Endovascular treatment of abdominal aortic aneurysms

Abstract

Patients with abdominal aortic aneurysms (AAAs) are usually treated with endovascular aneurysm repair (EVAR), which has become the standard of care in many hospitals for patients with suitable anatomy. Clinical evidence indicates that EVAR is associated with superior perioperative outcomes and similar long-term survival compared with open repair. Since the randomized, controlled trials that provided this evidence were conducted, however, the stent graft technology for infrarenal AAA has been further developed. Improvements include profile downsizing, optimization of sealing and fixation, and the use of low porosity fabrics. In addition, imaging techniques have improved, enabling better preoperative planning, stent graft placement, and postoperative surveillance. Also in the past few years, fenestrated and branched stent grafts have increasingly been used to manage anatomically challenging aneurysms, and experiments with off-label use of stent grafts have been performed to treat patients deemed unfit or unsuitable for other treatment strategies. Overall, the indications for endovascular management of AAA are expanding to include increasingly complex and anatomically challenging aneurysms. Ongoing studies and optimization of imaging, in addition to technological refinement of stent grafts, will hopefully continue to broaden the utilization of EVAR.

Figure 1

Imaging modalities used in the management of patients with AAA. a | Ultrasonography showing a transverse view of the distal aorta showing the diameter of the vessel. b | Ultrasonography showing a transverse view showing the aortic bifurcation; left and right iliac artery. c | Preoperative and d | postoperative 3D CTA reconstruction for a patient with AAA. e,f | Two postoperative 3D MRA reconstructions for a patient with AAA. g | IVUS demonstrating incomplete expansion of a stent graft in an AAA. Reprinted from Lee, J. T. & White, R. A. Basics of intravascular ultrasound: an essential tool for the endovascular surgeon. Semin. Vasc. Surg. 17, 110–118, Copyright 2004, with permission from Elsevier. h | IVUS demonstrating standard measurement of the aorta at the level of the renal arteries. Reprinted from Marrocco, C. J. et al. Intravascular ultrasound. Semin. Vasc. Surg. 25, 144–152, Copyright 2012, with permission from Elsevier. Abbreviations: AAA, abdominal aortic aneurysm; CTA, computed tomography angiography; IVUS, intravascular ultrasound; MRA, magnetic resonance angiography.

Figure 2

The endoanchor system, which can be used for transmural fixation of an aortic stent graft to the aortic wall at its landing zones.

Figure 3

A fenestrated stent graft. This type of stent graft overcomes the problem of an insufficient infrarenal neck for stent graft implantation in patients with juxtarenal or suprarenal aortic aneurysms, whilst preserving renal and/or mesenteric perfusion.

Figure 4

A chimney graft. Similarly to the fenestrated stent graft, the chimney graft preserves the renal and/or mesenteric perfusion. Notably, however, the chimney graft is cheaper than the fenestrated stent graft, and has broader applicability for emergent cases because customization is not needed.

Figure 5

Endovascular aneurysm repair strategies that enable the revascularization of up to four aortic side branches. a | In the sandwich technique, which can be used in patients not deemed suitable for conventional endovascular aneurysm repair, stents placed in the aortic branches are ‘sandwiched’ between two aortic stent grafts. b | The double two-chimney approach is an alternative to the sandwich technique. Of note, long-term outcomes are not yet available for the sandwich technique or the double two-chimney technique, and both techniques have only been used in situations not listed in the manufacturers’ instructions for use.

Figure 6

An off-the-shelf branched stent graft. These ‘ready to go’ stent grafts have been developed for treatment of patients with complex abdominal aortic aneurysm in the acute setting, as stent customization can lead to substantial treatment delay.

Figure 7

The multilayer stent graft. a | Blood flow through a saccular aortic aneurysm. b | A saccular aortic aneurysm with an increased flow velocity. c | A saccular aortic aneurysm treated with a multilayer stent, which decreases the flow velocity into the aneurysm. d | The blood flow though the multilayer stent as the aortic aneurysm is thrombosed.

Figure 8

The sac-anchoring system, consisting of two femorally inserted stent grafts with polymer-filled endobags on the outside of the stent. The polymer-filled endobags enlarge to a pressure preset to support the stents within the aneurysm sac. The technology eliminates the endoleak space via obliteration of the aortic aneurysm sac.