Aortic Dissection

Snapshot

• A 55-year-old man presents to the emergency department with chest pain. He describes the pain as excruciating and knife-like that began earlier in the morning. His pain is restricted to the anterior chest. Medical history is significant for hypertension, for which he is taking lisinopril. Physical examination is significant for unequal blood pressures in the arm and a diastolic murmur in the left sternal border. An electrocardiogram is unremarkable, his cardiac troponins are not elevated, and a chest radiograph demonstrates a widened mediastinum. Preparations are made to obtain a CT angiography.

Introduction

• Clinical definition
  • a separation of the media laminal planes, resulting in a blood-filled space in the aortic wall  
    • there are two types of aortic dissection
      • Stanford A type
        • a dissection involving the ascending aorta
      • Stanford B type 
        • a dissection involving only the descending aorta
• Etiology
  • hypertension (most common)
  • connective tissue disease
  • iatrogenic (e.g., coronary catheterization)
• Pathogenesis
  • an intimal tear of the aorta causes an intramural aortic hemorrhage that separates the intima from the media
    • the resulting hematoma may rupture through the adventitia, leading to a thoracic or abdominal cavity hemorrhage or cardiac tamponade
• Associated conditions
  • Marfan syndrome  
  • bicuspid aortic valve
• Prognosis
  • Stanford type A
    • effective blood pressure control and surgical treatment improves mortality
  • Stanford type B
• effective conservative or surgical treatment improves mortality

Presentation

• Symptoms 
  • acute chest or back pain (most common)
    • classically anterior chest pain that radiates to the back between the scapulae
• Physical exam
  • unequal blood pressures in the arms
  • weak or absent pulses
  • diastolic decrescendo murmur when the aortic valve is involved
• resulting in aortic regurgitation

Imaging

• Radiography of the chest
  • indication
    • to rule out other causes of chest pain (e.g., pneumothorax)
  • finding
    • widened mediastinum
• CT angiography of the chest  
  • indication
• most accurate imaging test for aortic dissection 

Differential

• Myocardial infarction 
  • differentiating factors
    • an electrocardiogram may be present (e.g., ST-segment elevation)
• increased cardiac biomarkers

Treatment

• Medical
  • β-blockers
    • indication
      • Stanford type B aortic dissection
• Surgical
  • vascular surgery
    • indication
• Stanford type A aortic dissection

Complications

• End-organ damage
  • secondary to poor perfusion
• Aneurysm rupture