What is the treatment for a saccular aneurysm associated with an infrarenal abdominal aortic aneurysm (AAA)?

Treatment of Saccular Infrarenal Abdominal Aortic Aneurysm

Elective repair should be considered for saccular infrarenal AAA ≥45 mm, with endovascular repair (EVAR) preferred over open repair when anatomy is suitable and life expectancy exceeds 2 years. 1

Key Treatment Thresholds

Saccular aneurysms require different management than fusiform AAAs due to their higher rupture risk at smaller diameters:

• Saccular AAA ≥45 mm warrants consideration for elective repair (Class IIb, Level C recommendation), which is notably lower than the 55 mm threshold for fusiform aneurysms in men 1

• Symptomatic saccular AAAs require urgent repair regardless of size, as 25% of acutely presenting saccular aneurysms have diameters <5.5 cm and 8.4% are <4.5 cm—far higher rates than fusiform aneurysms 1

• Saccular aneurysms are more common in women and more likely to be symptomatic at smaller sizes than fusiform aneurysms 1

Treatment Approach Algorithm

For Asymptomatic Saccular AAA ≥45 mm:

Step 1: Assess Life Expectancy and Surgical Risk

• If life expectancy <2 years: repair is not recommended 1
• If life expectancy >2 years: proceed to anatomic evaluation 1

Step 2: Anatomic Evaluation

• Obtain cardiovascular CT (CCT) as the optimal pre-operative imaging modality to assess entire aorta and determine EVAR feasibility 1
• Perform duplex ultrasound (DUS) of femoro-popliteal segment to detect concomitant aneurysms 1
• Assess adherence to device-specific instructions for use 1

Step 3: Select Repair Method

• EVAR is preferred when anatomy is suitable and life expectancy >2 years, reducing peri-operative mortality to <1% 1
• Open repair is reasonable if patient cannot comply with lifelong post-EVAR surveillance requirements 1
• For high perioperative risk patients with suitable anatomy, EVAR is reasonable to reduce 30-day morbidity and mortality 1

For Symptomatic Saccular AAA (Any Size):

Immediate Management:

• Admit to ICU for arterial blood pressure monitoring and tight BP control (target systolic <120 mmHg) 2
• Initiate anti-impulse therapy with IV beta-blockers as first-line (target heart rate 60-80 bpm) 2
• Provide adequate pain control 2
• Perform repair within 24-48 hours to reduce risk of free rupture 1

Definitive Treatment:

• EVAR is recommended over open repair when anatomy is suitable to reduce peri-operative morbidity and mortality 1

Technical Considerations

EVAR Advantages:

• Peri-operative mortality <1% compared to open repair 1
• Reduced 30-day morbidity in high-risk patients 1
• Percutaneous femoral approach with ultrasound guidance reduces access-related complications 1

EVAR Limitations:

• Requires lifelong surveillance for endoleaks, graft migration, and aneurysm sac changes 1
• Higher long-term re-intervention risk compared to open repair 1
• Type I and Type III endoleaks require prompt correction to prevent rupture 1, 2
• Chronic anticoagulation increases risk of re-intervention, late conversion, or mortality 1

Open Repair Considerations:

• Appropriate for patients unable to comply with post-EVAR surveillance 1
• Mid-line laparotomy with Dacron graft replacement typically required for infrarenal saccular AAA due to coexistent atherosclerosis making patch repair difficult 3
• Higher peri-operative morbidity but no long-term surveillance requirements 1

Critical Pitfalls to Avoid

• Do not wait for standard 55 mm threshold: Saccular morphology increases rupture risk at smaller diameters than fusiform aneurysms 1
• Do not delay repair of symptomatic aneurysms: Symptoms indicate impending rupture regardless of diameter 1, 2
• Do not perform EVAR without confirming adherence to manufacturer's instructions for use, as off-label use increases complication rates 1
• Do not neglect post-EVAR surveillance: Endoleaks occur in up to one-third of patients and require monitoring with CCT or DUS at 6-12 months, then annually for 5 years 1