The document discusses techniques for measuring pressure gradients in the cardiovascular system. It introduces pressure and its relationship to fluid flow as described by the Navier-Stokes equations. Pressure gradient is an important clinical biomarker. Techniques for measuring pressure gradient include cardiac catheterization, ultrasound, computational simulations, and 4D flow MRI. 4D flow MRI combined with the Poisson pressure equation and finite element methods provides a noninvasive, accurate, and automatic means for pressure gradient mapping.
Numerical simulation of blood flow in flexible arteries using Fluid-Structure...Mostafa Ghadamyari
We'll model and simulate a simple artery using pressure-based and velocity-based inlet profiles by Adina systems, Comsol Multiphysics, Ansys CFX & structural coupling and Ansys Fluent & structural coupling.
In this American Physiological Society (APS) webinar produced in partnership with ADInstruments, DeWayne Townsend, DVM, PhD and Adam Goodwill, PhD discuss how to collect and analyze quality pressure-volume loop data.
Specifically, they discuss why PV loops are considered the gold standard for measuring cardiac function in vivo, what equipment is required to collect PV loop data, and how to minimize variability in your data. The focus of the webinar is on data analysis – DeWayne and Adam demonstrate how to analyze load-independent measures of function and discuss what the data mean.
Key Learning Objectives Include:
– Why PV loops? What are the alternatives (e.g. echo, MRI, etc.) and how do PV loops compare?
– Why is the Starling effect important?
– Load independent measures: what are they and how are they measured? How are data analyzed and what do they mean?
– Equipment basics: what do you need to record PV loop data?
– What causes variability and how do you mitigate it?
Numerical simulation of blood flow in flexible arteries using Fluid-Structure...Mostafa Ghadamyari
We'll model and simulate a simple artery using pressure-based and velocity-based inlet profiles by Adina systems, Comsol Multiphysics, Ansys CFX & structural coupling and Ansys Fluent & structural coupling.
In this American Physiological Society (APS) webinar produced in partnership with ADInstruments, DeWayne Townsend, DVM, PhD and Adam Goodwill, PhD discuss how to collect and analyze quality pressure-volume loop data.
Specifically, they discuss why PV loops are considered the gold standard for measuring cardiac function in vivo, what equipment is required to collect PV loop data, and how to minimize variability in your data. The focus of the webinar is on data analysis – DeWayne and Adam demonstrate how to analyze load-independent measures of function and discuss what the data mean.
Key Learning Objectives Include:
– Why PV loops? What are the alternatives (e.g. echo, MRI, etc.) and how do PV loops compare?
– Why is the Starling effect important?
– Load independent measures: what are they and how are they measured? How are data analyzed and what do they mean?
– Equipment basics: what do you need to record PV loop data?
– What causes variability and how do you mitigate it?
Aging and the Cardiovascular System; An in vivo and in vitro approach to the ...Scintica Instrumentation
Almost one third of deaths world-wide can be attributed to cardiovascular diseases (CVD). More than half of those cases are related to systemic arterial hypertension (SAH). There are several risk factors that contribute to the development of SAH. Type II diabetes causes structural and functional damage to arterial walls, which leads to stiffness of compliance vessels and eventually SAH. Some studies have also related oxidative stress, genetics, and neuroendocrine changes to increasing stiffness. Another risk factor that effects everyone is age, and this webinar will explore the effect of vascular aging and how vascular aging and arterial stiffness can be assessed.
Experimental and clinical studies have demonstrated that changes in small artery structure and function are associated with age. These changes include decreased lumen diameter, increased wall thickness and diminished vasoreactivity. Other risk factors such as hypertension and diabetes accelerate and exacerbate these changes. Quantifying these parameters using isolated and pressurized, perfused, cannulated blood vessels is an ideal way to aid in elucidating the underlying causes of these changes to the vasculature and as they relate to aging and cardiovascular health.
