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For further information, see CMDT Part 12-12: Aortic Dissection

Key Features

Essentials of Diagnosis

  • Sudden searing chest pain with radiation to back, abdomen, or neck in a hypertensive patient

  • Widened mediastinum on chest radiograph

  • Pulse discrepancy in the extremities

  • Acute aortic regurgitation may develop

General Considerations

  • Occurs when a spontaneous intimal tear develops and blood dissects into the media of the aorta

  • Tear can result from repetitive torque applied to ascending and proximal descending aorta during the cardiac cycle

  • Blood entering the intimal tear may extend the dissection into the

    • Abdominal aorta

    • Lower extremities

    • Carotid arteries

    • Subclavian arteries (less commonly)

  • Hypertension is important component

  • Abnormalities of smooth muscle, elastic tissue, or collagen are more common in patients without hypertension

  • Both absolute pressure levels and the pulse pressure are important in propagation of dissection

  • Dissections are classified by the entry point and distal extent

  • Type A dissection

    • Involves the arch proximal to the left subclavian artery

    • Death may occur within hours, due to rupture of dissection into pericardial sac or dissection into the coronary arteries, resulting in myocardial infarction

    • Rupture into plural cavity also possible

    • Flap of aortic wall created by the dissection may occlude major aortic branches, resulting in ischemia of brain, intestines, kidney, or extremities

  • Type B dissection typically occurs in the proximal descending thoracic aorta just beyond the left subclavian artery

  • Conditions associated with increased risk of dissection

    • Pregnancy

    • Bicuspid aortic valve

    • Coarctation

Clinical Findings

Symptoms and Signs

  • Sudden onset of severe persistent chest pain

    • Characteristically radiates down the back or possibly into the anterior chest

    • May also radiate into the neck

  • Dissections may occur with minimal pain

  • Hypertension

  • Syncope

  • Hemiplegia

  • Paralysis of lower extremities

  • Intestinal ischemia or kidney injury

  • Peripheral pulses may be diminished or unequal

  • A diastolic murmur may develop as a result of a dissection in the ascending aorta close to the aortic valve, causing valvular regurgitation, heart failure, and cardiac tamponade

Differential Diagnosis

  • Myocardial infarction

  • Pulmonary embolism

  • Arterial embolism


Imaging Studies

  • Multiplanar CT scan with contrast enhancement

    • Immediate diagnostic imaging modality of choice

    • Should be obtained in any hypertensive patient with chest pain and equivocal findings on ECG

    • Should include both the chest and abdomen to fully delineate the extent of the dissected aorta

  • MRI

    • Excellent imaging modality for chronic dissections

    • The longer imaging time and the difficulty of monitoring patients in the scanner make CT scanning preferable in acute situations

  • Chest radiographs may reveal

    • An abnormal aortic contour

    • Widened superior mediastinum

  • Transesophageal echocardiography

    • An excellent diagnostic imaging method

    • However, it is not readily available in the acute setting

Diagnostic Procedures

  • ECG findings

    • May be normal in ...

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