Fenestrated vs Branched EVAR: Key Technical Differences
Fenestrated EVAR (fEVAR) uses openings (fenestrations) in the stent graft fabric to preserve blood flow to branch vessels, while branched EVAR (bEVAR) uses directional cuffs or branches extending from the main graft body to connect with target vessels. These are complementary techniques for treating complex aortic aneurysms involving visceral and renal arteries 1.
Technical Design Distinctions
Fenestrated grafts contain precisely positioned holes in the graft material that align with vessel origins. The target vessels are then stented through these openings, creating a seal between the fenestration edge and the vessel ostium 2, 3.
Branched grafts incorporate tubular extensions (cuffs or branches) that project from the main graft body at specific angles and orientations. These branches are then connected to the target vessels using bridging stent grafts 2, 3.
Anatomical Selection Criteria
The choice between fenestrated and branched approaches depends primarily on:
Aortic zone involvement: bEVAR is more commonly used for Ishimaru zone 0 (aortic arch) repairs, while fEVAR is typically employed for juxtarenal and pararenal aneurysms 4
Vessel angulation: Branched grafts handle more severe angulation and vessel orientation challenges better than fenestrations, which work optimally when vessels arise relatively perpendicular to the aortic wall 2
Extent of disease: For thoracoabdominal aneurysms (TAAA), the technique selection depends on which aortic segments require coverage. Both achieve technical success rates >95% 5
Clinical Outcomes
Both techniques demonstrate similar perioperative outcomes when used appropriately 1:
- 30-day mortality: 1-5% for pararenal aneurysms, 5-10% for TAAA 5
- Technical success: >93% for both approaches 6
- Spinal cord ischemia: Approximately 5% overall, with permanent paraplegia around 1.6-2.9% 7, 6
Target vessel durability represents a critical concern for both techniques. Renal arteries show higher instability rates (4.0%) compared to visceral arteries (3.1%), with reintervention rates of 4.1% and 2.9% respectively 7. Freedom from reintervention at 36 months is approximately 59-60% 8, 6.
Practical Considerations
Custom-made devices (used in 74.4% of cases) allow precise anatomical matching but require 6-8 weeks manufacturing time, making them unsuitable for urgent cases 6. Off-the-shelf devices provide immediate availability but may have higher spinal cord ischemia rates 6.
The techniques are often combined (fenestrated-branched EVAR) when anatomy requires both approaches simultaneously, particularly for extensive TAAA repairs 2, 5.
Common Pitfalls
- Inadequate preoperative imaging: High-quality CT angiography with thin slices (<1mm) is essential for accurate device planning
- Target vessel cannulation failure: Occurs in approximately 4-6% of cases; bail-out techniques must be available 2
- Endoleak management: Type III endoleaks at fenestration/branch sites require prompt reintervention
- Surveillance lapses: Lifelong imaging surveillance is mandatory given reintervention rates approaching 40-60% by 5 years 6