetrical stenosis and stenosis severity of 50% in spiral artery. Moreover, the spiral tortuosity tends to suppress the potential risks of atherosclerosis compared to curved tortuosity.

5

The effect of stenosis rate and Reynolds number on local flow characteristics and plaque formation around the atherosclerotic stenosis

Chen Xueping, Zhan Yiyi, Fu Yi, Lin Jiangguo, Ji Yanru, Zhao Chengbi, Fang Ying, Wu Jianhua

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 1

135--147

EN

Purpose: Atherosclerosis causes plaque to build-up in arteries. Effect of the specific local hemodynamic environment around an atherosclerotic plaque on the thrombosis formation does not remain quite clear but is believed to be crucial. The aim of this study is to uncover the flow effects on plaques formation. Methods: To study the mechanically regulated plaque formation, the flow fields in artery blood vessels with different stenosis rates at various Reynolds numbers were simulated numerically with the two-dimensional axisymmetric models, and the hemodynamic characteristics around the plaque were scaled with stenosis rate and Reynolds number. Results: The results showed that increases of both Reynolds number and stenosis rate facilitated the occurrence of flow separation phenomenon, extended recirculation zone, and upregulated the maximum normalized wall shear stress near the plaque throat section while downregulated the minimal normalized wall shear stress at the front shoulder of plaque, as it should be; in the atherosclerotic plaque leeside of the recirculation zone, an obvious catch bond region of wall shear stress might exist especially under low Reynolds number with stenosis rate smaller than 30%. This catch bond region in the plaque leeside might be responsible for the LBF (low blood flow)-enhanced formation of the atherosclerotic plaque. Conclusions: This work may provide a novel insight into understanding the biomechanical effects behind the formation and damage of atherosclerotic plaques and propose a new strategy for preventing atherosclerotic diseases.

6

Numerical insights into the determinants of stent performance for the management of aneurysm with a visceral vessel attached

Li Zhongyou, Chen Chong, Chen Yu, Wang Zhenze, Jiang Wentao, Tian Xiaobao

Acta of Bioengineering and Biomechanics

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2021

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Vol. 23, no. 2

41--53

EN

Purpose: As the factors affecting the efficacy of the bare-metal stent in the treatment of aneurysm with a visceral vessel attached were not fully understood, we aimed to discuss the effects of different characteristics of the stent on the hemodynamics and flexibility in the treatment of the aneurysm. Methods: Single-layer (with different strut widths) and multi-layer (with a different number of struts) stent models divided into three porosity groups, with porosities of 72.3, 60.5, and 52.4%, were modeled for a comparison of their hemodynamic isolation and flexibility performance via computational fluid dynamics and finite element methods. Results: The velocity and timeaveraged wall shear stress decreased more noticeably with multi-layer stent interventions. A higher oscillatory shear index and relative residence time occurred at the aneurysmal sac wall after multi-layer stents were employed. Time-averaged wall shear stress on the aneurysmal wall decreased with an increase in the number of struts or a decrease in pore size, but oscillatory shear index and relative residence time increased as the number of struts increased or the pore size decreased. Besides, all stents affect the branch patency slightly. In the bending test, when the porosity exceeded 60.5%, multi-layer stents were more flexible. Conclusion: The number of struts or pore size of stent dominated the isolation in the management of the aneurysm and affected the flexibility significantly when the porosity was below 60.5%. These findings may contribute to the special design of the stent in the treatment of such types of aneurysms.

7

Numerical investigation of renal artery hemodynamics based on the physiological response to renal artery stenosis

