CVT Peripheral Vascular Assessment 3 — Questions and Answers
Question 1: A patient with diabetes has an ABI of 1.4. What does this result most likely indicate?
- Normal arterial perfusion
- Mild peripheral arterial disease
- Severe peripheral arterial disease
- Non-compressible calcified vessels (Correct answer)
Correct answer: Non-compressible calcified vessels
An ABI greater than 1.3 typically indicates non-compressible, calcified vessels (often seen in diabetics and renal failure patients), making the ABI unreliable.
Question 2: Which segment of the lower extremity venous system is MOST commonly involved in deep vein thrombosis (DVT)?
- External iliac vein
- Femoral vein
- Calf (tibial/peroneal) veins (Correct answer)
- Inferior vena cava
Correct answer: Calf (tibial/peroneal) veins
Calf (distal) veins are the most common site of DVT origin, though thigh and pelvic DVTs carry higher risk of pulmonary embolism.
Question 3: During lower extremity arterial duplex imaging, a focal PSV greater than 400 cm/s with a velocity ratio greater than 4:1 compared to the proximal segment indicates what degree of stenosis?
- Less than 50%
- 50-75%
- Greater than 75% (Correct answer)
- Total occlusion
Correct answer: Greater than 75%
A PSV exceeding 400 cm/s with a velocity ratio greater than 4:1 corresponds to a hemodynamically severe stenosis of greater than 75% diameter reduction.
Question 4: What is the primary B-mode criterion used to diagnose acute DVT on duplex ultrasound?
- Hyperechoic thrombus within the lumen
- Non-compressibility of the vein with transducer pressure (Correct answer)
- Absence of color fill in the vein lumen
- Reversal of flow direction
Correct answer: Non-compressibility of the vein with transducer pressure
Non-compressibility of the vein lumen under transducer pressure is the gold standard B-mode criterion for diagnosing acute DVT.
Question 5: In the Allen test performed before radial artery harvest, what does a positive (abnormal) result indicate?
- Adequate collateral flow via the ulnar artery
- Adequate collateral flow via the radial artery
- Inadequate collateral flow to the hand from the ulnar artery (Correct answer)
- Normal palmar arch patency
Correct answer: Inadequate collateral flow to the hand from the ulnar artery
A positive (abnormal) Allen test indicates that the ulnar artery cannot adequately supply the hand if the radial artery is harvested, contraindicating radial artery use.
Question 6: Which characteristic distinguishes a pseudoaneurysm from a true aneurysm on duplex ultrasound?
- Pulsatile flow within the sac
- Yin-yang color pattern with to-and-fro flow in the neck (Correct answer)
- Acoustic shadowing posterior to the lesion
- Hyperechoic walls surrounding the sac
Correct answer: Yin-yang color pattern with to-and-fro flow in the neck
A pseudoaneurysm demonstrates a characteristic 'yin-yang' color pattern within the sac and to-and-fro flow in the communicating neck, distinguishing it from a true aneurysm.
Question 7: When evaluating a bypass graft with duplex ultrasound, which PSV threshold within the graft body suggests impending graft failure?
- Less than 20 cm/s
- Less than 45 cm/s (Correct answer)
- Greater than 180 cm/s
- Greater than 300 cm/s
Correct answer: Less than 45 cm/s
A mid-graft PSV less than 45 cm/s indicates low flow states associated with high risk of graft thrombosis and impending failure.
CVT Peripheral Vascular Assessment 3
A patient with diabetes has an ABI of 1.4.
What does this result most likely indicate?