Objective: To assess the effect of stent compression on FDS porosity, evaluate the influence of single and overlapping implantation of FDS on intra-aneurysmal flow profiles, and correlate stent porosity with changes of static mean intra-aneurysmal pressure.
Methods: Intra-aneurysmal time-density curves were recorded in a pulsatile in vitro flow model before and after implantation of FDS (Pipeline Embolization Device; ev3) in seven different types of aneurysm models. Reduction of the maximum contrast inflow and time to maximum intra-aneurysmal contrast were calculated. Micro-CT was performed and compression-related FDS-porosity was measured. Influence of FDS placement on mean static intra-aneurysmal pressure was measured.
Results: FDS compression resulted in an almost linear reduction of stent porosity. Stent porosity (struts/mm) correlated significantly with the reduction of aneurysm contrast inflow (R2=0.81, p<0.001) and delay until maximum contrast (R2=0.34, p=0.001). Circulating intra-aneurysmal high-velocity flow was terminated in all sidewall models after implantation of a single stent. Superimposition of two stents reduced maximum intra-aneurysmal contrast by 69.1+/-3.1% (mean+/-1SD) in narrow-neck sidewall aneurysm models, whereas no substantial reduction of maximum intra-aneurysmal contrast was observed in wide-neck sidewall aneurysm models. Intra-aneurysmal mean static pressure did not correlate with FDS porosity or number of implanted stents.
Conclusion: Implantation of FDS effectively reduces aneurysm inflow in a porosity-dependent way, without relevantly affecting static mean intra-aneurysmal pressure.
From: Implantation of Pipeline Flow-Diverting Stents Reduces Aneurysm Inflow Without Relevantly Affecting Static Intra-Aneurysmal Pressure by Kerl et al.