scholarly journals Device for modeling of intra-arterial circulation: application in experimental cardiology

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
O Germanova ◽  
V A Germanov ◽  
Y V Shchukin ◽  
A V Germanov ◽  
G Galati
Keyword(s):  
Glass Tube ◽  
Pressure Probe ◽  
Electric Pump ◽  
Silk Thread ◽  
Premature Ventricular Contractions ◽  
Arterial Circulation ◽  
Arterial Blood ◽  
Wide Range ◽  
Regular Rhythm ◽  
Original Device

Abstract Purpose of study Using an original device for modeling of intra-arterial blood circulation, to study the features of intravascular hemodynamics with a regular heart rhythm and with various rhythm disturbances. Material and methods We used an original device developed by us to simulate intra-arterial circulation (Document of invention No. RU 202780 U1). The main part of the device is a glass tube of a rotameter with a length of 365 mm, an inlet end with a diameter of 20 mm, an outlet end of 16.5 mm, which is a model of an arterial vessel. Flexible silicone tubes are attached to the rotameter on both sides, with free ends connected to an electric pump, with various modes of operation (imitation of pulse waves with regular rhythm, premature ventricular contractions (PVCs), atrial fibrillation (AF). An aqueous solution of glycerin was introduced into a closed system diluted with water corresponding to the viscosity of the blood. A 5 mm long silk thread was alternately installed inside the tube, an intravascular piezoelectric crystal pressure probe connected to an oscilloscope. Also it was injected inside the tube a dye - clerical ink. Results With electric pump, we simulated the spreading of the pulse wave in regular heart rate, PVCs and AF. We observed the effect of a pressure wave (deflection of a silk thread, the appearance of a turbulent flow when using a dye) on the walls of the rotameter, with the formation of standing, reflected waves during the PVCs and AF. The pressure probe registered an increase in pressure inside the tube during the spread of the 1st post-extrasystolic contraction wave up to 58%, the wave after a long pause of more than 2 seconds with AF by 44% compared to the regular rhythm. Conclusion A device for modeling of intra-arterial circulation allows a wide range of experimental work in cardiology, normal and pathological physiology, and biophysics. FUNDunding Acknowledgement Type of funding sources: None.

DIGITALIS TOLERANCE IN YOUNG PUPPIES

PEDIATRICS ◽  
1970 ◽  
Vol 46 (5) ◽  
pp. 730-736
Author(s):  
Katherine H. Halloran ◽  
Steven C. Schimpff ◽  
Jean G. Nicolas ◽  
Norman S. Talner
Keyword(s):  
Blood Gases ◽  
Acid Base Balance ◽  
Acid Base ◽  
Littermate Control ◽  
Premature Ventricular Contractions ◽  
Toxic Dose ◽  
Arterial Blood ◽  
Wide Range ◽  
Base Balance ◽  
The Mean

Tolerance to acetyl strophanthidin, a rapid-acting cardiac aglycone, was determined in 28 anesthetized mongrel puppies, ages 16 to 56 days, and compared to tolerance in 16 littermate puppies in whom acute hypercapnic acidemia was produced. The tolerance was also compared to that of four adult mongrel dogs. The toxic dose was defined as the intravenous amount required to produce four consecutive premature ventricular contractions. A marked variation in the toxic dose was found in the 28 control puppies (range 83 to 353 µg/kg, mean 169 µg/kg) which could not be correlated with age, arterial blood gases or pH, serum potassium or sodium, arterial pressure, or heart rate. The toxic dose was significantly greater in the puppies than in the adult dogs, in whom the mean toxic dose was 64 µg/kg (range 50 to 89 µg/kg). A significant increase in tolerance was also observed in the puppies with hypercapnic acidemia (mean toxic dose 220 µg/kg, range 93 to 375 µg/kg) in comparison to tolerance in the control puppies and despite the wide range of tolerance, each of the puppies with hypercapnic acidemia showed greater tolerance than its littermate control puppy. Assessment of the clinical implications of these findings will require study of the effects of alterations in acid-base balance on the inotropic effect of acetyl strophanthidin in addition to the toxic electrophysiologic effects.

scholarly journals Physical simulation of intra-arterial circulation using an experimental bench

2021 ◽  
pp. 133-139
Author(s):  
O. A. Germanova ◽  
V. A. Germanov ◽  
Yu. V. Shchukin ◽  
A. V. Germanov ◽  
A. E. Burmistrov ◽  
...  
Keyword(s):  
Clinical Studies ◽  
Physical Simulation ◽  
Arterial Circulation ◽  
Wide Range ◽  
Experimental Bench ◽  
Original Device

