Part 4/Chapter 21/7-min read

EVAR, Iliac Branch Devices, Endoleaks, and Post-EVAR Surveillance

Endovascular aneurysm repair as an anatomic operation before it is a device operation: proximal neck, iliac landing zones, pelvic perfusion, and durable seal. The chapter frames standard EVAR candidacy, iliac branch devices, endoleak classification and management, and post-EVAR surveillance.

Edited by Tal M. Hörer MD, PhD · David T. McGreevy MD, PhD·Reviewed ·5 sections · 35 references

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Planning conference: A practical planning-room conversation: anatomy, device or operative choices, surveillance, complications, and decision boundaries.

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Definition and presentation

Endovascular aneurysm repair (EVAR) aims to exclude an abdominal aortic aneurysm from the systemic circulation while preserving clinically important pelvic and lower-limb perfusion. All patients with aortic aneurysmal disease receive baseline medical management, which includes blood-pressure control, statin therapy, and smoking cessation. Elective repair is considered at a maximum aneurysm diameter of 5.5 cm or more in men and 5.0 cm or more in women, or for growth exceeding 10 mm per year . For patients with an appropriate threshold for repair, standard infrarenal EVAR candidacy is determined by the proximal neck length, angulation, and wall quality, alongside the iliac landing zone diameter. Standard elective devices typically require a proximal-neck length of 10 to 15 mm, with specific iliac diameter limits defined by the manufacturer label . A short, angulated, or highly diseased neck increases the risk of proximal seal failure and type Ia endoleak, which is associated with sac expansion and reintervention . Complex endovascular strategies are preferred over forcing a standard device into hostile anatomy. Patients with prohibitive operative risk, limited life expectancy, or incompatible care goals are managed by deliberate non-intervention rather than surgical or endovascular repair.

Endoleak classification and surveillance

Post-EVAR surveillance tracks the presence of endoleak and the trajectory of the aneurysm sac . Surveillance is lifelong because the early advantage of EVAR erodes with time. EVAR trial 1 at 15 years showed a perioperative survival benefit that was lost within the first few years, and beyond 8 years EVAR patients had higher aneurysm-related mortality driven by secondary sac rupture, 7% versus 1% with open repair . A stable or shrinking sac indicates technical success and permits lower-risk surveillance pathways. Baseline CT angiography is obtained within 30 days of EVAR. When the baseline study shows no endoleak and a stable sac, SVS 2018 images with CT at 1 and 12 months in the first year and then annually, with color duplex acceptable once the first year is clean; a type II endoleak or other abnormality on the baseline study brings imaging forward to 6 months. ESVS 2024 stratifies by risk after the baseline CT angiography: the lowest-risk patients, with adequate seal of 10 mm or more of proximal and distal overlap and no endoleak, may have imaging deferred as far as 5 years, while the remainder move to annual duplex or contrast-enhanced ultrasound with periodic CT angiography. Sac expansion indicates persistent systemic pressurisation. Computed tomography angiography is the reference standard for endoleak classification. Contrast-enhanced ultrasound and color duplex offer interval imaging alternatives that reduce contrast exposure and demonstrate good accuracy in pooled analyses, although performance varies by reader experience .

Postoperative sac pressurisation is defined by endoleak class, which links the imaging finding to the source of persistent flow :

  • Type Ia: Proximal seal failure.
  • Type Ib: Distal seal failure.
  • Type II: Retrograde branch flow into the sac.
  • Type III: Graft junction separation or fabric failure.
  • Type IV: Graft porosity (predominantly historical).
  • Type V: Endotension, a diagnosis of exclusion when the sac expands without a visualised leak.

