Occlusive Disease: Aorta & Iliac Arteries

Essentials of Diagnosis

• Claudication: cramping pain or tiredness in the calf, leg, or hip while walking

• Diminished femoral pulses

• Tissue loss (ulceration, gangrene) or rest pain

General Considerations

• Pathologic changes of atherosclerosis may be diffuse, but flow-limiting stenoses occur segmentally

• In the lower extremities, stenoses classically occur in three anatomic segments

  • The aorto-iliac segment

  • The femoral-popliteal segment

  • The infrapopliteal, or tibial, segment of the arterial tree

• Lesions in the distal aorta and proximal common iliac arteries often occur in relatively young men, age 50–60 years, who are smokers

• Disease progression may lead to complete occlusion of one or both common iliac arteries, which can precipitate occlusion of the entire abdominal aorta to the level of the renal arteries

• Atherosclerosis of the femoro-popliteal segment usually

  • Occurs about a decade following the development of aorto-iliac disease

  • Is evenly distributed between men and women

Demographics

• Prevalence of peripheral artery disease (PAD) is 30% in patients who are

  • 70 years old without other risk factors

  • 50 years old with risk factors such as diabetes mellitus or tobacco use

Symptoms and Signs

• About two-thirds of patients with PAD are either asymptomatic or do not have classic symptoms

• Intermittent claudication (pain with ambulation)

  • Occurs from insufficient blood flow relative to demand

  • Severe and cramping in quality

  • Usually located in the calf muscles

  • May be bilateral

  • Severity varies day by day

• The pain from aorto-iliac lesions may extend into the thigh and buttocks

• Weakness in the legs when walking or simply extreme limb fatigue

• Symptoms relieved with rest

• Erectile dysfunction common with bilateral common iliac disease

• Femoral and distal pulses are absent or very weak

• Bruits may be heard over the aorta, iliac, and femoral arteries

Differential Diagnosis

• Vascular disease of the femoral or popliteal arteries

• Lumbar spinal stenosis

• Degenerative joint disease of the hips

Imaging Studies

• CT angiography and magnetic resonance angiography can identify the anatomic location of disease

• Duplex ultrasound has a limited role in imaging the aortoiliac segment because of overlying bowel

• Imaging is required only when symptoms necessitate intervention, since vascular testing should identify the involved levels of the arterial tree

Diagnostic Procedures

• Doppler examination

  • Ratio of systolic blood pressure at ankle compared with brachial artery of upper arm is reduced to below 0.9 (normal ratio is 0.9–1.2)

  • This difference is exaggerated by exercise

• Segmental wave-forms or pulse volume recordings

  • Obtained by strain gaze technology through blood pressure cuffs

  • Demonstrate blunting of the arterial inflow throughout the leg

Medications

• All patients should receive high-dose statin (eg, atorvastatin 80 mg daily if tolerated) to treat hypercholesterolemia and inflammation

• Phosphodiesterase inhibitors, such as cilostazol 100 mg orally twice daily, may improve walking distance in about two-thirds of patients

• Antiplatelet agents (aspirin 81 mg daily or clopidogrel 75 mg orally daily) reduce overall cardiovascular morbidity and are recommended for all symptomatic patients

Surgery

• Consider intervention to relieve obstruction if claudication interferes appreciably with patient's essential activities or employment

• Aorto-femoral bypass graft

  • Highly effective and durable

  • Prosthetic graft extends from the infrarenal abdominal aorta to the common femoral arteries

  • Mortality is low, in range of 2–3%

  • Morbidity is higher with a 5–10% rate of myocardial infarction

• High-risk patients may also be treated with a graft from axillary artery to femoral arteries (axillo-femoral bypass graft)

• When iliac disease limited to one side, a graft from the contralateral femoral artery (fem-fem bypass) may be done

• Axillo-femoral and femoral-to-femoral grafts

  • Extra-anatomic bypasses because the abdominal cavity is not entered and the aorta is not cross clamped

  • Operative risk is less than with aorto-bifemoral bypass but the grafts are less durable

Therapeutic Procedures

• The cornerstones of PAD treatment are

  • Risk factor reduction

  • Medical optimization

  • Exercise program

• A program that includes smoking cessation, lipid and blood pressure management and weight loss is essential

• Angioplasty and stenting effectively treat occlusive lesions of the aortoiliac segment

Complications

• While mortality is low (2–3%), morbidity is higher and includes a 5–10% rate of myocardial infarction

• Endovascular approaches are safer, complication rate 1–3%, but less durable with extensive disease

Prognosis

• Without intervention, the prognosis for patients with isolated aorto-iliac disease include reduction in walking distance but rarely include rest pain or threatened limb loss

• Life expectancy is related to attendant cardiovascular disease, with a mortality rate of 25–40% at 5 years

• Symptomatic relief is generally excellent with supervised exercise or after intervention

• After aorto-femoral bypass, a patency rate of 90% at 5 years is common

• Endovascular patency rates and symptom relief for patients with short stenoses are also good with 80% symptom free at 3 years

• Recurrence rates for endovascular treatment of extensive disease are 30–50%

When to Refer

• Patients with progressive reduction in walking distance in spite of risk factor modification and consistent supervised exercise programs and those with limitations that interfere with their activities of daily living should be referred for consultation to a vascular surgeon