Outcomes of Open Surgery for Popliteal Artery Aneurysms:An 18-Year Experience in a Single Institution in Japan

Objective: To elucidate the outcomes of open surgery for popliteal artery aneurysm (PAA) in a single Japanese institution. Materials and Methods: Between 1999 and 2016, 35 patients (44 PAAs) underwent open surgery in our department. The first-line surgical strategy involved the medial approach, with excision of the aneurysm sac and autologous vein bypass grafting. Associations between the outcomes and 1) the surgical management of the aneurysmal sac (aneurysmectomy vs. ligation with bypass) and 2) the preoperative clinical symptoms were evaluated. Results: There were no aneurysm-related deaths during the follow-up period (mean, 4 years;range, 1 - 17.6 years). The 5-year primary, primary-assisted, and secondary patency rates were 67.9%, 72.7%, and 94.5%, respectively. Re-intervention was required for 19 PAAs (14 patients), including two PAAs in patients with suspected Behçet’s disease. Patency rates did not differ between the aneurysmectomy and ligation groups. Remnant sac enlargement occurred in 3 cases. Among asymptomatic patients, clinical symptoms did not deteriorate;however, the ankle brachial pressure index decreased ≥0.15 in patients with artery-graft mismatching. Conclusion: Patency rates were good, and our modified ligation with bypass procedure, which involves excising the sac as much as possible, exhibited less risk in terms of remnant sac enlargement compared to that in previous studies.

Impact of leg bending in the patient-specific computational fluid dynamics of popliteal stenting

Endovascular treatment of the femoro-popliteal artery has recently become a valuable therapeutic option for popliteal arterial aneurysms.However,its efficacy remains controversial due to the relatively high rate of complications,such as stent occlusion as result of intra-stent thrombosis.The elucidation of the interplay among vessel geometrical features,local hemodynamics,and leg bending seems crucial to understand onset and progression of popliteal intra-stent thrombosis.To this aim,patient-specific computational fluid dynamic simulations were performed in order to assess the intra-stent hemodynamics of two patients endovascularly treated for popliteal arterial aneurysm by stent-grafts and experiencing intra-stent thrombosis.Both Newtonian and non-Newtonian blood rheological models were considered.Results were presented in terms of tortuosity,luminal area exposed to low(<0.4 Pa)and high(>1.5 Pa)time-averaged wall shear stress(TAWSS),area exposed to high(>0.3)oscillatory shear index(OSI),and flow helicity.Study outcomes demonstrated that leg bending induced significant hemodynamic differences(>50%increase)in both patients for all the considered variables,except for OSI in one of the two considered patients.In both leg configurations,stent-graft overlapping induced a severe discontinuity of the lumen diameter where the proximal stented zone is characterized by low tortuosity,low velocity,low helicity,low TAWSS,and high OSI;while the distal part has higher tortuosity,velocity,helicity,TAWSS,and lower OSI.Sensitivity study on applied boundary conditions showed that the different inlet velocity profiles for a given inlet waveform affect slightly the numerical solution;conversely,the shape and magnitude of the prescribed inlet waveform is determinant.Focusing on the comparison between the Newtonian and non-Newtonian blood models,the area with low TAWSS is greater in the Newtonian model for both patients,while no significant difference occurs between the surfaces with high TAWSS.