Andayesh Mohammad, Shahidian Azadeh, Ghassemi Majid

Biocybernetics and Biomedical Engineering

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2020

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Vol. 40, no. 4

1458--1468

EN

Renal Artery Stenosis (RAS) is the narrowing of renal arteries, most often caused by atherosclerosis or fibromuscular dysplasia. Possible complications of renal artery stenosis are renovascular hypertension and renal ischemia. The goals of the current study were to investigate the physiological response to RAS and effects of the artery and stenosis geometry, quantify the performance of arterial pressure regulation mechanisms respect to stenosis severity, and predict future conditions of renal artery stenosis. Commercial software based on the finite volume method was utilized to solve governing equations. To determine the physiological response, simulations were done for two cases, with and without the involvement of arterial pressure regulation mechanisms. The numerical method was validated by experimental data, which obtained from two prototypes. Results showed that systemic blood pressure was increased as the physiological response to RAS; hence, the flow rate of the renal branch was improved and renal ischemia was relatively prevented. Furthermore, results demonstrated that the stenosis percentage and artery diameter were dominant geometric parameters on the hemodynamics and other parameters had negligible effects. It was demonstrated that 50% of stenosis was the critical point for the interaction of RAS and arterial pressure regulation mechanisms. Finally, wall shear stress was analyzed on an image-based geometry, and it was estimated and expected that acute renal artery stenosis was progressive and pathogenesis of arterial diseases.

8

Numerical and experimental analysis of balloon angioplasty impact on flow hemodynamics improvement

Tomaszewski Michał, Sybilski Kamil, Małachowski Jerzy, Wolański Wojciech, Buszman Piotr P.

Acta of Bioengineering and Biomechanics

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2020

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Vol. 22, no. 3

169--183

EN

Purpose: The paper focuses on the numerical and experimental evaluation of the fluid flow inside chosen fragments of blood vessels. In the first stage of the study, the experimental tests were conducted using a research test stand, designed to be used in this evaluation. The study evaluated the blood flow through a silicone vessel with an implanted coronary stent. Methods: The PIV method was used in order to visualize the flow vectors inside a silicone vessel. Deformed vessel geometry implemented for computational fluid dynamics purposes was obtained owing to a non-linear simulation of the stent expansion (angioplasty process) in a silicone vessel. Additionally, a vessel model with a statistical 55% area stenosis and an irregular real vessel with an atherosclerotic plaque were also subjected to analysis from the hemodynamic flow point of view. A vessel with a statistical stenosis was also used to simulate the angioplasty process, which resulted in obtaining a flow domain for the vessel with an atherosclerotic plaque after the stent implantation. Results: For each case, distributions of parameters such as OSI or TAWSS were also analyzed and discussed. The areas of low TAWSS values appear close to the stent struts. Conclusions: Stents with increased diameters, compared to the normal vessel diameter, create a higher risk of occurrence of the areas with low WSS values. Excessive stent deformation can cause inflammation by injuring the vessel and can initiate the restenosis and thrombotic phenomena through the increased vessel diameter.

9

Fåhræus effect revisited

Herczyński R.

Archives of Mechanics

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2016

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Vol. 68, nr 1

81--93

EN

A consistent hydrodynamic analysis of blood flow through capillaries is proposed. The approach, while suggested by empirical observations, is based solely on the properties of Newtonian fluids and suspensions. Blood flow is divided into three phases: the first is a thin erythrocyte-free layer near the wall, the second a core flow of constant hematocrit and the third an intermediate layer wherein the hematocrit varies. Based on the observation that viscosity depends exponentially on the local hematocrit, blood flow velocity profiles are obtained and the direct connection between the Fåhræus and the Fåhræus-Lindqvist effects is established.

10

Modelling of hemodynamics in 3D bypass models

Vimmr J., Jonasova A.

Modelling and Optimization of Physical Systems

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2010

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z. 9

87--92

EN

The study is divided into two parts. The first one deals with the modelling of non-Newtonian effects in occluded femoral bypass considering steady blood flow. The second part is devoted to the analysis of pulsatile Newtonian blood flow in stenosed coronary bypass applying realistic inlet flow rates. The bypass models are assumed to be idealized and complete, i.e. the native artery and the bypass graft are modelled as tubes with both proximal and distal parts. The governing equations are solved numerically with explicit and implicit schemes formulated in the sense of the finite volume method using developed in-house software.

CS

Tato studie je rozdělena na dvě části. První se zabývá modelováním nenewtonských efektů ve femorálním bypassu pří uvažováni ustáleného proudění krve. Druhá část je věnována analýze pulzujícího proudění krve jakožto newtonské kapaliny v koronárním bypassu. Matematický model je řešen pomocí explicitních a implicitních schémat formulovaných ve smyslu metody konečných objemů a za použití vlastního vyvinutého softwaru.