Treatment decisions and reintervention

Intervention targets the specific mechanism of repair failure. Structural exclusion failures, including type Ia, Ib, and III endoleaks, require definitive correction with endovascular adjuncts or open conversion. Type II endoleak is the most common finding after EVAR, and detection far outnumbers clinically meaningful sac growth. A stable sac is therefore watched, while an expanding sac is treated by transarterial or translumbar embolisation of the feeding branches, escalating to relining or open conversion if embolisation fails. Clinically significant sac expansion is an increase of 5 mm or more in maximum aneurysm diameter from the smallest prior post-EVAR measurement . ESVS 2024 recommends considering type II reintervention when the sac grows 10 mm or more, leaving the 5 to 10 mm band as the zone of centre-level variation. Emergency presentations, including post-EVAR rupture, acute graft infection, or a threatened limb, supersede elective algorithms and mandate an urgent endovascular or open intervention pathway.

Post-EVAR management and reintervention triggers

  • Medical management

    Clinical finding or trigger
    Aneurysmal disease baseline
    Recommended action
    Blood-pressure control, statin, and smoking cessation
    Citation

  • Proximal seal failure

    Clinical finding or trigger
    Type Ia endoleak with sac expansion
    Recommended action
    Proximal cuffs, sealing devices, or open conversion
    Citation

  • Distal seal failure

    Clinical finding or trigger
    Type Ib endoleak
    Recommended action
    Distal extension or landing zone revision
    Citation

  • Retrograde branch flow

    Clinical finding or trigger
    Type II endoleak without expansion
    Recommended action
    Continued imaging surveillance
    Citation

  • Retrograde branch flow

    Clinical finding or trigger
    Type II endoleak with sac expansion
    Recommended action
    Transarterial or translumbar embolisation of the feeding branches; reline or convert to open repair if embolisation fails
    Citation

  • Device failure

    Clinical finding or trigger
    Type III endoleak
    Recommended action
    Endovascular repair of fabric or graft junction
    Citation

  • No intervention

    Clinical finding or trigger
    Prohibitive risk or limited life expectancy
    Recommended action
    Deliberate non-intervention and supportive care
    Citation

  • Emergency

    Clinical finding or trigger
    Rupture, severe infection, or threatened limb
    Recommended action
    Urgent endovascular or open intervention
    Citation

Reintervention planning follows a stepwise assessment:

  1. Confirm patient suitability for reintervention versus the deliberate no-intervention pathway.
  2. Confirm the presence or absence of endoleak and classify its flow source.
  3. Assess sac dynamics as stable, shrinking, or expanding.
  4. Treat type Ia, Ib, and III endoleaks as mechanical failures requiring specific endovascular adjuncts or open conversion.
  5. Treat an expanding type II endoleak by embolisation of the feeding branches, reserving relining or open conversion for embolisation failure; watch a stable sac.
  6. Evaluate the continued patency and seal of any preserved iliac pathways.
  7. Escalate to urgent intervention for emergency rupture or infection outside the elective framework.

Iliac branch and pelvic perfusion management

Common iliac aneurysm extension necessitates a choice among iliac branch preservation, hypogastric embolisation, or alternative distal adjuncts such as bell-bottom techniques. Iliac branch devices preserve flow to at least one internal iliac artery and are associated with a reduction in buttock claudication compared with routine hypogastric exclusion, while maintaining acceptable technical success . Buttock claudication follows internal iliac embolisation or coverage in roughly 28% of patients, with new erectile dysfunction reported in up to 46% , against a side preserved by an iliac branch device, which returned about 95% internal iliac limb patency and high freedom from ipsilateral buttock claudication at 5 years. In bilateral iliac disease, preserving at least one internal iliac artery is the primary planning objective, and anatomical suitability dictates the specific side selected for preservation.

Areas of controversy

The limits of standard EVAR outside instructions for use remain a subject of debate, particularly regarding whether hostile neck anatomy is safely managed with standard-EVAR adjuncts or mandates fenestrated and branched repair . The exact threshold for type II endoleak intervention is not uniformly established, leading to centre-driven variation in whether to treat early sac expansion or employ pre-emptive branch embolisation . Finally, while ultrasound-based surveillance reduces contrast exposure, its reliance on local operator expertise limits universal adoption over computed tomography angiography .

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