What is the recommended diagnostic workup and treatment plan for peripheral arterial occlusive disease?

Peripheral Arterial Occlusive Disease: Diagnostic Workup and Treatment

Initial Diagnostic Approach

Begin with ankle-brachial index (ABI) measurement as the first-line diagnostic test after clinical examination, as an ABI <0.90 confirms peripheral arterial disease with 75% sensitivity and 86% specificity. 1

Essential Clinical Assessment

• Systematically palpate and grade bilateral femoral, popliteal, dorsalis pedis, and posterior tibial pulses to identify the anatomical level of disease 2
• Assess for rest pain (particularly nocturnal pain requiring leg dependency for relief), claudication occurring at predictable walking distances that resolves within 10 minutes of rest, and presence of non-healing wounds or tissue loss 2
• Document critical risk factors: age ≥65 years, or ≥50 years with diabetes, smoking history, dyslipidemia, hypertension, or chronic kidney disease 2
• Examine for elevation pallor with extended capillary refill time (>2 seconds), dependent rubor, hair loss, trophic skin changes, and temperature asymmetry 1, 2

Objective Testing Algorithm

For patients with ABI <0.90: Diagnosis of peripheral arterial disease is confirmed 1

For patients with ABI 0.90-1.00 (borderline): Perform post-exercise ABI and/or duplex ultrasound to unmask moderate stenosis 1

For patients with ABI >1.40 (medial calcification): Measure toe-brachial index, toe pressures, or transcutaneous oxygen pressure (TcPO2) as alternative tests 1, 2

Critical thresholds for wound healing assessment in diabetic patients:

• ABI <0.6 indicates significant ischemia impairing wound healing 1
• Toe pressure >55 mmHg and TcPO2 >50 mmHg predict likely healing 1
• Toe pressure <30 mmHg and TcPO2 <30 mmHg indicate severely impaired healing 1

Advanced Imaging

Duplex ultrasound (DUS) provides 85-90% sensitivity and >95% specificity for detecting stenosis >50%, and should be combined with ABI measurement 1

For revascularization planning, obtain one of the following:

• Computed tomography angiography (96% sensitivity, 98% specificity for aorto-iliac lesions) 1
• Magnetic resonance angiography (95% sensitivity for segmental stenosis) 1
• Intra-arterial digital subtraction angiography 1

Visualize the entire lower extremity arterial circulation with detailed below-the-knee and pedal artery imaging when revascularization is considered 1

Treatment Strategy by Disease Severity

Intermittent Claudication Management

Supervised exercise training is the first-line treatment for all claudication patients, with statins recommended to improve walking distance. 1 Revascularization should be reserved for patients who fail to respond to 3 months of exercise therapy or have disabling symptoms that substantially alter daily life activities 1

Cardiovascular risk factor modification (Class I, Level A):

• Target LDL cholesterol <1.8 mmol/L with statin therapy 3, 4
• Target blood pressure <130/80 mmHg 3
• Mandatory smoking cessation 5, 6
• Antiplatelet therapy with acetylsalicylic acid 4

Exercise therapy protocol:

• Supervised exercise training provides greatest improvement in maximal walking distance (superior to stenting at 6 months in the CLEVER trial) 1
• Unsupervised exercise training is recommended when supervised programs are unavailable 1
• Treadmill testing using the Strandness protocol (3 km/h, 10% slope) objectively assesses functional capacity 1

Pharmacotherapy for walking impairment has limited objective documentation of benefit, with mild to moderate effects at best 1. Drugs studied include cilostazol, naftidrofuryl, pentoxifylline, buflomedil, carnitine, and propionyl-L-carnitine 1

Revascularization for Intermittent Claudication

Aorto-iliac lesions:

• **Short stenosis/occlusion (<5 cm):** Endovascular therapy achieves >90% patency over 5 years with low complication risk 1
• Ilio-femoral lesions: Hybrid procedure (femoral endarterectomy/bypass combined with iliac endovascular therapy) 1
• Occlusion extending to infrarenal aorta: Consider covered endovascular reconstruction (87% 1-year, 82% 2-year patency) 1
• Occlusion to renal arteries: Aorto-bifemoral bypass surgery in fit patients 1

Femoro-popliteal lesions:

• Stenosis/occlusion <25 cm: Endovascular therapy is first choice 1
• Stenosis/occlusion >25 cm: Surgical bypass with great saphenous vein achieves superior long-term patency (>80% at 5 years above-knee) compared to endovascular therapy (66% with drug-eluting stents, 43% with conventional stents) 1
• Prosthetic conduits achieve 67% 5-year patency 1

If profunda femoral artery circulation is normal, exercise therapy alone often relieves claudication and intervention is mostly unnecessary 1

Critical Limb-Threatening Ischemia

Revascularization must be considered in all patients with critical limb-threatening ischemia to restore direct pulsatile flow to at least one foot artery, preferably the artery supplying the wound region. 1 Limb salvage rates after revascularization are 80-85% with ulcer healing >60% at 12 months 1

Exceptions to revascularization:

• Severely frail patients or life expectancy <6-12 months 1
• Pre-existing severe functional impairment unlikely to worsen with amputation 1
• Large volume tissue necrosis rendering foot functionally unsalvageable 1

Timing considerations:

• Patients with critical ischemia and foot infection require urgent treatment within 24 hours as "time is tissue" in infected ischemic diabetic foot ulcers 1
• Perioperative mortality is <5% with major systemic complications in approximately 10% 1
• End-stage renal disease patients have worse outcomes but can achieve approximately 70% 1-year limb salvage 1

Diabetic Foot Ulceration Protocol

For patients without ischemia symptoms, palpable pulses, or mild PAD (ABI >0.6, toe pressure >55 mmHg, TcPO2 >50 mmHg): Evaluate response to maximal 6-week optimal wound care before proceeding to revascularization 1

If wound healing response is poor: Reassess perfusion with duplex ultrasound or angiography 1

Comprehensive care must include: Treatment of infection, frequent debridement, biomechanical offloading, blood glucose control, and treatment of comorbidities 1

Critical Clinical Pitfalls

Never apply compression therapy without first checking ABI, as this can precipitate gangrene in patients with peripheral arterial disease 2

Never attribute bilateral discoloration to "just venous stasis" without ruling out PAD and infection through objective testing 2

Recognize "masked" disease in elderly patients with multiple comorbidities who may present with sudden severe ischemia despite being labeled "asymptomatic" because they cannot walk far enough to develop claudication 2

Patients with peripheral arterial disease have 3-fold increased risk of myocardial infarction, stroke, and vascular death compared to claudicants, with 5-year cardiovascular morbidity of 13% versus 5% in reference populations 1