A two-stage model of an arteriovenous fistula maturation process

Abstract

Purpose: An arteriovenous fistula has been a widely accepted vascular access for hemodialysis, however, a fistula maturation proces is still not fully understood. In the short period of time, right after vein and artery shunting, the physical and biological changes take place mainly in the venous wall. A two-stage modeling method of arteriovenous fistula maturation process was proposed and presented. Methods: The first stage of the maturation was modeled with two-way coupled fluid structure interaction computer simulations. Whereas for the second, biological stage, a model was based on the change in the elasticity of the venous wall due to wall shear stress (WSS) modifications. Results: The relation between stress and radial and circumferential strain, based on Lame’s theory, makes possible to introduce a mathematical model defining modulus of elasticity, averaged WSS, and venous diameter as time functions. The presented model enables one to predict changes in the monitored parameters in the arteriovenous fistula taking place in the time longer than 90 days. Conclusions: We found that probably the majority of fistulas can be assessed to be mature too early, when the adequate blood flow rate is achieved but mean WSS still remains at the non-physiological level (>10 Pa).

Fluid structure interaction versus rigid‐wall approach in the study of the symptomatic stenosed carotid artery: Importance of wall compliance and resilience of loose connective tissue

“…The mesh representing the walls (Figure 4), consisting of 146,221 elements, was significantly coarser than the fluid one (av. Skewness = 0.312) as structural computing is much more time‐demanding than fluid flow calculations 36 …”

“…The same value of the ratio was used in other FSI studies on blood flows presented in. 19,20,27,35,36 As the mass matrix is built within structural calculations, the arterial wall was assumed to be an isotropic and one-layered structure with density equal to 1060 kg/m 3 .…”

“…Skewness = 0.312) as structural computing is much more time-demanding than fluid flow calculations. 36…”

Hemodiyaliz için arteriyovenöz fistül oluşturulmasında lokal anestezi ve bölgesel blok anestezi tekniklerinin karşılaştırılması

“…However, th s durat on may prolong up to 16 weeks n certa n pat ents w th vascular compl cat ons. Maturat on of an AVF s a complex process w th several hemodynam c factors play ng a key role n b olog cal response 22 . e reasons for an nadequate maturat on may nclude accessory ve ns, d abetes mell tus and the use of platelet aggregat on nhb tors 23 .…”

Influence of Wall Compliance on the Flow Patterns in a Patient-Specific Brachio-Cephalic Arterio-Venous Fistula

“…De Villiers et al [4] performed FSI modeling in a patient-specific AVF and compared it to flow in vivo using four-dimensional (4D) magnetic resonance imaging (MRI); while flow patterns matched, quantitatively, there was a significant difference between the FSI and MRI due to the inaccuracy in spatial and temporal resolution of MRI. Jodko et al [5] examined the maturation process in a patient-specific AVF through two stages using FSI simulations. The first stage modeled was after AVF creation, where the vein begins dilating.…”