11

Biventricular pacemaker synchronization: A numerical cardiocirculatory model application to reproduce in vivo data

Di Molfetta A., De Lazzari C., Ferrari G., Moscariello F., Aguzzi G., Fresiello L., Darowski M., Trivella M. G., Alessandri N

Biocybernetics and Biomedical Engineering

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2010

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Vol. 30, no. 1

3-15

EN

Cardiac Resynchronization Therapy (CRT) seems to be the most encouraging treatment to limit the damages of ventricular remodelling in patients with moderate-severe cardiac insufficiency. Mathematical modelling of the cardiovascular system is a tool potentially useful to understand how the Biventricular Pacemaker (BPM) must be synchronised during CRT. In this work a computer simulator reproduces clinical data measured, on different patients affected by asynchronous ventricular contraction, before and after CRT. Three patients, affected by asynchronous ventricular contraction, were monitored before and after biventricular stimulation through CRT. Measured and simulated data were compared. Results show that the software simulator can well reproduce in vivo data. Besides, simulated results from BPM together with drug therapy are in accordance with literature data. Numerical modelling could be a useful tool to optimize the BPM synchronization.

12

Ocena odruchu z baroreceptorów tętniczych po zabiegu kriostymulacji ogólnoustrojowej u osób zdrowych

Zalewski P., Klawe J., Tafil-Klawe M., Buszko K., Panowicz I.

Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna

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2010

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Vol. 16, nr 1

38-43

PL

Krioterapia ogólnoustrojowa {whołe-body cryotherapy - WBC) jest powszechnie stosowaną metodą terapeutyczną w leczeniu dysfunkcji układu ruchu lub układu nerwowego oraz w odnowie biologicznej. Celem niniejszych badań była ocena zmian odruchu z baroreceptorow tętniczych pod wpływem krioterapii ogólno-ustrojowej u osób zdrowych. Badaniami objęto grupę 25 zdrowych mężczyzn, którzy przebywali 3 minuty w kriokomorze w temperaturze około -110 stopni C. Poza parametrami hemodynamicznymi ocenie poddano parametry oceniające reaktywność baroreceptorów tętniczych metodą sekwencyjną, m.in.: up-events slope mean - w zakresie sekwencji narastających, down-events slope mean - w zakresie sekwencji malejących, total events slope mean - wartość całkowita seltwencji. Rejestrację parametrów hemodynamicznych przeprowadzono dwukrotnie: przed (01) i po (02) po zabiegu kriostymulacji ogolnoustrojowej za pomocą systemu Task Force Monitor firmy CNSystems. Badania wykonano zgodnie z kryteriami oceny czynnościowej autonomicznego układu nerwowego. Po ekspozycji na temperatury kriogeniczne, poza zmianami parametrów hemodynamicznych, zarejestrowano istotny wzrost czułości odruchu z baroreceptorów tętniczych, zarówno w zakresie sekwencji malejących, jak i narastających. Wzmożona odpowiedź z baroreceptorów tętniczych na skutek działania temperatur kriogenicznych najprawdopodobniej była efektem wzmożonego powrotu żylnego i poziomu wypełniania komór, co skutkowało również zwiększoną objętością wyrzutową serca (S V - stroke volume).

EN

Whole-body cryotherapy (WBC) is a one of well known physical therapy methods. The assessment of arterial baroreceptors activity after exposure to the whole-body cryotherapy in healthy subject, is presented. Twenty five healthy subjects were exposed to 3-niinute whole-bo-ćy cryotherapy procedure (-110 degrees C). The following parameters were recorded: Up-Events Slope Mean, Down-Events Slope Mean, Total Events Slope Mean. Subjects were examined twice: before (01) and after (02) cryotherapy. The Task Force Monitor was used to measure beat-to-beat hemodynamic parameters during supine rest. Examination was made according to standards of autonomic nervous system assessment. Whole-body cryotherapy caused significant increase of arterial baroreceptors activity, both in decreasing sequences Down-Events Slope Mean and increasing sequences Up-Events Slope Mean. Boosted arterial baroreceptors response was a result of increased volume of venous return and ventricles volume, włiich caused an increased level of stroke volume (SV).

