American Board of Internal Medicine (ABIM) Certification Practice Exam

Which of the following indicates noncompressible vessels in the context of ABI?

1. ABI lower than 0.90

2. ABI greater than 1.40

3. ABI between 1.00 and 1.20

4. ABI exactly 1.00

The correct answer is: ABI greater than 1.40

Atherosclerosis and calcification of the arteries can make certain arteries noncompressible. The Ankle-Brachial Index (ABI) is a useful test for evaluating peripheral artery disease by measuring the ratio of the blood pressure in the lower legs to the blood pressure in the arms. An ABI value greater than 1.40 suggests that the vessels are likely noncompressible due to plaque or extensive calcification, which can prevent an accurate measurement of blood flow. This noncompressibility can occur in conditions such as advanced atherosclerosis or diabetes, making the arteries rigid and less capable of responding to pressure changes. In contrast, an ABI lower than 0.90 typically indicates the presence of arterial occlusion or significant reduction in blood flow, while values between 1.00 and 1.20 are generally considered normal, reflecting healthy, compressible vessels. An ABI exactly at 1.00 suggests that the pressures in the arms and ankles are equal, which again indicates normal vessel condition regarding compressibility. Thus, the indication of noncompressible vessels is uniquely associated with an ABI greater than 1.40.