Peripheral Artery Disease: Lower Extremity Ischemia and Ankle-Brachial Index
A hemodynamic analysis of femoral-popliteal atherosclerotic stenosis, Doppler ankle-brachial index calculation, and medial calcinosis artifacts.
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1. PAD is systemic atherosclerotic disease
Lower-extremity peripheral artery disease (PAD) usually results from atherosclerotic narrowing and is associated with cardiovascular risk elsewhere in the body. Exertional leg or buttock discomfort that improves with rest can be claudication, but many people have atypical symptoms or none. A single assumed stenosis percentage does not establish the diagnosis; clinicians combine history and examination with objective testing such as the ankle-brachial index (ABI).
2. ABI interpretation includes four categories
The 2024 ACC/AHA multisociety guideline classifies resting ABI as abnormal at 0.90 or lower, borderline at 0.91–0.99, normal from 1.00 through 1.40, and noncompressible above 1.40. The test compares ankle and brachial systolic pressures, commonly measured with Doppler after the patient rests supine. A lower value supports PAD but does not by itself determine symptom cause or treatment. Exercise ABI can be considered when exertional symptoms persist despite a normal or borderline resting result.
3. Noncompressible arteries need a different test
Arterial calcification, which is more common with diabetes or chronic kidney disease, can make ankle arteries difficult to compress and produce an ABI above 1.40. This result is not proof of severe ischemia and does not rule out PAD. If symptoms or examination still suggest disease, clinicians can use toe pressure and toe-brachial index (TBI), waveform testing, or imaging as appropriate. The multisociety guideline considers TBI of 0.70 or lower abnormal.
4. Vascular expert perspective: exercise, risk reduction, and revascularization
The 2024 ACC/AHA guideline recommends guideline-directed medical therapy, including antiplatelet treatment in appropriate symptomatic patients, and structured exercise rehabilitation to reduce risk and improve function. Supervised exercise therapy or a structured community program can improve walking performance and quality of life. Revascularization may be considered when function-limiting symptoms persist despite medical therapy and structured exercise. Rest pain, nonhealing wounds, or gangrene can indicate chronic limb-threatening ischemia and warrant prompt specialist assessment. Treatment choices depend on bleeding risk, comorbidities, anatomy, and patient goals.