Thoracic Aortic Aneurysms

• • Can be saccular, fusiform

  • Common etiologies include:

  • -Atherosclerosis

    -Medial degeneration of aortic wall

    -Marfan syndrome (defect in fibrillin gene)

    -Trauma and infection

  • Increased aneurysm rupture rate depend on:

  • -Size

    -Marfan syndrome

    -Family history of rupture or dissection

    -Advancing age

    -Chronic obstructive pulmonary disease

    -Growth rate > 0.1 cm yearly

  • Affect the ascending, arch, or descending aorta (descending is most common)

Epidemiology

• • More common in men

  • History of hypertension usual

Symptoms and Signs

• • Symptoms, if present, are due to local pressure or obstruction of adjacent structures

  • Ascending aorta

  • -Aortic regurgitation

    -Superior vena cava obstruction

    -Chest pain

  • Aortic arch: Tracheal compression

  • Descending aorta

  • -Recurrent laryngeal nerve compression

    -Phrenic paralysis

    -Dysphagia

    -Stridor

Imaging Findings

• • Chest x-ray: May show convex right cardiac border in ascending aneurysms, prominent aortic knob in arch aneurysms, posterior lateral thoracic mass in descending aneurysms

  • CT scans or magnetic resonance angiography (MRA): Define anatomy and extent of aneurysm

  • Aortography: Occasionally useful

• • Evaluate for peripheral aneurysms

• • Chest CT/MRA: Diagnostic

  • Consider aortography

  • Stress test: Examine for coronary artery disease

• • Primary determinants for repair: Aneurysm size, etiology, and symptoms

  • For asymptomatic aneurysms measuring ≤ 5.5 cm, aggressive blood pressure control with β-blockers

  • Consider repair when aneurysm measures > 5.5 cm, especially if symptoms present

  • Dacron replacement is standard

Surgery

• • Ascending aorta

  • -Cardiopulmonary bypass via RA and right femoral artery cannulation

    -If extends proximal toward sinuses of Valsalva, need composite prosthetic valve-ascending aortic graft conduit (patients with Marfan syndrome)

    -Isolated ascending aortic aneurysm, replace with Dacron graft

  • Arch

  • -Provide cerebral protection during repair via hypothermic circulatory arrest

    -Dacron graft, anastomose great vessels as single button

  • Descending aorta

  • -Dacron replacement via left thoracotomy with spinal cord protection via replacement of large intercostals, drainage of CSF

    -Percutaneous stent grafts now being used

Indications

• • Aneurysm > 5.5 cm, consider repair especially if symptoms are present

  • Marfan syndrome: Aneurysm > 5 cm

Complications

• • Spinal cord ischemia in descending aortic repair 5-15%

Prognosis

• • Operative mortality, 5-15%

  • 10-year survival: Ascending = 50%, descending = 38%

References