Spiral flow may be key to improving peripheral arterial stent performance


A review of haemodynamics in stent development, published in Annals of Biomedical Engineering, suggests that the re-introduction of spiral flow after endovascular treatment for peripheral artery disease (PAD) may support endothelial function and increase patency rates.

The paper—co-authored by Vascular Flow Technologies’ non-executive medical director Graeme Houston—reviews the importance of haemodynamics in stent development as a method of improving patency and longevity of the stent.

Although there has been an increase in the use of stents as treatment for PAD, failure rates are high due to re-narrowing of the stented region (in-stent restenosis) caused by the vessel’s immune response to the stent and the trauma of implantation. Using stent design to re-introduce spiral flow ultimately aims to reduce responses such as neointimal hyperplasia and therefore improve stent and vessel patency rates for PAD patients.

Following successful clinical results of its Spiral Flow vascular grafts, Vascular Flow Technologies (VFT) has developed an arterial spiral inducing stent for the treatment of PAD, which uses a spiral internal ridge to induce helical flow. CFD stimulations showing the spiral outflow of the stent, compared to the disturbed flow found in the outflow of control devices are included in the study. According to VFT, post-operative haematological analysis following Spiral Flow peripheral arterial stent implantation also shows significantly reduced thickening of the arterial walls. The stent is currently in pre-clinical testing.

Bill Allan, CEO of Vascular Flow, comments, “Stent development has traditionally focused on stent failure due to in-stent restenosis and fracture of the frame. This review shows that there is a clear need to address abnormal blood flow before failure rates can be improved.”

Computational fluid dynamics (CFD) and other flow models are used by the authors to investigate the effect of the force and direction of blood flow on a vessel that result from current stent designs. According to the review, potential benefits of inducing spiral flow following PAD treatment include:

  • Increased blood mixing.
  • Reduced blood flow stagnation.
  • Increased protection of the arterial wall due to enhanced oxygen and nutrient delivery.
  • Reduced risk of acute thrombus formation and neointimal hyperplasia in the implant.
  • Reduced size of disturbed flow zones.

These factors have been shown to potentially suppress restenosis after stent implantation.