What is a PAE (Percutaneous Arterial Embolization) of the lower extremity with a treadmill test?

Understanding PAD Lower Extremity Treadmill Testing

Exercise treadmill tests are recommended to provide objective evidence of functional limitation in claudication and to measure response to therapy in patients with peripheral arterial disease (PAD). 1

What is a PAD Lower Extremity Treadmill Test?

A PAD lower extremity treadmill test is a diagnostic procedure used to:

1. Objectively measure the functional limitations caused by claudication
2. Differentiate arterial claudication from non-arterial causes of leg pain ("pseudoclaudication")
3. Diagnose PAD when resting ankle-brachial index (ABI) values are normal or borderline
4. Assess response to therapy in patients with established PAD

Test Components and Protocol

The test involves:

• Pre-exercise measurements: Resting ABI and segmental pressures
• Standardized treadmill protocol: Either fixed or graded protocol 1
  • Fixed protocol: Constant speed and grade (e.g., 1.5 mph at 7.5% grade)
  • Graded protocol: Begins at lower intensity (e.g., 2 mph at 0% grade) with incremental increases (e.g., 2% every 2 minutes)
• Post-exercise measurements: Repeat ABI immediately after exercise

Key Measurements During Testing

• Pain-free walking distance (PFWD): Distance walked before claudication pain begins
• Maximum walking distance (MWD): Total distance walked until stopping due to maximum tolerable pain
• Pre- and post-exercise ABI values: A decrease in ABI of 15-20% post-exercise is diagnostic of PAD

When to Use PAD Treadmill Testing

Treadmill testing is indicated for:

1. Patients with exertional leg symptoms and normal or borderline resting ABI (>0.90 and ≤1.40) to evaluate for PAD 1
2. Patients with established PAD and abnormal resting ABI (≤0.90) to objectively assess functional status 1
3. Patients undergoing exercise training (PAD rehabilitation) to establish baseline function 1

Clinical Significance and Interpretation

• A post-exercise drop in ABI confirms the diagnosis of PAD in symptomatic patients with normal resting ABI
• The magnitude of functional limitation can be objectively documented
• The test helps differentiate claudication from pseudoclaudication
• Results can guide individualized exercise prescriptions and monitor treatment response

Alternative Testing Options

If a treadmill is not available:

• Pedal plantarflexion ABI test: A reasonable alternative that correlates well with treadmill ABIs 1
• Heel raising exercise: 30 seconds of heel raising can produce changes in ankle pressure that correlate well with treadmill exercise 2
• 6-minute walk test: A reasonable alternative for functional status assessment 1

Test Reliability Considerations

• For absolute claudication distance (maximum walking distance), graded protocols show higher reliability (ICC 0.95) compared to continuous protocols (ICC 0.76-0.91) 3
• For initial claudication distance, both protocols show similar reliability (ICC ~0.83-0.85) 3

Important Caveats and Pitfalls

• A normal resting ABI does not rule out PAD if clinical suspicion remains high
• In patients with noncompressible vessels (ABI >1.40), toe-brachial index should be used instead of ABI 1
• Standardized protocols should be used to ensure reproducibility of measurements 1
• The test should be performed in a controlled environment to minimize variables affecting performance

The PAD treadmill test is a valuable diagnostic tool that provides objective assessment of functional limitations and helps guide therapeutic decisions in patients with suspected or established peripheral arterial disease.