This is a national multicenter study with 25 patients with a complex AAA undergoing endovascular repair with the Fenestrated TREO™ stent graft. ECG and respiratory-gated CT scans will be performed pre-operatively, at discharge, after 6 months, and after 12 months follow up. If stent movement is still present in after 12 months, then another scan will be taken at 24 months. To include respiratory gated with the ECG-gated, patients will undergo ECG-gated CT scan during an inspiration breath-hold as well as an expiration breath-hold. This double gated CT scans will allow us to analyse the movement of the stent graft caused by the cardiac cycle and respiratory cycle.

The duration of this study is 2.5 years.

Fenestrated endovascular aortic repair (F-EVAR) uses stent grafts with customized fenestrations to treat complex aortic aneurysms in patients at risk of aneurysm rupture. The long-term durability of these stent grafts is hindered by complications requiring reintervention. Especially the perirenal fixation and sealing area is of vital importance. The customized fenestrations in the stent graft are cannulated with stents into the renal and/or mesenteric arteries, challenging the perirenal fixation. Once implanted, the aorta dynamics and the device affect each other in ways that are currently not understood. Pre and post- operative imaging of aortic aneurysm is routinely performed using computerized tomographic angiography (CTA). However, these static techniques do not consider the aorta dynamics. Consequently, our understanding of the dynamic behavior of the stent graft and stented target vessels is limited. ECG-gated CTA is a technique that takes the patient's heart cycle into account and taking the ECG-gated CTA during inspiration and during expiration takes the patients respiratory motion into account, creating a double gated CT scan. This double gated CTA enables studying the motion of aorta and implanted devices.

Inclusion Criteria:

• Asymptomatic AAA,
• Age > 65
• Indication for AAA treatment according to standard practice
• Anatomic suitability for the fenestrated Treo stent graft
• At least one stentable main renal artery and one other stentable renal or mesenteric artery
• Being able to hold their breath for 10 seconds.

Exclusion Criteria:

• No informed consent obtained
• eGFR < 30 ml/min
• Allergy for intra venous contrast fluid.

The study population consists of 25 patients with an abdominal aortic aneurysms to be treated with F-EVAR, aged >65. The study population are patients from either Medisch Spectrum Twente (MST), Rijnstate Ziekenhuis, Jeroen Bosch Ziekenhuis, Amsterdam UMC, UMC Utrecht and Zuyderland Medisch Centrum.