Abstract
Abdominal aortic aneurysm (AAA) is a focal dilatation of the abdominal aorta. The pathophysiology of AAA is a complex multifactorial process and much is still unknown. Histologic and biochemical analysis of AAA wall characteristics can contribute to a better insight in AAA pathophysiology. To make these characteristics clinically applicable, part
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1 of the thesis focuses on associations between aneurysmal wall degeneration and AAA imaging. The association between aneurysm wall characteristics and aneurysm diameter ratio, defined as the ratio between the native aortic diameter and maximum AAA diameter as well as the association with the thickness of the intraluminal thrombus (ILT) are studied in the first part of this thesis. The second part of the thesis contains studies on dedicated imaging techniques in endovascularly treated patients. Pulsatile distention during the cardiac cycle can be visualized by a dynamic electrocardiogram (ECG)-gated CTA scan. Because young healthy individuals have a large pulsatile distension and since it is known that complications after endovascular aneurysm repair (EVAR) are more often seen in patients with large pulsatile distension, we examined whether a difference in preoperative pulsatile distension between young and old AAA patients could be observed. However, no differences in pulsatile distension were found between older and younger patients. Previous studies on pulsatile distension were not able to correct for potential through-plane movement. Now, we were able to assess the through-plane movement and analyzed the movement of the aorta during the 8 phases of an ECG-gated CTA scan. The through-plane movement was small and at levels relevant for EVAR, around the renal arteries, even smaller. This strengthens previously found results from our studies on dynamic CTA’s. CTA plays also an important role in postoperative imaging surveillance and is the current gold standard for endoleak detection. A review of the literature was performed to examine whether CTA or MRI is more sensitive for the detection of endoleaks in patients after EVAR. This showed that CTA may miss endoleaks and that MRI was able to detect more endoleaks than CTA, especially type II endoleaks. We performed a prospective study in patients with an enlarging aneurysm after EVAR and no or uncertain endoleak on CTA and demonstrated that MRI with a blood pooling contrast agent has additional value for the detection of endoleaks in this selected patient population. In the last part of the thesis we focus on the clinical outcome after EVAR. Long-term results are necessary to judge the durability of EVAR. We evaluated the 4-year follow-up results of one of the current commercially available stent grafts. Although patients with challenging anatomy were treated in our series, secondary intervention rates were comparable to other grafts. The use of a standard stent graft is not possible for the treatment of patients with juxtarenal or suprarenal aneurysms.The chimney technique, which offers an endovascular opportunity for preserving the vascularization of aortic side branches in these patients, appeared to be an acceptable method for exclusion of juxtarenal or suprarenal aneurysms and is a good alternative until off-the-shelf fenestrated endoprostheses become widely available. The last chapter of the thesis provides a summary, general discussion, and future perspectives
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