Peripheral Arterial Testing and Interpretation
Peripheral Arterial Testing and Interpretation
This domain covers physiologic arterial testing: ankle-brachial index (ABI), segmental pressures, pulse volume recording (PVR), exercise testing, and waveform interpretation.
Core rules
- Rest supine 5-10 minutes. Use a cuff 10-20% wider than the limb diameter; a cuff that is too narrow falsely raises pressure. Measure brachial pressures bilaterally and ankle pressures at dorsalis pedis and posterior tibial with Doppler.
- ABI = highest ankle pressure / highest brachial pressure. ≤0.90 is abnormal; 0.91-0.99 is borderline; 1.00-1.40 is normal; >1.40 suggests noncompressible calcified arteries. Toe-brachial index <0.70 indicates obstruction when ABI is falsely normal.
- A ≥20 mmHg drop between adjacent segmental cuffs suggests stenosis; ≥30 mmHg is more specific. Normal PVR is triphasic; dampened or monophasic contours indicate proximal disease.
- Exercise ABI: a fall ≥0.15 or ankle pressure drop ≥20 mmHg after treadmill exercise supports hemodynamically significant disease.
Worked example
Rest ABI is 0.85, and after exercise the ankle pressure falls 30 mmHg and ABI is 0.55. The resting value is borderline, but the exercise response confirms exercise-induced arterial insufficiency. Localize with segmental pressures and PVR before planning intervention.
Traps
Do not use the lower brachial pressure, omit the posterior tibial, or measure immediately after exercise without a protocol. Calcified vessels can yield a normal or high ABI despite severe disease. A single normal waveform does not exclude multilevel disease.