Measuring stiffness in progressive diseases can be challenging, but pulse wave velocity (PWV) is considered the gold standard to assess arterial stiffness in vivo. There is epidemiological evidence of the predictive value of PWV for cardiovascular events, and PWV assessment can be done non-invasively and longitudinally for monitoring the progression and improvement of arterial stiffness through different disease models and treatments. For translational researchers, the PWV measurement technique can be adapted from the traditional clinical technique to be used to assess PWV in preclinical animal research studies. As many of the models for CVD use rodents, PWV in small animals is one of the best ways to monitor treatment efficacy and disease progression for pre-clinical research.
By combining these two modalities, both in vivo and in vitro, researchers can assess arterial stiffness and resulting vascular dysfunction. In this webinar we will discuss both methodologies, the techniques and instrumentation used, and some relevant journal articles that use these techniques to assess vascular aging.
This webinar will cover the following topics:
Vascular stiffness, systemic arterial hypertension and other associated effects of aging on the cardiovascular system
Pulse Wave Velocity (PWV) and Pressure Arteriography and how they can be used to assess arterial stiffness:
PWV as the gold-standard for longitudinal, non-invasive estimates of arterial stiffness
Pressure Arteriography and why it is essential for measuring isolated vessel structure and function to assess vascular activity
A brief summary of relevant literature
The blood circulates in a closed system of branching conduits. Haemodynamics refers to the studies of blood flow and related forces in moving the blood through the circulatory system. It
discusses the physical principles of blood flow t through the blood vessels with reference to the interrelationships among pressure, flow, and resistance.
Studying Flow Mediated Responses in Isolated VasculatureInsideScientific
During this webinar Dr. Éric Thorin, a leading expert in the effects of shear stress in the vasculature, explains key concepts in setting up a system for the purpose of examining flow-mediated responses in isolated blood vessels. The webinar sponsor, Living Systems Instrumentation, has been supplying tools for in vitro studies of cardiovascular function for over 20 years. Viewers will gain an understanding of how to setup and utilize a pressure arteriograph capable of simultaneous control of intravascular pressure and intraluminal flow.
Background information: The physiological significance and effects of flow on controlling and coordinating vascular function are well-appreciated. However, flow-mediated regulation of vascular function is a complex and difficult mechanism to study experimentally. Care must be taken to select appropriate instrumentation to allow for precise control of intravascular pressure and intraluminal flow, while minimizing artifacts introduced by the small size of glass cannulae. With proper simultaneous control of intravascular pressure and intraluminal flow, the researcher will be able to explore such responses as flow-mediated dilation, flow-induced constriction and other physiological responses that depend upon shear stress in the vasculature.
About Our Presenter:
Dr. Éric Thorin has a long-standing interest in the study and mechanisms of ageing related to the vascular endothelium. His laboratory has developed several approaches to investigate the functional consequences of ageing combined with risk factors for cardiovascular diseases (CVD) on the evolution of a reversible endothelial dysfunction to an irreversible vascular disease. His main areas of research include the study of the cerebrovascular and peripheral vascular dysfunction in the mouse model of human dyslipidemia and atherosclerosis, the molecular mechanisms leading to endothelial cell senescence and the impact of risk factors for CVD in patients with obesity, diabetes and coronary artery disease.
Statistical analysis for measuring the effects of stenotic shapes and spiral ...Iwate University
Numerical simulations have been done for a statistical analysis to investigate the effect of stenotic shapes and spiral flows on wall shear stress in the three-dimensional idealized stenotic arteries. Non-Newtonian flow has been taken for the simulations. The wall of the vessel is considered to be rigid. Physiological, parabolic and spiral velocity profile has been imposed for inlet boundary condition. Moreover, the time-dependent pressure profile has been taken for outlet boundary condition. Reynolds number at the inlet has been ranged approximately from 86 to 966 for the investigation. Low Reynolds number k-w model has been used as governing equation. 120 simulations have been performed for getting the numerical results. However, the numerical results of wall shear stress have been taken for the statistical analysis. The simulations and the statistical analysis have been performed by using ANSYS-18.1 and SPSS respectively. The statistical analyses are significant as p-value in all cases are zero. The eccentricity is the most influencing factor for WSSmax. The WSSmin has been influenced only by the flow spirality. The stenotic length has an influence only on the WSSmax whereas the stenotic severity has an influence on the WSSmax and WSSave.
