Wyniki wyszukiwania - Biblioteka Nauki

1

Circulatory assistance: basic classification of heart assistance methods and devices

100%

Górczyńska K.

Biocybernetics and Biomedical Engineering

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2011

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tom Vol. 31, no. 1

3-15

EN

This paper is focused on basic classification of mechanical circulatory assistance methods and devices regarding a way of their connection to the circulatory system (parallel, "in-series"), different manner of work (pulsatile, continuous-flow) or a goal of appliance (bridge to recovery, bridge to transplant, Total Artificial Heart). Also schematic layout of subjectively chosen assist devices are shown and discussed. The paper does not pretend to give an exhaustive description of mechanical circulatory assistance but rather evidence, after some brief historical remarks, the substance of the circulatory support itself.

2

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

51%

Górczyńska K. , Darowski M. , Kozarski M.

Biocybernetics and Biomedical Engineering

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2002

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tom 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.

3

Open loop hybrid circulatory model: the effect of the arterial lumped parameter loading structure on selected ventricular and circulatory variables

38%

Kozarski M. , Ferrari G. , Zieliński K. , Górczyńska K. , Pałko K. J. , Tokarz A. , Darowski M.

Biocybernetics and Biomedical Engineering

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2008

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tom Vol. 28, no. 1

17-27

EN

Different combinations of the artero-ventricular coupling design (numerical, physical and hybrid) and the arterial system structure (four-element standard, simplified, modified and three-element three-lump "ladder" Windkessel) have been applied in an open loop circulatory model to test their influence on selected ventricular and circulatory variables. Numerical investigations have shown that a four-element Windkessel with an introduced in series lumped inertance can evoke some numerical problems e.g. when combined with the simplified ventricular model containing "ideal" zero switching time heart valves or constant valve resistance during opening. The four-element Windkessel structure modification i.e. replacing the in series inertance by the parallel one, considerably improves the network match. Also the three-element three-lump "ladder" Windkessel has been found very useful in the blood circulation modelling thanks to relatively small input inertance and high input capacitance of its first lump.

4

Development of hybrid (numerical-physical) models of the cardiovascular system: numerical-electrical and numerical hydraulic applications

38%

Ferrari G. , Kozarski M. , De Lazzari C. , Górczyńska K. , Darowski M. , Tosti G.

Biocybernetics and Biomedical Engineering

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2005

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tom Vol. 25, no. 4

3-15

EN

Circulatory models are relevant to research, education and prosthetic devices/components testing. Their structure can be both numerical and physical, according to the specific needs. Numerical models are often developed first and then followed or accompanied by physical models. This approach is associated with higher costs, less accuracy and time-consuming development. Circulatory models defined as hybrid (merger of numerical and physical sections) can solve these problems. This paper presents two applications of the hybrid model with the physical section based on two different structures (electrical and hydraulic). The results show that the model can represent hemodynamic relationships in different circulatory conditions, including IABP assistance.

5

The electrohydraulic impedance converter in mock circulatory system design

38%

Kozarski M. , Ferrari G. , Darowski M. , Górczyńska K. , Clemente F. , Pałko K. J.

Biocybernetics and Biomedical Engineering

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2003

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tom Vol. 23, no. 2

27-34

EN

In the paper a new concept of a mock circulatory circuit design, utilizing the special impedance converter, i.e. the electrohydraulic gyrator, has been presented as well as basic theoretical considerations and simple examples of impedance conversions. Some results of experiments, illustrating physical and systemic features of the electrohydraulic gyrator, have been shown. A simple hybrid windkessel model has been investigated. Obtained results fully confirmed advantages of the presented new concept of a mock circulatory circuit design.

6

A hybrid (hydro-numerical) cardiovascular model: application to investigate continuous-flow pump assistance effect

32%

Kozarski M. , Ferrari G. , Zieliński K. , Górczyńska K. , Pałko K. J. , Fresiello L. , Di Molfetta A. , Darowski M.

