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AnkleBrachial Index for Assessment

of Peripheral Arterial Disease
S. Marlene Grenon, M.D.C.M., Joel Gagnon, M.D., and York Hsiang, M.D.

Overview

The anklebrachial index is used in the evaluation of patients for peripheral arterial disease. The initial examination of such patients usually includes palpation of
peripheral pulses. However, because there is inconsistency in the ability of practitioners to palpate pedal pulses, this method can be unreliable. Occasionally, it may
not be possible to palpate pedal pulses in a healthy patient for example, when
there is a congenital absence of the dorsalis pedis or posterior tibial pulses, which
occurs in 10% of the population.1,2

From the Department of Vascular Surgery,

Vancouver General Hospital, University of
British Columbia, Vancouver, BC, Canada.
N Engl J Med 2009;361:e40.
Copyright 2009 Massachusetts Medical Society.

Indications

Although other methods exist to assess the peripheral vasculature more objectively,
the anklebrachial index represents a simple, reliable method for diagnosing peripheral arterial disease. More specific indications include evaluation of leg pain,
evaluation for ischemia of the legs (symptoms of claudication, pain at rest, and the
presence of foot ulcers or gangrene), screening for atherosclerosis, and evaluation of
vascular compromise in patients with trauma of the lower legs.3 Measurement of the
anklebrachial index may also be useful in determining the prognosis for patients
with diffuse vascular disease and for evaluating the success of interventional or
surgical procedures, such as angioplasty, stenting, or lower-extremity bypass surgery.
Contraindications

The few contraindications for the measurement of the anklebrachial index include
excruciating pain in the patients legs or feet and the presence of deep venous
thrombosis, which could lead to thrombus dislodgment. In a patient with suspect
ed deep venous thrombosis, it would be prudent to perform a duplex ultrasound
study to exclude this possibility before measuring the anklebrachial index. Although the readings may be altered when vessels are calcified or incompressible
(such as in elderly patients, patients with diabetes, or patients with end-stage renal
failure requiring dialysis), these conditions are not absolute contraindications to
measuring the anklebrachial index.
Equipment and Preparation

To measure an anklebrachial index, you will need the following equipment: a

continuous-wave Doppler machine, ultrasonic gel, and a sphygmomanometer with
a blood-pressure cuff (Fig. 1). To examine peripheral blood vessels, you will need a
Doppler ultrasound probe with a frequency of 8 to 9 MHz. A handheld Doppler
probe is usually adequate to measure the anklebrachial index. The width of the

Figure 1. Equipment Used in the Measurement of an AnkleBrachial Index.

n engl j med 361;19 nejm.org november 5, 2009

The New England Journal of Medicine

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AnkleBr achial Index for Assessment of Peripher al Arterial Disease

bladder for the blood-pressure cuff should be 20% larger than the diameter of the
limb to be measured put another way, the bladder should correspond to 40% of
the limb circumference.4 The patient should be examined in a supine position and
in a warm environment to improve the patients comfort and to ensure the accuracy
of the examination.
Procedure and Calculation
Figure 2. Measurement of Blood Pressure in the Arm.

Figure 3. Measurement of the Systolic

Pressure in the Dorsalis Pedis Artery.

Figure 4. Measurement of the Systolic

Pressure in the Posterior Tibial Artery.

Place the blood-pressure cuff on the patients right or left arm (Fig. 2). Palpate the
brachial pulse. Apply gel at the site where you feel the pulse, and obtain a Doppler
signal by placing the probe at a 60-degree angle toward the patients head. Inflate
the cuff rapidly to 20 to 30 mm Hg above the point of cessation of brachial-artery
flow, then slowly deflate the blood-pressure cuff in order to note the systolic value.
Wipe the gel from the patients skin and repeat the procedure on the other arm.
After measuring the systolic blood pressure in the arms, place the cuff just
above the ankle on the right or left leg. The anatomical landmark of the dorsalis
pedis artery should be lateral to the extensor hallucis longus tendon (Fig. 3). Place
the Doppler probe on the palpable dorsalis pedis pulse or on the site that produces the best arterial Doppler signal from the dorsalis pedis artery. Once again,
inflate the blood-pressure cuff to 20 to 30 mm Hg above the level at which flow
ceases, then deflate the cuff slowly and note the systolic pressure (the pressure at
which you first hear the flow from the dorsalis pedis artery). Repeat the procedure
for the posterior tibial artery (Fig. 4). Then repeat the procedure for the contralateral leg to obtain the systolic pressure from both the dorsalis pedis and posterior
tibial arteries.
To calculate the anklebrachial index, divide the systolic blood pressure in the
ankle by the systolic blood pressure in the arm. The higher brachial systolic pressure is usually chosen for calculation, simply because the vessels of an arm may be
affected by arterial occlusive disease. The higher of the systolic pressures from the
dorsalis pedis or posterior tibial artery is used to determine the anklebrachial
index.
Interpretation

