Thoracic Aortic Aneurysm (TAA)

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Thoracic Aortic Aneurysm (TAA)

Definition

  • True aneurysm = dilatation of all 3 layers of aortic wall (intima, media, adventitia)

  • Cut-off: ≥ 1.5 × normal diameter

    • Ascending aorta: > 5.0 cm

    • Descending aorta: > 4.0 cm

Epidemiology

  • Less common than abdominal aortic aneurysm (AAA)

  • Peak: 60–65 yrs

  • M > F (3:1)

Etiology / Risk factors

  • Hypertension, smoking, advanced age

  • Connective tissue disorders: Marfan, Ehlers–Danlos

  • Bicuspid aortic valve

  • Aortitis (GCA, Takayasu, infectious)

  • Trauma

  • Tertiary syphilis (obliterative endarteritis of vasa vasorum)

  • Family history

Classification

  • Ascending aorta (most common)

  • Aortic arch

  • Descending thoracic aorta (thoracoabdominal)

Pathophysiology

  • Ascending TAA: cystic medial necrosis

  • Descending TAA: atherosclerosis

  • Degeneration of elastin/collagen → loss of wall integrity → dilatation

  • May → turbulent flow, thrombus formation, emboli

Clinical features

Often asymptomatic (incidental finding).
If symptomatic:

  • Chest pressure

  • Thoracic back pain

  • Compression signs:

    • Dysphagia (esophagus)

    • Hoarseness (RLN)

    • Cough, wheeze, stridor (trachea)

    • SVC syndrome

    • Horner syndrome

Diagnosis

Initial: CXR → widened mediastinum, abnormal aortic contour
Best confirmatory: CT angiography (CTA chest)
Other:

  • MR angiography (for follow-up, if avoiding radiation)

  • TTE/TEE (bedside, intra-op, unstable patients)

  • Catheter angiography (less common, coronary evaluation)

Management

General

  • Reduce CV risk factors:

    • BP control: β-blockers, ACEi, ARBs

    • Target BP <140/90 (or <130/80 if DM/CKD)

    • Statins if atherosclerosis (LDL <70)

    • Smoking cessation, lifestyle mods (no heavy lifting/competitive sports)

  • Regular imaging surveillance (intervals depend on diameter)

Surgical / Endovascular repair

  • Indications:

    • Rupture (emergency)

    • Symptomatic aneurysm

    • Asymptomatic but ≥ threshold size or rapid growth

      • Ascending/root/arch ≥ 5.5 cm

      • Descending ≥ 5.5 cm (or 6.0 cm if thoracoabdominal)

      • Growth ≥ 0.3 cm/year (x2 years) or ≥ 0.5 cm/year (1 year)

  • Procedures:

    • Open surgical repair (OSR): preferred for ascending/arch, young pts, connective tissue disease

    • TEVAR: descending aneurysms (if adequate landing zone, access feasible)

    • Lifelong imaging surveillance after repair

Complications

  • Embolism (thrombus in aneurysm sac)

  • Aortic regurgitation (root dilation)

  • Aortic dissection

  • Rupture

Rupture

  • Risk factors: large size, rapid expansion, trauma, smoking

  • Clinical:

    • Severe chest/back pain ± syncope

    • Hypotension, shock, hemothorax, tamponade

    • 50% die before ED arrival

  • Treatment:

    • Immediate stabilization (fluids, blood products, pressors if needed)

    • Emergency surgery: OSR or TEVAR

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