Blood vessels simulators

The speeifieations of blood vessel simulator are 4 mm, 5 mm and 8 mm in internal diameter, turning angle of 45-95 and sectional diameter of 2-8 mm in aneurysms. The catheters used for experiments are 6Fr, 4Fr, 3Fr in outer diameter. When the temperature of... 

Figure 6.5 Schematic drawing of a system of blood vessel simulator for testing a microcatheter with the IPMC active guide wire (Reprinted with permission from Guo, S., Fukuda, T., Kosuge, K. et al. Micro catheter system with active guide wire-structure, experimental results and characteristic evaluation of active guide wire catheter using ICPF actuator. Proceedings of the IEEE 5th International Symposium on Micro Machine and Human Science, 191-8. Copyright (2004) IEEE).

The mechanical force most relevant to platelet-mediated thrombosis is shear stress. The normal time-averaged levels of venous and arterial shear stresses range between 1-5 dyn/cm2 and 6 10 dyn/cm2, respectively. However, fluid shear stress may reach levels well over 200 dyn/cm2 in small arteries and arterioles partially obstructed by atherosclerosis or vascular spasm. The cone-and-plate viscometer and parallel-plate flow chamber are two of the most common devices used to simulate fluid mechanical shearing stress conditions in blood vessels. 

Next, the researchers simulated heart attacks in the rabbits by tying off their heart blood vessels, the arteries leading to the heart muscle called coronary arteries. Ordinarily, this will lead to ventricular fibrillation and death... 

Other stimuli may be incorporated into the culture environment to cultivate proper tissue function. Mechanical or electrical stimulation, provided at frequencies simulating in vivo conditions, have been shown to improve the resulting properties of the cultivated tissue. For example, pulsatile conditions that simulate a beating heart are utilized in the culture of blood vessels resulting in improved strength and function relative to cultures lacking this stimulus. ... 

Finally, the PRF method was used to measure temperature distributions in phantoms mimicking the effect of counter-current flow in large blood vessels.This effect can produce heterogeneous temperature distributions in vivo, even from spatially homogeneous heating sources. Experimental results agreed well with numerical simulations. 

Models begin conceptually for example, the concept that a blood vessel behaves as a fluid-filled pipe. Concepts may be developed into physical models, for example, using a latex tube to describe a blood vessel, upon which experiments are performed. Often, concepts are realized as mathematical models, whereby the concept is described by physical laws, transformed into a set of mathematical equations, and solved via computer. Simulations, distinct from models, are descriptions that mimic the physiological system. The quantitative nature of physiological models allows them to be employed as components of systems for the study of physiological control, illustrated in several of this section s chapters. 

For the dynamic lung impedance model to be useable in Finite Difference Method or Finite Element Method impedance signal simulations, the dynamic tissue sample model is discretized into volume data. At first 3D data with 35 x 35 x 35 voxel resolution is prepared from each of the 40 time frames. This allows for easy import into MATLAB or COMSOL based calculation. The volume data includes percentage of blood vessels (blood) for each of the 35 X 35 X 35 X 40 voxels. It can readily be transformed into electric/dielectric properties for each voxel with tissue data available on the internet. But data can also be exported with arbitrary resolution depending on calculation-simulation requirements. The simulations are run separately for each of the 40 time-frames to get full frequency characteristic of impedance measurement across the tissue sample. Finally we can get 40 frequency characteristics—one for each time-frame and to see a dynamic electrical impedance signal on a certain frequency, we just need to plot the impedance value at the chosen frequency from the 40 time-frames. 

Electric analog models are a class of lumped models and are often used to simulate flow through Ae network of blood vessels. These models are useful in assessmg Ae overall performance of a system or a subsystem. Integration of Ae fluid momentum equation (longitudinal direction, in cy-... 

Equations 16 and 23 [or (1.15) and (1.22)] can be used to simulate either a segment of a blood vessel or the entire blood vessel itself. In small blood vessels, the inductance L is very low compared to the resistance term R, and therefore the inductance term can be neglected in small arteries, arterioles, and capillaries. Since there is no oscillation of pressure in the capillaries, the inductance term can be neglected in vessels downstream of the capillary (i.e., venules, veins, and vena cava, etc.). 

The problem is reduced to a set of linear differential equations and can be solved for given boundary conditions. The RCL characteristics of a given problem may be derived fixim the known physical properties of blood and blood vessels (Dinnar, 1981 Van der Twell, 1957). This compartmental approach allowed for computer simulations of complex arterial circuits with clinical applications (McMahon et al., 1971 Clark et al., 1980 Bamea et al., 1990 Olansen et al., 2000 Westerhof and Stergiopulos, 2000 Ripplinger et al., 2001). 

Kleinstreuer, C., Lei, M., and Archie, J. P., Hemodynamics simulations and optimal computer-aided designs of branching blood vessels, in Biofiidd Methods in Vascular and Pulmonary Systems, C. Leondes, ed., CRC Press, Boca Raton, Florida, Chap. 1,2001. 

In vitro and in vivo models have been studied to evaluate the healing efficacy of new bioactive molecules and biomaterials in full-thickness and chronic wound repair. In vitro models are laboratory products, known as skin-equivalents. They consist of a collagen gel containing fibroblasts, covered by a keratinocyte layer (Mertsching et al., 2008). Skin-equivalents allow a skin lesion to be simulated and active agent performance to be studied without the use of animal models. However, the absence of blood vessels or skin appendages limits their predictability (Zhang and Michniak-Kohn, 2012). 

Figure 3 is showing blood vessels and parenchyma as taken for finite element simulation. 

The third parameter investigated is the effect of trachea stiffness. As explained in previous section, due to difficulty of acquiring images for bronchial tube, blood vessels images are assumed to be the trachea. In this simulation, equivalent stiffness method is used to investigate the stiffness effect at the increase rate of 1 [%] in the range from 0 5[%]. The values are as shown in table 3. 

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