Indications for aortic replacement.

This monograph reviews currently accepted criteria for extirpation of the aneurysmal thoracic aorta. Presence of symptoms suffices to justify resection regardless of size. For asymptomatic patients, resection of the ascending aorta at 5 to 5.5 cm is warranted. The descending aorta can be watched until slightly larger sizes (ie, 5.5-6 cm). Marfan disease or bicuspid aortic valve encourages resection in the smaller region of these size ranges. A nomogram permits adjustment of intervention criteria for extremes of body size. A recently computerized aortic risk calculator automatically applies exponential equations for determination of yearly risk of rupture or dissection for individual patients (available at: http://aorta.yale.edu). Evolving modalities to enhance decision making include positron emission tomography imaging of aneurysm metabolic activity, measurement of mechanical properties of the aorta by echocardiography, and assessment of the biomolecular state of the aneurysm with the "RNA Signature" test.