The article describes the device and possibilities of application of the original device developed by us for simulation of intra-arterial circulation. The principles of operation of the device, a wide range of experimental and clinical studies in which it can be applied are outlined. The use of this useful model is illustrated by clinical examples.

scholarly journals Modeling of restenosis of main arteries after the intravascular stenting interventions

2021 ◽  
Vol 6 (1) ◽  
pp. 45-49
Author(s):  
Olga A. Germanova ◽  
Vladimir A. Germanov ◽  
Yurii V. Shchukin ◽  
Andrei V. Germanov ◽  
Maksim V. Piskunov ◽  
...  
Keyword(s):  
Blood Flow ◽  
Glass Tube ◽  
Heart Rhythm ◽  
Arterial Blood Flow ◽  
Human Blood Plasma ◽  
Hydraulic Shock ◽  
Arterial Blood ◽  
Arterial Vessel ◽  
Starting Point ◽  
Original Device

Objectives to study the mechanism of restenosis after the intra-arterial stenting using the original device for modeling of intra-arterial blood flow. Material and methods. To perform the experiment, we have created the original device simulating the intra-arterial blood flow. A glass tube of rotameter was the imitation of the arterial vessel. The closed system was filled with the liquid imitating blood, specifically the solution of glycerin the same viscosity as the human blood plasma. Using our original model of intra-artetial blood flow, we were able to study the intra-arterial hemodynamics under different conditions of cardiovascular system functioning, including arrhythmias. Results. In extrasystolic arrhythmia, during the spread of the first post-extrasystolic wave, we observed the intensive impact of pressure wave (the indicator was the silk thread) on the vessel walls with forming of reflected and standing waves. Putting the piezo crystal probe of pressure inside the tube, we verified our observations. The increase of pressure during the spread of the first post-extrasystolic wave in multiple measurements had a mean value of 160% in comparison with the pressure during the regular heart rhythm. Conclusion. The hydraulic shock appears during the spread of the first post-extrasystolic wave in the arterial vessel. Its effect on hemodynamics grows in case of the frequent extrasystoles and allorhythmia. The mechanical impact of hydraulic shock in extrasystoles can be the starting point of the restenosis onset and progressing in the intra-arterial stent.

Electron sources: Past, present, and future

1993 ◽  
Vol 51 ◽  
pp. 764-765
Author(s):  
David C Joy
Keyword(s):  
Glass Tube ◽  
Source Size ◽  
Electron Gun ◽  
Operating Parameters ◽  
Operational Parameters ◽  
Electron Sources ◽  
Difficult Decision ◽  
Probe Size ◽  
Wide Range ◽  
Overall Performance

The electron source is the most important component of the Scanning electron microscope (SEM) since it is this which will determine the overall performance of the machine. The gun performance can be described in terms of quantities such as its brightness, its source size, its energy spread, and its stability and, depending on the chosen application, any of these factors may be the most significant one. The task of the electron gun in an SEM is, in fact, particularly difficult because of the very wide range of operational parameters that may be required e.g a variation in probe size of from a few angstroms to a few microns, and a probe current which may go from less than a pico-amp to more than a microamp. This wide range of operating parameters makes the choice of the optimum source for scanning microscopy a difficult decision.Historically, the first step up from the sealed glass tube ‘cathode ray generator’ was the simple, diode, tungsten thermionic emitter.

scholarly journals Stochastic cycle selection in active flow networks

2016 ◽  
Vol 113 (29) ◽  
pp. 8200-8205 ◽  
Author(s):  
Francis G. Woodhouse ◽  
Aden Forrow ◽  
Joanna B. Fawcett ◽  
Jörn Dunkel
Keyword(s):  
Broad Class ◽  
Generic Model ◽  
Rate Theory ◽  
Flow Networks ◽  
Complex Flow ◽  
Slime Molds ◽  
Arterial Blood ◽  
Wide Range ◽  
Theoretical And Numerical Analysis ◽  
Active Flow

Active biological flow networks pervade nature and span a wide range of scales, from arterial blood vessels and bronchial mucus transport in humans to bacterial flow through porous media or plasmodial shuttle streaming in slime molds. Despite their ubiquity, little is known about the self-organization principles that govern flow statistics in such nonequilibrium networks. Here we connect concepts from lattice field theory, graph theory, and transition rate theory to understand how topology controls dynamics in a generic model for actively driven flow on a network. Our combined theoretical and numerical analysis identifies symmetry-based rules that make it possible to classify and predict the selection statistics of complex flow cycles from the network topology. The conceptual framework developed here is applicable to a broad class of biological and nonbiological far-from-equilibrium networks, including actively controlled information flows, and establishes a correspondence between active flow networks and generalized ice-type models.

