CCI Peripheral Arterial Evaluation 3 — Questions and Answers
Question 1: A patient with diabetes has non-compressible ankle vessels on ABI testing. Which alternative measurement is most appropriate?
- Femoral artery pressure
- Toe-brachial index (Correct answer)
- Segmental thigh pressure only
- Aortic pressure measurement
Correct answer: Toe-brachial index
The toe-brachial index (TBI) is the preferred alternative because digital arteries are rarely calcified in diabetic patients.
Question 2: During exercise ABI testing, a patient's ABI drops from 0.85 at rest to 0.52 immediately after treadmill walking. What does this indicate?
- Normal physiologic response
- Venous insufficiency
- Hemodynamically significant arterial stenosis (Correct answer)
- Vasospasm only
Correct answer: Hemodynamically significant arterial stenosis
A post-exercise ABI drop of ≥20% or to below 0.90 confirms hemodynamically significant PAD not apparent at rest.
Question 3: Which artery is the most common site of atherosclerotic occlusion in the lower extremity?
- Common iliac artery
- Superficial femoral artery at the adductor canal (Correct answer)
- Popliteal artery
- Anterior tibial artery
Correct answer: Superficial femoral artery at the adductor canal
The superficial femoral artery at the adductor (Hunter's) canal is the most common site of lower extremity atherosclerotic occlusion.
Question 4: What is the significance of a high-thigh pressure that is lower than the brachial pressure in segmental limb pressure testing?
- Normal finding in elderly patients
- Suggests aortoiliac occlusive disease (Correct answer)
- Indicates common femoral artery disease
- Suggests popliteal artery disease
Correct answer: Suggests aortoiliac occlusive disease
A high-thigh pressure lower than brachial pressure indicates inflow disease at the aortoiliac level.
Question 5: On a lower extremity duplex scan, color flow imaging shows aliasing at a focal arterial segment. What is the primary cause of aliasing?
- Vessel wall calcification
- Velocity exceeding the Nyquist limit (Correct answer)
- Improper transducer angle
- Venous contamination
Correct answer: Velocity exceeding the Nyquist limit
Aliasing occurs when blood flow velocity exceeds the Nyquist limit (half the pulse repetition frequency), causing color wraparound.
Question 6: A patient undergoing lower extremity arterial evaluation has a biphasic waveform at the posterior tibial artery. What does this suggest compared to a normal triphasic waveform?
- Completely normal finding
- Mild proximal disease with preserved forward flow (Correct answer)
- Complete occlusion
- Venous reflux contaminating the signal
Correct answer: Mild proximal disease with preserved forward flow
A biphasic waveform with loss of the reverse flow component suggests mild to moderate proximal arterial disease reducing peripheral resistance.
Question 7: In peripheral arterial duplex imaging, what insonation angle should be maintained for accurate velocity measurements?
- 0 degrees
- 30 degrees
- 60 degrees or less (Correct answer)
- Greater than 60 degrees
Correct answer: 60 degrees or less
An angle of 60 degrees or less is required for accurate Doppler velocity measurements; angles above 60 degrees introduce significant error.
CCI Peripheral Arterial Evaluation 3
A patient with diabetes has non-compressible ankle vessels on ABI testing.
Which alternative measurement is most appropriate?