Evars
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- EVARS (a medical/anatomical term or acronym)
- Evar (a brand name, e.g., a stent graft used in EVAR - Endovascular Aneurysm Repair)
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FeEVar,Bevar
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FeEVAR BeEVAR fenestrated branched endovascular aneurysm repair comparison
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fenestrated branched endovascular aortic repair FEVAR BEVAR
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Here is a thorough comparison of FEVAR (Fenestrated EVAR) and BEVAR (Branched EVAR):
FEVAR vs BEVAR - Fenestrated and Branched Endovascular Aortic Repair
Overview
Both are advanced variants of EVAR developed to treat aortic aneurysms that extend into or near the visceral/renal vessels - territory where a standard EVAR device cannot be placed without compromising organ blood supply.
FEVAR - Fenestrated EVAR
Mechanism: The graft fabric has reinforced holes (fenestrations) or scallops precisely cut into the stent graft. These openings are aligned with the origins of visceral/renal arteries, allowing perfusion to continue while the aneurysm sac is excluded.
Indications:
- Juxtarenal and pararenal aortic aneurysms
- Short-neck infrarenal aneurysms (inadequate proximal seal zone)
- Suprarenal aneurysms where renal/mesenteric origins arise from the aneurysmal aorta
Key device: The Z-Fen device (Cook Medical) was the first commercially available custom fenestrated graft in the USA. FDA approved fenestrated stent grafts for pararenal/juxtarenal AAA in 2012.
5-year outcomes (Z-Fen trial):
- Renal artery patency: 98%
- Freedom from mortality: 91%
- No aneurysm ruptures or conversion to open repair
- Freedom from reintervention: only 63% (reintervention remains a challenge)
Limitations:
- Requires absolute precision in aligning scallops/fenestrations with vessel origins
- Custom-made (based on CT angiography reconstructions) - takes significant time and cost to manufacture
- Not suitable for emergency repair
BEVAR - Branched EVAR
Mechanism: Instead of holes in the fabric, axially oriented cuffs (branches) are attached to the endograft. Surgeons cannulate and stent the target mesenteric or renal vessels through these branches.
Key difference from FEVAR: The branches provide a small margin of movement - the device can be shifted slightly up or down the aorta without the need to precisely align a fenestration right at the vessel origin. This is particularly useful for more extensive and complex anatomy.
Indications:
- Thoracoabdominal aortic aneurysms (TAAAs) - especially extensive (Type I-III)
- When anatomical constraints make precise fenestration alignment difficult
- Complex pararenal disease where branching anatomy is variable
Downsides:
- BEVAR devices tend to be longer, covering a greater portion of the descending thoracic aorta
- Greater coverage = higher spinal cord ischemia risk - spinal cord protection strategies (e.g., CSF drainage, staged procedures, avoiding hypotension) are mandatory
- Also custom-made, costly, and not available for urgent cases (long manufacturing time)
Head-to-Head Comparison
| Feature | FEVAR | BEVAR |
|---|---|---|
| Structural addition | Holes/scallops in fabric | Cuffs/branches on graft |
| Precision needed | Very high (exact alignment) | Less stringent |
| Device length | Shorter | Longer (more thoracic coverage) |
| Spinal cord risk | Lower | Higher |
| Best for | Juxtarenal/pararenal AAA | TAAA (extensive disease) |
| Off-shelf availability | Being studied | Very limited |
| Emergency use | No (custom) | No (custom) |
| Cost | High | Higher |
Alternatives: Chimney/Snorkel EVAR (Ch-EVAR)
When neither FEVAR nor BEVAR is available (e.g., emergencies), a chimney graft technique is used - a separate endograft placed in parallel to the main graft body, running between the graft and the aortic wall, to preserve visceral flow. Available "off the shelf" and cheaper, but associated with a risk of type Ia endoleak ("gutter leak").
Recent Evidence
A 2024 meta-analysis in Annals of Surgery (PMID 38214159) found that fenestrated/branched endovascular repair of TAAA had lower 30-day mortality and spinal cord ischemia than open surgery. A 2024 systematic review (PMID 37757916) also reviewed F/BEVAR outcomes after prior open aortic repair, showing acceptable results even in redo cases.
The Mayo Clinic series of 600 consecutive F/BEVAR repairs (2007-2019) reported:
- Overall 30-day mortality: 2%
- Intraoperative adverse events in 18% of patients
- Most common complications: target artery issues (55 events) and access complications (46 events)
Sources: Miller's Anesthesia, 10e - Barash Clinical Anesthesia, 9e - Sabiston Textbook of Surgery
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