Editing Open AAA repair

== Indications ==

* '''Patients who cannot undergo EVAR'''
** Unfavourable anatomy for EVAR
*** No aortic neck/hostile aortic neck (main indication)
*** Proximal aortic necks that are short (<2cm), angled, trapezoidal, have a high burden of thrombus, or are heavily calcified can compromise seal
*** Iliac artery occlusive disease (especially chronic total occlusion) can mean EVAR Is hard
*** Concomitant CIA or EIA aneurysms (might still be able to do EVAR)
*** Horseshoe kidney
*** Where IMA patency needs to be preserved
** Coexisting disease processes
* Emergency situations and endovascular unavailable
* Younger patients (EVAR durability is questionable)
* Patients with complex aortic neck anatomy (pararenal/suprarenal aneurysms)
* Conversion of EVAR 
** Failure of EVAR due to migration or recalcitrant endoleak that is unable to be resolved by endovascular means
** Tends to be a much more complex operation than de novo AAA repair
** Don't have to completely remove the previous EVAR graft unless it's infected
* Infection of native aorta or previous repair
** Can't be done as open unless in certain situations
**

== Outcomes ==

* Mortality rates with pararenal/ruprarenal AAA repair approach 5-10%
** Infrarenal repair <5%

== Preparation ==

* Import external scans
* Confirm intended proximal clamp zone and warn aesthetist
* Confirm required aortic graft stock is in the hospital
* Document lower limb pulses and neurologic status
* Crossmatch 4 units
* Book ICU bed
* Book cell saver

== Operative plan should include ==

* Extent of resection
* Location of cross-clamp application
* Qualitative assessment of aorta
* Evaluation of visceral vessel topography and patency
** IMA preservation may be indicated if there is significant SMA disease. Can be done by either re-implanting into graft, or from a sidearm attached to the graft
* Identification of aneurysmal or occlusive iliac disease
* Need for concomitant renovisceral reconstructions

Patient preparation

* CARP trial - only patients with left main coronary artery disease, EF<20% and valvular disease should have that fixed prior to AAA.
* Cell saver

== Approach (essentially transperitoneal vs retroperitoneal) ==

* Transabdominal approach favoured by most, through midline laparotomy
** Better in emergency - quicker and easier
** Good access to infra-renal AAA, but more difficult to expose visceral aorta
** Better access to iliacs and right renal artery this way

== Transabdominal AAA repair ==
Setup

* Supine with arms out
* Prep from nipples to knees

Approach

* Midline laparotomy
* Omentum and transverse colon brought cephalad
* Root of mesentery and small bowel retracted to right and maintained with retractor like Omnitract
* Divide ligament of Treitz and retroperitoneum tissues over aneursym itself
** Avoid injury to IMV, but can be ligated if necessary
** Track the right of the aorta to avoid injury to IMA, sigmoid mesentery and autonomic nervous plexus at the bifurcation
**
* If the aneurysm itself is covered by left renal vein, may need to ligate the branches to retract it superiorly

Supracoeliac clamping

* Most useful in setting of ruptured AAA or juxtarenal AAA
* Requires specific steps
* Consider renal preservation therapy
* Aim clamp time <30mins

Aortic repair

* Aortic sac opened longitudinally, and mural thrombus and debris are evacuated with care
* Reconstruction with appropriate Dacron or polytetrafluoroethylene (PTFE) tube grafts
* Cover graft with aortic sac and omentum to reduce migration

Closing

* Careful haemostasis - look at intercostals and lumbar vessels

== Post-op: ==

* Check distal perfusion in recovery
* SCDS and enoxaparin, no TEDS
* Monitor fluid balance carefully
* NPO until any ileus resolved
* Neurovasc obs
* Antibiotics as per surgeon

== Follow-up ==

* Wound review 2-6 weeks
* Aortoiliac USS at 6 months with clinic review
* Surveillance imaging every five years, or more often in clinical concern
* Check popliteals and thoracic aorta
* Remind family members to be screened for AAA
* Long term risk factor management with GP
* Repeat duplex 2-5 years post-op for progressive suprarenal or iliac aneurysm. GP can arrange.

== Complications ==

* Early
** Cardiac
*** Up to 10%
*** Risk factors:
**** Recent MI, old age, diabetes, poor functional status, arrhythmia, or CCF
*** Ensure patients are on aspirin, statin, beta blockers (aim HR< 60, BP <100
** Pulmonary
*** Periop smoking cessation, optimal bronchodilator therapy, chest physio
*** Delayed extubation if more complex repair involving higher proximal aortic control
*** 17% get pneumonia
** Renal
*** AKI rate is 10%-20%
*** Consider failed renal artery reconstruction or cholesterol embolization
*** Close attention to volume status 
** Colonic ischaemia
*** 0.2-6%
**** 4% for tube grafts
**** 2.7% for aorto-iliac grafts
**** 22% for an aortobifemoral graft
*** Operative risk factors:
**** Ligation of IMA
**** Failure to revascularise hypogastric arteries
*** Patient factors:
**** Pre-existing iliofemoral occlusive disease
**** Previous colonic resection
*** Signs:
**** Early post-op diarrhoea
**** Melaena
**** '''Haematochaezia'''
*** Investigation
**** Flex sig/colonoscopy
**** CT
*** Management
**** Aggressively resuscitatied
**** Broad-spectrum Abx
**** Partial-thickness ischaemia/stable patient: conservative. Mostly doesn't progress to full-thickness necrosis, but still can.
**** Full-thickness ischaemia/peritonitic/unstable: urgent laparotomy and bowel resection. Mortality 55%. Thorough assessment of IMA - if vigorous back-bleeding, probably ok. 
** Lower extremity ischaemia
*** Operative factors:
**** Anastomotic complications
**** Clamp injury
**** Acute thrombosis
**** Acute embolic disease
*** Management:
**** Treat the cause
**** All the above causes need intervention
** Spinal cord ischaemia
*** Extremely rare
*** Extent of proximal coverage of aorta is the biggest risk factor
*** CSF drainage and pelvic revascularisation are main treatments
** Venous thrombosis
*** Clinically rare due to systemic anticoagulation

[[Category:Vascular]]