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Challenges of distal bypass surgery in patients with diabetes: Patient selection, techniques, and outcomes

  • Michael S. Conte
    Correspondence
    Reprint requests: Michael S. Conte, MD, Professor and Chief, Division of Vascular and Endovascular Surgery, University of California – San Francisco, 400 Parnassus Avenue, Suite A-581, San Francisco, CA 94143
    Affiliations
    Division of Vascular and Endovascular Surgery, University of California – San Francisco, San Francisco, Calif
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      Surgical revascularization of the lower extremity using bypass grafts to distal target arteries is an established, effective therapy for advanced ischemia. Recent multicenter data confirm the primacy of autogenous vein bypass grafting, yet there remains significant heterogeneity in the utilization, techniques, and outcomes associated with these procedures in current practice. Experienced clinical judgment, creativity, technical precision, and fastidious postoperative care are required to optimize long-term results. The patient with diabetes and a critically ischemic limb offers some specific challenges; however, numerous studies demonstrate that the outcomes of vein bypass surgery in this population are excellent and define the standard of care. Technical factors, such as conduit, and inflow/outflow artery selection play a dominant role in determining clinical success. An adequate caliber, good quality great saphenous vein (GSV) is the optimal graft for distal bypass in the leg. Alternative veins perform acceptably in the absence of GSV, whereas prosthetic and other non-autogenous conduits have markedly inferior outcomes. Graft configuration (reversed, non-reversed, or in situ) seems to have little influence on outcome. Shorter grafts have improved patency. Inflow can be improved by surgical or endovascular means if necessary, and distal-origin grafts (eg, those arising from the superficial femoral or popliteal arteries) can perform as well as those originating from the common femoral artery. The selected outflow vessel should supply unimpeded runoff to the foot, conserve conduit length, allow for adequate soft tissue coverage of the graft, and simplified surgical exposure. This review summarizes the available data linking patient selection and technical factors to outcomes, and highlights the importance of surgical judgment and operative planning in the current practice of infrainguinal bypass surgery.
      The use of an autogenous vein graft to bypass peripheral artery occlusions, first reported by Kunlin in 1949,
      • Kunlin J.
      [The treatment of arterial obstruction by vein grafting].
      is firmly established as an effective method of revascularization for chronic, advanced limb ischemia. Numerous studies over the last 4 decades have provided evidence of the versatility, durability, and sustained hemodynamic benefit of lower extremity bypass grafting in appropriately selected patients. However, perioperative morbidity after lower extremity bypass (LEB) surgery may be substantial, and graft failure remains a significant limitation that has not been substantially reduced despite 5 decades of technical improvements. Therefore, considerable effort has been made to define the clinical, anatomic, and technical factors which predict perioperative and long-term success. Although much of this literature is comprised of retrospective single center experiences, recent multicenter prospective studies have provided opportunity to broadly examine the contemporary outcomes of LEB. This review will describe an approach to clinical and operative decision-making and postoperative management based on the available evidence and surgical experience.

      Patient selection for LEB

      Distal (ie, infrapopliteal) bypass surgery in the leg is generally performed for signs or symptoms of critical limb ischemia (CLI; Rutherford ischemia grade 4-6), and all of the ensuing discussion in this review will pertain directly to that population at risk for limb loss. Patients with CLI present with a large systemic burden of atherosclerosis and multiple comorbidities.
      • Conte M.S.
      • Belkin M.
      • Upchurch G.R.
      • Mannick J.A.
      • Whittemore A.D.
      • Donaldson M.C.
      Impact of increasing comorbidity on infrainguinal reconstruction: a 20-year perspective.
      The primary goals of treatment are preservation of a functional limb in a surviving patient, relief of pain, healing of wounds, and improved/maintained quality of life. Numerous studies have demonstrated that advanced peripheral artery disease is the risk-equivalent (or worse) of advanced coronary artery disease in terms of secondary cardiovascular events
      • Steg P.G.
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      • Wilson P.W.
      • D'Agostino Sr, R.
      • Ohman E.M.
      • Röther J.
      • et al.
      One-year cardiovascular event rates in outpatients with atherothrombosis.
      ; therefore, minimizing such risk is an important overall goal in patient management.
      • Hirsch A.T.
      • Haskal Z.J.
      • Hertzer N.R.
      • Bakal C.W.
      • Creager M.A.
      • Halperin J.L.
      • et al.