Biocybernetics and Biomedical Engineering

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2012

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tom Vol. 32, no. 4

77-91

EN

A hybrid (Hydro-numerical) model of blood circulation developed at the Institute of Biocybernetics and Biomedical Engineering (IBIB) of the Polish Academy of Sciences (PAN) -Warsaw, Poland, in co-operation with the Institute of Clinical Physiology (IFC) of the National Council of Research (CNR) - Rome, Italy, is a basic model of this type solutions commonly accepted by the researchers. It is able to simulate all essential hemodynamic functions of the human cardiovascular system including the heart. During last years, resumption of works on constant-flow non pulsatile rotary pumps to be used as heart support devices is observed because of their small dimensions and easier way of implantation. Control modes of rotary pumps are different and evidently influence heart support effects. The main aim of this paper was to investigate different control systems of rotary pumps in a role of the assist devices. To fulfill this task on the hybrid model, a special computer application was worked out. The investigations included: a) loading characteristics p(q) of the rotary pump assignment at two values of a control voltage - 18V, 24V; b) physiological and pathological states simulation including parallel atrial-aortic assistance by the rotary pump. The results of the simulations obtained on the model treated as a 'virtual patient' are in agreement with the data received in medical conditions.

7

A hybrid (hydro-numerical) circulatory model: investigations of mechanical aortic valves and a numerical valve model

32%

Kozarski M. , Suwalski P. , Zieliński K. , Górczyńska K. , Szafron B. , Pałko K. J. , Smoczyński R. , Darowski M.

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8

A new hybrid (hydro-numerical) model of the circulatory system

32%

Darowski M. , Kozarski M. , Ferrari G. , Zieliński K. , Górczyńska K. , Szczepanowski A. , Pałko K. J. , Fresiello L. , Di Molfetta A.

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nr 4

9

Physical modelling of the cardiovascular system : development of a new simulation system based on hybrid (numerical-hydraulic) components

32%

Ferrari G. , De Lazzari C. , Kozarski M. , Clemente F. , Górczyńska K. , Mimmo R. , Tosti G. , Guaragno M.

Biocybernetics and Biomedical Engineering

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2003

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tom Vol. 23, no. 2

3-15

EN

Research, education, testing of assist devices and training are among the applications of physical models of the circulation. Unfortunately, they are rather expensive and the scope of their use is structure-dependent as it is not easy to modify them. As numerical models do not have these limitations, our aim is to develop a physical model of the circulation limited to the sections of interest merging them with numerical models representing the remaining parts of the circulatory system. The system under development is therefore a hybrid where physical and numerical sections, merged together, represent the circulatory system. The sections developed till now represent one of the ventricles and part of the arterial tree. This paper is devoted to the description of the hybrid ventricular model and its first applications.

10

Evaluation of influence of LVAD assistance on haemodynamics and ventricular energetics in closed-loop mock circulatory system

32%

Ferrari G. , Górczyńska K. , Lazzari C. , Engliasz M. , Tosti G. , Ambrosi D. , Mimmo R. , Fabrizio C.

Biocybernetics and Biomedical Engineering

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1998

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tom Vol. 18, no. 1-2

19-34

EN

The choice of control strategy of a Left Ventricle Assist Device in heart recovery is an open problem. It affects circulatory parameters, myocardial perfusion and energetic variabies, directly related to oxygen consumption in both ventricles. The experiments were performed by a computer controlled closed loop mock circulatory system, in known and constant pathological condition, connected to a pneumatic LVAD. The assistance was realized by changing artificial left ventricular systole duration and its relation to the QRS complex of ECG signal. The data were analysed as a function of haemodynamic parameters as well as energetic variabies (external work EW, oxygen consumption V0(2), cardiac mechanical efficiency CME). The results have shown: 1) assistance effect, besides driving pressure of the artificial ventricle, depends on its systole beginning and duration and on the value of peripheral resistance; 2) left heart assistance influences right ventricular parameters in limited way; it increases right atrial pressure and decreases arterial pulmonary pressure and oxygen consumption.

PL

Wybór strategii sterowania urządzenia wspomagającego LVAD dla poprawy kondycji niewydolnego serca jest problemem otwartym. Proces wspomagania oddziaływuje na parametry cyrkulacji, perfuzję mięśnia sercowego i parametry energetyczne związane bezpośrednio ze zużyciem tlenu przez obie komory serca. Opisane w niniejszej pracy eksperymenty przeprowadzono na sterowanym komputerowo fizycznym modelu układu krążenia, na którym zamodelowano stany patologiczne, poddane następnie wspomaganiu kontrpulsacyjnemu za pomocą urządzenia LVAD. W procesie wspomagania zmieniano czas trwania fazy skurczu sztucznej lewej komory urządzenia LVAD poprzez zmianę opóźnienia końca fazy skurczu tej komory względem zespołu QRS przebiegu EKG "sztucznego pacjenta". Opóźnienie początku fazy skurczu sztucznej komory pozostawało nie zmienione. Uzyskane wyniki analizowano na gruncie hemodynamicznym (ciśnienia, przepływy) i energetycznym (praca zewnętrzna EW, zużycie tlenu V0(2), współczynnik wydajności mechanicznej serca CME). Stwierdzono: 1) na efektywność wspomagania, oprócz ciśnienia sterującego pracą sztucznej komory, wpływa czas trwania jej fazy skurczu i czas opóźnienia względem zespołu QRS oraz wielkość oporności peryferyjnej; 2) wspomaganie lewej komory wywiera ograniczony wpływ na prawe serce, co się objawia niewielkim wzrostem ciśnienia w prawym przedsionku i pewnym spadkiem ciśnienia arterialnego płucnego oraz zużycia tlenu.