With a patient at rest, a normal anklebrachial index ranges from 0.91 to 1.30. A
reading above 1.30 is usually suggestive of incompressible tibial arteries. Decreases
in the anklebrachial index are consistent with peripheral arterial disease. Mild-tomoderate peripheral arterial disease usually produces an anklebrachial index in
the range of 0.41 to 0.90. A reading below 0.40 suggests the presence of severe
peripheral arterial disease5,6 (see guidelines7,8). Depending on the patients presentation and symptoms, further investigations may be required, including the use of
computed tomography, catheter angiography, magnetic resonance imaging, or duplex ultrasound imaging.5
Limitations

Use of the anklebrachial index does have limitations. These include inaccurate
measurements as a result of calcified or incompressible vessels (which would produce falsely elevated readings) and the presence of a subclavian-artery stenosis
(which could also falsely elevate the anklebrachial index on the side of the stenosis). A difference of more than 10 mm Hg between the two arm pressures suggests
the presence of a subclavian-artery stenosis.

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n engl j med 361;19 nejm.org november 5, 2009

The New England Journal of Medicine

Downloaded from nejm.org on March 15, 2015. For personal use only. No other uses without permission.
Copyright 2009 Massachusetts Medical Society. All rights reserved.

AnkleBr achial Index for Assessment of Peripher al Arterial Disease

Conclusions

Measurement of the anklebrachial index represents a noninvasive, objective way to

diagnose peripheral arterial disease. This test has been reported to have a sensitivity above 90% and a specificity of 95% for the diagnosis of peripheral arterial disease.9,10 It can be used with versatility in the physicians office.
No potential conflict of interest relevant to this article was reported.
References
1. Reich RS. The pulses of the foot: their value in
the diagnosis of peripheral circulatory disease. Ann
Surg 1934;99:613-22.
2. Clain A, ed. Hamilton Baileys demonstrations
of physical signs in clinical surgery. 16th ed. Bristol,
United Kingdom: John Wright, 1980.
3. Gerhard-Herman M, Gardin JM, Jaff M, Mohler
E, Roman M, Naqvi TZ. Guidelines for noninvasive
vascular laboratory testing: a report from the American Society of Echocardiography and the Society of
Vascular Medicine and Biology. J Am Soc Echocardiogr 2006;19:955-72.
4. Rumwell C, McPharlin M. Vascular technology.
2nd ed. Pasadena, CA: Davies Publishing, 2000:1120.
5. White C. Intermittent claudication. N Engl J Med
2007;356:1241-50.
6. Hiatt WR. Medical treatment of peripheral arterial disease and claudication. N Engl J Med 2001;
344:1608-21.
7. Norgren L, Hiatt WR, Dormandy JA, Nehler MR,
Harris KA, Fowkes FG. Inter-society consensus for
the management of peripheral arterial disease (TASC
II). J Vasc Surg 2007;45:Suppl S:S5-S67.

8. Hirsch AT, Haskal ZJ, Hertzer NR, et al. ACC/

AHA Guidelines for the Management of Patients

with Peripheral Arterial Disease (lower extremity,
renal, mesenteric, and abdominal aortic): a collaborative report from the American Associations for
Vascular Surgery/Society for Vascular Surgery, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology,
Society of Interventional Radiology, and the ACC/
AHA Task Force on Practice Guidelines (writing
committee to develop guidelines for the management of patients with peripheral arterial disease)
summary of recommendations. J Vasc Interv Radiol
2006;17:1383-97.
9. Ouriel K, McDonnell AE, Metz CE, Zarins CK.
Critical evaluation of stress testing in the diagnosis
of peripheral vascular disease. Surgery 1982;91:68693.
10. Yao ST, Hobbs JT, Irvine WT. Ankle systolic pressure measurements in arterial disease affecting the
lower extremities. Br J Surg 1969;56:676-9.
Copyright 2009 Massachusetts Medical Society.

n engl j med 361;19 nejm.org november 5, 2009

The New England Journal of Medicine

Downloaded from nejm.org on March 15, 2015. For personal use only. No other uses without permission.
Copyright 2009 Massachusetts Medical Society. All rights reserved.

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