Ankle Brachial Index (ABI)
Ankle-brachial index testing (ABI) is an office procedure designed to screen
patients for peripheral vascular disease (PVD), or cholesterol buildup in the arteries. It begins by measuring the blood pressure in both arms and both legs (ankles),
using blood pressure cufffs and a Doppler probe. An ABI index is obtained for each leg. This is calculated by dividing
the ankle pressure in that leg by the higher of both arm blood pressures.
A normal ABI index is 0.9 to 1.3. If the ABI index is less than 0.9, it
indicates the presence of peripheral arterial disease. The lower the ABI index is, the more severe disease is present.
ABI measurement can be obtained both at rest and after exercise. In some
cases, the resting ABI may be normal, but the ABI obtained after treadmill exercise may be less than 0.9, indicating the presence
of PVD. Further testing, such as peripheral angiography, CT or MRI
may be needed to determine the location and extent of PVD, as well as the best treatment strategy. Symptoms of PVD include
calf pain, heaviness or numbness, which are brought on by walking and resolve quickly at rest. In more advanced stages, ulcers
and blackening (gangrene) of the lower extremities may appear.
Treatment of PVD include medications to prevent cholesterol build-up, such
as cholesterol lowering medication. Medications to prevent heart attacks are also given, as the presence of PVD
indicates an increased risk for heart disease. Initial treatment may include an exercise program. If symptoms
are more severe, some medications can be used to improve the blood flow to the legs. Ultimately, percutaneous intervention (balloons,
stents, or removal of plaque) or bypass surgery is often needed to improve blood flow.
