Ankle brachial index
Ankle brachial index (ABI) is a means of detecting and quantifying peripheral arterial disease. It can be performed in conjuction with ultrasound for better results.
Many patients with peripheral arterial disease may be asymptomatic (~20-50%), but they may also present with
- limb pain / claudication
- critical limb ischemia
- chest pain
- blood pressure cuff
- pulse volume recording (PVR) Doppler ultrasound
- grayscale duplex Doppler can be useful to map the arterial disease and problem solve
- for mapping, evaluate the iliac arteries, common femoral arteries, the proximal, mid, and distal femoral arteries, popliteal artery, and the tibial and peroneal artery run offs
- evaluated acceleration times, velocities, and waveforms in the segments
A blood pressure cuff or ultrasound is used to evaluate the pressure in the brachial artery in both arms and the anterior and posterior tibial arteries in both legs.
The higher of the two brachial artery pressures is used for the index.
The higher of the anterior or posterior tibial artery pressures is used for the index.
The index is a ratio of the pressure in the highest ankle artery / the highest brachial artery
- 1.0-1.4: Normal
- 0.90-0.99 Borderline
- <0.9: Abnormal
There is a special category for an index 1.3-1.4 or above. These vessels are considered "noncompressible", and this is either because the arteries are very healthy or because there is heavy arteriolosclerotic or atherosclerotic calcification in the artery, preventing compression. The ultrasound waveform of the artery helps differentiate between these possibilities.
ABI values correlate with morbidity and mortality of not only the affected lower limb, but also with cardiovascular risk 2.
- ABI <0.90: 10% chance of cardiac event in 5 years
- ABI <0.70: ~20% chance of cardiac event in 5 years
- 1. Sibley RC, Reis SP, MacFarlane JJ, Reddick MA, Kalva SP, Sutphin PD. Noninvasive Physiologic Vascular Studies: A Guide to Diagnosing Peripheral Arterial Disease. Radiographics : a review publication of the Radiological Society of North America, Inc. doi:10.1148/rg.2017160044 - Pubmed
- 2. Leng GC, Fowkes FG, Lee AJ, Dunbar J, Housley E, Ruckley CV. Use of ankle brachial pressure index to predict cardiovascular events and death: a cohort study. BMJ (Clinical research ed.). 313 (7070): 1440-4. Pubmed
- 3. , Tendera M, Aboyans V, Bartelink ML, Baumgartner I, Clément D, Collet JP, Cremonesi A, De Carlo M, Erbel R, Fowkes FG, Heras M, Kownator S, Minar E, Ostergren J, Poldermans D, Riambau V, Roffi M, Röther J, Sievert H, van Sambeek M, Zeller T. ESC Guidelines on the diagnosis and treatment of peripheral artery diseases: Document covering atherosclerotic disease of extracranial carotid and vertebral, mesenteric, renal, upper and lower extremity arteries: the Task Force on the Diagnosis and Treatment of Peripheral Artery Diseases of the European Society of Cardiology (ESC). European heart journal. 32 (22): 2851-906. doi:10.1093/eurheartj/ehr211 - Pubmed