In-Vivo Quantification of Femoro-popliteal Artery Deformations: Percutaneous Transluminal Angioplasty vs. Nitinol Stent Placement

Purpose: To quantify the deformations of the femoro-popliteal (FP) arteries in patients undergoing endovascular revascularization of the FP arterial tract and to compare the effects of primary Nitinol stent implantation on the post-treatment arterial deformations with the effects of percutaneous transluminal angioplasty (PTA). Methods: 35 patients with peripheral arterial disease (PAD) were recruited for the study. During endovascular interventions, angiographic images were acquired with the legs straight and with a hip/knee flexion of 20°/70°. Image acquisition was performed before PTA for all patients; after PTA for 17 patients that only underwent balloon angioplasty; and after primary Nitinol stent implantation for the remaining 18 patients. A semi-automatic approach was used to reconstruct the 3D patient-specific artery models from 2D radiographs. Axial shortening and curvature changes in the arteries were calculated in-vivo for the calcified, ballooned and stented regions, as well as the regions that are distal and proximal to the diseased and treated segments. Results: Leg flexion resulted in arterial shortening in all investigated segments. The ballooned arteries exhibited higher shortening compared to their stented counterparts (post-balloon: 7.6% ± 4.9%; post-stent: 3.2% ± 2.9%; P: 0.004). Leg flexion also led to an increase in the curvatures of all the segments of the FP arteries. Although there were no statistically significant differences between the bending behaviors of the arteries treated with different methods, 40% of the stented arteries exhibited arterial kinking during leg flexion. Conclusion: The choice of the treatment method affects the post-interventional axial deformations of the FP arteries, but does not influence their curvatures. While PTA results in a more flexible artery, stents restrict the arteries’ shortening capabilities. Depending on the anatomical position of the stents, this axial stiffening of the arteries may lead to chronic kinking, which may cause occlusions and, consequently, impact the long-term success of the procedure.