7,964 research outputs found
Dataset on the use of 3D speckle tracking echocardiography in light-chain amyloidosis
The dataset presented in this article is related to the research article entitled “Biventricular assessment of light-chain amyloidosis using 3D speckle tracking echocardiography: Differentiation from other forms of myocardial hypertrophy” (Vitarelli et al.,2018) [1], which examined the potential utility of left ventricular (LV) and right ventricular (RV) deformation and rotational parameters derived from three-dimensional speckle-tracking echocardiography (3DSTE) to diagnose cardiac amyloidosis(CA) and differentiate this disease from other forms of myocardial hypertrophy. The combined assessment of LV basal longitudinal strain, LV basal rotation and RV basal longitudinal strain had a high discriminative power for detecting CA. The data of this study provides more understanding on the value of LV 3DSTE deformation parameters as well as RV parameters in this particular cardiomyopathy
Early and late systolic wall stress differentially relate to myocardial contraction and relaxation in middle-aged adults: the Asklepios study
Experimental studies implicate late systolic load as a determinant of impaired left ventricular (LV) relaxation. We aimed to assess the relationship between the myocardial loading sequence and left ventricular (LV) contraction and relaxation. Time-resolved central pressure and time-resolved LV geometry were measured with carotid tonometry and speckle-tracking echocardiography, respectively, for computation of time-resolved ejection-phase myocardial wall stress (EP-MWS) among 1,214 middle-aged adults without manifest cardiovascular disease from the general population. Early diastolic annular velocity, systolic annular velocities were measured with tissue Doppler imaging and segmentaveraged longitudinal strain was measured with speckle-tracking echocardiography. After adjustment for age, gender and potential confounders, late EP-MWS was negatively associated with early diastolic mitral annular velocity (e', standardized β=-0.25; P<0.0001) and mitral inflow propagation velocity (Vpe, standardized β=-0.13; P=0.02). In contrast, early EP-MWS was positively associated with e' (standardized β=0.18; P<0.0001) and Vpe (standardized β=0.22; P<0.0001). A higher late EP-MWS predicted a lower systolic mitral annular velocity (S', standardized β=-0.31; P<0.0001) and lesser myocardial longitudinal strain (standardized β=0.32; P<0.0001), whereas a higher early EP-MWS was associated with a higher S' (standardized β=0.16; P=0.002) and greater longitudinal strain (standardized β=-0.24; P=0.002). The loading sequence remained independently associated with e' after adjustment for S' or systolic longitudinal strain. In the context of available experimental data, our findings support the role of the myocardial loading sequence as a determinant of LV systolic and diastolic function. A loading sequence characterized by prominent late systolic wall stress was associated with lower longitudinal systolic function and diastolic relaxation
Well-balanced finite difference WENO schemes for the blood flow model
The blood flow model maintains the steady state solutions, in which the flux
gradients are non-zero but exactly balanced by the source term. In this paper,
we design high order finite difference weighted non-oscillatory (WENO) schemes
to this model with such well-balanced property and at the same time keeping
genuine high order accuracy. Rigorous theoretical analysis as well as extensive
numerical results all indicate that the resulting schemes verify high order
accuracy, maintain the well-balanced property, and keep good resolution for
smooth and discontinuous solutions
Fluid dynamic aspects of cardiovascular behavior during low-frequency whole-body vibration
The behavior of the cardiovascular system during low frequency whole-body vibration, such as encountered by astronauts during launch and reentry, is examined from a fluid mechanical viewpoint. The vibration characteristics of typical manned spacecraft and other vibration environments are discussed, and existing results from in vivo studies of the hemodynamic aspects of this problem are reviewed. Recent theoretical solutions to related fluid mechanical problems are then used in the interpretation of these results and in discussing areas of future work. The results are included of studies of the effects of vibration on the work done by the heart and on pulsatile flow in blood vessels. It is shown that important changes in pulse velocity, the instantaneous velocity profile, mass flow rate, and wall shear stress may occur in a pulsatile flow due to the presence of vibration. The significance of this in terms of changes in peripheral vascular resistance and possible damage to the endothelium of blood vessels is discussed
