Surrounding tissues affect the passive mechanics of the vessel wall: theory and experiment

Abstract

The stress and strain in the vessel wall are important determinants of vascular physiology and pathophysiology. Vessels are constrained radially by the surrounding tissue. The hypothesis in this work is that the surrounding tissue takes up a considerable portion of the intravascular pressure and significantly reduces the wall strain and stress. Ten swine of either sex were used to test this hypothesis. An impedance catheter was inserted into the carotid or femoral artery, and after mechanical preconditioning pressure-cross-sectional area relations were obtained with the surrounding tissue intact and dissected away (untethered), respectively. The radial constraint of the surrounding tissue was quantified as an effective perivascular pressure on the outer surface of the vessel, which was estimated as 50% or more of the intravascular pressure. For carotid arteries at pressure of 100 mmHg, the circumferential wall stretch ratio in the intact state was approximately 20% lower than in the untethered state and the average circumferential stress was reduced by approximately 70%. For femoral arteries, the reductions were approximately 15% and 70%, respectively. These experimental data support the proposed hypothesis and suggest that in vitro and in vivo measurements of the mechanical properties of vessels must be interpreted with consideration of the constraint of the surrounding tissue.

Geometric multiscale modeling of the cardiovascular system, between theory and practice

“…For tuning α ST , we refer the reader to [43,112]. Under several regularity assumptions, these data may guarantee well posedness to the coupled fluid-structure problem, see e.g.…”

Inexact accurate partitioned algorithms for fluid–structure interaction problems with finite elasticity in haemodynamics

“…At the fluid outlets, we used an absorbing resistance boundary condition, see [42,50,41] for details. At the external surface Σ 0 out we prescribed a Robin boundary condition with Robin coefficient α e with the aim of modeling the presence of a surrounding tissue around the vessel [35,38,10,41]. In particular, we set α e = 3 · 10 6 dyne/cm 3 .…”

Effects of material, coating, design and plaque composition on stent deployment inside a stenotic artery—Finite element simulation

“…As shown in Liu et al (2007), the artery deformation, subjected to internal pressure, is considerably less in the presence of surrounding tissues when compared to the untethered case. This indicates the importance of considering surrounding medium in modelling of stent deployment, which however has often been neglected by modellers.…”

“…We plan to take this into account in our future studies of the stent-artery system. According to published work (Liu et al, 2007;Kim et al, 2013), neglecting of surrounding tissues will make the artery less stiff and easier to deform, consequently leading to increased expansion during 20 balloon inflation and reduced recoiling during deflation. To quantify such effect, a significant amount of new work needs to be carried out which is beyond the scope of the current paper.…”