11

A new hybrid (hydro-numerical) model of the circulatory system

32%

Darowski M. , Kozarski M. , Ferrari G. , Zieliński K. , Górczyńska K. , Szczepanowski A. , Pałko K. J. , Fresiello L. , Di Molfetta A.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2013

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tom Vol. 61, nr 4

993--1003

EN

The paper presents a hybrid (hydro-numerical) circulatory model built to be used as a complementary tool for clinical purposes. It was developed at the Institute of Biocybernetics and Biomedical Engineering - Polish Academy of Sciences (Poland) in co-operation with the Institute of Clinical Physiology - National Council of Research (Italy). Main advantages of the model are: 1) high accuracy and repeatability of parameters setting, characteristic of numerical solutions, 2) maximum flexibility achieved by implementing the largest possible number of the model’s elements in the numerical way, 3) ability to test mechanical heart assist devices provided by special computer applications; in the model two physically different signal environments - numerical and hydraulic - are connected by special impedance transformers interfacing physical and numerical parts of the model; 4) eliminating flowmeters, as the voltage controlled flow sources embedded in the system provide information on flows. In vitro tests were performed to evaluate the circulatory model: a) modelling and simulation of physiological and pathological states parameters vs. left ventricular end-systolic elastance (Emax l) and rest volume (Vol) variations, b) testing the effect of LVAD counterpulsation on circulatory hemodynamics and ventricular energetics; it resulted in the increase of total cardiac output (COLV tot) from pathological value 3.8 to 5.4 l·min−1, mean aortic pressure mPas from 67.8 to 96.1 mmHg and in the decrease of left atrial pressure mPla from 15.7 to 7.7 mmHg and External Work nEW by 37.5%. The model was verified based on literature data.

12

Role and applications of circulatory models in cardiovascular pathophysiology

32%

Ferrari G. , Kozarski M. , De Lazzari C. , Górczyńska K. , Pałko K. J. , Zieliński K. , Di Molfetta A. , Darowski M.

Biocybernetics and Biomedical Engineering

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2009

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tom Vol. 29, no. 4

3-24

EN

Circulatory models are relevant for research, education and testing of prosthetic devices/components. Independently of its structure that can be numerical, physical or hybrid the models can be used in different areas of cardiovascular pathophysiology. However, the models are often used to reproduce specific circulatory conditions instead of being used as 'systemic' tools. That is to say, the models are used to evaluate the global effects of external disturbances such as pathologies, therapies, special environments or surgery on the circulatory system. Aim of this paper is to illustrate a family of circulatory models developed to represent the whole circulatory system in pathophysiological conditions describing some of the possible applications.

13

A hybrid (hydro-numerical) circulatory model: investigations of mechanical aortic valves and a numerical valve model

32%

Kozarski M. , Suwalski P. , Zieliński K. , Górczyńska K. , Szafron B. , Pałko K. J. , Smoczyński R. , Darowski M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2015

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tom Vol. 63, nr 3

605--612

EN

In most cases of diseased heart valves, they can be repaired or replaced with biological or mechanical prostheses. Biological prostheses seem to be safer than mechanical ones and are applied with good clinical outcomes. Their disadvantage, when compared with mechanical valves, is durability. In the development and application of mechanical and biological heart valves, a significant role can be played by a Hybrid (Hydro-Numerical) Circulatory Model. The aim of this paper is to demonstrate the opportunities created by the hybrid model for investigations of mechanical heart valves and their computer models under conditions similar to those of the circulatory system. A diode-resistor numerical valve model and three different design mechanical aortic valves were tested. To perform their investigations, computer applications were developed under RT LabView to be run on a PC. Static and dynamic characteristics of the valves were measured and registered - pressure in the numerical time-varying elastance left ventricle (pLV), in the aorta (pas) and flow (f), proving, among other factors, that 1) time delay of pas with respect to pLV is mainly related to the valve’s opening time, and 2) the valves of substantially different designs tested under identical hydrodynamic conditions reveal nearly the same dynamic performance.

