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AORTIC ANEURYSM

Abnormal dilatation of the abdominal or thoracic aorta; in ascending aorta most commonly secondary to cystic medial necrosis (e.g., familial, Marfan syndrome, Ehlers-Danlos syndrome type IV); aneurysms of descending thoracic and abdominal aorta are primarily atherosclerotic. Rare causes of aneurysms are infections (syphilitic, tuberculous, mycotic) and vasculitides (e.g., Takayasu's arteritis, giant cell arteritis).

History

May be clinically silent, but thoracic aortic aneurysms can result in deep, diffuse chest pain, dysphagia, hoarseness, hemoptysis, dry cough; abdominal aneurysms may result in abdominal pain or thromboemboli to the lower extremities.

Physical Examination

Abdominal aneurysms are often palpable, most commonly in periumbilical area. Pts with ascending thoracic aneurysms may show features of Marfan syndrome (Chap. 363, HPIM-18).

Laboratory

Suspect thoracic aneurysm by abnormal CXR (enlarged aortic silhouette) and confirm by echocardiography, contrast CT, or MRI. Confirm abdominal aneurysm by abdominal plain film (rim of calcification), ultrasound, CT, MRI, or contrast aortography. If clinically suspected, obtain serologic test for syphilis, especially if ascending thoracic aneurysm shows thin shell of calcification.

TREATMENT Aortic Aneurysm

Pharmacologic control of hypertension (Chap. 126) is essential, usually including a beta blocker. Preliminary studies suggest inhibition of the renin-angiotensin system (e.g., with the ARB losartan) may reduce rate of aortic dilation in Marfan syndrome via blockade of TGF-β signaling. Surgical resection for large aneurysms (ascending thoracic aortic aneurysms >5.5–6 cm, descending thoracic aortic aneurysms >6.5–7.0 cm, or abdominal aortic aneurysm >5.5 cm), for persistent pain despite bp control, or for evidence of rapid expansion. In pts with Marfan syndrome or bicuspid aortic valve, thoracic aortic aneurysms >5 cm usually warrant repair. Less invasive endovascular repair is an option for some pts with descending thoracic or abdominal aortic aneurysms.

AORTIC DISSECTION

FIGURE 134-1

Classification of aortic dissections. Stanford classification: Top panels illustrate type A dissections that involve the ascending aorta independent of site of tear and distal extension; type B dissections (bottom panels) involve transverse and/or descending aorta without involvement of the ascending aorta. DeBakey classification: Type I dissection involves ascending to descending aorta (top left); type II dissection is limited to ascending or transverse aorta, without descending aorta (top center + top right); type III dissection involves descending aorta only (bottom left). [From DC Miller, in RM Doroghazi, EE Slater (eds.), Aortic Dissection. New York, McGraw-Hill, 1983, with permission.]

Potentially life-threatening condition in which disruption or aortic intima allows dissection of blood into vessel wall; may involve ascending aorta (type II), descending aorta (type III), or both (type I). Alternative classification: Type A—dissection involves ascending aorta; type B—limited to transverse and/or descending aorta. Involvement of the ascending aorta ...

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