What are the symptoms of Peripheral Arterial Disease (PAD) and what diagnostic tests to order next?

Peripheral Arterial Disease: Symptoms and Diagnostic Workup

Clinical Presentation

PAD presents with a spectrum of symptoms, but only 10% of patients have classic claudication—most are either asymptomatic or have atypical leg symptoms. 1, 2

Key Symptoms to Assess

Claudication characteristics: 1

• Pain quality: Aching, burning, cramping, discomfort, or fatigue in the muscles (not joints) 1
• Location: Buttock, thigh, calf, or ankle 1
• Onset pattern: Triggered by walking a specific distance or uphill; resolves within 10 minutes of rest 1

Atypical presentations (more common than classic claudication): 1

• Leg weakness, numbness, or fatigue during walking without pain 1
• Muscular discomfort requiring >10 minutes rest to resolve 1
• Paresthesias (tingling, burning, throbbing sensations) 3
• Impaired walking function without classic pain patterns 1

Advanced disease indicators: 1

• Ischemic rest pain (pain at rest, particularly at night) 1
• Nonhealing or slow-healing lower extremity wounds 1
• Lower extremity gangrene 1

Associated findings: 1

• Erectile dysfunction 1

Physical Examination Findings

Vascular examination must include: 1

• Pulse palpation: Femoral, popliteal, dorsalis pedis, and posterior tibial arteries (grade as 0=absent, 1=diminished, 2=normal, 3=bounding) 1, 3
• Auscultation: Listen for femoral, epigastric, periumbilical, or groin bruits 1
• Bilateral arm blood pressures: Difference >15-20 mmHg suggests subclavian stenosis 1, 3

Inspection findings suggestive of PAD: 1

• Nonhealing wounds or ulcers 1
• Gangrene 1
• Asymmetric hair growth 1
• Nail bed changes 1
• Calf muscle atrophy 1
• Elevation pallor or dependent rubor 1

Diagnostic Testing Algorithm

The resting ankle-brachial index (ABI) is the cornerstone initial diagnostic test and should be performed immediately when PAD is suspected. 1, 4

Step 1: Resting ABI with Pulse Volume Recording (PVR) and/or Doppler Waveforms

Perform resting ABI in all patients with: 1

• Age ≥65 years 1, 4
• Age 50-64 years with atherosclerotic risk factors (diabetes, smoking, dyslipidemia, hypertension, chronic kidney disease, or family history of PAD) 1, 4
• Age <50 years with diabetes plus one additional atherosclerotic risk factor 1
• Known atherosclerotic disease in another vascular bed (coronary, carotid, subclavian, renal, mesenteric stenosis, or abdominal aortic aneurysm) 1, 4

ABI interpretation: 1, 4

• ≤0.90: Abnormal—PAD confirmed 1, 4
• 0.91-0.99: Borderline 1
• 1.00-1.40: Normal 1
• >1.40: Noncompressible arteries (proceed to toe-brachial index) 1

Step 2: Additional Testing Based on Resting ABI Results

If ABI >1.40 (noncompressible arteries): 1, 4

• Perform toe-brachial index (TBI) with waveforms immediately 1, 4
• TBI <0.70 confirms PAD 4
• This is particularly important in patients with diabetes or chronic kidney disease who commonly have arterial calcification 1

If ABI 0.91-1.40 (normal/borderline) with symptoms: 1, 4

• Perform exercise treadmill ABI testing 1, 4
• Post-exercise ABI decrease >20% confirms PAD 4
• This identifies PAD that manifests only with exertion 4

If ABI ≤0.90 (PAD confirmed) with symptoms: 1

• Exercise treadmill ABI can objectively assess functional status and walking performance 1
• Segmental leg pressures with PVR and/or Doppler waveforms help delineate anatomic level of disease 1

Step 3: Assessment for Chronic Limb-Threatening Ischemia (CLTI)

If patient has rest pain, nonhealing wounds, or gangrene, perform: 1

• Toe pressure/TBI with waveforms 1
• Transcutaneous oxygen pressure (TcPO2) 1
• Skin perfusion pressure (SPP) 1

Critical limb perfusion parameters indicating CLTI: 4

• Ankle pressure <50 mmHg 4
• Toe pressure <30 mmHg 4
• TcPO2 <30 mmHg 4

Step 4: Anatomic Imaging (Only When Revascularization Considered)

If symptoms are functionally limiting despite guideline-directed medical therapy and structured exercise: 1

• Duplex ultrasound, CT angiography, MR angiography, or catheter angiography to assess anatomy and determine revascularization strategy 1
• Do not perform invasive angiography in asymptomatic PAD patients 4

Critical Pitfalls to Avoid

Do not dismiss atypical symptoms: Only 10% of PAD patients present with classic claudication; most have atypical leg symptoms or are asymptomatic 1, 2. Paresthesias, weakness, or numbness should prompt vascular assessment, not just neuropathy workup 3.

Do not skip bilateral arm blood pressures: Failing to measure both arms leads to inaccurate ABI calculations and missed subclavian stenosis 4, 3.

Do not rely solely on resting ABI when clinical suspicion is high: Normal resting ABI with symptoms requires exercise treadmill ABI testing 4.

Do not use ABI alone in diabetes or renal disease: These patients frequently have noncompressible arteries (ABI >1.40); use TBI instead 4.

Do not miss acute limb ischemia: If paresthesia is accompanied by the "6 Ps" (pain, pallor, pulselessness, poikilothermia, paralysis, paresthesia), this requires immediate revascularization 3.

Do not screen low-risk patients: Screening is not recommended for patients without risk factors or suggestive symptoms 1.