scholarly journals Alterations in pulse wave propagation reflect the degree of outflow tract banding in HH18 chicken embryos

2013 ◽  
Vol 305 (3) ◽  
pp. H386-H396 ◽  
Author(s):  
Liang Shi ◽  
Sevan Goenezen ◽  
Stephen Haller ◽  
Monica T. Hinds ◽  
Kent L. Thornburg ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Wave Propagation ◽  
Transit Time ◽  
Congenital Heart ◽  
Cardiac Cycle ◽  
Pulse Wave ◽  
Pulse Transit Time ◽  
Pulse Wave Propagation ◽  
Chicken Embryos

Hemodynamic conditions play a critical role in embryonic cardiovascular development, and altered blood flow leads to congenital heart defects. Chicken embryos are frequently used as models of cardiac development, with abnormal blood flow achieved through surgical interventions such as outflow tract (OFT) banding, in which a suture is tightened around the heart OFT to restrict blood flow. Banding in embryos increases blood pressure and alters blood flow dynamics, leading to cardiac malformations similar to those seen in human congenital heart disease. In studying these hemodynamic changes, synchronization of data to the cardiac cycle is challenging, and alterations in the timing of cardiovascular events after interventions are frequently lost. To overcome this difficulty, we used ECG signals from chicken embryos (Hamburger-Hamilton stage 18, ∼3 days of incubation) to synchronize blood pressure measurements and optical coherence tomography images. Our results revealed that, after 2 h of banding, blood pressure and pulse wave propagation strongly depend on band tightness. In particular, while pulse transit time in the heart OFT of control embryos is ∼10% of the cardiac cycle, after banding (35% to 50% band tightness) it becomes negligible, indicating a faster OFT pulse wave velocity. Pulse wave propagation in the circulation is likewise affected; however, pulse transit time between the ventricle and dorsal aorta (at the level of the heart) is unchanged, suggesting an overall preservation of cardiovascular function. Changes in cardiac pressure wave propagation are likely contributing to the extent of cardiac malformations observed in banded hearts.

Nonlinear Response of Shells Conveying Pulsatile Flow With Pulse-Wave Propagation

2016 ◽  
Author(s):  
Eleonora Tubaldi ◽  
Marco Amabili ◽  
Michael P. Paidoussis
Keyword(s):  
Blood Flow ◽  
Wave Propagation ◽  
Pulsatile Flow ◽  
Pulse Wave ◽  
Pulse Wave Propagation ◽  
Vascular Prostheses ◽  
Axial Coordinate ◽  
Pulsatile Pressure ◽  
Velocity Changes ◽  
Oscillatory Pressure

In deformable shells conveying pulsatile flow, oscillatory pressure changes cause local movements of the fluid and shell wall, which propagate downstream in the form of a wave. In biomechanics, it is the propagation of the pulse that determines the pressure gradient during the flow at every location of the arterial tree. In this study, a woven Dacron vascular prosthesis is modelled as a transversely isotropic circular cylindrical shell described by means of nonlinear Novozhilov shell theory. Flexible boundary conditions are considered to simulate connection with the remaining tissue. Nonlinear vibrations of the shell conveying pulsatile flow and subjected to pulsatile pressure are investigated taking into account the effects of the pulse-wave propagation. An input oscillatory pressure at the shell entrance is considered and it propagates down the shell causing a wave motion within the shell where, as a consequence, the pressure gradient and the flow velocity are functions of both the axial coordinate and time. For the first time in literature, coupled fluid-structure Lagrange equations for a non-material volume with wave propagation in case of pulsatile flow are developed. The fluid is modeled as a Newtonian inviscid pulsatile flow and it is formulated using a hybrid model based on the linear potential flow theory and considering the unsteady viscous effects obtained from the unsteady time-averaged Navier-Stokes equations. Contributions of pressure and velocity changes’ propagation are also considered in the pressure drop along the shell and in the pulsatile frictional traction on the internal wall in the axial direction. A numerical bifurcation analysis employs a refined reduced order model to investigate the dynamic behavior of a pressurized Dacron vascular graft conveying blood flow. A pulsatile time-dependent blood flow model is considered in order to study the effect of pressurization by applying the first and second harmonic of the physiological waveforms of velocity and pressure during the heart beating period. Geometrically nonlinear vibration response to pulsatile flow and transmural pulsatile pressure considering the propagation of pressure and velocity changes inside the shell are here presented via frequency-response curves and time histories. It is shown how traveling waves of pressure and velocity cause a delay in the radial displacement of the shell at different values of the axial coordinate. This study provides a deep insight into the currently unknown nonlinear behavior of vascular prostheses whose dynamic response can cause unwanted hemodynamic effects leading to failure. Indeed, it is well known that vascular prostheses mechanical properties are very different from those of natural arteries. In particular, the compliance mismatch between the host artery and the prosthesis causes a different wave speed resulting in a change in the performance of the cardiovascular system. In the near future, a more refined model to the one here presented will be applied to reproduce and compare the dynamic behavior of vascular prostheses and the human aorta, helping in vascular prostheses design and implementation.

