cardiovascular disorders
Aortic Dissection
Diagnosis of Aortic Dissection
Transesophageal echocardiography (TEE), CT angiography (CTA), or magnetic resonance angiography (MRA) Aortic dissection must be considered in any patient with chest pain, thoracic back pain, unexplained syncope, unexplained abdominal pain, stroke, or acute-onset heart failure, especially when pulses or blood pressures in the limbs are unequal. Such patients require a chest x-ray; in 60 to 90%, the mediastinal shadow is widened, usually with a localized bulge signifying the site of origin. Left pleural effusion is common. Patients presenting with acute chest pain, electrocardiography (ECG) changes of acute inferior myocardial infarction, and a previously undocumented murmur of aortic regurgitation (AR) are of particular concern for a type I aortic dissection into the right coronary artery (causing inferior myocardial infarction), and the aortic valve (causing AR). If chest x-ray suggests dissection, TEE, CTA, or MRA is done immediately after the patient is stabilized. Findings of an intimal flap and double lumina confirm dissection. 20 minutes and does not require contrast agents. However, CTA is typically the first-line imaging modality because it is often available more rapidly and widely than TEE. The sensitivity and specificity of CTA have been reported in the ranges of 90 to 100% and 87 to 100% , respectively ( Diagnosis reference ). MRA has nearly 100% sensitivity and specificity for aortic dissection. But it is time-consuming and ill-suited for emergencies. It is best used when dissection is suspected in patients who are stable and have subacute or chronic chest pain. Contrast aortography is an option if surgery is being considered. In addition to identifying the origin and extent of dissection, severity of aortic regurgitation, and extent of involvement of the aorta’s major branches, aortography helps determine whether simultaneous coronary artery bypass surgery is needed. Echocardiography should be done to check for aortic regurgitation and thus determine whether the aortic valve should be repaired or replaced concomitantly. Electrocardiography (ECG) is nearly universally done. However, findings range from normal to markedly abnormal (in acute coronary artery occlusion or aortic regurgitation), so the test is not diagnostically helpful for dissection itself. Serum creatine kinase-MB and troponin levels may help distinguish aortic dissection from myocardial infarction, except when dissection causes myocardial infarction. Routine laboratory tests may detect slight leukocytosis and anemia if blood has leaked from the aorta. Increased lactate dehydrogenase may be a nonspecific sign of celiac or mesenteric arterial trunk involvement. A cardiothoracic surgeon should be consulted early during the diagnostic evaluation. 1.Expert Panel on Cardiac Imaging, Kicska GA, Hurwitz Koweek LM, et al. ACR Appropriateness Criteria® Suspected Acute Aortic Syndrome.J Am Coll Radiol2021;18(11S):S474-S481. doi:10.1016/j.jacr.2021.09.004 