      ACC/AHA 2005 Practice Guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic): a collaborative report from the American Association for Vascular Surgery/Society for Vascular Surgery, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, Society of Interventional Radiology, and the ACC/AHA Task Force on Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Peripheral Arterial Disease): endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation; National Heart, Lung, and Blood Institute; Society for Vascular Nursing; TransAtlantic Inter-Society Consensus; and Vascular Disease Foundation.
      In considering treatment of the limb, the primary choices are conservative management (medical therapy, wound care), endovascular intervention, open surgical bypass, or major amputation. Assessment of the patient's ambulatory function, quality of life, CLI severity, long-term survival, and periprocedural risks are key determinants in selecting a primary approach. Vascular anatomy plays a final critical role in decision-making, particularly in regard to the selection of endovascular vs surgical revascularization. The overall dire natural history of CLI is often quoted in the literature - mortality and major amputation rates between 10% and 40% at 6 months
      • Norgren L.
      • Hiatt W.R.
      • Dormandy J.A.
      • Nehler M.R.
      • Harris K.A.
      • Fowkes F.G.
      TASC II Working Group
      Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II).
      ; however, the clinical severity spectrum of CLI is broad and many patients in Rutherford classes 4 and 5 who are not good candidates for revascularization may be managed conservatively for a considerable time. It is important to keep this in mind not only when choosing the initial strategy, but in the event of subsequent treatment failure and recrudescence of symptoms. Primary amputation may be the procedure of choice for patients at elevated systemic risk or those without good options for revascularization. The approach to medical and cardiac risk stratification and management is beyond the scope of this review, but is clearly of central importance before embarking on a limb-salvage treatment plan.
      Selection of a revascularization strategy between catheter-based and open surgical approaches is often considered as a trade-off between short-term risk and longer-term efficacy. However, at least in terms of 30-day mortality, there seems to be minimal difference between the two modalities. Numerous single center and multicenter reports demonstrate a 2% to 5% early mortality for surgical bypass in the CLI population,
      • Adam D.J.
      • Beard J.D.
      • Cleveland T.
      • Bell J.
      • Bradbury A.W.
      • Forbes J.F.
      • et al.
      Bypass versus angioplasty in severe ischaemia of the leg (BASIL): multicentre, randomised controlled trial.
      • Conte M.S.
      • Bandyk D.F.
      • Clowes A.W.
      • Moneta G.L.
      • Seely L.
      • Lorenz T.J.
      • et al.
      Results of PREVENT III: a multicenter, randomized trial of edifoligide for the prevention of vein graft failure in lower extremity bypass surgery.
      and endovascular outcomes reported have been notably similar.
      • Adam D.J.
      • Beard J.D.
      • Cleveland T.
      • Bell J.
      • Bradbury A.W.
      • Forbes J.F.
      • et al.
      Bypass versus angioplasty in severe ischaemia of the leg (BASIL): multicentre, randomised controlled trial.
      • Giles K.A.
      • Pomposelli F.B.
      • Spence T.L.
      • Hamdan A.D.
      • Blattman S.B.
      • Panossian H.
      • et al.
      Infrapopliteal angioplasty for critical limb ischemia: relation of TransAtlantic InterSociety Consensus class to outcome in 176 limbs.
      Early major adverse cardiovascular event rates also seem relatively similar (3% to 8%), although wound-related and other major complications are clearly higher for open bypass, as is length of initial hospitalization.
      • Adam D.J.
      • Beard J.D.
      • Cleveland T.
      • Bell J.
      • Bradbury A.W.
      • Forbes J.F.
      • et al.
      Bypass versus angioplasty in severe ischaemia of the leg (BASIL): multicentre, randomised controlled trial.
      Estimating the likelihood of long-term survival, therefore, becomes an important consideration in treatment selection, as both the durability and hemodynamic efficacy of surgical bypass with autogenous veins are superior. Patient age, cardiopulmonary status, renal function, cerebrovascular disease, and functional state are important predictors of long-term survival. Recently, there have been reports of risk-prediction models in the CLI population, including one based on a surgical bypass cohort (Project or Ex Vivo vein graft Engineering via Transfection [PREVENT] III) that has been externally validated in multiple centers, albeit retrospectively.
      • Schanzer A.
      • Mega J.
      • Meadows J.
      • Samson R.H.
      • Bandyk D.F.
      • Conte M.S.
      Risk stratification in critical limb ischemia: derivation and validation of a model to predict amputation-free survival using multicenter surgical outcomes data.
      • Schanzer A.
      • Goodney P.P.
      • Li Y.
      • Eslami M.