scholarly journals Early diagnosis of increased stiffness of great vessels in adolescents with functional pathology of vegetative genesis

2021 ◽  
Vol 66 (3) ◽  
pp. 52-61
Author(s):  
I. V. Leontyeva ◽  
I. A. Kovalev ◽  
M. A. Shkolnikova ◽  
Yu. S. Isayeva ◽  
A. N. Putintsev ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Wave Propagation ◽  
Pulse Wave Velocity ◽  
Arterial Hypertension ◽  
Pulse Wave ◽  
Diastolic Pressure ◽  
Augmentation Index ◽  
Normal Blood ◽  
Normal Blood Pressure ◽  
Pulse Wave Propagation

40 adolescents aged 15–17 years with functional cardiovascular pathology of vegetative origin underwent a 24-hour blood pressure monitoring (using the oscillometric method BPLabVasotens, Peter Telegin LLC, Nizhny Novgorod) with an assessment of central blood pressure parameters and rigidity of the main arteries.The scientists found significantly higher values of central systolic pressure during the day and night hours in the group of adolescents with arterial hypertension (n=13) compared to adolescents with normal blood pressure (n=27). They determined significantly higher values of the pulse wave velocity both during 24 hours and in the day and night hours in the group with arterial hypertension compared to the group of adolescents with normal blood pressure. No differences were found in the parameters of the propagation time of the reflected pulse wave and the augmentation index. The time of the reflected pulse wave propagation was significantly lower at nighttime compared to the daytime. In the group with arterial hypertension, the rate of pulse wave propagation in the aorta correlated only with the values of diastolic pressure over 24 hours and diastolic pressure in the daytime. In the adolescents with normal blood pressure, the pulse wave velocity correlated with systolic and pulse blood pressure. The augmentation index in the group of adolescents with arterial hypertension correlated with diastolic pressure, in contrast to the group of adolescents with normal blood pressure, where such a correlation was not detected.

scholarly journals Mathematical modeling of pulse wave propagation along human aorta

2018 ◽  
Keyword(s):  
Blood Flow ◽  
Wave Propagation ◽  
Pulse Wave ◽  
Medical Diagnostics ◽  
Human Aorta ◽  
Circulation System ◽  
Pulse Wave Propagation ◽  
Blood Circulation System ◽  
Pulse Waves ◽  
The Individual

Background: Physical characteristics of pulse waves, which are generated by the heart contractions and propagated along the arteries, are used in medicine for diagnostics of the blood circulation system and blood supply to the organs and tissues. At the sites with significant wave reflections the high local pressure oscillations appear that may lead to damage of the endothelium, development of atherosclerotic plaques and aortic aneurysm. Therefore, elaboration of a detailed biophysical model of the individual aorta based on tomography and determination of the dangerous sites with high wave reflections are important for medical diagnostics. Objectives: The aim of the work is to study the regularities of the pulse wave propagation and reflection along the aorta and to propose new methods for early diagnosis of disorders in the blood circulation system. Materials and methods: The measurement data on diameters and lengths of segments of aorta and its branches conducted on 5 corpses have been used. Calculations of the wave conduction and reflection coefficients are based on the linear theory of pulse waves developed by J. Lighthill. Results: It is shown that from the biophysical point of view, the aorta is an optimal waveguide, which provides almost zero local reflections of the pulse waves. Most of the branches possess negative reflection, which accelerates the blood flow and decreases the load on the heart due to the suction effect. The calculated values of the branching coefficients and pulse waves speeds correspond to the data of the previous experimental measurements. It is shown that most of the branches have an optimal Murray coefficient close to one. It implies, aorta also provides the optimal volumetric blood flow over the period of cardiac contraction with minimal energy expenses. Conclusions: Human aorta and its branches possess optimal biophysical properties, which ensure the blood flow with minimal energy consumption. Aorta as an optimal waveguide provides pulse wave propagation with almost without reflection. The proposed method of estimation of the biophysical properties of aorta as a waveguide can be useful for medical diagnostics, allowing early identification of the regions which are dangerous in terms of the progressive development of vascular pathologies in the individual geometry of the patient's vasculature.