Water Absorption From the Intestine via Portal and Lymphatic Pathways

1956 ◽  
Vol 184 (3) ◽  
pp. 441-444 ◽  
Author(s):  
John A. Benson ◽  
Philip R. Lee ◽  
John F. Scholer ◽  
Kwang S. Kim ◽  
Jesse L. Bollman
Keyword(s):  
Small Intestine ◽  
Venous Blood ◽  
The Body ◽  
Sodium Ion ◽  
Arterial Circulation ◽  
Intestinal Lymph ◽  
Arterial Blood ◽  
Portal Venous Blood ◽  
Lymphatic Pathway ◽  
Lymphatic Pathways

The content of either D2O or Na24 has been measured in the intestinal lymph, portal venous blood, and femoral arterial blood of unanesthetized hydrated rats after administration of the isotope into the stomach, duodenum, or peripheral or portal vein. Little, if any, water or sodium ion is delivered to the body by a lymphatic pathway after absorption from the small intestine. At least 99% is carried in portal venous blood. The amount of isotope found in intestinal lymph was proportional to lymph volume whatever the route of administration, and derived mainly from the arterial blood. Even during absorption of water or sodium ion from the small intestine the arterial circulation is the principal source of the water and sodium of the lymph.

Neonatal intestinal oxygen consumption during arterial hypoxemia

1983 ◽  
Vol 244 (3) ◽  
pp. G278-G283
Author(s):  
D. I. Edelstone ◽  
D. R. Lattanzi ◽  
M. E. Paulone ◽  
I. R. Holzman
Keyword(s):  
Intestinal Tract ◽  
Concentration Difference ◽  
Fick Principle ◽  
Arterial Blood ◽  
Wide Range ◽  
O2 Extraction ◽  
Neonatal Lambs ◽  
O2 Supply ◽  
Oxygen Requirements ◽  
O2 Delivery

In 12 chronically catheterized neonatal lambs, we determined intestinal tract blood flow (Qi) and O2 consumption (VO2i) at O2 contents of arterial blood (CaO2) ranging from 15.3 to 3.2 ml O2/dl blood. We measured Qi with the radioactive microsphere technique and computed intestinal O2 delivery (DO2i), VO2i, and O2 extraction (VO2i/DO2i) using the Fick principle. In lambs breathing air, mean Qi = 214 ml X min-1 X 100 g intestine-1, DO2i = 27.0 ml O2 X min-1 X 100 g-1, O2 extraction = 21%, and VO2i = 5.6 ml O2 Xmin-1 X 100 g-1. During reductions in CaO2, Qi and DO2i decreased. Intestinal O2 extraction increased sufficiently, however, so that VO2i was maintained over the range of CaO2 from 15.3 to about 6.5 ml O2/dl blood. VO2i was independent of Qi at Qi greater than 160 ml X min-1 X 100 g-1. When CaO2 was reduced below values of 6.5 ml O2/dl blood, corresponding to Qi less than 160 ml X min-1 X 100 g-1, VO2i fell in association with increases in the H+ concentration difference between mesenteric venous and arterial blood. These data indicate that the intestinal tract of the neonatal lamb can meet its oxygen requirements when O2 supply varies over a wide range. When O2 availability reaches a critically low level, intestinal anaerobic metabolism develops as the O2 supply to the neonatal intestinal tract becomes inadequate for the O2 demand.

scholarly journals Characterization of Periodic Incoming Wakes in a Low-Pressure Turbine Cascade Test Section by Means of a Fast-Response Single Sensor Virtual Three-Hole Probe

2019 ◽  
Vol 4 (3) ◽  
pp. 26
Author(s):  
Julien Clinckemaillie ◽  
Tony Arts
Keyword(s):  
Total Pressure ◽  
High Speed ◽  
Control Volume ◽  
Low Pressure ◽  
Fast Response ◽  
Pressure Probe ◽  
Flow Angle ◽  
Low Pressure Turbine ◽  
Wide Range ◽  
Good Agreement

