Impact of Bypass Flow Assessment on Long-Term Outcomes in Patients with Chronic Limb-Threatening Ischemia

Importance of Flow Waveform and Flow Volume as Prognostic Indicators for the Patency of Infra-Inguinal Autologous Vein Bypass

OBJECTIVE

To investigate the association of the intra-operative flow waveform and the flow volume with graft prognosis of the infra-inguinal vein bypass.

METHODS

This was a retrospective study of intra-operative flowmetry performed for infra-inguinal autologous vein bypass between 2011 and 2020. Flow waveforms were classified as type 0 - IV according to the Kyushu University (KU) classification. The patients (n = 340) were divided into three groups based on the flow waveform predicting the graft patency: type 0/I (long patency), type II (no early occlusion but late occlusion possible), and type III/IV (early occlusion). The graft occlusion rates of popliteal artery bypass (PAB) and infrapopliteal artery bypass (IPAB) within 30 days of surgery were compared between type 0/I + II and type III/IV groups, while the midterm graft patency rates were compared between type 0/I and type II groups. Additionally, a multivariate analysis was performed to identify independent risk factors for early and late graft occlusion.

RESULTS

The early graft occlusion rates of type 0/I + II and type III/IV groups were 3.9% and 0%, respectively, (p = 1.0) for PAB, and 5.3% and 46.2%, respectively, (p < .001) for IPAB. The two year primary patency rates of type 0/I and type II groups were 91% and 75%, respectively, (p = .030) for PAB, and 58% and 63%, respectively, (p = .72) for IPAB. Independent risk factors for early occlusion were none in PAB and flow waveform (type IV) in IPAB. Independent risk factors for patency loss in PAB were flow waveform (type II), end stage renal disease, and dual antiplatelet use, and those in IPAB were older age, women, lower flow volume, and iterative bypass.

CONCLUSION

Intra-operative flowmetry is useful for predicting the graft prognosis in infra-inguinal vein bypass and this is dependent on the distal target artery.

Prognostic Significance of Intraoperative Graft Flow in Distal Bypass on Long-Term Outcomes in Patients with Chronic Limb-Threatening Ischemia

BACKGROUND

The aim of the study was to determine the prognostic significance of measurement of graft flow on the patency of distal bypass.

METHODS

A retrospective analysis was performed for 208 distal bypasses (208 limbs, 170 patients) with a single segment great saphenous vein conducted in a nonreversed manner from January 2009 to December 2019 in Japan. Patient backgrounds, operative details (including intraoperative mean graft flow), hospital outcomes, and long-term outcomes were evaluated. The primary endpoints were the primary, assisted primary, and secondary patency of the distal bypass graft and the secondary endpoints were limb salvage and wound healing.

RESULTS

The median intraoperative graft flow was 18 [10-30] mL/min. The follow-up rate was 98% in a mean follow-up period of 31 ± 26 months. Primary, assisted primary, and secondary patency in the cohort were 51%, 72%, and 73% at 1 year, and 39%, 59%, and 61% at 3 years, respectively. In multivariate analysis, the independent risk factors for primary patency were low graft flow (P = 0.0022) and female sex (P = 0.0016), and those for secondary patency were also low graft flow (P = 0.0025) and female sex (P < .001). The cut-offs for graft flow predicting primary and secondary patency were both 16 mL/min. The limb salvage rate was 94% at 1 year and 89% at 3 years; and the wound healing rates were 55%, 71% and 84% at 3, 6, and 12 months, respectively. Limb salvage and wound healing were not significantly associated with intraoperative graft flow.

CONCLUSIONS

Intraoperative graft flow was an independent predictor for graft patency in distal bypass, but had no influence on limb salvage and wound healing. The cut-off value for the mean graft flow predicting primary and secondary patency was 16 mL/min.