• Clinical science
  • Clinician

Aortic dissection

Summary

An aortic dissection is a tear in the inner layer of the aorta that leads to a progressively growing hematoma in the intima-media space. Risk factors for aortic dissection include age and hypertension. Patients typically present with sudden onset severe pain radiating into the chest, back, or abdomen. A widened mediastinum on chest x-ray is characteristic of the diagnosis. The diagnosis is usually confirmed with CT angiogram in stable patients and transesophageal echocardiography (TEE) in unstable patients. Treatment options range from conservative measures (e.g., blood pressure optimization) to surgery (aortic stent graft), depending on the localization and severity of the dissection. Complete occlusion of branching vessels and aortic rupture are common complications. Even with treatment, mortality rates associated with aortic dissection are high.

Epidemiology

References:[1][2][3]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

References:[4][3]

Classification

There are two classifications of aortic dissection to help direct management. Stanford classification groups dissections by whether the ascending or descending aorta is involved. DeBakey classification categorizes dissections according to their origin and extent.

Stanford classification [5]

Stanford A = Affects ascending aorta; Stanford B = Begins beyond brachiocephalic vessels

DeBakey classification (rarely used) [5]

  • Type I: Dissections originate in the ascending aorta and continue to at least the aortic arch but typically as far as the descending aorta.
  • Type II: Dissections originate in, and are restricted to, the ascending aorta.
  • Type III: Dissections originate in the descending aorta and most often extend distally.
    • Most cases can be managed by medical therapy.
    • Can be further subdivided into:
      • Type IIIa: limited to the descending thoracic aorta above the level of the diaphragm
      • Type IIIb: extends below the diaphragm

Pathophysiology

  • Common anatomic sites of origin
  • Transverse tear in the aortic intima (“entry”) → blood enters the media of the aorta and forms a false lumen in the intima-media space hematoma forms and propagates longitudinally downwards
    • Rising pressure within the aortic wall → rupture
    • Occlusion of every single branching vessel (e.g., coronary arteries, arteries supplying the brain, renal arteries, arteries supplying the lower limbs) → ischemia in the affected areas (see “Complications” below)
    • A second intimal tear may result in a “reentry” into the primary aortic lumen.

References:[1][6]

Clinical features

References:[4]

Diagnostics

Approach

  • Assess the risk of acute aortic dissection using the aortic dissection detection risk score (ADD-RS).
  • Check ECG in all patients to exclude other causes of severe chest pain.
  • Consider which imaging modality is indicated
    • CXR: low to moderate-risk patients
    • Definitive imaging (e.g., CTA, MRA): high-risk patients, unexplained hypotension, abnormal CXR, no alternative diagnosis

Aortic dissection detection risk score (ADD-RS) [7]

The ADD-RS is a highly sensitive bedside clinical tool used to assess the risk of acute aortic dissection based on high-risk conditions, pain, and examination features.

Aortic dissection detection risk score (ADD-RS)
Risk categories Features Score if any feature present
Conditions 1
Pain characteristics
  • Chest, back, or abdominal pain with:
    • Abrupt onset
    • Severe intensity
    • Ripping or tearing
1
Examination findings 1
Interpretation
  • Score 2–3 (high risk): Expedite definitive imaging.
  • Score 0–1 (low or moderate risk): diagnostic workup (e.g., ECG, laboratory studies, and chest x-ray) as clinically indicated

ECG [8]

Should be ordered for all patients. Findings are variable and include:

Laboratory studies

Imaging

Initial imaging in low to moderate risk patients [10][11]

  • Chest x-ray (AP view)
    • Characteristic findings
    • Additional findings that may be present

Normal chest x-ray findings do not rule out aortic dissection. If clinical suspicion for acute aortic dissection persists, perform a second imaging study!

Definitive imaging [5]

Definitive imaging is used to determine the type of lumen, location, and extent of the dissecting membrane. The identification of a false lumen is highly suggestive of aortic dissection.

Indications

  • All high-risk patients: ADD-RS score of 2 or 3
  • Moderate and low-risk patients (ADD-RS score of 0 or 1) with:
    • Unexplained hypotension
    • No other diagnosis to explain the symptoms
    • Any concerning features present on chest x-ray

Modalities [5]

  • CT angiography of the chest, abdomen, and pelvis [5]
    • Indications: stable patients, surgical planning
    • Advantages: very high sensitivity and specificity (considered to be the gold standard) [5]
    • Suggestive findings
      • Intimal dissection flap
      • Double lumen
      • Aortic dilatation
      • Regions of malperfusion
      • Aortic hematoma (high-attenuation)
      • Contrast leak: indicates rupture

  • Magnetic resonance angiography (MRA) of the chest, abdomen, and pelvis
    • Indications: stable patients, contraindications to CTA
    • Advantages:
    • Disadvantages:
      • Time-consuming
      • Contraindications: renal insufficiency, claustrophobia, metallic implants, pacemakers
      • Not widely available on an emergency basis
    • Suggestive findings: similar to CT angiography
  • Transesophageal echocardiography (TEE)
    • Indications:
      • Unstable patients
      • Intraoperative visualization
      • Renal insufficiency or contrast allergy
    • Advantages:
      • Rapid; can be performed at the bedside
      • Quick differentiation between thoracic aortic aneurysm and thoracic aortic dissection
    • Disadvantages: dissection flap can be difficult to distinguish from artifact
    • Findings may include:
  • Other: catheter angiography, ultrasound [5]

Differential diagnoses

The differential diagnoses listed here are not exhaustive.

Treatment

Approach [5]

  • Urgent cardiothoracic surgical consult for all patients with suspected or confirmed dissection, regardless of location. [5]
  • Blood pressure control is essential in all patients to prevent progression of the dissection
  • Supportive care
  • Admission to surgical ICU with close monitoring and surveillance imaging

Surgical therapy [5]

  • Indications
  • Procedure
    • Open surgery with the replacement of the dissection with a polyester graft implantation [5]
    • Endovascular treatment with aortic stent implantation (only in type B dissections and if the open operative risk is too high) [5]

Ascending aortic dissection is a surgical emergency!

Medical therapy

Hypotensive patients [5]

Avoid inotropes as they can worsen aortic wall stress.

Hypertensive patients [5]

Start beta-blocker therapy before vasodilators to avoid a reflex tachycardia!

Supportive care

Avoid thrombolytic therapy in patients with suspected aortic dissection.

Acute management checklist

Complications

We list the most important complications. The selection is not exhaustive.

Prognosis

  • In-hospital mortality due to aortic dissection ranges from 9 to 39%, depending on the type of dissection and treatment modality. [15][16]

Prevention

  • Blood pressure control
  • Smoking cessation [5]
  • Screening and repair of rapidly expanding aneurysms (also see “Therapy” and “Prevention” sections in aortic aneurysms)
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last updated 06/11/2020
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