Regional differences in veins wall viscosity, compliance. energetics and damping: analysis of the pressure-diameter relationship during cyclical overloads

Abstract

Background:The characterization of the dynamic process of veins walls is essential to understand venous functioning under normal and pathological conditions. However, little work has been done on dynamic venous properties. Aim: To characterize vein compliance (C), viscosity (η), peak-strain (W St ) and dissipated (W D ) energy, damping (ξ), and their regional differences in order to evaluate their role in venous functioning during volume-pressure overloads. Methods: In a mock circulation, pressure (P) and diameter (D) of different veins (anterior cava, jugular and femoral; from 7 sheep), were registered during cyclical volume-pressure pulses. From the P-D relationship, C, W St and ξ (at low and high P-D levels), η and W D were calculated. Results: For each vein there were P-dependent differences in biomechanical, energetics, and damping capability. There were regional-differences in C, η, W St and W D (p<0.05), but not in ξ. Conclusion: The regional-dependent differences in dynamics and energetics, and regional-similitude in damping could be important to ensure venous functioning during acute overloads. The lower C and higher W St and W D found in back-limb veins (femoral), commonly submitted to high volume-pressure loads (i.e. during walking), could be considered relevant to ensure adequate venous system functionality and venous wall protection simultaneously.

Cerebrospinal fluid dynamics coupled to the global circulation in holistic setting: Mathematical models, numerical methods and applications

“…The same happens in the venous circulation. Zocalo et al 136 showed the importance of the dynamic process of veins walls to understand venous functioning under normal and pathological conditions; pressures and diameters of anterior cava, jugular and femoral veins from sheep were registered during cyclical volume‐pressure pulses. The vein viscosity was higher in the peripheral segments and this could be important in the response to acute overloads and in haemodynamic control.…”

Consistent treatment of viscoelastic effects at junctions in one-dimensional blood flow models

“…By using the mass conservation equation in (1), one can replace the time derivative of A in (3) by the spatial derivative of the flow q. Replacing (2) in the momentum equation in (1) results in a set of PDEs containing second order derivatives.…”

“…By using the mass conservation equation in (1), one can replace the time derivative of A in (3) by the spatial derivative of the flow q. Replacing (2) in the momentum equation in (1) results in a set of PDEs containing second order derivatives. The way this term is treated at vessels edges, especially at junctions, is not clearly established in the literature, as previously discussed in Section 1.…”

“…The viscoelastic behavior of arterial and venous walls is well-known [1,2,3]. It has an impact on fundamental hemodynamic characteristics of the cardiovascular system [4] and plays a determinant role in setting the functional level of the cardiovascular system under physiological and, especially, under pathological conditions such as hypertension [5].…”

Modeling blood flow in networks of viscoelastic vessels with the 1-D augmented fluid-structure interaction system

“…The fluid-structure interaction (FSI) in blood propagation phenomena requires the introduction of a constitutive law which defines the transfer of energy between the two means [12,29,34,56]. Mechanically speaking, rheological properties of arteries and veins are welldescribed by viscoelastic typical features [7,67,73]. Although neglected in some works in favor of simpler elastic models [18,46,65,72], viscoelasticity adds a valuable contribution to the representation of the problem, being able to capture damping effects related to a partial loss of energy occurring during the deformation of the vessel [1,5,12,14,15,16,41,55,67].…”