Acute dissection of the thoracic aorta is uncommon, but if left unrecognized and untreated it carries a mortality rate of up to 2% per hour and 50% within the first few weeks.
Clinical presentation—the pain of acute dissection is typically of instantaneous onset, cataclysmic in severity, pulsatile and tearing in quality, located either in the anterior thorax or back, and migrating as it follows the course of the dissection through the thorax. Patients usually appear shocked, but blood pressure may be normal or raised and heart rate relatively slow. Physical signs typically reflect the region of the aorta involved in the dissection and effects of pressure on adjacent structures: evidence of new aortic regurgitation or development of pulse deficits should be actively sought.
Diagnosis—abnormalities on the chest radiograph and ECG are common, but neither investigation is diagnostic and further imaging is always necessary by MRI, contrast-enhanced CT, or transoesophageal echocardiography, depending on local availability and the clinical condition of the patient.
Management—every patient with a clinical suspicion of dissection should receive effective pain relief and antihypertensive medication (intravenous labetalol or esmolol), aiming to maintain systolic blood pressure <120 mmHg. For confirmed dissection of the ascending aorta (type A), emergency surgery is indicated. When the ascending aorta is spared (type B), aggressive control of blood pressure is the usual initial management, with surgery being considered if there is evidence of further progression of dissection or ischaemic complications. In the long term, strenuous efforts to control blood pressure are indicated for all patients who have survived aortic dissection, with repeat imaging at least once a year.
Other related aortic conditions—modern imaging techniques have demonstrated variants of acute aortic dissection, including spontaneous intramural haematoma, with 50% of patients subsequently developing dissection or aortic rupture, and penetrating atherosclerotic ulcer, which has a high risk of rupture.
Chapter. 3833 words. Illustrated.
Subjects: Cardiovascular Medicine
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