Comparative evaluation of ballet-type and conventional stent graft configurations for endovascular aneurysm repair: A CFD analysis

Abstract

PURPOSE: Cross limb stent graft (SG) configuration technique for endovascular aneurysm repair (EVAR) is employed for splayed aortic bifurcations to avoid device kinking and smoothen cannulation. The present study investigates three types of stent graft (SG) configurations for endovascular aneurysm repair (EVAR) in abdominal aortic aneurysm. A computational fluid dynamic analysis was performed on the pulsatile non-Newtonian flow characteristics in three ideally modeled geometries of abdominal aortic (AA) SG configurations. METHODS: The three planar and crosslimb SG configurations were ideally modeled, namely, top-down nonballet-type, top-down ballet-type, and bottom-up nonballet-type configurations. In top-down SG configuration, most of the device is deployed in the main body in the vicinity of renal artery and the limbs are extended to the iliac artery. While in the bottom-up configuration, some of the SG device is deployed in the main body, the limbs are deployed in aortic bifurcation, and the extra stent graft of the main body is extended to the proximal aorta until the below of the renal artery. The effects of non-Newtonian pulsatile flow on the wall stresses and flow patterns of the three models were investigated and compared. Moreover, the average wall shear stress (AWSS), oscillatory shear stress index (OSI), absolute helicity, pressure distribution, graft displacement and flow visualization plots were analyzed. RESULTS: The top-down ballet-type showed less branch blockage effect than the top-down nonballet-type models. Furthermore, the top-down ballet-type configuration showed an increased tendency to sustain high WSS and higher helicity characteristics than that of the bottom-up and top-down non-ballet type configurations. However, displacement forces of the top-down ballet-type configuration were 40%and 9.6%higher than those of the bottom-up and top-down nonballet-type configurations, respectively. CONCLUSIONS: Some complications such as graft tearing, thrombus formation, limb disconnection during long term follow up periods might be relevant to hemodynamic characteristics according to the configurations of EVAR. Hence, the reported data required to be validated with the clinical results.

DANCER: Study protocol of a prospective, non-randomized controlled trial for crossed limb versus standard limb configuration in endovascular abdominal aortic aneurysm repair

“…While in our previous cohort study, which was characterized by the largest sample size and additional subgroup analysis, patients with large aneurysm sac and tortuous iliac arteries encountered fewer type I endoleaks in the CL group ( 22 ). This conclusion was consistent with a recent hemodynamic study revealing that this non-standard configuration could sustain higher wall shear stress and helicity characteristics ( 16 , 17 ). However, it was questioned that it may be modified delivering system, instead of CL, that improved prognosis ( 36 ).…”

“…For efficacy of the CL in practice, however, related studies have drawn inconsistent conclusions, which makes the true effect of CL doubtful. By analysis of computed fluid dynamics, CL showed a tendency to prevent stent thrombosis, accompanied by tolerance for higher wall shear stress and helicity characteristics ( 16 , 17 ). On the contrary, long-term fatigue and displacement implications were revealed by the same studies and another one demonstrated that it was the angle of the aneurysm neck other than the configuration that affected hemodynamic index ( 18 ).…”

Contralateral Snare Cannulation vs. Retrograde Gate Cannulation during Endovascular Aortic Repair in Difficult Iliac Artery Anatomy: A Single Center Experience

“…However, the postoperative outcomes of this technique have yet to be clarified, and no indications or contraindications have been described. A recent study has shown that this configuration supported high wall shear stress and helicity characteristics [ 11 , 12 ]. Alternatively, brachial access can be performed, but this approach is associated with several complications, such as bleeding and thrombosis [ 13 ].…”

The impact of endovascular stents types on perioperative outcomes of ruptured abdominal aortic aneurysms: a single-center experience

“…Given the extensive utilization of EVAR in managing rAAA, the choice of endovascular stents, as a critical determinant, can significantly impact surgical procedures and prognostic outcomes ( 7 , 8 ). Presently, a variety of endovascular stents with distinct characteristics and delivery platforms are available for EVAR implementation.…”