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Thoracic aortic dissection
Patients present with acute onset severe tearing chest pain which radiates to the back and is associated with hypertension (50%), pulse or BP differential between the arms (30%), and mediastinal widening (64%) or abnormal aortic contour (71%) on CXR.
Pain that is not of abrupt onset was associated with an LR- of 0.3, as was the finding of a normal CXR, whereas the presence of a pulse deficit yielded a LR+ of 5.7, and the combination of typical pain, a pulse deficit, and a widened mediastinum had a LR+ of 66.0[1]. A meta-analysis1 found that most of the traditional signs performed rather poorly, with only focal neurology, a pulse deficit and hypotension having positive likelihood ratios of more than 2. Very severe (tearing) chest pain was an important indicator on history, as was migrating pain.
Diagnosis can be confirmed on ultrasound, or CT angiography. The condition is a surgical emergency, particularly if the dissection is in the ascending aorta.
Control the BP and the pain, and ask for thoracic surgical advice. Morphine is appropriate for pain. For the BP, aim to reduce pulsatile load (wall stress) by starting with a beta-blocker – e.g. labetalol 20 mg IV over 2 minutes and then in increments of 20 mg every 10 minutes until BP is controlled, or to a maximum of about 300 mg. Oral atenolol can be introduced (and the IV labetalol stopped) once the BP is controlled. Do not start off with other conventional BP lowering medication, particularly vasodilators and ACE inhibitors, before the patient is adequately beta-blocked. As getting control of the blood pressure is often the most important medical component in management, it is worthwhile being fairly quick with medication escalation.
Ohle R, Kareemi HK, Wells G, Perry JJ. Clinical Examination for Acute Aortic Dissection: A Systematic Review and Meta-analysis. Acad Emerg Med. 2018 Apr;25(4):397-412. doi: 10.1111/acem.13360. Epub 2018 Jan 24. PMID: 29265487. ↩