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Pomiar dokładności odwzorowania kształtu membrany wiotkiej pompy wspomagania serca

Sulej W., Murawski K.

Biuletyn Wojskowej Akademii Technicznej

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2017

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Vol. 66, nr 4

43--56

PL

W artykule przedstawiono wynik eksperymentu, który stanowi kontynuację pracy dotyczącej wykorzystania technik przetwarzania i analizy obrazów do wyznaczania kształtu membrany wiotkiej pozaustrojowej, pneumatycznej pompy wspomagania serca (VAD). Badanie polegało na opracowaniu techniki pomiaru dokładności odwzorowania kształtu membrany opisywanej w wymiarach rzeczywistych. Dokładność odwzorowania jest istotna z uwagi na zapewnienie wymaganej precyzji wyznaczania chwilowej objętości wyrzutowej VAD. Eksperyment przeprowadzono na modelach membrany wypukłej, wklęsłej oraz płaskiej. Celem badania było opracowanie funkcji oceny technik odwzorowywania kształtu membrany.

EN

The paper presents the research results which are a continuation of work on the use of image processing techniques to determine the membrane shape of the artificial ventricle. The studies were focused on developing a technique for measuring the accuracy of the membrane shape mapping. It is important in view of ensuring the required accuracy of determining the instantaneous stroke volume of controlled pneumatic artificial ventricular. Experiments were carried out on the models of convex, concave, and flat membranes. The purpose of the research was to obtain a numerical indicator, which will be used to evaluate the options to improve mapping techniques of the membrane shape.

2

In-silico evaluation of left ventricular unloading under varying speed continuous flow left ventricular assist device support

Bozkurt S., Bozkurt S.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 3

373--387

EN

Continuous flow left ventricular assist device (cf-LVAD) operating speed modulation techniques are proposed to achieve different purposes such as improving arterial pulsatility, aortic valve function or ventricular unloading etc. Although it is possible to improve the left ventricular unloading by modulating the operating speed of a cf-LVAD, it is still unclear what type of pump operating mode should be applied to generate a better left ventricular unloading. This study presents a comparison of different heart pump support modes including constant speed support, copulsative and counterpulsative direct cf-LVAD speed modulation and pump flow rate control to regulate the cf-LVAD operating speed. The simulations were performed using a cardiovascular system model, which consists of active left atrium and ventricle, mitral and aortic valve leaflets, circulatory loop and a cf-LVAD. The cf-LVAD was operated between 7500 rpm and 12,500 rpm with 1000 rpm intervals to simulate constant speed support. The same mean pump operating speeds over a cardiac cycle were applied in the direct operating speed modulation for the copulsative and counterpulsative direct speed modulation cf-LVAD support as in the constant speed support while the same pump-output over a cardiac cycle was applied to drive the pump in flow rate controlled copulsative and counterpulsative cf-LVAD support modes as in the constant speed support. Simulation results show that flow rate controlled counterpulsative pump support mode generates lower end-diastolic left ventricular volume and pressure–volume loop area while generating more physiological left ventricular volume signals over a cardiac cycle with respect to the other pump operating modes.

3

Examination of left cardiac ventricle's contractility based on spectral analysis of ultrasound imaging

Przytulska M., Kulikowski J. L.

Biocybernetics and Biomedical Engineering

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2007

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Vol. 27, no. 4

17-28

EN

A method of left cardiac ventricle's contractility abnormalities recognition and assessment, based on computer-aided analysis of sequences of ultrasonographic images is presented. The method is based on an analytical model of ventricle's shape time-variations during a single or several heart evolution cycles. An approach to ventricle's contractility abnormalities detection and evaluation based on a concept of spectral analysis of the shape coefficients' time-variations is proposed. The shape coefficients can be obtained by a computer-aided analysis of sequences of ultrasonographic cardiac images. The contraction process is characterized by spectral indicators: the contraction-depth ratio and the smoothness ratio. The results of preliminary testing of the method on clinical data are presented.

4

Influence of the inlet and outlet compliance on the effectiveness and work safety of a pneumatically-driven paracorporeal prosthetic ventricle

Paszkowski M., Nawrat Z.

Acta of Bioengineering and Biomechanics

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2005

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Vol. 7, nr 2

40-50

EN

The paper deals with the problems connected with mechanical assistance to cardiovascular system by means of the pneumatically driven artificial ventricle POLVAD-MEV and, more precisely, the influence of the pump elements' compliance being placed directly in the front of the inflow valve (inlet compliance) and behind the outflow valve (outlet compliance) on the effectiveness and safety of this assistance. The authors concentrated mainly on the changes in the output flow of the aniflcial ventricle and inertia phenomena (water-hammer effect) occurring together with different values of the compliance. All experiments were carried out in the Biocybernetics Laboratory of the Institute of Heart Prostheses in Cardiac Surgery Development Foundation in Zabrze by means of a mock circulation and a physical model of the inlet and outlet compliance.