MODELLING OF CARDIOVASCULAR SYSTEM REGULATION

The article deals with principles of cardiovascular system regulation. The work describes physiological basis of selected regulation mechanisms such as autoregulation and baroregulation. An overview of cardiovascular system models is presented. The paper contains description of linear regulation models and also models containing nonlinear phenomenon. The article describes implementation of heart rate and vascular resistance regulation to existing model of arterial system based on the principle of electromechanical analogy. The implemented regulation model is based on baroreceptor regulation application. There are analysed characteristic properties of baroreceptor regulation such as saturation, hysteresis or step change in baroreceptor impulse rate

IMPACT OF DIFFERENT HEART RATES AND ARTERIAL ELASTIC MODULI ON PULSE WAVE VELOCITY IN ARTERIAL SYSTEM MODEL

The article describes the analysis of a pulse wave propagating through arteries towards periphery. For this analysis the model of arterial system based on the electromechanical analogy was used. Using the theory of transmission lines we estimated phase and group velocity of the arterial pulse wave. Both types of velocities were compared and dispersive properties of the selected arterial segments were evaluated. Pulse wave velocity corresponding to group velocity was calculated. We performed simulations for different heart rates and for different arterial elastic moduli. An increase in the heart rate causes that phase and group velocities converge to the same values. The higher magnitude of the arterial elastic module has the impact in the form of the increase in the both types of pulse wave velocities indicating the pathological state of the arterial system – arteriosclerosis

Low Frequency Electromagnetic Fields: Friend or Foe?

The issue of electromagnetic fields and their effects on human health has long been discussed within the scientific community. The lack of undisputable evidence confirming the dangers of these fields leads to great uncertainty and public concerns. On the other hand, positive effects and possible therapeutic use of the mentioned fields has also been explored and currently hints at feasible application thereof in regenerative and therapeutic applications. The following article provides a balanced insight into the issue at hand and provides details of recently proposed mechanisms of actions

Measurement and Analysis Possibilities of Pulse Wave Signals

This article deals with the implementation of wireless data transfer in biomedical applications concretely in photoplethysmography and pressure wave measurements. It deals with the application of a Bluetooth module for data transfer to the computer where further signal processing can be performed. The work describes a use of microcontroller serving for data flow control, communication and analog signal digitalization.<br /

Electromagnetic Phenomena as the Principles of Material Nondestructive Evalution

In the paper the principles and application of nondestructive evalution by both electromagnetic acoustic transducer (EMAT) and the eddy current (EC) methods are introducted. The ultrasonic testing (UT) and the electromagnetic nondestructive testing (NDT) are presented with their fundamental properties and the experimental results concerning the defect of conducting object characterization are shown

The Investigation of Terminal Segment Effect on Blood Pressure Propagation Patterns in Cardiovascular System Models

The electro-mechanical analogy method is used for the simulation of blood flow in blood vessels. Particularly the subject of this paper is the investigation of the influence of terminal segment topology on the blood pressure propagation patterns. The cardiovascular system is widely branched and therefore very complex. Thus, it is impractical to create the simulation model consisting of all blood vessels and attention is focused to development of models for smaller parts of vascular system. The selection and adjustment of terminal segments for such simulation model is important on behalf of the model accuracy. Three different types of terminal segments were implemented in order to show their influence to the blood pressure and blood flow propagation patterns in two model complexities

Resonant Frequencies of Small Arterial Segments as Determining Factors For Estimation of Terminal Segments in Electromechanical Arterial Tree Model

A model of the nonsymmetrical arterial tree was analyzed. The arterial branching model was based on the principle of the electromechanical analogy. The nonsymmetrical arterial tree was divided to 7 arterial generations, starting from larger arteries towards small arteries and arterioles. For each generation the resonant frequency and the transfer function were calculated and there are presented the pressure simulation results for each arterial generation. Terminal segments were determined regarding to calculation of the resonant frequencies and the transfer functions and simulation results

Basic Principles and Utilization Possibilities’ of Ultrasonic Phased Array in Material Nondestructive Evaluation

The paper deals with the basic principles of operation and with the utilization possibilities of phased array (PA) in materials nondestructive testing (NDT). The first part deals with description of PA arrangement modes, which enable to generate, focus and steer the ultrasonic beem. The second part deals with the description of electromagnetic acoustic transducer PA operation. The last part deals with the description of the utilization of PA in nondestructive testing of conductive materials and the advantages of PA utilization in inhomogeneous materials NDT

Pathological Deformations of Brain Vascular System Modelling Using Analogous Eletromagnetic Systems

The contribution deals with the modelling and simulation of human brain haemodynamics using analogous electromagnetic systems characteristic especially propagation properties of distributed parameters circuits. The cascade connection of analogical transmission line elements represents the vascular tree both from the point of the parameters and the topology as well. In the paper there are presented simulation examples of the healthy cerebral system mainly in the big arteries in comparing with the pathologically changed ones. The various degrees of stenosis are considered for the simulations of blood pressure and blood flow velocity and the results are compared with the healthy arteries. According to the last investigations the pathological deformations of brain arteries are th most frequently reasons of deaths in the world. The stenoses or aneurysms change the physical properties of arteries and they follow insufficient vascularisation of the brain. These computer-aided non-invasive methods together with the non-invasive experimental techniques represent a helpful tool both for the diagnostics and the treatment of vascular pathological deformations