Post-Intervention and Grafts Flashcards

Which duplex criterion is MOST specific for occlusion (rather than high-grade stenosis) of a bypass graft?

Answer: Complete absence of color flow and Doppler signal within the graft lumen

Complete absence of color flow and spectral Doppler signal throughout the graft lumen is the definitive duplex finding of graft occlusion.

A 65-year-old man has a popliteal aneurysm repaired with an interposition vein graft. Duplex at 6 months shows the vein graft is patent with a mid-graft PSV of 45 cm/s and triphasic waveforms. This finding suggests:

Answer: A low-risk, well-functioning graft that should continue surveillance

A mid-graft PSV of 45 cm/s with triphasic waveforms indicates adequate graft flow without focal stenosis; surveillance should continue per protocol.

During evaluation of a hemodialysis access graft, a PSV of 400 cm/s is found at the venous anastomosis with a PSV ratio of 3.2. What is the clinical implication?

Answer: Significant venous anastomotic stenosis likely contributing to access dysfunction

Elevated PSV (>400 cm/s) and PSV ratio >2.0 at the venous anastomosis of a dialysis graft indicate significant stenosis, the most common cause of access dysfunction.

After endovenous laser ablation (EVLA) of the great saphenous vein, which duplex finding at 1 week indicates a successful procedure?

Answer: Closure of the GSV with absence of flow and echogenic occlusive thrombus within the treated segment

Successful EVLA results in GSV occlusion demonstrated by absence of color flow and an echogenic thrombus filling the treated lumen.

A patient with a femoral-popliteal vein bypass graft presents with calf pain. Duplex shows deep vein thrombosis (DVT) adjacent to the graft. Which additional graft-specific complication must be actively excluded?

Answer: Perigraft infection with adjacent venous thrombosis secondary to inflammation

Perigraft infection can present with adjacent DVT due to inflammatory thrombosis; this is a limb- and life-threatening complication that must be excluded in the clinical context.

Which waveform change at the proximal anastomosis of an aortoiliac bypass graft is most indicative of a distal outflow obstruction in the graft limb?

Answer: High-resistance monophasic waveform with reversal of diastolic flow

Distal graft occlusion or severe outflow stenosis creates high resistance, producing monophasic waveforms with reversed diastolic flow at the proximal anastomosis.

A surveillance duplex of an above-knee femoropopliteal PTFE graft shows a mid-graft PSV of 18 cm/s. What is the most appropriate action?

Answer: Urgent clinical referral for angiography, as low graft velocity predicts impending thrombosis

A mid-graft PSV <25 cm/s is a strong predictor of impending graft thrombosis and warrants urgent clinical evaluation and possible intervention.