VT ABI & Segmental Pressure Testing 3 — Questions and Answers
Question 1: A segmental study reveals a normal high-thigh pressure but a 35 mmHg drop at the below-knee cuff. Where is the occlusive lesion most likely located?
- Iliac artery
- Superficial femoral artery
- Popliteal artery (Correct answer)
- Tibial-peroneal trunk
Correct answer: Popliteal artery
A significant pressure drop between the above-knee and below-knee cuffs localizes the obstructive lesion to the popliteal artery segment.
Question 2: What is the primary reason photoplethysmography (PPG) is used alongside segmental pressures in some vascular labs?
- To measure venous reflux time
- To assess digital perfusion when ankle pressures are unreliable (Correct answer)
- To calculate mean arterial pressure
- To replace Doppler waveform analysis
Correct answer: To assess digital perfusion when ankle pressures are unreliable
PPG detects digital pulse waveforms at the toe level, providing perfusion data when calcified vessels make ankle pressures unreliable.
Question 3: During post-exercise ABI testing, how soon after the treadmill protocol should ankle pressures be measured?
- Immediately within 1–2 minutes, then every 2–3 minutes for up to 10 minutes (Correct answer)
- Only once at 10 minutes post-exercise
- Every 30 seconds for 5 minutes
- After a 15-minute rest period
Correct answer: Immediately within 1–2 minutes, then every 2–3 minutes for up to 10 minutes
Post-exercise pressures should be measured immediately and serially because the pressure nadir occurs quickly and recovery time also carries diagnostic value.
Question 4: Which ABI value best represents borderline or mild PAD according to standard ACC/AHA guidelines?
- 0.91–1.00
- 0.70–0.90 (Correct answer)
- 0.50–0.69
- Less than 0.50
Correct answer: 0.70–0.90
An ABI of 0.70–0.90 is classified as mild PAD, while values 0.50–0.69 indicate moderate disease and below 0.50 indicate severe disease.
Question 5: In a three-cuff segmental pressure technique, which arterial segment cannot be individually assessed compared to the four-cuff method?
- Iliac artery
- Superficial femoral artery (Correct answer)
- Popliteal artery
- Tibial arteries
Correct answer: Superficial femoral artery
The three-cuff method lacks separate high-thigh and above-knee cuffs, so it cannot independently isolate SFA disease from aortoiliac disease.
Question 6: A patient has bilateral ABI values of 0.6. The right high-thigh pressure is 20 mmHg below the brachial pressure. What does this pattern suggest?
- Bilateral tibial disease
- Right-sided iliac or aortoiliac disease with bilateral runoff disease (Correct answer)
- Isolated left SFA disease
- Bilateral popliteal occlusion
Correct answer: Right-sided iliac or aortoiliac disease with bilateral runoff disease
A reduced high-thigh pressure indicates inflow (iliac) disease on that side, and the bilateral low ABI with distal cuff drops suggests multilevel disease.
Question 7: Which standard treadmill protocol is most commonly used for exercise ABI testing in vascular laboratories?
- Bruce protocol at 4.2 mph and 16% grade
- Gardner protocol at 2 mph and 12% grade (Correct answer)
- Naughton protocol at 1 mph and 10% grade
- Standard protocol at 3.5 mph and 10% grade
Correct answer: Gardner protocol at 2 mph and 12% grade
The Gardner protocol (2 mph, 12% grade for up to 5 minutes) is the standard vascular lab treadmill protocol for PAD evaluation.
VT ABI & Segmental Pressure Testing 3
A segmental study reveals a normal high-thigh pressure but a 35 mmHg drop at the below-knee cuff.
Where is the occlusive lesion most likely located?