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The Role of Shear Stress in Arteriovenous Fistula Maturation and Failure: A Systematic Review.

Browne LD, Bashar K, Griffin P, Kavanagh EG, Walsh SR, Walsh MT - PLoS ONE (2015)

Bottom Line: Non-maturation and post-maturation venous stenosis are the primary causes of failure within arteriovenous fistulae (AVFs).A systematic review of studies comparing remodelling data with hemodynamic data obtained from computational fluid dynamics of AVFs during and after maturation was conducted.Further lines of evidence are needed to support the disturbed flow theory and outward remodelling findings before surgical configurations and treatment strategies are optimised to conform to them.

View Article: PubMed Central - PubMed

Affiliation: Centre for Applied Biomedical Engineering Research (CABER), Department of Mechanical, Aeronautical and Biomedical Engineering, Materials and Surface Science Institute, The Health Research Institute, University of Limerick, Limerick, Ireland.

ABSTRACT

Introduction: Non-maturation and post-maturation venous stenosis are the primary causes of failure within arteriovenous fistulae (AVFs). Although the exact mechanisms triggering failure remain unclear, abnormal hemodynamic profiles are thought to mediate vascular remodelling and can adversely impact on fistula patency.

Aim: The review aims to clarify the role of shear stress on outward remodelling during maturation and evaluate the evidence supporting theories related to the localisation and development of intimal hyperplasia within AVFs.

Methods: A systematic review of studies comparing remodelling data with hemodynamic data obtained from computational fluid dynamics of AVFs during and after maturation was conducted.

Results: Outward remodelling occurred to reduce or normalise the level of shear stress over time in fistulae with a large radius of curvature (curved) whereas shear stress was found to augment over time in fistulae with a small radius of curvature (straight) coinciding with minimal to no increases in lumen area. Although this review highlighted that there is a growing body of evidence suggesting low and oscillating shear stress may stimulate the initiation and development of intimal medial thickening within AVFs. Further lines of evidence are needed to support the disturbed flow theory and outward remodelling findings before surgical configurations and treatment strategies are optimised to conform to them. This review highlighted that variation between the time of analysis, classification of IH, resolution of simulations, data processing techniques and omission of various shear stress metrics prevented forming pooling of data amongst studies.

Conclusion: Standardised measurements and data processing techniques are needed to comprehensively evaluate the relationship between shear stress and intimal medial thickening. Advances in image acquisition and flow quantifications coupled with the increasing prevalence of longitudinal studies commencing from fistula creation offer viable techniques and strategies to robustly evaluate the relationship between shear stress and remodelling during maturation and thereafter.

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Related in: MedlinePlus

A section of an artery wall shows the endothelial cells that form the inner lining and align longitudinally in the direction of the flow.Pressure (P) acts normal to the vessel wall, which results in circumferential stretching of the vessel wall. Shear stress (τ) is parallel to the vessel wall and is exerted longitudinally in the direction of blood flow. The intima, media and adventitia layers of an artery and vein are shown. Vascular smooth muscle cells form the outer layers and align circumferentially. IMT refers to intima media thickness.
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pone.0145795.g002: A section of an artery wall shows the endothelial cells that form the inner lining and align longitudinally in the direction of the flow.Pressure (P) acts normal to the vessel wall, which results in circumferential stretching of the vessel wall. Shear stress (τ) is parallel to the vessel wall and is exerted longitudinally in the direction of blood flow. The intima, media and adventitia layers of an artery and vein are shown. Vascular smooth muscle cells form the outer layers and align circumferentially. IMT refers to intima media thickness.

Mentions: Endothelial cells (ECs) which line the internal surface of a blood vessel are important mediators of maturation. ECs are continually exposed to shear stress, compression via blood pressure and to tension from strain in the extracellular matrix (ECM) as shown in [Fig 2]. Each of these factors is known to modulate intracellular signalling pathways and gene expression. Variations of these mechanical factors from the normal level can alter EC function and stimulate remodelling [10–12]. Exposure of a vein to the arterial environment during AVF creation is a paradigm of such.


