Thoracic Aortitis

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CHAPTER 95 Thoracic Aortitis

Aortitis is often characterized by inflammation of the media and adventitia.1 Aortitis has many causes and may be related to autoimmune diseases or noninfectious causes as well as infection by microorganisms. Aortitis belongs to the group of diseases collectively known as the large-vessel vasculitides, as defined by the Chapel Hill Consensus Conference on the classification of systemic vasculitides.2 Regardless of the source, inflammation of the aorta often results in dilation of the aortic root and aortic insufficiency. As a consequence, aortic valve replacement with aortic root reconstruction is often needed. It can be divided into an acute inflammatory phase and a chronic fibrotic phase.

Classification can be based on whether the aortitis is inflammatory. Other classification systems are based on whether the cause is associated with antineutrophil cytoplasmic antibodies. The exact cause is often difficult to define with certainty (Table 95-1).

TABLE 95-1 Classification of Aortitis

Infectious Noninfectious
Syphilis

Nonspecific aortic inflammation can also be seen in atherosclerosis. Because assessment of the vessel wall is critical in these patients, magnetic resonance angiography (MRA) or computed tomographic angiography (CTA) is preferred to conventional angiography. In general, inflammatory aortitis tends to affect the thoracic aorta rather than the abdominal aorta, whereas atherosclerosis affects the abdominal aorta.3

The more common diseases are discussed in this chapter.

TAKAYASU ARTERITIS

Manifestations of Disease

Clinical Presentation

Usual presenting symptoms are systemic or constitutional—fatigue, weakness, arthralgias, weight loss, and low-grade fever—probably secondary to released cytokines. Vascular symptoms are rare at presentation; when they do develop, it is secondary to dilation or stenosis of the affected vessels. Classically, the disease is characterized by stenosis, but the incidence of aneurysmal lesions is increasing (30% to 50%).7 Patients may present in heart failure secondary to aortic dilation and regurgitation. Late-phase symptoms include diminished or absent pulses, bruits, hypertension, and heart failure (Fig. 95-1). Dissection is possible, but giant cell arteritis has a higher incidence.

Subclavian artery involvement is very common and often results in a blood pressure difference between the arms of more than 10 mm Hg. Lesions proximal to the vertebral artery may result in amaurosis fugax and subclavian steal. Up to 50% of patients have involvement of the pulmonary arteries.8 Pulmonary artery involvement can give rise to chest pain, dyspnea, hemoptysis, and pulmonary hypertension,9 but pulmonary function is generally not compromised despite extensive involvement, although unilateral pulmonary artery occlusion has been reported.10 Most frequently affected arteries apart from the aorta are subclavian (90%), carotid (45%), vertebral (25%), and renal (20%).11 Angina secondary to coronary ostial narrowing or coronary involvement is also possible. Affected arteries need to have vasa vasorum and are thus muscular, a feature lacking in peripheral arteries, which explains their lack of involvement in this condition. Patients may also present with abdominal pain, diarrhea, and skin lesions such as erythema nodosum and pyoderma gangrenosum.

Imaging Techniques and Findings

Magnetic Resonance

MR can detect mural thickening. It can also detect perivasculitis, a rim of soft tissue around a great vessel, along with aortic valvular thickening and pericardial effusion. Wall enhancement can be seen as an indicator of disease activity, secondary to edema and inflammation. Mural edema is seen as elevated T2 signal. Studies have shown reduced wall enhancement on follow-up, presumably secondary to reduced inflammation.12 Three-dimensional MRA does have decreased sensitivity for small vessels in comparison with conventional angiography (Figs. 95-4 and 95-5). One can do cine sequences to detect aortic regurgitation. Maximum intensity projection images should be used with caution because they can exaggerate the degree of vascular stenoses. Whereas MR is a longer examination, it benefits from its lack of ionizing radiation exposure, a feature preferable for long-term surveillance of Takayasu arteritis, which typically affects younger women.

Angiography

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