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Role and applications of circulatory models in cardiovascular pathophysiology

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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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.

2

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

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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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.

3

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

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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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.

4

In vitro evaluating system for prosthetic heart valves in a case of the Jyros valve

Fujimoto T., Tsutsumi Y., Shiraishi Y., Iwasaki K., Yoshida M., Umezu M., Begg J., Woodard J.

Biocybernetics and Biomedical Engineering

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2002

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Vol. 22, no. 4

41-46

EN

The Jyros valve has unique hydrodynamic characteristics comparing with other types of valves. In this study, precise hydrodynamic characteristics of the valve were examined using a mock circulatory system, which we have developed. Further, the influence of leaflet rotation is shown to reduce flow resistance under the rotational flow condition which was produced by a spiral vortex pump. However, hemolysis was not revealed to be reduced by the Jyros.

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

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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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.