Computational Modelling of Nitinol Guidewires in Anatomically Relevant Tortuous Paths

Guidewires are thin, flexible wires designed to navigate complex vascular pathways and direct larger medical devices, such as stents, to their target locations. However, guidewires, including those made from Nitinol, can exhibit undesirable phenomena such as “lag” and “whip,” where input rotations are not accurately transmitted to the output end, hindering control and risking tissue damage. The mechanisms driving these behaviours remain poorly understood.

Previous research by the authors has highlighted the role of phase transformations in Nitinol wires for causing these undesirable phenomena. As the wires rotates in the curved path, the material cycles from tension to compression and undergoes reversible martensitic transformation during which energy is dissipated.

Here, we expand on previous research by performing detailed validation of the simulations using a bench-top experiment whereby the angle of twist along the wire is recorded with a vison-based measurement system and subsequently compared to simulations across different path geometries and guidewires. Verification in line with ASME V&V40 is also performed.

Considering tortuous paths with a variety of path radii and straight sections reveals the complex behaviour whereby energy is stored elastically, when the guidewire acts as torsional spring, and dissipated during material transformations. This allows for a more complete understanding of how a guidewire will behave in an anatomically relevant tortuous path.