RVT Post-Intervention and Grafts 3 — Questions and Answers
Question 1: When performing duplex surveillance of a femoral-femoral crossover bypass graft, which vessel should be evaluated as the primary inflow source?
- The donor common iliac and external iliac artery ipsilateral to the graft origin (Correct answer)
- The contralateral superficial femoral artery
- The profunda femoris artery
- The recipient external iliac artery
Correct answer: The donor common iliac and external iliac artery ipsilateral to the graft origin
The donor iliac system is the inflow for a femoral-femoral crossover graft, so iliac stenosis on the donor side directly threatens graft patency.
Question 2: A synthetic aortobifemoral bypass graft is being evaluated. Flow in the right limb is triphasic and normal. The left limb shows monophasic, low-velocity waveforms. The most likely cause is:
- Stenosis or occlusion of the left graft limb or its outflow (Correct answer)
- Bilateral iliac disease
- Aortic anastomotic pseudoaneurysm
- Contralateral steal from the right limb
Correct answer: Stenosis or occlusion of the left graft limb or its outflow
Asymmetric waveforms between graft limbs indicate a unilateral problem; monophasic low-velocity waveforms in the left limb suggest stenosis or occlusion within that limb or distal to it.
Question 3: During duplex evaluation of an infrainguinal vein graft, a segment with absent color fill and no detectable Doppler signal is identified. What is the most likely diagnosis?
- Focal graft thrombosis or occlusion (Correct answer)
- Graft artifact from calcification
- Venous contamination
- Normal graft hibernation
Correct answer: Focal graft thrombosis or occlusion
Absence of color fill and Doppler signal in a graft segment indicates focal thrombosis, which may be amenable to thrombolysis or surgical revision if identified promptly.
Question 4: Which of the following is the MOST important parameter to document when performing post-angioplasty surveillance of the superficial femoral artery?
- PSV at the treatment site, PSV ratio, and waveform character (Correct answer)
- Only ABI before and after exercise
- Cross-sectional area of the artery on B-mode
- Resistive index of the SFA
Correct answer: PSV at the treatment site, PSV ratio, and waveform character
Post-SFA angioplasty surveillance should document PSV at the treated segment, PSV ratio versus proximal normal SFA, and waveform character to classify residual or recurrent stenosis.
Question 5: A patient undergoes carotid artery stenting (CAS). At 1-month follow-up duplex, the ICA PSV within the stent is 180 cm/s with an ICA/CCA ratio of 2.2. How should this be categorized?
- Moderate in-stent restenosis (approximately 50%), requiring close surveillance (Correct answer)
- Severe restenosis requiring urgent re-intervention
- Normal post-stent velocity expected from stent geometry
- Stent thrombosis
Correct answer: Moderate in-stent restenosis (approximately 50%), requiring close surveillance
ICA PSV 125–300 cm/s with ICA/CCA ratio 2.0–4.0 after CAS suggests moderate restenosis (approximately 50%), which warrants intensified duplex surveillance intervals.
Question 6: After EVAR, a type I endoleak at the proximal neck is identified by duplex. What is the typical color flow direction within the endoleak channel?
- Antegrade systolic flow from the aortic lumen into the perigraft space (Correct answer)
- Bidirectional to-and-fro flow
- Retrograde diastolic flow from lumbar collaterals
- No Doppler-detectable flow
Correct answer: Antegrade systolic flow from the aortic lumen into the perigraft space
Type I endoleaks involve direct communication between the aortic lumen and the aneurysm sac, producing antegrade pulsatile arterial flow into the perigraft space during systole.
Question 7: A patient with prior angioplasty of the right renal artery presents with recurrent hypertension. Duplex shows a peak renal artery PSV of 220 cm/s and a RAR (renal-aortic ratio) of 4.5. What does this indicate?
- Significant recurrent or residual renal artery stenosis (>60%) (Correct answer)
- Normal post-angioplasty hemodynamics
- Renal artery occlusion
- Aortic stenosis as confounding factor
Correct answer: Significant recurrent or residual renal artery stenosis (>60%)
A renal artery PSV >200 cm/s combined with a RAR >3.5 meets duplex criteria for significant (>60%) renal artery stenosis, indicating restenosis after angioplasty.
RVT Post-Intervention and Grafts 3
When performing duplex surveillance of a femoral-femoral crossover bypass graft, which vessel should be evaluated as the primary inflow source?