VT Lower & Upper Extremity Arterial 2 — Questions and Answers
Question 1: Which waveform characteristic is most indicative of a hemodynamically significant proximal arterial stenosis when evaluating a lower extremity artery?
- Triphasic waveform with sharp systolic peak
- Monophasic waveform with slow systolic upstroke and no diastolic reversal (Correct answer)
- Biphasic waveform with preserved reverse flow component
- High-resistance waveform with prominent diastolic notch
Correct answer: Monophasic waveform with slow systolic upstroke and no diastolic reversal
A monophasic waveform with slow systolic upstroke (tardus parvus) and absent diastolic reversal indicates significant proximal arterial obstruction.
Question 2: During upper extremity arterial duplex evaluation, the subclavian steal syndrome is confirmed when:
- Antegrade vertebral artery flow is present bilaterally
- Retrograde flow is detected in the ipsilateral vertebral artery during arm exercise (Correct answer)
- The brachial artery ABI exceeds 1.2 on the affected side
- Biphasic flow is noted in the radial artery at rest
Correct answer: Retrograde flow is detected in the ipsilateral vertebral artery during arm exercise
Subclavian steal is confirmed by reversed (retrograde) vertebral artery flow on the side of the subclavian stenosis, augmented by arm exercise.
Question 3: A patient with diabetes presents with an ankle-brachial index of 1.35. What is the most appropriate next diagnostic step?
- Accept the ABI as normal and discharge the patient
- Perform toe-brachial index (TBI) measurement (Correct answer)
- Order CT angiography immediately
- Repeat the ABI measurement after exercise
Correct answer: Perform toe-brachial index (TBI) measurement
An ABI >1.3 suggests arterial calcification causing non-compressibility; toe pressures are not affected and should be obtained instead.
Question 4: On spectral Doppler, a peak systolic velocity ratio (stenotic site/prestenotic) of 3.5 across a femoral artery segment corresponds to approximately what degree of diameter reduction?
- Less than 50%
- 50–74%
- 75–99% (Correct answer)
- Complete occlusion
Correct answer: 75–99%
A PSV ratio ≥3.5 at the stenosis versus the prestenotic segment correlates with ≥75% diameter reduction.
Question 5: Which collateral pathway most commonly reconstitutes the popliteal artery below a superficial femoral artery occlusion?
- Deep femoral (profunda femoris) artery via geniculate branches (Correct answer)
- Obturator artery via medial circumflex branches
- Internal iliac artery via gluteal branches
- Saphenous vein via perforator connections
Correct answer: Deep femoral (profunda femoris) artery via geniculate branches
The profunda femoris (deep femoral) artery provides the major collateral network reconstituting the popliteal artery below an SFA occlusion through its genicular and muscular branches.
Question 6: When performing a lower extremity arterial duplex, the gastrocnemius point (GP) is used to assess which artery?
- Peroneal artery
- Posterior tibial artery (Correct answer)
- Anterior tibial artery
- Popliteal artery
Correct answer: Posterior tibial artery
The posterior tibial artery is evaluated at the gastrocnemius point in the posterior calf, between the gastrocnemius and soleus muscles.
Question 7: A normal toe-brachial index (TBI) in a non-diabetic adult is generally considered to be:
- Greater than 0.6 (Correct answer)
- Greater than 0.9
- Greater than 1.0
- Greater than 1.3
Correct answer: Greater than 0.6
A normal TBI is ≥0.6; values below 0.6 suggest peripheral arterial disease, particularly useful in patients with non-compressible ankle vessels.
VT Lower & Upper Extremity Arterial 2
Which waveform characteristic is most indicative of a hemodynamically significant proximal arterial stenosis when evaluating a lower extremity artery?