P5.5 Compensatory Effect Between Aortic Stiffening and Remodelling During Ageing

Abstract

The arterial tree exhibits a complex spatio-temporal wave pattern, whose healthy behaviour depends on a subtle balance between mechanical and geometrical properties. Several clinical studies demonstrated that such a balance progressively breaks down during ageing, when the aorta stiffens and remodels by increasing its diameter. These two degenerative processes however, have different impacts on the arterial wave pattern. They both tend to compensate for each other, thus reducing the detrimental effect they would have had if they had arisen individually. This remarkable compensatory mechanism is investigated by a validated multi-scale model, with the aim to elucidate how aortic stiffening and remodelling quantitatively impact the complex interplay between forward and reflected backward waves in the arterial network. We focus on the aorta and on the pressure at the ventricular-aortic interface, which epidemiological studies demonstrate to play a key role in cardiovascular diseases.

P5.4 Central Pressure Appraisal: Clinical Validation of a Subject-Specific Mathematical Model

“…Forward pressure waves generated by systolic contraction propagate through the arterial tree, and they are partially reflected at every impedance mismatch generating backward propagating pressure waves. These backward propagating waves are further reflected at upstream bifurcation, creating a complex pattern rapidly smoothed out by blood and vessel wall viscosity [12]. Therefore, arterial pressure in a given measurement location results from the sum of the location-specific forward and backward components.…”

“…The mathematical model used for central pressure appraisal has been previously presented and described [9,12,13]. Blood flow/pressure dynamics in the large artery network are described by one-dimensional modeling, which includes the non-linear viscoelasticity of the arterial walls, while left ventricle, its valves and distal microcirculation are described by lumped models.…”

“…In particular, multi-scale models-most of them relying on a one-dimensional description of the wave propagation through the large arteries and on a simpler zero-dimensional characterization of the left ventricle, aortic valve and microcirculation-are now being used in a number studies. E.g., to analyze the pressure waveforms [9,12], the coronary function [9,13], and the effect of the aortic shape [11].…”

Influence of ageing on human body blood flow and heat transfer: A detailed computational modelling study

“…Modelling of these components was validated against experimental data and the global methodology was shown to achieve excellent agreement between simulations and flow measurements. Another relevant study was carried out by Guala et al, which proposed a modelling strategy describing aortic stiffening and remodelling compensation during ageing. Zulliger and Stergiopulos provided a valuable contribution on vascular ageing, by proposing a new strain energy function accounting for ageing in the human aorta.…”