Biomechanical Differential Equations of Variables of the Arterial Pulse Based on Vessel Wall and Blood Flow Features. Die biomechanischen Differentialgleichungen der Variablen des arteriellen Pulses auf der Basis der Gefäßwand- und Blutströmungs-Eigenschaften

1998 ◽  
Vol 43 (4) ◽  
pp. 100-106
Author(s):  
U. Bendel
Keyword(s):  
Blood Flow ◽  
Differential Equations ◽  
Vessel Wall ◽  
Arterial Pulse ◽  
Flow Features

Blood Flow Pattern and Anastomotic Compliance for Interrupted versus Continuous Coronary Bypass Grafts

2005 ◽  
Vol 6 (2) ◽  
pp. 65 ◽  
Author(s):  
Marc Gerdisch ◽  
Thomas Hinkamp ◽  
Stephen D. Ainsworth
Keyword(s):  
Blood Flow ◽  
Vessel Wall ◽  
Coronary Bypass ◽  
Bypass Grafts ◽  
Cross Sectional ◽  
Coronary Bypass Grafts ◽  
Geometric Consistency ◽  
Suturing Technique ◽  
Suturing Techniques ◽  
Key Indicators

<P>Background: Use of the interrupted coronary anastomosis has largely been abandoned in favor of the more rapid continuous suturing technique. The Coalescent U-CLIP anastomotic device allows the surgeon to create an interrupted distal anastomosis in the same amount of time that it would take to create a continuous anastomosis. This acute bovine study examined the effect of the anastomotic technique on blood flow and vessel wall function. </P><P>Methods: End-to-side coronary anastomoses were created in an open chest bovine model using the left and right internal thoracic arteries and the left anterior descending coronary artery. All other variables except suturing technique were carefully controlled. In each animal, one anastomosis was completed using a continuous suturing technique and the other was performed in an interrupted fashion using the Coalescent U-CLIP anastomotic device. Volumetric flow curves through each graft were analyzed using key indicators of anastomotic quality, and anastomotic compliance was evaluated using intravascular ultrasound. Luminal castings were created of each vessel to examine the interior surface of each anastomosis for constrictions and deformities. </P><P>Results: The interrupted anastomoses created with the Coalescent U-CLIP anastomotic device showed significant differences with respect to anastomotic compliance, pulsatility index, peak flow, and percentage of diastolic flow. The cross-sectional area and degree of luminal deformity were also different for the two suturing techniques. </P><P>Conclusions: In this acute bovine model, interrupted coronary anastomoses demonstrated superior geometric consistency and greater physiologic compliance than did continuously sutured anastomoses. The interrupted anastomosis also caused fewer disturbances to the flow waveform, behaving similarly to a normal vessel wall. The combination of these effects may influence both acute and long-term patency of the coronary bypass grafts.</P>

Effect of Blood Viscosity on Thrombosis Potential Near a Step Wall Transition

2009 ◽  
Author(s):  
Scott C. Corbett ◽  
Amin Ajdari ◽  
Ahmet U. Coskun ◽  
Hamid N.-Hashemi
Keyword(s):  
Blood Flow ◽  
Vessel Wall ◽  
Coagulation Factors ◽  
Artificial Organs ◽  
Physical Factors ◽  
Local Geometry ◽  
Induce Platelet Aggregation ◽  
Shear Rates ◽  
Chemical Factors ◽  
Low Shear

Thrombosis and hemolysis are two problems encountered when processing blood in artificial organs. Physical factors of blood flow alone can influence the interaction of proteins and cells with the vessel wall, induce platelet aggregation and influence coagulation factors responsible for the formation of thrombus, even in the absence of chemical factors in the blood. These physical factors are related to the magnitude of the shear rate/stress, the duration of the applied force and the local geometry. Specifically, high blood shear rates (or stress) lead to damage (hemolysis, platelet activation), while low shear rates lead to stagnation and thrombosis [1].

scholarly journals Radiation Effect on MHD Blood Flow Through a Tapered Porous Stenosed Artery with Thermal and Mass Diffusion

2019 ◽  
Vol 24 (2) ◽  
pp. 411-423
Author(s):  
M. Sharma ◽  
R.K. Gaur ◽  
B.K. Sharma
Keyword(s):  
Blood Flow ◽  
Partial Differential Equations ◽  
Differential Equations ◽  
Partial Differential ◽  
Soret And Dufour Effects ◽  
Linear Partial Differential Equations ◽  
Flow And Heat Transfer ◽  
Stenosed Artery ◽  
Flow Through ◽  
Explicit Finite Difference

Abstract A mathematical model for MHD blood flow through a stenosed artery with Soret and Dufour effects in the presence of thermal radiation has been studied. A uniform magnetic field is applied perpendicular to the porous surface. The governing non-linear partial differential equations have been transformed into linear partial differential equations, which are solved numerically by applying the explicit finite difference method. The numerical results are presented graphically in the form of velocity, temperature and concentration profiles. The effects of various parameters such as the Reynolds number, Hartmann number, radiation parameter, Schmidt number and Prandtl number, Soret and Dufour parameter on the velocity, temperature and concentration have been examined with the help of graphs. The present results have an important bearing on the therapeutic procedure of hyperthermia, particularly in understanding/regulating blood flow and heat transfer in capillaries.