A "well-balanced" finite volume scheme for blood flow simulation
We are interested in simulating blood flow in arteries with a one dimensional
model. Thanks to recent developments in the analysis of hyperbolic system of
conservation laws (in the Saint-Venant/ shallow water equations context) we
will perform a simple finite volume scheme. We focus on conservation properties
of this scheme which were not previously considered. To emphasize the necessity
of this scheme, we present how a too simple numerical scheme may induce
spurious flows when the basic static shape of the radius changes. On contrary,
the proposed scheme is "well-balanced": it preserves equilibria of Q = 0. Then
examples of analytical or linearized solutions with and without viscous damping
are presented to validate the calculations. The influence of abrupt change of
basic radius is emphasized in the case of an aneurism.Comment: 36 page
Impact of diabetes mellitus on ventricular structure, arterial stiffness, and pulsatile hemodynamics in heart failure with preserved ejection fraction
Background-Heterogeneity in the underlying processes that contribute to heart failure with preserved ejection fraction (HFpEF) is increasingly recognized. Diabetes mellitus is a frequent comorbidity in HFpEF, but its impact on left ventricular and arterial structure and function in HFpEF is unknown. Methods and Results-Weassessed the impact of diabetesmellitus on left ventricular cellular and interstitial hypertrophy (assessedwith cardiacmagnetic resonance imaging, including T1mapping pregadolinium and postgadolinium administration), arterial stiffness (assessed with arterial tonometry), and pulsatile arterial hemodynamics (assessed with in-office pressure-flow analyses and 24-hour ambulatory monitoring) among 53 subjects with HFpEF (32 diabetic and 21 nondiabetic subjects). Despite few differences in clinical characteristics, diabetic subjects with HFpEF exhibited a markedly greater left ventricular mass index (78.1 [95% CI, 70.4-85.9] g versus 63.6 [95% CI, 55.8-71.3] g; P=0.0093) and indexed extracellular volume (23.6 [95% CI, 21.2-26.1] mL/m(2) versus 16.2 [95% CI, 13.1-19.4] mL/m(2); P=0.0008). Pronounced aortic stiffening was also observed in the diabetic group (carotid-femoral pulse wave velocity, 11.86 [95% CI, 10.4-13.1] m/s versus 8.8 [95% CI, 7.5-10.1] m/s; P=0.0027), with an adverse pulsatile hemodynamic profile characterized by increased oscillatory power (315 [95% CI, 258-373] mWversus 190 [95% CI, 144-236] mW; P=0.0007), aortic characteristic impedance (0.154 [95% CI, 0.124-0.183] mmHg/mL per second versus 0.096 [95% CI, 0.072-0.121] mm Hg/mL per second; P=0.0024), and forward (59.5 [95% CI, 52.8-66.1] mm Hg versus 40.1 [95% CI, 31.6-48.6] mm Hg; P=0.0010) and backward (19.6 [95% CI, 16.2-22.9] mm Hg versus 14.1 [95% CI, 10.9-17.3] mm Hg; P=0.0169) wave amplitude. Abnormal pulsatile hemodynamics were also evident in 24-hour ambulatory monitoring, despite the absence of significant differences in 24-hour systolic blood pressure between the groups. Conclusions-Diabetes mellitus is a key determinant of left ventricular remodeling, arterial stiffness, adverse pulsatile hemodynamics, and ventricular-arterial interactions in HFpEF
Intrinsic Frequency Analysis and Fast Algorithms
Intrinsic Frequency (IF) has recently been introduced as an ample signal
processing method for analyzing carotid and aortic pulse pressure tracings. The
IF method has also been introduced as an effective approach for the analysis of
cardiovascular system dynamics. The physiological significance, convergence and
accuracy of the IF algorithm has been established in prior works. In this
paper, we show that the IF method could be derived by appropriate mathematical
approximations from the Navier-Stokes and elasticity equations. We further
introduce a fast algorithm for the IF method based on the mathematical analysis
of this method. In particular, we demonstrate that the IF algorithm can be made
faster, by a factor or more than 100 times, using a proper set of initial
guesses based on the topology of the problem, fast analytical solution at each
point iteration, and substituting the brute force algorithm with a pattern
search method. Statistically, we observe that the algorithm presented in this
article complies well with its brute-force counterpart. Furthermore, we will
show that on a real dataset, the fast IF method can draw correlations between
the extracted intrinsic frequency features and the infusion of certain drugs.
In general, this paper aims at a mathematical analysis of the IF method to show
its possible origins and also to present faster algorithms
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