Pre and per-operative assessment of femoro-distal non-reversed vein grafts.
journal contributionposted on 19.11.2015, 08:51 by David Julian Ashbridge. Scott
The expected increase in the elderly population over the next decade or so will result in an increase in the number of patients presenting with lower limb critical ischaemia. The use of non-reversed vein grafting and more distal bypasses has increased the scope for possible limb salvage and improved the quality of life, but case selection has become more difficult. In order to improve patient selection calf vessel runoff and long saphenous vein suitabihty were assessed pre and per-operatively to try and prevent unnecessary reconstructions. In total 88 patients were studied. Conventional arteriography in combination with IA-DSA views of the distal runoff were performed in all cases. Three arteriographic scoring systems were used to grade the runoff. Pulse Generated Runoff (PGR) was used to assess calf vessel and pedal arch patency. Duplex ultrasound was used to assess the long saphenous vein before bypass. At operation peripheral resistance and flow were measured before and after reconstruction. Samples of the LSV were taken before and after valve stripping for both light and electron microscopy. Intra-arterial DSA improved the correlation between the scoring systems and the measured peripheral resistance in the distal popliteal artery, but not in single calf vessels. In contrast PGR correlated much better with peripheral resistance in single calf vessels (rs = -0.82, p < 0.001). Using multiple linear regression analysis, a non-invasive resistance value was determined which could accurately predict the measured peripheral resistance at the time of surgery. PGR assessment of the pedal arch confirmed that grafts to an absent pedal arch all failed and underwent amputation at six months. Duplex scanning of the long saphenous vein is an accurate method of determining the suitability for reconstruction and has helped to reduce the incidence of skin flap necrosis. The criteria for a successful graft were applied to a prospective series of 49 grafts with a sensitivity of 97%, specificity of 67% and a predictive value of the test of 90%. Both light and electron microscopy of the excised LSV revealed evidence of early neointimal hyperplasia before implantation and highlighted the damage caused by the passage of the Hall valvulotome. Long term follow up confirmed the value of PGR and graft resistance after papaverine (GR2) in predicting successful grafts. Grafts with a PGR score of > 2 had 1 and 2 year patency rates of 79% and 64% respectively which were significantly higher than grafts with a PGR score of < 2 of 14% (Lee-Desu p< 0.002). Grafts with resistances (GR2) of 1 after the administration of papaverine had patency rates of 85% and 14% at one year. PGR will identify patent calf vessel and confirm continuity with the pedal arch. Duplex assessment of the LSV will accurately identify suitable LSV for bypass. Per-operative haemodynamic monitoring will confirm the pre-operative assessment, define the level of the distal anastomosis and exclude the majority of technical errors. Morphological examination of the LSV has shown it to be a potential cause of graft failure and revealed evidence of early atherosclerosis previously thought to develop as a consequence of arterialization. This approach will hopefully improve the selection of patients for femoro-distal bypass and ensure that patients are not rejected on the basis of the arteriogram.