03-07-2010, 05:26 PM
The most important predisposing risk factor for acute aortic dissection in older patients is hypertension. In the International Registry of Acute Aortic Dissection (IRAD), 72% of patients had a history of hypertension, but only 34% of those younger than 40 years. Bicuspid aortic valve was more common in younger patients. In patients with Marfan's syndrome, 50% of those younger than 40 years had a family history of aortic dissection compared with 2% in older patients. Pain is also quite common, with only 6% of patients in the IRAD registry having painless dissection. A history of diabetes mellitus, aortic aneurysm, or cardiovascular surgery was more common in patients with silent dissection, along with a slight increase in age. Syncope occurs in a small minority of cases, with an increased risk of tamponade and stroke, as well as a worse outcome.
The evaluation of patients with suspected thoracic aortic aneurysm or dissection includes chest CT with contrast, contrast-enhanced aortic MR angiography, and transesophageal echocardiography. Although chest CT without contrast may be acceptable for detecting an aortic aneurysm, it has a low sensitivity for aortic dissection. Chest radiographs have a low sensitivity and low specificity for aortic dissection. Although gadolinium contrast is not nephrotoxic, a chest MRI or contrast-enhanced aortic MR angiography would be relatively contraindicated in this patient because he has an older pacemaker. Transesophageal echocardiography is the most appropriate imaging and can safely be performed in the emergency department for patients with suspected acute aortic dissection.
The evaluation of patients with suspected thoracic aortic aneurysm or dissection includes chest CT with contrast, contrast-enhanced aortic MR angiography, and transesophageal echocardiography. Although chest CT without contrast may be acceptable for detecting an aortic aneurysm, it has a low sensitivity for aortic dissection. Chest radiographs have a low sensitivity and low specificity for aortic dissection. Although gadolinium contrast is not nephrotoxic, a chest MRI or contrast-enhanced aortic MR angiography would be relatively contraindicated in this patient because he has an older pacemaker. Transesophageal echocardiography is the most appropriate imaging and can safely be performed in the emergency department for patients with suspected acute aortic dissection.