validation of endovascular aneurysm sealing for treatment of abdominal aortic aneurysm
Infrarenal abdominal aortic aneurysm (AAA) is dilation of the infrarenal aorta of more than twice the normal diameter. The risk of AAA rupture increases with size. The standard treatment of infrarenal AAA is endovascular aneurysm repair (EVAR), in which the diseased part of the aorta is supported by a stent that provides flow lumens to both legs. The EVAR stent components are oversized in the landing zones proximal and distal to the aneurysm to achieve aneurysm seal and anatomical fixation. Endovascular aneurysm sealing (EVAS) is a new treatment for infrarenal AAA. The EVAS endosystem consists of two parallel stents, that are each surrounded by an endobag that is filled with polymer to achieve aneurysm seal and anatomical fixation. In this thesis several features of the EVAS therapy have been studied.
Proper filling of endobags is needed for adequate AAA exclusion and EVAS stent fixation. In this thesis, the reproducibility and precision of preoperative computed tomography angiography (CTA) aortoiliac flow lumen measurements in estimating endobag fill volume has been studied. In addition, aortoiliac changes post-EVAS were assessed to study conformability of the EVAS endosystem to the anatomy, which is important for predictable (stent) sizing and positioning.
EVAR in patients with an infrarenal AAA and a common iliac aneurysm has been associated with a higher incidence of complications due to a short or missing distal seal zone. In this thesis clinical outcomes of EVAS in common iliac artery aneurysms have been studied.
The transition of the aortic flow lumen into two 10-mm in diameter stents after EVAS may enhance blood recirculation in the aorta proximal to the endobags with a risk of thrombus formation. In vitro research has been performed to study flow recirculation in the suprarenal aorta, renal artery and common iliac artery after EVAS and EVAR compared to the flow in an unstented aneurysm model. In addition, flow after EVAS in different infrarenal aortic neck diameters was studied.
Chimney endovascular aneurysm repair (ch-EVAR) for treatment of a juxtarenal AAA is associated with gutter formation and chimney stent graft compression. Gutter formation and chimney stent graft compression may affect aneurysm seal and chimney stent graft lumen patency, respectively. In vitro research has been performed to study gutter formation, chimney stent graft compression and renal flow in ch-EVAR and chimney endovascular aneurysm sealing (ch-EVAS) configurations.
This thesis provided answers to some (pre-)clinical questions regarding EVAS. The outcomes of in vitro research should be further studied in a clinical setting. Long-term clinical outcomes are needed to demonstrate sustainability of EVAS for treatment of AAA.
