VasQ and Hemodynamic Conditions in AVFs
Condition: Renal Insufficiency, Chronic
MeSH terms: Renal Insufficiency; Renal Insufficiency, Chronic
Study type: Interventional

Summary: 
      End-stage renal disease (ESRD) is a growing global health problem, strictly connected with
      progressive ageing population and longer survival of patients living on renal replacement
      therapy. The majority of ESRD patients is on hemodialysis (HD) treatment. A successful HD
      procedure requires a functional vascular access (VA) to provide safe and long-lasting way to
      connect patient circulation to the artificial kidney. To date, VA dysfunction is the major
      cause of morbidity and hospitalisation in HD patients, and the major limitation of HD
      treatment. The current recommendation for VA is the native artero-venous fistula (AVF),
      surgically created in the forearm, but is still affected by high non-maturation and early
      failure rates. The most common cause of AVF early-failure is vascular stenosis due to
      neointimal hyperplasia (NH). Despite the exact mechanisms underlying stenosis development
      remain tentative, there is general consensus that hemodynamic conditions play a key role in
      the formation of NH. Previous computational fluid dynamics (CFD) investigations inside
      patient-specific AVF models conducted by our group revealed transitional laminar-to-turbulent
      flow in the juxta-anastomotic vein.

      Various vascular access devices have been designed to incorporate features to regularize the
      hemodynamics and favour spiral flow development in the venous segment of the AVF. The VasQ
      external support device (Laminate Medical Technologies, Israel) is a novel Nitinol implant,
      externally surrounding and supporting the vein and "hugging" the artery near the junction
      site, without being in contact with the blood flow.

      VasQ attempts at constraining and shaping geometrical parameters of the AVF, as well as
      reinforcing the vulnerable perianastomotic vein against high pressure, wall tension and flow
      levels. A prospective single-centre study demonstrated the safety of the VasQ external
      support device, but the effect of its use on hemodynamic conditions and the advantages in
      terms of flow regularization in patient-specific AVFs still need to be investigated.

      A detailed analysis of the local blood flow field in patient-specific AVFs can be obtained
      coupling non contrast-enhanced MRI (NCE-MRI) and high-resolution CFD simulations, using a
      NCE-MRI protocol recently optimized by our group. Our MRI sequence has the advantage of
      providing high-quality images in a short acquisition time of 5-10 minutes compared to other
      MRI protocols that require more than 45 minutes for a single acquisition. Combined with
      high-resolution CFD, our MRI-to-CFD pipeline allowed us to characterize morphological and
      hemodynamic changes in the AVF of one patient at two timepoints, immediately after AVF
      surgery and at AVF maturation. Therefore, it seems to be a promising approach to perform
      morphological and hemodynamic analysis also in AVF created using the VasQ device and can be
      used to elucidate the effects of VasQ device on hemodynamic conditions, as compared to
      hemodynamic conditions present in AVFs created using conventional surgery without the use of
      any device.
    


Intervention name(s): Implantation of VasQ device
Intervention type(s): Device
Intervention description(s): The VasQ external support device (Laminate Medical Technologies, Israel) is a novel Nitinol implant, externally surrounding and supporting the vein and "hugging" the artery near the junction site, without being in contact with the blood flow.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Device Feasibility
Keywords: artero-venous fistula; non-Contrast Enhanced MRI; hemodynamics; CFD simulations; VasQ