The ABI is a useful test for comparing pressures in the lower extremity with pressures in the upper extremity. Blood pressure normally is slightly higher in the lower extremities than in the upper extremities. Comparison with the contralateral side may suggest the degree of ischemia. The ABI is obtained by applying blood pressure cuffs to the calf and the upper arm. The blood pressure is measured, and the systolic ankle pressure is divided by the systolic brachial pressure. Normal ABI is higher than 1; a value less than 0.95 is considered abnormal. This test can be influenced by arteriosclerosis and small-vessel disease (eg, diabetes), which reduce its reliability. Progressive PAD, indicated by an ABI decline of more than 0.15, has been associated with increased cardiovascular disease risk.
Elevated levels of inflammatory blood markers such as D dimer, CRP, IL-6, and homocysteine have been linked to PAD. Angiography is still the criterion standard arterial imaging study for the diagnosis of PAD. Duplex ultrasonography is performed to evaluate the status of a patient's vascular disease. Duplex scanning has the advantage of being noninvasive and requiring no contrast media or radiation. Unfortunately, it is highly technician-dependent. Plain films are of little use in the setting of PAD.
For more on the workup of PAD, read here.
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Cite this: Yasmine S. Ali. Fast Five Quiz: Refresh Your Knowledge of Key Aspects of Peripheral Artery Disease - Medscape - Jul 05, 2018.
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