Chapter30 Aorta

789

Chapter 30: Thoracic Aorta

is usually seen in anticoagulated patients as a blush of contrast around the stent graft on catheter angiography around the time of stent placement. Type V endoleak, also referred to as endotension leak, is a diagnosis of exclusion in which there is expansion of the excluded aortic lumen without a visible con- trast leak. This presumably represents an occult type I to III endoleak. A small endoleak may only be detected on delayed images, so it is important to acquire delayed images in addition to angiographic phase images in post EVAR patients. Additional complications of TEVAR include stent collapse, migration, and ischemia. Ischemic complications occur sec- ondary to occlusion of branch vessels and occur in 30% to 50% of patients with type B aortic dissection. Aortitis The term aortitis refers to inflammation of the aortic wall (specifically the media and/or adventitia), which may be focal/segmental or multifocal, may also affect large and small branch vessels, and is broadly classified into noninfectious and infectious causes. The noninfectious causes are myriad and include numerous primary vasculitides, both large- (e.g., giant cell or Takayasu arteritis) and variable-vessel predominant varieties. Aortitis is also commonly seen in the setting of other rheumatic dis- eases including chronic ankylosing spondylitis, rheumatoid arthritis, and relapsing polychondritis; and aortic valve/vessel disease is an uncommon but known manifestation of IgG4-associated autoimmune disease, systemic lupus erythematosus (SLE), Behçet disease, and the seronegative arthritides—for example, reactive arthritis. Radiation-induced aortitis may manifest as thrombosis, pseudoaneurysm/rupture, stenosis, and accelerated calcification confined to the treated field. Finally, an idiopathic form of aortitis may result in acute and/ or chronic periaortic inflammation, associated with the for- mation of “inflammatory” aortic aneurysms and chronic sec- ondary retroperitoneal inflammation/fibrosis. It is likely that many cases previously thought to represent idiopathic disease were undiagnosed IgG4-associated disease, a multisystem dis- order that has been better understood in the last decade. The native aorta is resistant to infection, but vessel abnor- mality related to atherosclerosis, pre-existing aneurysm, cystic medial necrosis, or other disease renders the vessel more vul- nerable. Classically, infectious aortitis was seen commonly in the setting of tertiary syphilis (also called “luetic” aortitis) and tuberculosis infection, in addition to other bacterial and viral

Figure 30.53.  Endoleak, Type I. Patient status post remote repair of aortic coarctation with two overlapping stents. Small extravasation of contrast ( arrow ) at the junction of these two stents is compatible with a type I endoleak.

in expansion of an aortic aneurysm, pseudoaneurysm, or dis- section false lumen with increased risk for rupture. There are five types of endoleaks. Type I endoleak is most common and occurs at the proximal (type IA) or distal (type IB) margins of the stent graft. Contrast will be seen in the excluded aortic lumen, directly communicating with the prox- imal or distal end of the stented aorta (Fig. 30.53). Type II endoleak is retrograde opacification of the excluded aortic lumen through an aortic branch vessel such as an intercostal or bronchial artery within the thorax and inferior mesenteric or lumbar arteries in the abdomen. Type III endoleak results from device failure, with contrast leaking through a fracture or defect in the stent graft (Fig. 30.54). Type IV endoleak is caused by graft wall porosity and does not require repair. This

A

B

C

Figure 30.54.  Endoleak, Type III. Patient presented with descending thoracic aortic aneurysm rupture into the mediastinum and pleura (axial CT, A ). Postendovascular repair (3D VR, B ) with extravasation of contrast through the graft near the ostium of a stented renal artery ( arrow , axial CT, C ).