Shear accumulation as a means for evaluating risk of thromboembolic events in novel endovascular stent graft designs.

OBJECTIVE: This study proposes to establish a simulation-based technique for evaluating shear accumulation in stent grafts and to use the technique to assess the performance of a novel branched stent graft system.

METHODS: Computational fluid dynamics models, with transient boundary conditions, particle injection, and rigid walls, simplifying assumptions were developed and used to evaluate the shear accumulation in various stent graft configurations with a healthy aorta as comparison.

RESULTS: Shear streamlines are presented for the various configurations. Shear accumulation was also calculated for each configuration. The number of particles with shear accumulations >3.5 Pa-s for each configuration was compared with the shear accumulation values of commercially available mechanical aortic valves from the literature.

CONCLUSIONS: The stent graft configuration with the diaphragm does have particles with shear accumulation >3.5 Pa-s. However, the percentage of particles with shear accumulation above 3.5 Pa-s is less than the two commercially available mechanical aortic valves, and more surprisingly, is smaller than in the healthy aorta.