The role of duplex ultrasound surveillance after prosthetic femoropopliteal bypass

Background: Current guidelines on the follow-up after infrainguinal bypass recommend clinical examination with history, pulse palpation and ankle-brachial-index assessment. Depending on the guideline, duplex ultrasound may or may not be recommended due to the lack of evidence. Data on this topic is sparse, especially after prosthetic bypass. Patients and methods: In a retrospective single-centre analysis, ultrasound surveillance examinations of 181 patients after femoropopliteal prosthetic bypass were analysed. Flow-velocities and flow-patterns of the inflow, anastomoses, the bypass as well as the outflow vessels were evaluated. The primary endpoint was primary patency, while primary-assisted and secondary patency as well as amputation-free survival were secondary endpoints. Results: By applying the Fine-Gray Model five ultrasound criteria were identified to increase the risk of loss of primary patency. A monophasic flow-pattern of the bypass as well as the popliteal artery showed a hazard-ratio of 2.0 (95% CI: 1.26-3.1, p=.003) and 1.7 (95% CI: 1.09-2.64, p=.02), respectively. A peak systolic velocity <60cm/sec of the deep femoral artery was significantly associated with loss of primary patency (p=.025). Decrease of inflow velocity as well as the deep femoral artery during follow-up were also significantly connected to loss of primary patency (p<.001). Primary-assisted and secondary patency as well as amputation-free survival were significantly associated with the waveform in the bypass and the popliteal artery (p<.001, p=.011, p=.031, p=.013). Conclusions: Ultrasound surveillance after femoropopliteal prosthetic bypass can identify factors associated with lower patency rates and amputation-free survival. These findings can help detect patients at higher risk of bypass occlusion and may improve their outcome.