What is an EVAR (Endovascular Aneurysm Repair) and its complications?

Endovascular Aneurysm Repair (EVAR) and Its Complications

EVAR is a minimally invasive procedure for treating aortic aneurysms that offers significantly decreased perioperative morbidity and mortality compared to open surgical repair, but requires lifelong surveillance due to potential complications including endoleaks, device migration, and infection. 1

What is EVAR?

EVAR is a minimally invasive endovascular procedure that involves the placement of a stent graft (endograft) over an abdominal aortic aneurysm to exclude it from arterial circulation. This procedure offers several advantages over traditional open surgical repair:

• Lower perioperative 30-day mortality (1.7% vs 4.7% for open repair) 2
• Decreased perioperative morbidity 1, 3
• Shorter hospital stays 1
• Reduced blood loss 3
• No need for aortic cross-clamping 3
• Faster recovery periods 3

EVAR was initially developed for patients considered unfit for traditional open surgical repair due to comorbidities or high surgical risk. However, as experience with the procedure has grown, it has become the preferred treatment option for many patients with suitable anatomy. 1

Types of EVAR

• Standard EVAR: Used for infrarenal abdominal aortic aneurysms with suitable neck anatomy
• Fenestrated EVAR (FEVAR): Alternative approach for patients with inadequate aortic neck length, featuring fenestrations in the graft material to allow perfusion of major visceral arteries 1
• Thoracic EVAR (TEVAR): Used for thoracic aortic aneurysms, with higher reported infection rates (up to 5%) compared to abdominal EVAR (approximately 1%) 1

Complications of EVAR

The main disadvantage of EVAR is the high rate of post-procedural complications requiring secondary interventions. Complication rates range from 16-30% following abdominal EVAR and up to 38% following thoracic EVAR. 3

1. Endoleaks

Endoleaks are the most common complication of EVAR, contributing to aneurysm sac enlargement and potential rupture. 1, 3

Types of endoleaks:

• Type I: Blood flow into the aneurysm sac from inadequate seal at proximal or distal attachment sites
• Type II: Retrograde flow from collateral vessels
• Type III: Graft defect, component separation, or fabric tear
• Type IV: Porosity of the graft material
• Type V: Endotension (aneurysm enlargement without detectable endoleak)

Types I and III endoleaks most commonly lead to rupture and require prompt intervention. 1

2. Device-Related Complications

• Stent graft migration: Can lead to type I endoleaks and aneurysm rupture 1, 3
• Endograft collapse or kinking: May cause flow obstruction 1, 3
• Stent graft limb stenosis or occlusion: Results in limb ischemia 1, 3
• Graft infection: Rare but serious complication with high mortality 1
• Aortoenteric or aortobronchial fistula: Can develop due to graft migration or severe angulation causing repetitive friction wear and mucosal tear 1

3. Access-Related Complications

• Access vessel injury: Can occur during device delivery 3, 4
• Femoral pseudoaneurysms: May develop at access sites 4

4. Systemic Complications

• End-organ ischemia: Due to coverage of critical vessels or embolization 3
• Cerebrovascular and cardiovascular events: More common in patients with pre-existing disease 3
• Post-implantation syndrome: Characterized by fever, leukocytosis, and elevated inflammatory markers 3, 4
• Renal dysfunction: Can result from contrast nephropathy or renal artery coverage 1

Post-EVAR Surveillance

The advantages of EVAR come at the cost of lifelong imaging surveillance due to the higher rate of complications requiring reintervention compared to open repair. 1

Surveillance Protocol

• Initial imaging: 30 days post-procedure to assess intervention success 5
• Follow-up visits: At 1 month and 12 months post-procedure, then annually if no abnormalities 5
• Long-term surveillance: CT every 5 years after 5 post-operative years without complications 5

Imaging Modalities

• CT angiography (CTA): Currently considered the gold standard for surveillance 1, 3
• Dual-energy CT: Can reduce radiation exposure while maintaining diagnostic accuracy 1
• Ultrasound: Alternative for patients with contraindications to CTA 1
• MR angiography: Option for patients with contraindications to iodinated contrast 3

Management of Complications

Endoleak Management

• Type I and III endoleaks: Usually require prompt intervention with additional endovascular components or embolization 3
• Type II endoleaks: May be observed if the aneurysm sac is stable or shrinking; intervention is indicated for sac enlargement 3

Device-Related Complications

• Migration or kinking: May require placement of additional stent grafts or cuff extensions 3
• Limb occlusion: Often managed with thrombolysis and/or additional stenting 3
• Infection: May require device explantation and in situ reconstruction or extra-anatomic bypass 1

Surgical Conversion

• Device removal and extra-anatomic revascularization was traditionally preferred for infected EVAR devices
• Currently, explantation and in situ reconstruction may be considered using rifampin-bonded polyester grafts, venous autografts, or cryopreserved arterial allografts 1

Post-EVAR Activity Guidelines

• Avoid heavy lifting (>10-15 lbs) for at least 4 weeks after EVAR 5
• Return to work timeline:
  • Sedentary/office work: 2 weeks post-EVAR if no access site complications 5
  • Intermediate physical demand jobs: 2-4 weeks post-EVAR with successful 30-day imaging 5
  • Physically demanding occupations: 4-6 weeks post-EVAR with no complications 5
• Resume driving 1-2 weeks after procedure if not taking narcotic pain medications 5

Patient Education

Patients should be educated about symptoms requiring urgent medical attention:

• Severe or worsening pain in the abdomen, back, or access site
• Signs of infection at the access site
• Leg pain, numbness, or color changes 5

Key Pitfalls to Avoid

1. Missing follow-up imaging: Regular surveillance is crucial for detecting complications before they become life-threatening 5
2. Treating aneurysms outside manufacturer's instructions: Increases failure rates, risks of graft migration, endoleaks, and late rupture 5
3. Inadequate pre-procedure planning: Meticulous patient selection and preprocedural work-up can reduce complication incidence 4
4. Failing to recognize endoleaks: Proper classification is crucial for subsequent management 1
5. Delaying intervention for type I or III endoleaks: These endoleaks carry high risk of rupture and require prompt treatment 1