THE EFFECT OF RESIDUAL STRESSES ON WAVE SPEED IN ARTERIES

1996 ◽  
Vol 04 (02) ◽  
pp. 171-180
Author(s):  
H.R. CHAUDHRY ◽  
B. BUKIET ◽  
M. LACKER
Keyword(s):  
Blood Flow ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Wave Speed ◽  
Traditional Approach ◽  
Clinical Applications ◽  
Arterial Pulse ◽  
Wave Speeds ◽  
Nonlinear Elasticity Theory ◽  
As Stress

The traditional approach to calculating stress distribution in arteries has been to assume (incorrectly) that the unloaded intact artery is stress-free. We consider the unloaded intact artery to have initial (i.e. residual) stresses and study how this affects the calculated wave speed of the arterial pulse. We use a set of equations that describe, in a simplified way, the blood flow in arteries and apply nonlinear elasticity theory to derive a formula for wave speed. We compare wave speed calculations under two assumptions (considering unloaded intact arteries as stress-free and considering these arteries to have residual stresses). We find that wave speeds calculated assuming residual stresses are more realistic. Clinical applications of this work are suggested.

Computational Mechanical Analysis of the Platelets Behavior in the Blood Flow Using Discrete Element Method

2000 ◽  
Author(s):  
Hisako Miyazaki ◽  
Hao Liu ◽  
Takami Yamaguchi
Keyword(s):  
Blood Flow ◽  
Vessel Wall ◽  
Thrombus Formation ◽  
Mechanical Analysis ◽  
Soluble Form ◽  
Blood Constituents ◽  
Fibrin Network ◽  
Insoluble Form ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Platelets play an important role in blood coagulation, particularly in the formation of primary thrombi. It is thought that the aggregation of platelets, which initiates primary thrombi formation, is mediated by a macromolecule called von Willebrand Factor (vWF). vWF is a long chain macromolecule that exists in the blood flow as a soluble form and in the vessel wall as an insoluble form. Figure 1 schematically shows normal (a) and pathological (b) thrombus formation processes as illustrated by Ikeda (1998) In both cases, platelets adhere to the injured vessel wall and then form a thrombus in cooperation with the fibrin network, red cells, and other blood constituents. vWF is thought to play a more important role in pathological thrombosis formation than in the normal hemostatic process, particularly due to its ability to react to hemodynamic stress.

PULSE-WAVEFORM AND LASER-DOPPLER INDICES FOR IDENTIFYING COLORECTAL-CANCER PATIENTS

2020 ◽  
pp. 2150005
Author(s):  
Chao-Tsung Chen ◽  
Chin-Tsing Ting ◽  
Chun-Yeh Chen ◽  
Zong-Jhe Lyu ◽  
Chien-Cheng Chen ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Blood Flow ◽  
Pulse Wave ◽  
Skin Surface ◽  
Laser Doppler ◽  
Waveform Analysis ◽  
Arterial Pulse ◽  
Doppler Flowmetry ◽  
Control Subjects ◽  
Arterial Pulse Wave

This study aimed to determine the effectiveness of using noninvasive arterial pulse-wave and laser-Doppler flowmetry (LDF) measurements to discriminate between colorectal-cancer (CC) patients and healthy control subjects. Radial-artery blood pressure waveform (BPW), finger photoplethysmography (PPG), and skin-surface LDF signals were measured noninvasively in 12 CC patients and 25 control subjects. Beat-to-beat, spectral, and variability analyses were applied to 20-minute-long recorded signals. Significant intergroup differences were found. In BPW, [Formula: see text]–[Formula: see text] amplitude indices were significantly larger while [Formula: see text]–[Formula: see text] phase-angle indices were significantly smaller in the CC patients than in the controls. The PPG and LDF variability indices were significantly larger and smaller, respectively, in CC patients. The relative energy contributions of the endothelial-, neural-, and myogenic-related frequency bands in LDF were significantly smaller in CC patients. The present findings indicate that pulse and LDF waveform analysis can be used to evaluate the arterial pulse-wave transmission condition, the responses of the blood-flow perfusion, and its regulatory activities in CC patients. There could be some similarities and differences in the present indices for different types of cancer. These findings could be utilized in the development of a rapid, noninvasive, and objective technique for evaluating the CC-induced blood-flow responses.

Vascular manifestations of extensive thermal skin injury in rat mesentery

1964 ◽  
Vol 207 (1) ◽  
pp. 137-143 ◽  
Author(s):  
Leif Horn ◽  
Ole J. Malm
Keyword(s):  
Blood Flow ◽  
Vessel Wall ◽  
Terminal Phase ◽  
Burn Shock ◽  
Red Cell ◽  
Skin Injury ◽  
Cell Agglutination ◽  
Vascular Contractility ◽  
Rat Mesentery ◽  
Mesenteric Microcirculation

After 40% body surface area skin burns, mesenteric microcirculation revealed initially augmented vasomotion and increased epinephrine responsiveness. Lowered precapillary epinephrine thresholds persisted throughout the terminal phase of early fatalities. Animals surviving 48 hr went through a phase with elevated epinephrine thresholds. Venodilatation coexisted with precapillary constriction. Initially most capillaries were empty; a few were dilated and congested with sluggish blood flow, indicating stasis. Lowered epinephrine responsiveness appeared first on the venous side coincident with apparent relief of stasis. Whitish aggregates or "clots" were frequently observed in circulation, but sludging or red cell agglutination was virtually absent. Morphologically the small blood vessels revealed endothelial swelling and there was a tendency for leukocytes to adhere to the vessel wall, the latter feature being more pronounced in later stages of burn shock. Other hemodynamic data indicated general peripheral vasoconstriction which gradually subsided in recovering animals. The circulatory changes are not consistent with circulating "burn toxins" impairing vascular contractility but with disruption of local control of vascular smooth muscle responsiveness, resulting in decompensatory venodilatation.

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