Thoracic Aortic Dissection

Thoracic Aortic Dissection

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1-Minute Review Video

Take Home Points

  1. Identify the typical symptoms consistent with a thoracic aortic dissection.
  2. A Type A dissection requires surgical intervention.
  3. A Type B dissection can be managed medically.
  4. For a Type A dissection you need to start a beta blocker prior to reducing the blood pressure
  5. For decompensating patients IV, O2 & Monitor first. ALWAYS
  6. Hypertension is the most common risk factor for an aortic dissection

Typically Asked Questions

  1. What imaging modality is best to diagnose an aortic dissection?
  2. How does the treatment of Type A and Type B dissections differ?
  3. What are the first steps in the management of a Type A Dissection?
  4. What are the classification systems for aortic dissections?

 Overview:

An aortic dissection is a violation of the intimal surface of the aorta. This violation of the intima creates a false lumen. There are two classification systems for aortic dissections. The Stanford classification considers any involvement of the ascending aorta to be Type A. Type B classification is used solely to describe dissections limited to the descending aorta. The DeBakey classification describes the lesions as Type 1, Type 2 and Type 3. Type 1 involves the ascending and descending aorta. Type 2 only involves the ascending aorta. Type 3 dissection involves only the descending aorta. The most common risk factor associated with aortic dissection is hypertension.

Presentation:

Typically, the location of the dissection is predictive of the symptoms patients will present with. The classic complaint is severe “tearing” chest pain that radiates to the back. Other presenting symptoms may include syncope, abdominal pain, or focal neurological deficits (stroke symptoms). Patients may also present in extremis if the dissection has extended to the aortic root, causing a cardiac tamponade or severe aortic insufficiency.

Diagnosis:

The differential for patients presenting with chest pain is broad. It is imperative that one has aortic dissection in his/her differential. There are multiple modalities that help aid in the diagnosis of aortic dissection. A chest x-ray is often the first modality used. Unfortunately, it has neither a high sensitivity or specificity and can be normal in up to 37% of cases. Findings that may be suggestive of an aortic dissection on chest radiograph are widened mediastinum or an abnormal aortic contour. CT angiography of the aorta is a reliable test to detect or exclude aortic dissection. It has an extremely high specificity and sensitivity. Other modalities include transesophageal echocardiography, coronary artery angiography, or the “triple rule-out study”.

Management:

If the patient is not presenting in extremis then patients with thoracic aortic dissection typically present with hypertension. If this is the case then treatment should be centered around reducing the blood pressure and decreasing the shear force on the aorta in addition to contacting a CT surgeon. Typically, the shear force is reduced by using beta-blockers. The best agents to use for this are labetalol, esmolol and less frequently propranolol. One of these agents should be used prior to using an antihypertensive to prevent reflexive tachycardia. After initiating a beta-blocker the patient should be started on antihypertensives. Typically used antihypertensives include nicardipine or nitroprusside. No definitive guidelines have been established for target pressures, however, a goal systolic blood pressure of 120 mmHg is reasonable.

Beyond The Boards

  1. LITFL: Aortic Dissection
  2. EM Cases: Symptoms of Aortic Dissection
  3. EM Cases: D-dimer in Aortic Dissection

Flashcards

  1. Flashcards: Thoracic Aortic Dissection

Resources

  1. Johnson GA, Prince LA. Aortic Dissection and Related Aortic Syndromes. In: Tintinalli JE, Stapczynski J, Ma O, Yealy DM, Meckler GD, Cline DM. eds.Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 8e New York, NY: McGraw-Hill; 2016
  2. Rivers CS, Weber DE. Preparing for the Written Board Exam in Emergency Medicine. Vol 1. Milford, OH: Emergency Medicine Educational Enterprises; 2000.

 

Author: Farhad Aziz, MD Assistant Professor of Emergency Medicine, The Ohio State University Department of Emergency Medicine

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