This paper aims at evaluating the characteristics of the wakes periodically shed by the rotating bars of a spoked-wheel type wake generator installed upstream of a high-speed low Reynolds linear low-pressure turbine blade cascade. Due to the very high bar passing frequency obtained with the rotating wake generator (fbar = 2.4−5.6 kHz), a fast-response pressure probe equipped with a single 350 mbar absolute Kulite sensor has been used. In order to measure the inlet flow angle fluctuations, an angular aerodynamic calibration of the probe allowed the use of the virtual three-hole mode; additionally, yielding yaw corrected periodic total pressure, static pressure and Mach number fluctuations. The results are presented for four bar passing frequencies (fbar = 2.4/3.2/4.6/5.6 kHz), each tested at three isentropic inlet Mach numbers M1,is = 0.26/0.34/0.41 and for Reynolds numbers varying between Re1,is = 40,000 and 58,000, thus covering a wide range of engine representative flow coefficients (ϕ = 0.44−1.60). The measured wake characteristics show fairly good agreement with the theory of fixed cylinders in a cross-flow and the evaluated total pressure losses and flow angle variations generated by the rotating bars show fairly good agreement with theoretical results obtained from a control volume analysis.

Quantification of O2 consumption and arterial pressure as independent determinants of coronary flow

1987 ◽  
Vol 252 (3) ◽  
pp. H545-H553 ◽  
Author(s):  
I. Vergroesen ◽  
M. I. Noble ◽  
P. A. Wieringa ◽  
J. A. Spaan
Keyword(s):  
Coronary Artery ◽  
Arterial Pressure ◽  
Coronary Flow ◽  
Left Main Coronary Artery ◽  
External Pressure ◽  
Arterial Blood Flow ◽  
O2 Consumption ◽  
Left Main ◽  
Arterial Blood ◽  
Wide Range

The steady-state relationship between coronary arterial blood flow (CBF) and both myocardial O2 consumption (MVO2) and coronary arterial pressure (P) was explored in anesthetized dogs and goats. Both species were subjected to constant pressure perfusion of the left main coronary artery by an external pressure-controlling circuit. In addition a group of goats was studied with normal aortic perfusion using an occluder around the left main coronary artery to vary coronary arterial pressure. The statistical analysis revealed that despite the direct effect of P on MVO2 (the Gregg effect) the effects of both variables on CBF were independent and linear over a wide range of P and MVO2 so that multiple regression analysis with a linear equation (CBF = a X P + b X MVO2 + c) gave an excellent fit which was not improved by the introduction of an addition interactive term b3MVO2 X P. The mean correlation coefficient for all animals was greater than 0.9. From these data we conclude that any factor regulating coronary arterial flow would be influenced by both MVO2 and perfusion pressure in an independent way. This study characterizes the stationary behavior of local coronary flow control. Hence, it specifies quantitatively the relations to be predicted by hypotheses aiming to explain this control mechanism.

Noninvasive intracranial compliance and pressure based on dynamic magnetic resonance imaging of blood flow and cerebrospinal fluid flow: review of principles, implementation, and other noninvasive approaches

2003 ◽  
Vol 14 (4) ◽  
pp. 1-8 ◽  
Author(s):  
Patricia B. Raksin ◽  
Noam Alperin ◽  
Anusha Sivaramakrishnan ◽  
Sushma Surapaneni ◽  
Terry Lichtor
Keyword(s):  
Magnetic Resonance Imaging ◽  
Cerebrospinal Fluid ◽  
Magnetic Resonance ◽  
Cardiac Cycle ◽  
Venous Blood ◽  
Pressure Probe ◽  
Intracranial Volume ◽  
Resonance Imaging ◽  
Intracranial Compliance ◽  
Arterial Blood

Current techniques for intracranial pressure (ICP) measurement are invasive. All require a surgical procedure for placement of a pressure probe in the central nervous system and, as such, are associated with risk and morbidity. These considerations have driven investigators to develop noninvasive techniques for pressure estimation. A recently developed magnetic resonance (MR) imaging–based method to measure intracranial compliance and pressure is described. In this method the small changes in intracranial volume and ICP that occur naturally with each cardiac cycle are considered. The pressure change during the cardiac cycle is derived from the cerebrospinal fluid (CSF) pressure gradient waveform calculated from the CSF velocities. The intracranial volume change is determined by the instantaneous differences between arterial blood inflow, venous blood outflow, and CSF volumetric flow rates into and out of the cranial vault. Elastance (the inverse of compliance) is derived from the ratio of the measured pressure and volume changes. A mean ICP value is then derived based on a linear relationship that exists between intracranial elastance and ICP. The method has been validated in baboons, flow phantoms, and computer simulations. To date studies in humans demonstrate good measurement reproducibility and reliability. Several other noninvasive approaches for ICP measurement, mostly nonimaging based, are also reviewed. Magnetic resonance imaging–based ICP measurement may prove valuable in the diagnosis and serial evaluation of patients with a variety of disorders associated with alterations in ICP.

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