scholarly journals Pulse Transit Time-Pulse Wave Analysis Fusion Based on Wearable Wrist Ballistocardiogram for Cuff-Less Blood Pressure Trend Tracking

IEEE Access ◽  
2020 ◽  
Vol 8 ◽  
pp. 138077-138087
Author(s):  
Peyman Yousefian ◽  
Sungtae Shin ◽  
Azin Sadat Mousavi ◽  
Ali Tivay ◽  
Chang-Sei Kim ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Transit Time ◽  
Pulse Wave ◽  
Pulse Transit Time ◽  
Pulse Wave Analysis ◽  
Wave Analysis ◽  
Time Pulse

scholarly journals Pulse Transit Time Derivation Using Xiphoidal and Carotid Seismocardiograms

2017 ◽  
Author(s):  
Ajay K. Verma ◽  
John Zanetti ◽  
Reza Fazel-Rezai ◽  
Kouhyar Tavakolian
Keyword(s):  
Blood Pressure ◽  
Aortic Valve ◽  
Transit Time ◽  
Pulse Wave ◽  
Blood Pressure Measurement ◽  
Pulse Transit Time ◽  
Non Invasive ◽  
Arterial Blood ◽  
Pressure Estimation ◽  
Blood Pressure Estimation

Blood pressure is an indicator of a cardiovascular functioning and could provide early symptoms of cardiovascular system impairment. Blood pressure measurement using catheterization technique is considered the gold standard for blood pressure measurement [1]. However, due its invasive nature and complexity, non-invasive techniques of blood pressure estimation such as auscultation, oscillometry, and volume clamping have gained wide popularity [1]. While these non-invasive cuff based methodologies provide a good estimate of blood pressure, they are limited by their inability to provide a continuous estimate of blood pressure [1–2]. Continuous blood pressure estimate is critical for monitoring cardiovascular diseases such as hypertension and heart failure. Pulse transit time (PTT) is a time taken by a pulse wave to travel between a proximal and distal arterial site [3]. The speed at which pulse wave travels in the artery has been found to be proportional to blood pressure [1, 3]. A rise in blood pressure would cause blood vessels to increase in diameter resulting in a stiffer arterial wall and shorter PTT [1–3]. To avail such relationship with blood pressure, PTT has been extensively used as a marker of arterial elasticity and a non-invasive surrogate for arterial blood pressure estimation. Typically, a combination of electrocardiogram (ECG) and photoplethysmogram (PPG) or arterial blood pressure (ABP) signal is used for the purpose of blood pressure estimation [3], where the proximal and distal timing of PTT (also referred as pulse arrival time, PAT) is marked by R peak of ECG and a foot/peak of a PPG, respectively. In the literature, it has been shown that PAT derived using ECG-PPG combination infers an inaccurate estimate of blood pressure due to the inclusion of isovolumetric contraction period [1–3, 4]. Seismocardiogram (SCG) is a recording of chest acceleration due to heart movement, from which the opening and closing of the aortic valve can be obtained [5]. There is a distinct point on the dorso-ventral SCG signal that marks the opening of the aortic valve (annotated as AO). In the literature, AO has been proposed for timing the onset of the proximal pulse of the wave [6–8]. A combination of AO as a proximal pulse and PPG as a distal pulse has been used to derive pulse transit time and is shown to be correlated with blood pressure [7]. Ballistocardiogram (BCG) which is a measure of recoil forces of a human body in response to pumping of blood in blood vessels has also been explored as an alternative to ECG for timing proximal pulse [5, 9]. Use of SCG or BCG for timing the proximal point of a pulse can overcome the limitation of ECG-based PTT computation [6–7, 9]. However, a limitation of current blood pressure estimation systems is the requirement of two morphologically different signals, one for annotating the proximal (ECG, SCG, BCG) and other for annotating the distal (PPG, ABP) timing of a pulse wave. In the current research, we introduce a methodology to derive PTT from seismocardiograms alone. Two accelerometers were used for such purpose, one was placed on the xiphoid process of the sternum (marks proximal timing) and the other one was placed on the external carotid artery (marks distal timing). PTT was derived as a time taken by a pulse wave to travel between AO of both the xiphoidal and carotid SCG.

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