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Updated: Dec 7 2021

Aortic Dissection

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  • Snapshot
    • A 32-year-old man with eunuchoid proportions and arachnodactyly presents to the emergency department with severe substernal chest pain that radiates to the back. He says that the pain occurred acutely and denies any recent trauma. Medical history is significant for Marfan syndrome. On physical exam, there are unequal blood pressures in the upper extremity. A chest radiograph demonstrates a widened mediastinum. A CT angiography demonstrates a Stanford A type aortic dissection.
  • Summary
    • Aortic dissection is a condition that results from a tear in the innermost layer of the aorta leading to a hematoma and separation of layers of the aortic wall. Patients with hypertension and advanced age are more at risk for dissection. These patients typically present with abrupt onset of severe, tearing chest pain.
    • Diagnosis is made with CT angiography or transoesophageal echocardiogram. Chest X-ray is often acquired first, which may show a widening of the mediastinum. 
    • Treatment depends on the type of dissection. Regardless though, medical therapy is concurrently initiated with IV beta-blockers, IV fluids for hypotension, and surgical therapy indicated for type A dissections.
  • Epidemiology
    • Incidence
      • common > 1/100,000 annual incidence
    • Demographics
      • 3:1 male to female ratio
      • typically affects adults between the ages of 40-70
      • risk factors include
        • hypertension
        • atherosclerosis
        • aortic aneurysm
        • Turner syndrome
        • Marfan syndrome
        • Ehlers-Danos syndrome
  • Etiology
    • Pathophysiology
      • mechanism
        • 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
        • 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
      • cell biology
        • dissection involves fragility of the media layer of the aorta
          • formation of extracellular matrix on the media wall with accumulation of mucoid material resulting in cystic degeneration
    • Associated conditions
      • Hypertension (most common)
      • Connective tissue disease
      • Iatrogenic (e.g., coronary catheterization)
      • Trauma
      • bicuspid aortic valves lead to backflow which can enlarge the aorta and weaken the wall stability
        • e.g., Turner syndrome
      • Marfan syndrome results in cystic medial necrosis in the tissue of the aorta
  • Anatomy
    • The aorta has three distinct wall layers
      • Adventitia
        • outermost layer
          • loose connective tissue
      • Media
        • middle layer
          • smooth muscle cells organized in concentric layers
          • collagen, elastin, and proteoglycans composing the extracellular matrix
          • tears in the intima allows blood to collect between the intima and media
      • Intima
        • innermost layer
          • single layer of vascular endothelium
          • initial tear in the intima leads to the progression of aortic dissection
  • Presentation
    • History
      • sudden onset of severe, 'tearing' chest pain
      • can be painless in some patients, commonly those with Marfan syndrome
    • Symptoms
      • acute chest or back pain (most common)
        • classically anterior chest pain that radiates to the back between the scapulae
    • Physical exam
      • inspection
        • unequal blood pressures in the arms
        • weak or absent pulses
        • auscultation findings
          • diastolic decrescendo murmur when the aortic valve is involved
            • resulting in aortic regurgitation
  • Imaging
    • Radiographs
      • indication
        • to rule out other causes of chest pain (e.g., pneumothorax)
      • recommended views
        • chest x-ray with anteroposterior (AP) view
      • finding
        • widened mediastinum
        • deviation of the trachea to the right
        • deviation of the esophagus 
    • CT angiography of the chest
      • indication
        • most accurate imaging test for aortic dissection
        • MR angiography of the chest can be used in stable patients with iodine contrast allergies
        • considered gold standard for diagnosis
      • findings
        • intimal dissection flap
        • dilation of the aorta and hematoma
        • double lumen
        • contrast leak
    • Transesophageal echocardiography
      • indications
        • can be used if kidney injury is present or patient is allergic to contrast
      • findings
        • thrombosis in the new lumen
        • pericardial effusion
  • Differential
    • Aortic embolism
      • findings found with aortic embolism but not with aortic dissection
        • occlusion at aortic bifurcation on CT angiography
        • limb pain
        • cyanosis, pulselessness, and pallor
    • Myocardial infarction (MI)
      • findings found with myocardial infarction but not with aortic dissection
        • electrocardiogram findings (e.g., ST-segment elevation)
        • increased cardiac biomarkers (i.e. troponin)
  • Treatment
    • Medical
      • Pharmacological
        • IV ß-blockers and anti-hypertensives
          • indications
            • Initial treatment for all stable patients
            • rate control with a goal of around 60 bpm
        • IV fluids and vasopressors
          • indications
            • unstable and hypotensive patients
    • Surgical
      • Aortic dissection repair
        • indication
          • Stanford type A aortic dissection
          • considered a surgical emergency
        • outcomes
          • excellent 1- and 3-year survival rate for patients surgically treated for Type A aortic dissection
  • Techniques
    • Aortic dissection repair
      • approach
        • open heart surgery with a cardiothoracic surgeon under general anesthesia
      • technique
        • sternotomy and aortic flap creation
      • complications
        • endoleak
        • infection
        • bleeding
        • stroke
        • lower limb ischemia
  • Complications
    • End-organ damage
      • secondary to poor perfusion
        • acute renal failure
        • acute abdomen
        • mesenteric ischemia
        • ischemic colitis
        • paraplegia or weakness of lower extremities
        • aortoiliac occlusive disease
        • aortic regurgitation
    • Myocardial infarction from coronary artery occlusion
      • incidence
        • estimated to be 1% to 5%
      • risk factors
        • coronary artery disease
        • hypertension
      • treatment
        • percutaneous coronary intervention
        • dual antiplatelet therapy
        • anticoagulation
    • Stroke
      • incidence
        • between 3-32% of aptients
      • risk factors
        • patients with concomitant chest pain, shock, and hypotension.
      • treatment
        • anti-thrombolytics or tPA
        • mechanical thrombectomy
    • Cardiac tamponade
      • incidence
        • between 8-31% of patients
      • risk factors
        • surgical repair for type A aortic dissection
      • treatment
        • pericardiocentesis
        • pericardectomy
  • Prognosis
    • Overall poor prognosis
      • 20-30% mortality rate for patients
      • prognosis dependent on type of dissection
        • Stanford type A
          • effective blood pressure control and surgical treatment improve mortality
          • up to 30% of patients die prior to reaching the emergency room
        • Stanford type B
          • effective conservative or surgical treatment improves mortality
          • up to 90% of patients survive to discharge following medical therapy
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