What are the criteria for thoracoabdominal (thoracoabdominal) aneurysm repair?

Criteria for Thoracoabdominal Aneurysm Repair

For unruptured degenerative thoracoabdominal aortic aneurysms (TAAA), elective repair is recommended when the diameter reaches ≥60 mm. 1

Size Criteria

The primary criteria for TAAA repair are based on aneurysm size:

• Standard threshold: ≥60 mm diameter for unruptured degenerative TAAA 1
• Lower threshold (≥55 mm) should be considered if:
  • Patient presents with high-risk features
  • Patient is at very low surgical risk
  • Patient is under care of experienced surgeons in a multidisciplinary aorta team 1

Additional Indications for Repair

Beyond size thresholds, repair should be considered in the following scenarios:

• Symptomatic aneurysms: Patients with symptoms suggestive of aneurysm expansion should be evaluated for prompt surgical intervention 1
• Rapid growth: Aneurysms growing at >0.5 cm/year 1 or >1 cm/year 1
• Saccular morphology: Associated with increased risk of rupture 2

Repair Method Selection

When elective repair is indicated, the method should be selected based on:

Endovascular Repair

• Preferred when: Anatomy is suitable for fenestrated/branched endografts 1
• Benefits: Lower perioperative mortality (<1%), reduced morbidity, shorter hospital stay 2
• Considerations: Higher reintervention rates (5.1% vs 1.7% for open repair) 2, 3

Open Surgical Repair

• Indicated when:
  • Anatomy is unsuitable for endovascular approach 1
  • Patient has life expectancy >2 years 1
  • Patient cannot comply with long-term surveillance required after endovascular repair 2

Risk Factors Affecting Decision-Making

Several factors influence the risk of rupture and should be considered when determining timing of intervention:

• Patient-specific factors:

  • Female sex (women may benefit from repair at smaller diameters) 1, 2
  • Continued smoking (doubles aneurysm expansion rate) 2
  • Uncontrolled hypertension 2
  • COPD 2, 3
  • Chronic kidney disease 3

• Aneurysm-specific factors:

  • Crawford extent (types I-III associated with higher mortality) 3
  • High-risk morphological features 1

Perioperative Considerations

• Surgical expertise: Outcomes are strongly associated with surgeon and center volume/expertise 4
• Adjunctive measures to reduce complications:
  • Cerebrospinal fluid drainage (best-proven mechanism to prevent spinal cord injury) 4
  • Left heart bypass 5
  • Hypothermia 5
  • Neuromonitoring 5
  • Beta-blocker therapy to reduce shear force on aortic wall 6

Post-Repair Surveillance

• Endovascular repair: CT or ultrasound evaluation at 6-12 months post-procedure, then annual surveillance for first 5 years 2
• Monitor for: Endoleaks (present in up to one-third of cases), with immediate intervention for type I and type III endoleaks 2

Mortality Considerations

• Contemporary operative mortality ranges from <5% to >20% 4
• Long-term survival is significantly affected by aneurysm extent, with Crawford extent I-III having worse outcomes (18.4% 1-year mortality vs. 7.8% for extent IV-V) 3
• Despite initial perioperative advantage with endovascular repair, long-term mortality is similar between endovascular and open repair 2

The decision for TAAA repair should be made by an experienced multidisciplinary aortic team, carefully weighing the risk of rupture against the risk of intervention, with consideration of the patient's comorbidities and life expectancy.