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Prognostic Significance Of Intraoperative Graft Flow On Long-term Patency Of Below Knee Popliteal And Tibial Bypasses With Autologous Vein In Patients With Chronic Limb Threatening Ischemia
Venkata Vineeth Vaddavalli, M.B.B.S., Peter Gloviczki, M.D., Thomas C. Bower, M.D., Jill J. Colglazier, M.D., Randall R. DeMartino, M.D., M.S., Fahad Shuja, M.B.B.S., Bernardo C. Mendes, M.D., Todd E. Rasmussen, M.D., Melinda S. Schaller, M.D., Manju Kalra, M.B.B.S.
Mayo Clinic, Rochester, MN, USA.
Objectives: Intraoperative graft flow (GF) is a composite measure of bypass graft status, encompassing adequacy of conduit, technique as well as inflow/outflow. Previous studies suggested that low GF predicted failure of vascular grafts. The aim of this study was to evaluate the prognostic significance of GF on long-term patency of below knee (BKPB) popliteal and tibial (TB) bypasses performed with autogenous vein conduit in patients with chronic limb threatening ischemia (CLTI).
Methods: Data of consecutive patients who underwent BKPB or TB for CLTI using autologous vein conduit between July 2003 and July 2023 and had intraoperative GF measurement (Optima Flow-QC transit-time ultrasound) were retrospectively reviewed. Primary endpoints were primary (PP), primary assisted (PAP), secondary (SP) graft patencies and major limb amputation. Youden index was used to determine cutoff of GF.
Results: There were 177 bypasses in 163 patients (69% males, median age 71 years); 68% had Rutherford IV and 32% had V/VI ischemia. Patient comorbidities included hypertension(84%), coronary artery disease(59%), diabetes mellitus(49%), end-stage renal disease(7%), and 26% were active smokers. Outflow targets included BKP or TP trunk in 36%, tibial in 64%. Venous conduit was single segment great saphenous vein in 102(58%), composite vein in 69(39%), and arm vein in 6(3%). Median GF was 132ml/min (BKPB vs TB; 150 vs 120, p=0.054). Median follow-up was 22 months (IQR 6 to 64). One-year primary patency, freedom from major amputation and overall survival after BKPB were 58%, 100% and 87%; and after TB these were 40%, 87% and 88%, respectively. On multivariate analysis, Rutherford VI (HR 3.28), GF <110ml/min (HR 1.72), composite vein conduit (HR 1.65) and tibial outflow (HR 1.62), were associated with loss of patency. Grafts with flow>110 ml/min had significantly higher (p<0.01) PP, PAP, and SP at one year (54%, 77%, 85%) and 5 years (37%, 68%, 70%) than when GF<110/min (1 year: 31%, 48%, 66% and 5 year: 16%, 34%, 50%,
Figure).
Conclusions: Graft flow was an independent predictor of patency of distal bypass grafts for CLTI in addition to non-modifiable factors such as ischemic severity, outflow target and composite vein conduit. This information can be used to modify graft surveillance protocol.
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