Aortoiliac occlusive disease

Pathophysiology

• AIOD typically begins at aortic terminus and COA origins and slowly progresses proximally and distally
• Claudication symptoms can often be managed easily non-operatively for years due to good collaterals (lumbar and hypogastric arteries connecting to circumflex iliac, hypogastric, femoral, PFA recipients), and rarely leads to CLTI
• 40% have concomitant SFA disease and 35% have orifical PFA disease
• Generally doesn't progress proximally to level of visceral arteries
• 'Small aortic syndrome' or 'hypoplastic aortic syndrome'
  • Typically found in young women smoke
  • Focal stenosis posteriorly at or proximal to the aortic bifurcation
  • Durability of endovascular intervention or endarterectomy is often poor, especially if they keep smoking
• Leriche syndrome
  • Impotence
  • Claudication
  • Lower extremity pallor and atrophy of leg muscles
  • Absent femoral pulses
• Pelvic ischaemia
  • Hip and buttock claudication, erectile discomfort, cauda equina syndrome

Evaluation

• Risk factors
  • Old age
  • Smokers
  • HTN
  • Hyperlipidaemia
  • Diabetes
• Symptoms
  • Hip/thigh/buttock claudication, along with absent femoral pulses
  • Leriche syndrome
  • Tissue loss
  • Rest pain
• Exam
  • >20mm Hg drop between brachial and proximal thigh pressure represents significant aortoiliac stenosis

Imaging

• Segmental Doppler pressures
• Duplex USS is hard because of overlying bowel gas patterns
• CTA is best first imaging option, probably
• Criteria for iliac stenosis:

Stenosis	PSV
>50%	>200cm/s; PSV ratio >2.5
>75%	PSV 400cm/s; PSV ratio >5; EDV >40cm/s

• • CFA velocity <45cm/s with an associated monophasic waveform pattern are nearly 90% accurate in identifying a proximal iliac artery lesion

Treatment

Indications for intervention

• Disabling intermittent claudication that significantly affects a patient's daily lifestyle despite optimal medical therapy
• Ischaemic rest pain
• Tissue loss

Medical interventions:

• Smoking cessation
• Weight loss
• Antiplatelets
• Treat:
  • HTN
  • Hyperlipidaemia
  • Diabetes
• Trial of organised exercise program

Endovascular vs open:

• Type A and B: endovascular offered first
• Type D: open revasculararisation, unless precluded by comorbidity
• Type C: probably also endovascular first now

Surgical revascularisation

• Aortobifemoral bypass grafting is now the preferred open approach for patients with advanced disease but acceptable operative risk
  • Dacron graft tunneled directly on top of existing vessels down to CFA
• Femorofemoral bypass
  • Dependent on a nice patent contralateral inflow vessel
  • Graft is tunneled across superfiscial to the pubis from one side to the other
• Axillobifemoral bypass
  • Used in ill, older patients with infrarenal aortic or iliac occlusive disease resulting in critical limb ischaemia
• Results are excellent, with 10 year AFB graft patency of 85%. Younger patients do worse, unknown why. Extra-anatomic graft results are slightly worse but still acceptable.

Pre-op optimisation

• Evaluate cardiac, pulmonary, renal, cerebrovascular and haematologic disease
• Assume CAD
• In CKD, delay until after contrast load has been excreted from angiogram
• Periop beta blockade and continuation of aspirin