13. • Inefficiency of the flow
• Energy losses
• Related to changes in Wall Shear Stress
• Methodologically challenging: II order spatial derivatives
Aortic coarctation
Kelly et al. (2005) EHJ Cardiov Imag, 6:288-290
Pressure gradient is accepted biomarker in clinical pre- and post- operative guidelines
Valvular stenosis
Baumgardtner et al. (2009) Eur J Echo, 10:1-25
Hypertrophic Cardiomyopathy
Allen et al. (2014) JCMR, 16
Introduction and Motivation
Why do we care about pressure in a clinical arena?
Why viscous pressure gradient?
14. • Inefficiency of the flow
• Energy losses
• Related to changes in Wall Shear Stress
• Methodologically challenging: II order spatial derivatives
Aortic coarctation
Kelly et al. (2005) EHJ Cardiov Imag, 6:288-290
Pressure gradient is accepted biomarker in clinical pre- and post- operative guidelines
Valvular stenosis
Baumgardtner et al. (2009) Eur J Echo, 10:1-25
Hypertrophic Cardiomyopathy
Allen et al. (2014) JCMR, 16
Introduction and Motivation
Why do we care about pressure in a clinical arena?
Why viscous pressure gradient?
Why laminar pressure gradient?
15. • Inefficiency of the flow
• Energy losses
• Related to changes in Wall Shear Stress
• Methodologically challenging: II order spatial derivatives
Aortic coarctation
Kelly et al. (2005) EHJ Cardiov Imag, 6:288-290
Pressure gradient is accepted biomarker in clinical pre- and post- operative guidelines
Valvular stenosis
Baumgardtner et al. (2009) Eur J Echo, 10:1-25
Hypertrophic Cardiomyopathy
Allen et al. (2014) JCMR, 16
Introduction and Motivation
Why do we care about pressure in a clinical arena?
Why viscous pressure gradient?
Why laminar pressure gradient?
• Turbulence does need time to develop
• Pulsatile regime is not so prone for it
62. ✓ SePPE method is fully automatic
✓ PPE enables computation of time-dependent, convective and viscous gradients separately
✓ Velocity reconstruction reduces error in viscous gradient irrespective of lumen detection error
x Segmentation is fundamental! (lumen detection error <5% to get 80% accuracy in gradients)
x Optimal segmentation threshold choice is function of SNR level
x 3D Poiseuille flow is not representative of physiological aortic flows (no inertial terms)
Discussion
• Performing validation tests on more realistic in silico cases (Womersley pulsatile flow field)
• Using Navier-Stokes' simulation to reconstruct velocity profile in boundary region
• Laminar viscous dissipation is higher at the vessels' boundary
• Viscous gradients are not captured correctly with PPE
63. ✓ SePPE method is fully automatic
✓ PPE enables computation of time-dependent, convective and viscous gradients separately
✓ Velocity reconstruction reduces error in viscous gradient irrespective of lumen detection error
x Segmentation is fundamental! (lumen detection error <5% to get 80% accuracy in gradients)
x Optimal segmentation threshold choice is function of SNR level
x 3D Poiseuille flow is not representative of physiological aortic flows (no inertial terms)
Hybrid method improves estimation of laminar viscous dissipation
Discussion
• Performing validation tests on more realistic in silico cases (Womersley pulsatile flow field)
• Using Navier-Stokes' simulation to reconstruct velocity profile in boundary region
• Laminar viscous dissipation is higher at the vessels' boundary
• Viscous gradients are not captured correctly with PPE