The Role of Shear Stress in Arteriovenous Fistula Maturation and Failure: A Systematic Review.

Browne LD, Bashar K, Griffin P, Kavanagh EG, Walsh SR, Walsh MT - PLoS ONE (2015)

A section of an artery wall shows the endothelial cells that form the inner lining and align longitudinally in the direction of the flow.Pressure (P) acts normal to the vessel wall, which results in circumferential stretching of the vessel wall. Shear stress (τ) is parallel to the vessel wall and is exerted longitudinally in the direction of blood flow. The intima, media and adventitia layers of an artery and vein are shown. Vascular smooth muscle cells form the outer layers and align circumferentially. IMT refers to intima media thickness.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4696682&req=5

pone.0145795.g002: A section of an artery wall shows the endothelial cells that form the inner lining and align longitudinally in the direction of the flow.Pressure (P) acts normal to the vessel wall, which results in circumferential stretching of the vessel wall. Shear stress (τ) is parallel to the vessel wall and is exerted longitudinally in the direction of blood flow. The intima, media and adventitia layers of an artery and vein are shown. Vascular smooth muscle cells form the outer layers and align circumferentially. IMT refers to intima media thickness.
Mentions: Endothelial cells (ECs) which line the internal surface of a blood vessel are important mediators of maturation. ECs are continually exposed to shear stress, compression via blood pressure and to tension from strain in the extracellular matrix (ECM) as shown in [Fig 2]. Each of these factors is known to modulate intracellular signalling pathways and gene expression. Variations of these mechanical factors from the normal level can alter EC function and stimulate remodelling [10–12]. Exposure of a vein to the arterial environment during AVF creation is a paradigm of such.

Bottom Line: Non-maturation and post-maturation venous stenosis are the primary causes of failure within arteriovenous fistulae (AVFs).A systematic review of studies comparing remodelling data with hemodynamic data obtained from computational fluid dynamics of AVFs during and after maturation was conducted.Further lines of evidence are needed to support the disturbed flow theory and outward remodelling findings before surgical configurations and treatment strategies are optimised to conform to them.

View Article: PubMed Central - PubMed

Affiliation: Centre for Applied Biomedical Engineering Research (CABER), Department of Mechanical, Aeronautical and Biomedical Engineering, Materials and Surface Science Institute, The Health Research Institute, University of Limerick, Limerick, Ireland.

ABSTRACT

Introduction: Non-maturation and post-maturation venous stenosis are the primary causes of failure within arteriovenous fistulae (AVFs). Although the exact mechanisms triggering failure remain unclear, abnormal hemodynamic profiles are thought to mediate vascular remodelling and can adversely impact on fistula patency.

Aim: The review aims to clarify the role of shear stress on outward remodelling during maturation and evaluate the evidence supporting theories related to the localisation and development of intimal hyperplasia within AVFs.

Methods: A systematic review of studies comparing remodelling data with hemodynamic data obtained from computational fluid dynamics of AVFs during and after maturation was conducted.

Results: Outward remodelling occurred to reduce or normalise the level of shear stress over time in fistulae with a large radius of curvature (curved) whereas shear stress was found to augment over time in fistulae with a small radius of curvature (straight) coinciding with minimal to no increases in lumen area. Although this review highlighted that there is a growing body of evidence suggesting low and oscillating shear stress may stimulate the initiation and development of intimal medial thickening within AVFs. Further lines of evidence are needed to support the disturbed flow theory and outward remodelling findings before surgical configurations and treatment strategies are optimised to conform to them. This review highlighted that variation between the time of analysis, classification of IH, resolution of simulations, data processing techniques and omission of various shear stress metrics prevented forming pooling of data amongst studies.

Conclusion: Standardised measurements and data processing techniques are needed to comprehensively evaluate the relationship between shear stress and intimal medial thickening. Advances in image acquisition and flow quantifications coupled with the increasing prevalence of longitudinal studies commencing from fistula creation offer viable techniques and strategies to robustly evaluate the relationship between shear stress and remodelling during maturation and thereafter.

Show MeSH
Related in: MedlinePlus