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Compensatory Effect between Aortic Stiffening and Remodelling during Ageing.

Guala A, Camporeale C, Ridolfi L - PLoS ONE (2015)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: DIATI, Politecnico di Torino, Torino, Italy.

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.

No MeSH data available.


Related in: MedlinePlus

Left: Systolic pressure along the aorta at different ages. From top to down: (a) physiologic ageing, (b) ageing without increase of pulse wave velocity and (c) ageing without plastic geometric remodelling. Distances are normalized to aortic length. From 20 to 80 years of age, with 10 years step. The darker the younger (see arrows). Right: characteristic impedance at different ages along the aorta (the inset shows aortic root values with age)(d), LV work during ageing (e) and LV pressure-volume loops at 80 years old (f) for complete ageing (continuous line) and in the absence of arterial stiffening (dashed line) and remodelling (dotted line).
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pone.0139211.g003: Left: Systolic pressure along the aorta at different ages. From top to down: (a) physiologic ageing, (b) ageing without increase of pulse wave velocity and (c) ageing without plastic geometric remodelling. Distances are normalized to aortic length. From 20 to 80 years of age, with 10 years step. The darker the younger (see arrows). Right: characteristic impedance at different ages along the aorta (the inset shows aortic root values with age)(d), LV work during ageing (e) and LV pressure-volume loops at 80 years old (f) for complete ageing (continuous line) and in the absence of arterial stiffening (dashed line) and remodelling (dotted line).

Mentions: Fig 3 focuses on the effects of ageing along the aorta. As already shown by Pedley [35], systolic pressure increases downstream, but key features become apparent when ageing is properly modelled. Coherently with in-vivo observations [43–45], simulations highlight a local peak at the thoracic aorta for young people (see Fig 3a). This aspect has so far been unexplored and has two causes. Firstly, aorta tapering entails an increment of the characteristic impedance moving away from the heart: in fact, Fig 3d shows an eight-fold increase of ZC from the root to the abdominal section, especially marked at thoracic sections [43]. A large amount of diffused reflections are thus generated at the thoracic aorta, and add to forward waves enhancing the amplification just upstream from this region. Secondly, backward pressure waves from the iliac bifurcation encounter a progressive reduction of characteristic impedance at the thoracic segment, which generates diffuse negative re-reflections that propagate downstream, reducing pressure after the peak. This second cause is mirrored for forward waves in the negative reflection coefficient of the renal bifurcations (Fig 2a–2c). In summary, negative reflected waves are subtracted from forward waves after the thoracic section, contributing to the local minimum.


Compensatory Effect between Aortic Stiffening and Remodelling during Ageing.

Guala A, Camporeale C, Ridolfi L - PLoS ONE (2015)

Left: Systolic pressure along the aorta at different ages. From top to down: (a) physiologic ageing, (b) ageing without increase of pulse wave velocity and (c) ageing without plastic geometric remodelling. Distances are normalized to aortic length. From 20 to 80 years of age, with 10 years step. The darker the younger (see arrows). Right: characteristic impedance at different ages along the aorta (the inset shows aortic root values with age)(d), LV work during ageing (e) and LV pressure-volume loops at 80 years old (f) for complete ageing (continuous line) and in the absence of arterial stiffening (dashed line) and remodelling (dotted line).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4591291&req=5

pone.0139211.g003: Left: Systolic pressure along the aorta at different ages. From top to down: (a) physiologic ageing, (b) ageing without increase of pulse wave velocity and (c) ageing without plastic geometric remodelling. Distances are normalized to aortic length. From 20 to 80 years of age, with 10 years step. The darker the younger (see arrows). Right: characteristic impedance at different ages along the aorta (the inset shows aortic root values with age)(d), LV work during ageing (e) and LV pressure-volume loops at 80 years old (f) for complete ageing (continuous line) and in the absence of arterial stiffening (dashed line) and remodelling (dotted line).
Mentions: Fig 3 focuses on the effects of ageing along the aorta. As already shown by Pedley [35], systolic pressure increases downstream, but key features become apparent when ageing is properly modelled. Coherently with in-vivo observations [43–45], simulations highlight a local peak at the thoracic aorta for young people (see Fig 3a). This aspect has so far been unexplored and has two causes. Firstly, aorta tapering entails an increment of the characteristic impedance moving away from the heart: in fact, Fig 3d shows an eight-fold increase of ZC from the root to the abdominal section, especially marked at thoracic sections [43]. A large amount of diffused reflections are thus generated at the thoracic aorta, and add to forward waves enhancing the amplification just upstream from this region. Secondly, backward pressure waves from the iliac bifurcation encounter a progressive reduction of characteristic impedance at the thoracic segment, which generates diffuse negative re-reflections that propagate downstream, reducing pressure after the peak. This second cause is mirrored for forward waves in the negative reflection coefficient of the renal bifurcations (Fig 2a–2c). In summary, negative reflected waves are subtracted from forward waves after the thoracic section, contributing to the local minimum.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: DIATI, Politecnico di Torino, Torino, Italy.

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.

No MeSH data available.


Related in: MedlinePlus