Editing EVAR


= Indications =

* 80% of infrarenal AAA are now done with EVAR
* Open repair reserved for those with complex anatomy or coexisting disease processes preventing EVAR

Relative contraindications

* CKD (high contrast load)
* Poor iliofemoral access

Absolute contraindications

* Connective tissue disorders
* Infected aneurysms
* IMA is primary intestinal circulation

Requirements

* Adequate iliofemoral access - patency, diameter, ?calcification/thrombus, tortuosity
* Adequate seal zone proximally between graft and normal aorta - 10-15mm depending on device
* Adequate seal zone distally, proximal to iliacs - 10-15mm dependent on device

= Preparation: =

* External CT scans imported to PACS at earliest opportunity
* Confirm with consultant which EVAR device they require and ensure that the liaison nurses are in contact with the relevant company, and that the stock has arrived
* Document lower limb pulses and neurologic status on admission
* Book angio suite
** In most cases straightforward EVAR can be done in angio suite 2
** Any cases requiring adjunctive procedures should be done in suite 1
* Confirm that anaesthetics is available
* Confirm theatre scrub nurses are available

= Post-op =

* Document pulses at end of procedure
* Check for and document neurologic function once patient awake
* Especially check for:
** Bleeding/haematoma (consider femoral USS to exclude pseudoaneurysm)
** Hypotension/anaemia
** Neurologic changes (spinal cord ischaemia)
** Acute ischaemia or change in pulse status

= Follow-up =

* CT aortogram (EVAR follow-up protocol) at 6 weeks (unless already done prior to discharge, in which case do an EVAR surveillance USS at 6 weeks)
* Ensure screening for thoracic and popliteal aneurysm has been done
* Remind family members to be screened for AAA
* Long term risk factor management with GP
* Lifelong surveillance with alternating EVAR surveillance USS and CT aortogram - usually 6 monthly (check for residual aneurysm sac size, evidence of endoleak, graft separation and migration, and progressive suprarenal or iliac artery aneurysm)

= Complications =

* Endoleak (persistent blood entry into aneurysmal sac after EVAR). There is continued pressurisation of the sac - can lead to continued growth and rupture

*
* Type I: persistent blood flow into the sac either from around the graft proximally (IA) or distally (type IB)
** Late:
*** Typically secondary to caudad migration of the stent graft, or continued dilation of the neck
*** Proximal extension may be deployed to achieve a proximal seal
* Type II: persistent sac filling from back-bleeding side branches (IMA, lumbar arteries, middle sacral artery)
** Occurs in 10-20% of EVAR patients
** Relatively benign course - up to 80% resolve spontaneously within 6-12 months, with low risk of aneurysm rupture. No association between type II endoleak and risk of aneurysm rupture or need for surgical conversion.
** Typically not treated unless sac enlargement is documented.
** Embolisation can be performed using coils or glue - either via SMA or through sac
** If endovascular techniques fail, operative explant may be required
* Type III: fabric erosion or leak between the stent-graft components - occurs in modular components
** Effectively treated with re-lining
* Type IV - porosity of graft fabric
** Noted within 30 days of graft implantation
** No treatment usually required
* Type V: 'endotension' - elevated sac aneurysm pressure without a demonstrable endoleak
** Aetiology likely to be undetected endoleak or transmission of systemic pressure through thrombus

* Graft occlusion - limb thrombosis or kinking - 3%
** Claudication in buttock/thigh/calf
** Rest pain
** Acute ischaemia
** Mostly occurs early on
* Ischaemic complications
** Direct vessel occlusion by stent-graft, or occlusion of the stent-graft itself; atheroembolic events during catheter manipulation or device deployment; inadequate collateralisation of mesenteric or pelvic circulation
* Spinal cord ischaemia - 0.25%
** Dreaded complication, not really understood exactly why it happens
* AKI - common
* Late conversion to open - 1%
* Infection

[[Category:Vascular]]