Successful use of retrograde branched extension limb assembling technique in endovascular repair of pararenal abdominal aortic aneurysm

Retrograde branched extension limb assembling stent of pararenal abdominal aortic aneurysm: A longitudinal hemodynamic analysis for stent graft migration

PURPOSE

Pararenal abdominal aortic aneurysms (PRAAAs) are a life-threatening disease, and hemodynamic analysis may provide greater insight into the effectiveness and long-term outcomes of endovascular aneurysm repair (EVAR). However, the lack of patient-specific boundary conditions on the periphery compromises the accuracy. Windkessel (WK) boundary conditions coupled to hemodynamic follow-up models of a PRAAA patient, aims to provide insights into the link between hemodynamics and poor prognosis.

METHOD

One PRAAA patient underwent EVAR and reintervention after one branch of stent-graft (SG) had migrated. Totally five computational follow-up models were studied. Patient-specific flow data acquired via ultrasound were used to define the boundary conditions in the ascending aorta and the following three branches. Coupled zero-dimensional WK models representing the distal vasculature were used to define the outlet boundary conditions under the abdomen.

RESULTS

Flow divisions of the main SG branches were 40.7% and 24.7%, respectively. Time-averaged wall shear stress and oscillatory shear index (OSI) increased at the junction connected the SG branch and the stent leading to the right common iliac artery (RCIA) where the stent migrated. The OSI and relative residence time (RRT) value in superior mesenteric artery increased notably after the migration, the RRT continuously increased following the reintervention.

CONCLUSION

Unbalanced flow, resulting in locally high-speed flow, high WSS and OSI might significantly affect stent stability. Results suggest that diameters and interconnection design of stents in complex cases should take the flow division into consideration and computational simulations might be considered as a tool for intervention protocol design.

Retrograde Branched Endovascular Repair as a Feasible Option to Treat Complex Aortic Aneurysm Using the Retrograde Branched Extension Limb Assembling Technique

PURPOSE

To present the primary experiences in treating suprarenal aneurysms, juxtarenal aneurysms, thoracoabdominal aortic aneurysms, and aneurysms after dissection with hostile anatomical features using the retrograde branched extension limb assembling (REBEL) technique.

MATERIALS AND METHODS

The study included 23 consecutive patients undergoing total endovascular repair with the REBEL technique from August 2014 to January 2019. Twelve patients had abdominal aortic aneurysms (4 juxtarenal, 8 suprarenal), 6 had thoracoabdominal aortic aneurysms (type IV), and 5 had postdissection aneurysms. The patients were unsuitable for treatment with current off-the-shelf devices or required emergent repair. The evaluated outcomes were technical success, operative mortality, complication morbidity, late survival, endoleakage, and reintervention during follow-up.

RESULTS

Technical success rate was 100%. In total, 60 visceral vessels were targeted (38 renal arteries, 1 accessory renal artery, 14 superior arteries, and 7 celiac arteries). The mean follow-up period was 20.1 ± 15.1 months (range 2-56), and no aneurysm-related mortality occurred during follow-up. No occlusion of target vessels occurred. Two type II endoleaks and 1 stent migration occurred in 3 (13.0%) patients, and reinterventions were successfully performed. One patient (4.3%) died of myocardial infarction at 38 months.

CONCLUSIONS

The REBEL technique is a feasible option with acceptable results for complex aortic aneurysms. Long-term follow-up of a large sample size is needed to determine the efficacy and durability of this novel technique.