13

Metoda grafów wiązań w zastosowaniu do opracowania szczególnego obwodu elektrycznego

Muc A., Matulewicz W., Retkowski M.

Przegląd Elektrotechniczny

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2008

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R. 84, nr 9

173-178

PL

Grafy wiązań wykorzystano do odwzorowania krwiobiegu nerki. Zaproponowany model, uwzględnia również odcinek tętnicy głównej oraz, w uproszczeniu, dystrybucję krwi do pozostałych segmentów krwiobiegu. Opisanie zjawisk przepływu krwi w naczyniach krwionośnych za pomocą grafów wiązań pozwala w łatwy sposób przejść do modelu w postaci obwodu elektrycznego. Sprowadzenie problemu dystrybucji krwi do modelu elektrycznego umożliwia zastosowanie sieciowych metod analizy obwodów i uproszczenia analizy zjawisk hemodynamicznych.

EN

The bond graph to modelling of the kidney blood circulation system was applied. Main artery and system of vessels of abdominal cavity in model were included as well. The created model is easy to change into the equivalent electric circuit. By applying electric circuit to modelling the blood circulation system the networks methods of electric circuits analysis are possible to use. Simplification of analysis of the hemodynamics phenomena is main advantage of this approach.

14

A newly-designed myocardial assist device using a sophisticated shape memory alloy fibre

Shiraishi Y., Yambe T., Sekine K., Ogawa D., Nagatoshi J., Itoh S., Park Y., Uematsu M., Sakata R., Wada Y., Saijo Y., Higa M., Hori Y., Liu H., Wang Q., Konno S., Kuwayama T., Olegario P., Tanaka A., Masumoto N., Ibuki R., Maruyama S., Okamoto E., Fujimoto T., Yoshizawa M., Umezu M., Imachi K., Nitta S.-I., Sasada H., Tabayashi K., Homma D.

Biocybernetics and Biomedical Engineering

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2007

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Vol. 27, no. 1-2

147-154

EN

Recently, the ventricular assist devices are widely applied for a surgical treatment of the final stage of severe heart failure as the bridge to heart transplantation or the destination therapy. However, it was anticipated that the artificial components in the ventricular assist devices might cause the problems concerning thrombosis and infection. As heart failure involves the decrease in myocardial contractile function, the mechanical assistance by using an artificial myocardium might be effective. In this study, the authors developed a mechano-electric artificial myocardial assist system (artificial myocardium), which is capable of supporting natural contractile function from the outside of the ventricle.

15

Rheological models of human blood as a non-Newtonian fluid

Wojnarowski J., Mirota K.

International Journal of Applied Mechanics and Engineering

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2004

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Vol. 9, no 2

413-421

EN

One of the most important problems of model hemodynamics is the descriptions of the rheological properties of the flowing blood. In this work, two basic classes of a hemorheology models have been analysed. The first one considers human blood as a non-Newtonian and time-independent fluid. However, the dynamical formation of its time-dependent collective structure leads to a viscoelastic and tixotropic blood response. In consequence, this study presents a second class of hemorheology model, considering blood as a fluid thinning and thickening with time.

16

The influence of ventilatory support on coronary flow and oxygen consumption in different circulatory conditions

De Lazzari C., Darowski M., Ferrari G., Mimmo R., Guaragno M., Tosti G.

Biocybernetics and Biomedical Engineering

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2003

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Vol. 23, no. 1

103-110

EN

The aim of this work is to predict the influence of mechanical ventilation on cardiac output, coronary flow and left ventricular myocardial oxygen consumption in different circulatory conditions. To study this interaction we used a computer simulator of human cardiovascular system in which lumped parameters models were used to reproduce the circulatory phenomena in terms of pressure and volume relationships. Variable elastance models reproduce the Starling's law of the heart, for each ventricle. In the study the left ventricular elastance assumed two different values. Symetric arterial resistance was changed during the simulation. The influenece of mechanical ventilation was introduced by positive mean thoracic pressure. Positive thoracic pressure, changes of peripheral resistance and different ventricular elastance values have a significant influence on cardiac output, coronary flow and myocardial oxygen consumption.

17

The analysis of heart valve dysfunction and effectiveness of disc-designed prostheses

Shilko S. V., Hizhenok V. F., Kuzminsky Yu. G., Salivonchik S. P.