14

The influence of selected left ventricular and systemic parameters on cardiovascular hemodynamics and energetics - modeIIing study

32%

Górczyńska K. , Ferrari G. , De Lazzari C. , Mimmo R. , Tosti G. , Clemente F. , Englisz M. , Guaragno M.

Biocybernetics and Biomedical Engineering

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2000

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tom Vol. 20, no. 3

35-47

EN

Ventricular sufficiency can be estimated basing on the heart muscle's ability to effective ejection in systole and filling conditions created in diastole. These features, in quantitative sense, can be evaluated by selected energetic and hemodynamic parameters of the ventricle and the circulatory system. In the computer model and the physical model of blood circulation, pathological states of the left ventricle and the systemic arterial tree, represented by ventricular compliance, the filling characteristic and peripheral resistance have been simulated. The influence of the modelled pathological states on hemodynamics and energetics of the circulatory system has been discussed. In some cases, left ventricular assistance using an LVAD has been appIied. The computer model CARDIOSIM and the physical model MCS, with computer-controIled ventricles and peripheral resistances, were developed at the Institute of Biomedical Technologies CNR in Rome (Italy). In these models, the energetic relations among the ventricle, the arterial system and the assist device are analysed on the pressure-volume piane (P-V). The LVAD was developed at the Institute of Biocybernetics and Biomedical Engineering PAS. It consists of the foIlowing units: the artificial left ventricle ALV, the pneumatic drive unit PDU and the electronic control system ECS. In the device, the driving positive and negative pressure signals for the systole and diastole phases are realised by means of one pneumatic element in the PDU of special original design. The foIlowing parameters were used to estimate condition of the circuIatory system in different pathological states, including left ventricular assistance: left atrial pressure P(LA) aortic pressure P(as), arterial pulmonary pressure P(ap) cardiac output CO, cardiac output index CI, external work EW, oxygen consumption V(O2) and cardiac mechanicaI efficiency CME.

PL

Sprawność komory serca może być oceniana na podstawie zdolności mięśnia sercowego do efektywnego wyrzutu krwi z komory w fazie skurczu i warunków napełniania komory krwią w fazie rozkurczu. W sensie ilościowym, cechy te mogą być oceniane na podstawie wybranych parametrów energetycznych i hemodynamicznych serca i układu krążenia. Na fizycznym i komputerowym modelu układu krążenia zamodelowano stany patologiczne lewej komory i systemowego układu tętniczego, reprezentowane przez podatność komory, charakterystykę jej napełniania i oporność peryferyjną. Dokonano analizy wpływu zamodelowanych stanów patologicznych na hemodynamiczne i energetyczne parametry układu krążenia i lewej komory, również w przypadku jej wspomagania za pomocą urządzenia LVAD. Komputerowy model układu krążenia CARDIOSIM i fizyczny model MCS ze sterowanymi komputerowo komorami serca i opornościami peryferyjnymi, zostały opracowane i wykonane w Instytucie Technologii Biomedycznej CNR w Rzymie. W modelach tych energetyczne zależności pomiędzy sercem, układem krążenia i urządzeniem wspomagającym analizowane są na płaszczyźnie P-V (ciśnienie-objętość). Urządzenie LVAD, służące do wspomagania pracy serca za pomocą sztucznej lewej komory, zostało opracowane i wykonane w Instytucie Biocybernetyki i Inżynierii Biomedycznej PAN w Warszawie. W skład urządzenia wchodzą: sztuczna lewa komora ALV, pneumatyczny układ napędowy PDU i elektroniczna jednostka sterująca EIS. W urządzeniu tym, dodatni i ujemny sygnał ciśnieniowy dla fazy skurczu i fazy rozkurczu jest realizowany w PDU, za pomocą tego samego elementu pneumatycznego o specjalnej, oryginalnej konstrukcji. W niniejszej pracy, do ogólnej oceny kondycji układu krążenia w różnych stanach patologicznych, z uwzględniem wspomagania lewej komory serca, użyto następujących parametrów: ciśnienie w lewym przedsionku P(LA) ciśnienie aortalne P(as) ciśnienie w tętnicy płucnej P(ap) wskaźnik serca CI, praca zewnętrzna EW, zużycie tlenu V(O) i mechaniczna wydajność serca CME.