Registered Cardiovascular Invasive Specialist (RCIS) Practice Test

What does the Ankle-Brachial Index (ABI) measure?

1. The difference between the heart rate and blood pressure

2. The difference between brachial and ankle systemic blood pressure

3. The ratio of oxygen saturation in blood

4. Blood flow velocity in major arteries

The correct answer is: The difference between brachial and ankle systemic blood pressure

The Ankle-Brachial Index (ABI) is a clinical measurement that specifically evaluates the difference in blood pressure between the brachial artery in the arm and the posterior tibial or dorsalis pedis arteries in the leg. This assessment is used to diagnose conditions such as peripheral artery disease (PAD), where reduced blood flow in the lower extremities can indicate atherosclerosis or other vascular issues. By comparing the blood pressure readings from these two sites, healthcare providers can derive a ratio that helps determine the presence and severity of arterial blockages. A lower ABI value suggests further reduction in blood flow to the legs, which is critical for diagnosing and managing vascular health. The other choices relate to different cardiovascular measurements or functions that do not apply to what ABI specifically assesses, emphasizing the unique role of ABI in evaluating systemic blood pressure disparity between the arms and legs.