Peripheral Arterial Disease

Procedure

Measure systolic blood pressure at the dorsalis pedis and posterior tibial arteries bilaterally using a handheld Doppler ultrasound probe, and at both brachial arteries. Calculate the ratio of ankle systolic pressure to arm systolic pressure for each leg.

Positive Finding

ABI <0.9 in one or both legs indicates hemodynamically significant stenosis. ABI 0.9–1.1 is normal; 0.6–0.9 suggests mild-to-moderate disease; <0.6 suggests severe disease.

Sensitivity / Specificity

95% / 100%

Mohler et al., 2012, Circulation (AHA/ACC PAD Guidelines); Aboyans et al., 2017, European Journal of Vascular and Endovascular Surgery

Interpretation

ABI is the gold standard non-invasive screening test for lower extremity PAD. Values <0.9 have high sensitivity and specificity for angiographically significant stenosis (>50% diameter reduction). Helps stratify symptom severity and cardiovascular risk.

Procedure

Have patient walk on a treadmill at 3.2 km/h (2 mph) on flat grade, or perform a standardized six-minute walk test on a corridor. Record distance to onset of leg pain (claudication distance) and maximum distance tolerated before stopping.

Positive Finding

Reproducible leg pain (cramping, heaviness, or fatigue in the calf, thigh, or buttock) that limits walking distance and resolves with rest within 10 minutes.

Sensitivity / Specificity

85–95% (for symptomatic claudication) / null

Hiatt, 2002, Circulation; Regensteiner et al., 2008, Journal of the American College of Cardiology

Interpretation

Establishes functional limitation and baseline for monitoring disease progression or treatment response. Claudication distance correlates with severity of underlying stenosis. Used to differentiate vascular claudication from neurogenic claudication.

Procedure

Palpate bilateral femoral, popliteal, dorsalis pedis, and posterior tibial pulses with firm fingertip pressure. Auscultate over the femoral artery for bruits using the bell of the stethoscope.

Positive Finding

Diminished or absent pulses, or presence of a systolic bruit over a major artery, suggests hemodynamically significant stenosis proximal to the point of examination.

Sensitivity / Specificity

50–80% (varies by artery and severity) / 70–90%

Hirsch et al., 2006, Circulation (AHA PAD Guidelines)

Interpretation

Simple bedside test with moderate diagnostic value; absence of pulse or presence of bruit raises suspicion for stenosis. Palpable pulses do not exclude PAD. Must be correlated with ABI and clinical presentation.

Procedure

Elevate the patient's legs above heart level for 60 seconds while assessing skin pallor. Lower legs and observe for return of skin colour and venous filling. Note time to colour recovery (normally <3 seconds) and severity of pallor during elevation.

Positive Finding

Prolonged pallor on elevation and delayed return of colour (>3 seconds) or persistent pallor on dependency suggests compromised arterial inflow.

Sensitivity / Specificity

null / null

Interpretation

Qualitative bedside test indicating reduced arterial perfusion. Useful in assessing functional vascular reserve but has poor standardization. Findings support clinical suspicion but should not be used in isolation.

Procedure

Obtain Doppler ultrasound recordings of systolic pressures at multiple levels: upper thigh, lower thigh, calf, and ankle. Calculate pressure gradients between segments.

Positive Finding

A pressure drop of ≥20 mmHg between adjacent segments indicates significant stenosis within that vascular segment. Ankle-to-brachial pressure gradient >20 mmHg suggests hemodynamically significant disease.

Sensitivity / Specificity

85–90% / 90–95%

Zwolak et al., 2003, Journal of Vascular Surgery; Rooke et al., 2011, Circulation

Interpretation

More detailed than ABI alone; localizes the level of stenosis. Helps direct further diagnostic imaging (CTA or MRA) and vascular intervention. Non-invasive alternative to angiography for anatomical assessment.

Procedure

High-frequency ultrasound imaging of the iliac, femoral, popliteal, and tibial arteries assessing luminal narrowing, plaque morphology, and peak systolic velocity (PSV). Calculate peak systolic velocity ratio (PSVR) at stenosis relative to normal proximal segment.

Positive Finding

Peak systolic velocity >200 cm/s, elevated PSVR (>2.0–2.4), or visible >50% diameter stenosis on B-mode imaging indicates significant hemodynamic narrowing.

Sensitivity / Specificity

85–98% (for >50% stenosis) / 87–99%

Stein et al., 2006, Journal of Vascular Surgery (Duplex ultrasonography standards)

Interpretation

Non-invasive imaging gold standard for detecting and grading PAD severity. Guides decision for intervention and monitors post-intervention patency. Operator-dependent; requires vascular-trained technicians. Excellent first-line imaging modality.