Understanding the Ankle-Brachial Index (ABI)
The Ankle-Brachial Index (ABI) is a simple, non-invasive test that compares the blood pressure in your ankle to the blood pressure in your arm. It's a crucial diagnostic tool used to screen for Peripheral Artery Disease (PAD), a common circulatory problem in which narrowed arteries reduce blood flow to your limbs.
Why is ABI Important?
PAD can cause leg pain when walking (claudication), numbness, or other symptoms. More importantly, it's a strong indicator of a higher risk of heart attack, stroke, and other cardiovascular events. An ABI test can help detect PAD early, even before symptoms appear, allowing for timely intervention and management.
How is ABI Measured?
During an ABI test, a healthcare professional uses a standard blood pressure cuff and a Doppler ultrasound device. Blood pressure readings are taken from both arms (brachial artery) and from two arteries in each ankle (dorsalis pedis and posterior tibial arteries). The highest systolic pressure from each ankle is then divided by the highest systolic pressure from either arm to calculate the ABI for each leg.
Interpreting ABI Results
The ABI value provides insight into the health of your arteries:
- 1.00 – 1.29: Normal ABI – Indicates healthy blood flow.
- 0.91 – 0.99: Borderline ABI – Suggests a mild degree of arterial narrowing.
- 0.70 – 0.90: Mild PAD – Indicates mild to moderate arterial narrowing.
- 0.40 – 0.69: Moderate PAD – Suggests significant arterial narrowing, often associated with symptoms.
- < 0.40: Severe PAD – Points to severe arterial narrowing, typically causing significant symptoms even at rest.
- > 1.30: Non-compressible Arteries – This high reading can occur in individuals with stiff, calcified arteries (e.g., severe diabetes, elderly), making accurate pressure measurement difficult. Further investigation is usually needed.
It's important to note that this calculator provides an estimate based on your inputs. A medical professional should always interpret actual ABI results in the context of your overall health and medical history.
ABI Calculator
Enter the systolic blood pressure readings (in mmHg) from your arms and ankles to calculate your Ankle-Brachial Index.