Abstract
Endovascular therapy in patients suffering from peripheral arterial disease shows high rates of restenosis. The poor clinical outcomes are commonly explained by the demanding mechanical environment due to leg movements, but the mechanisms responsible for restenosis remain unknown. In this study, we hypothesized that restenosis following revascularization is associated with hemodynamical markers derived from blood flow during leg flexion. Therefore, we performed personalized computational fluid dynamics (CFD) analyses of 20 patients, who underwent routine endovascular femoro-popliteal interventions. The CFD analyses were conducted using 3D models of the arterial geometry in straight and flexed positions, which were reconstructed from 2D angiographic images. Based on restenosis rates reported at 6-month follow-up, logistic regression analyses were performed to predict restenosis from hemodynamical parameters. Results showed that severe arterial deformations, such as kinking, induced by leg flexion in stented arteries led to adverse hemodynamic conditions that may trigger restenosis. A logistic regression analysis based solely on hemodynamical markers had an accuracy of 75%, which showed that flow parameters are sufficient to predict restenosis (p = 0.031). However, better predictions were achieved by adding the treatment method in the model. This suggests that a more accurate image acquisition technique is required to capture the localized modifications of blood flow following intervention, especially around the stented artery. This approach, based on the immediate postoperative configuration of the artery, has the potential to identify patients at increased risk of restenosis. Based on this information, clinicians could take preventive measures and more closely follow these patients to avoid complications.
Highlights
Obstructions of the femoro-popliteal (FP) arteries in the lower limbs of the body—clinically called peripheral arterial disease (PAD)—affect about 20% of the population over 70 years of age (Norgren et al 2007)
For the majority of the patients, leg flexion resulted in an increase in the area that was affected by low time-averaged WSS (TAWSS), a decrease in the area affected by high TAWSS, and a decrease in the area affected by high oscillatory shear index (OSI) (Table 2)
Leg flexion caused a statistically significant difference in the areas affected by low TAWSS (p = 0.044), whereas no difference was observed for the patients that only underwent percutaneous transluminal angioplasty (PTA) (p = 0.789; Table 2)
Summary
Obstructions of the femoro-popliteal (FP) arteries in the lower limbs of the body—clinically called peripheral arterial disease (PAD)—affect about 20% of the population over 70 years of age (Norgren et al 2007). Replacing the use of stents as the predominant treatment method for PAD, with stents being implanted only if balloon angioplasty produces sub-optimal results (Casserly 2017) Even with this change in paradigm, the rates of primary patency and freedom from target lesion revascularization (TLR) have not shown significant improvements. This observation is confirmed by long-term outcomes from two recent controlled clinical studies; the 2-year results of the Lutonix SFA Registry report a primary patency of 76% and a TLR rate of 11%, which are similar to the 1-year results observed in the DEFINITIVE AR study (Thieme et al 2017; Zeller et al 2017). These values are more likely to increase in non-controlled clinical trials as real-world outcomes tend to show higher restenosis rates (Iida et al 2015)
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