Acta of Bioengineering and Biomechanics

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2003

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Vol. 5, nr 2

53-62

EN

The function of heart (in good condition and in poor condition) and hemodynamic characteristics of mechanical prosthetic cardiac valves influencing hemolysis and blood coagulation have been investigated. The solid-state models of disc-designed prosthetic cardiac valves have been constructed. The finite element analysis of blood velocity and pressure at direct and inverse blood flows has shown better characteristics of bi-leaflet valves. The advantage of the numerical modelling is in the possibility of thorough description of blood flow with determination of turbulence and depression zones for different sizes, curvature and ultimate opening angle of leafs. It allows minimising hydraulic resistance, thrombus formation and hemolysis-preserving high reliability of valve closing. The individual design of valve is discussed and aimed at improving a valve function by creating the blood flow twisting.

18

Cardiovascular, respiratory and veno-lymphatic assistance. Modelling and simulation

Górczyńska K., Darowski M., Kozarski M.

Biocybernetics and Biomedical Engineering

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2002

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Vol. 22, no. 2-3

135-175

EN

In the paper some problems concerning investigations conducted at Bioflows Departament of the Institute of Biocybernetics and Biomedical Engineering on cardiovascular , respiratory and veno-lymphatic assistance have been discussed. The investigations were mainly focused on modelling of cardiovascular and respiratory systems, cardiopulmonary interaction and veno-lymphatic non-invasive support. The results of physical and computer simulation of cardiopulmonary assistance and clinical results of veno-lymphatic support studies have been presented.

19

A PC based model to simulate artero-ventricular interaction and the effect of mechanical circulatory and ventilatory support

De Lazzari C., Darowski M., Clemente F., Guaragno M., Ferrari G.

Biocybernetics and Biomedical Engineering

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1999

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Vol. 19, no. 4

79-89

EN

A software package for the simulation of the cardiovascular system and of artero-ventricular interaction has been developed. It includes the reproduction of the effects of mechanical circulatory like Left Ventricular Assist Device (LVAD), Biventricular Assist Device (BVAD), Intra-aortic Balloon Pump (IABP) and ventilatory support systems. Lumped parameters models were used to reproduce the circulatory phenomena in terms of pressure and volume relationships. Variable elastance models reproduce the Starling's law of the heart, for each ventricle. LVAD and BVAD are inserted with atrial-arterial cannulation and can be synchronised with the onset of the natural ventricle systole. IABP model, inserted in the arterial tree, is considered as a flow source. Controlling the level of thoracic pressure (Pt) performs the simulation of mechanical ventilation. The examples of simulations are presented in the paper as the effects of LVAD and mechanical ventilatory support on circulatory system, in terms of hemodynamic parameters changes.

PL

W artykule przedstawiono model komputerowy CARDIOSIM@ i oprogramowanie do symulacji zależności hemodynamicznych w układzie sercowo-naczyniowym na komputerze zgodnym z PC. Oprogramowanie to umożliwia także symulację wpływu różnych metod mechanicznego wspomagania krążenia, np. sztucznej lewej komory serca (LVA]), wspomagania dwukomorowego (BVAD), lub pompy wewnątrzaortalnej (lABP) i oddychania na parametry hemodynamiczne i energetyczne. Modele LV AD, BVAD i IABP są zsynchronizowane z pracą naturalnej lewej komory serca (z początkiem fazy systolu). LVAD i BVAD są umieszczone równolegle z komorami serca, a IABP jest traktowane jako źródło przepływowe w tętniczej części modelu. Regulacja poziomu średniego, dodatniego ciśnienia w klatce piersiowej w modelu oddaje wpływ sztucznej wentylacji płuc na układ sercowo-naczyniowy. Model komputerowy opisujący zależności ciśnieniowo-przepływowe w poszczególnych częściach układu sercowo-naczyniowego jest modelem liniowym o staIych skupionych. Do opisu własności każdej z komór serca wg prawa Starlinga wykorzystano model zmiennej elastancji. W pracy przedstawiono przykłady symulacji komputerowej, jako cenną możliwość przewidywania wpływu stosowania LVAD i wspomagania oddychania na hemodynamikę.