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While we dwell on preventing heart attack, heart failure, stroke, and renal disease, we sometimes lose sight of another target organ—peripheral arterial disease (PAD). Both palpation of the peripheral pulses (qualitative) and direct determination of blood pressure at the level of the ankle (quantitative) are means of assessing the peripheral circulation. Patients with PAD may be asymptomatic in 20% to 50% of cases. Physical examination results can be normal, but may reveal a loss of at least one of the pedal pulses at least 20% of the time.1 In many cases, the diagnosis can be made by noting a diminished or absent dorsalis pedis or posterior tibial pulse.

Ankle-brachial index (ABI) testing is a relatively simple and inexpensive method to confirm the suspicion of PAD. The ABI provides a measure of the severity of PAD.2 Calculation of ABI is performed by measuring systolic blood pressure by means of a Doppler probe over the brachial, posterior tibial, and dorsalis pedis arteries.3 The highest of the 4 measurements in the ankles is divided by the higher of the 2 brachial measurements to calculate the index.

An ABI value of 1.0 to 1.3 is considered normal. ABI >1.3 suggests a poorly compressible calcified vessel. ABI <0.9 has a 95% sensitivity and 100% specificity for detecting angiogram-positive PAD and is associated with >50% stenosis in one or more major vessels. ABI of 0.4 to 0.9 suggests a degree of arterial obstruction often associated with claudication. In addition, an ABI of <0.4 represents advanced peripheral arterial ischemia.

If ABI is normal at rest but symptoms strongly suggest claudication, ABIs and segmental pressures should be obtained before and after exercise on a treadmill.4

The ABI correlates well with clinical measures of lower extremity function such as walking distance, speed of walking, balance, and overall physical activity. Low ABI has been associated with a higher risk of coronary artery disease, stroke, transient ischemic attack, progressive renal insufficiency, and all-cause mortality.5,6 PAD is now recognized as a cardiovascular disease equivalent and warrants aggressive management.

Detection of asymptomatic PAD also has value because it identifies patients at increased risk of atherosclerosis at other sites. For example, as many as 50% of patients with PAD have been shown to have at least a 50% stenosis in one renal artery.7 Thus, this simple physical examination finding (palpation) and convenient (often done in the office) noninvasive test (ABI) of peripheral vascular health helps identify people with greater cardiovascular disease risk and assists in identifying patients who may benefit the most from efforts to reduce the growing vascular disease burden in hypertensives. In patients with hypertension who are at increased risk for PAD, performing a simple examination of palpating the peripheral pulses is a useful first step in detecting asymptomatic PAD. In patients with PAD symptoms like claudication and/or diminished or absent pedal pulses, consider referral for ABI testing.

References

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  2. References
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    Black HR, Unger D, Burlando A, et al. Systolic Hypertension in the Elderly Program (SHEP). Part 6: Baseline physical examination findings. Hypertension. 1991;17(3 suppl II):II77II101.
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    Olin JW, Kaufman JA, Bluemke DA, et al. Atherosclerotic Vascular Disease Conference: Writing Group IV: imaging. Circulation. 2004;109:26262633.
  • 3
    Belch JJ, Topol EJ, Agnelli G, et al. Critical issues in peripheral arterial disease detection and management: a call to action. Arch Intern Med. 2003;163:884892.
  • 4
    McPhail IR, Spittell PC, Weston SA, et al. Intermittent claudication: an objective office-based assessment. J Am Coll Cardiol. 2001;37:13811385.
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    Resnick HE, Lindsay RS, McDermott MM, et al. Relationship of high and low ankle brachial index to all cause and cardiovascular disease mortality: the Strong Heart Study. Circulation. 2004;109:733739.
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    Murabito JM, Evans JC, Larson MG, et al. The ankle-brachial index in the elderly and the risk of stroke, coronary disease and death: the Framingham Study. Arch Intern Med. 2003;163:19391942.
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    Rimmer JM, Gennari FJ. Atherosclerotic renovascular disease and progressive renal failure. Ann Intern Med. 1993;118:712719.