      • Cronenwett J.
      • Messina L.
      • et al.
      Validation of the PIII CLI risk score for the prediction of amputation-free survival in patients undergoing infrainguinal autogenous vein bypass for critical limb ischemia.
      This model (“PIII Risk Score”; Fig 1) assigns a point score based on five easily defined preoperative variables; dialysis, tissue loss (Rutherford grades 5/6), age ≥75, anemia, and history of advanced coronary artery disease. Those in the highest risk category (which comprised only 9% of the 1404 patients in the PREVENT III cohort) demonstrate a markedly reduced (45% to 55%) amputation-free survival 1 year after surgical bypass. In contrast, those in the low or moderate risk categories (>90% of those receiving surgery for CLI in the PREVENT III and the Vascular Surgery Group of Northern New England data sets) can expect a 73% to 86% rate of survival with intact limbs at 1 year after bypass. The PREVENT III Risk Score, and others like it, need to be validated in a large prospective CLI cohort, but can serve as relevant guideposts for patient selection.
      Figure thumbnail gr1
      Fig 1The PIII Risk Score was developed to predict amputation-free survival (AFS) following lower extremity bypass for CLI, using preoperative variables. Risk calculator shown on left panel, with bar graph showing stratified outcomes from the PREVENT III clinical trial. Right panel shows results of a validation study in the multicenter Vascular Study Group of Northern New England (VSGNNE) cohort of 1166 patients who underwent vein bypass for CLI (from
      • Schanzer A.
      • Mega J.
      • Meadows J.
      • Samson R.H.
      • Bandyk D.F.
      • Conte M.S.
      Risk stratification in critical limb ischemia: derivation and validation of a model to predict amputation-free survival using multicenter surgical outcomes data.
      • Schanzer A.
      • Goodney P.P.
      • Li Y.
      • Eslami M.
      • Cronenwett J.
      • Messina L.
      • et al.
      Validation of the PIII CLI risk score for the prediction of amputation-free survival in patients undergoing infrainguinal autogenous vein bypass for critical limb ischemia.
      ).
      There is scant high-quality evidence to support therapeutic decision-making in CLI. The Bypass vs Angioplasty for Severe Ischemia of the Leg (BASIL) trial, the only randomized trial to date to compare endovascular and surgical revascularization for advanced limb ischemia, recently reported its long-term outcomes.
      • Bradbury A.W.
      • Adam D.J.
      • Bell J.
      • Forbes J.F.
      • Fowkes F.G.
      • Gillespie I.
      • et al.
      Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) trial: an intention-to-treat analysis of amputation-free and overall survival in patients randomized to a bypass surgery-first or a balloon angioplasty-first revascularization strategy.
      For those patients who survived to 2 years or longer, which comprised 70% of the study population, open bypass was associated with improved survival and a trend of improved amputation-free survival. In a treatment-received analysis, which should be interpreted with some caution, patients who initially received a vein bypass graft fared significantly better than those who had received a prosthetic, and those who underwent bypass after failed angioplasty fared considerably worse than those who received a bypass graft initially.
      • Bradbury A.W.
      • Adam D.J.
      • Bell J.
      • Forbes J.F.
      • Fowkes F.G.
      • Gillespie I.
      • et al.
      Bypass versus Angioplasty in Severe Ischaemia of the Leg (BASIL) trial: analysis of amputation free and overall survival by treatment received.
      Taken together, these data suggest that a vein bypass-first strategy is superior for patients likely to survive to 2 years and beyond, and critically question the “free-shot” view of angioplasty in the patients with CLI. Further studies are clearly needed to improve the evidence base for treatment selection in CLI. At the present time, the author advocates a selective management approach to the patient with CLI, favoring vein bypass for acceptable risk candidates with an available autogenous vein conduit. Those with elevated medical risk (eg, highest category PREVENT III Risk Score), more favorable arterial anatomy (non-TransAtlantic InterSocietal Consensus D), inadequate veins, no or minor tissue loss, or other factors complicating a surgical approach (eg, soft tissue coverage of the graft) are considered for a primary endovascular option. Other authors have advocated an “endo-first” strategy for all patients, but in my view, this is not substantiated by current evidence (eg, BASIL) and a short-term treatment mentality may do significant disservice to many patients with CLI who are bypass candidates.
      The impact of diabetes and renal failure, per se, on treatment selection bear special mention. Data from a number of large single-center series, and randomized trials (PREVENT III), have demonstrated that diabetes is not a risk factor for vein graft failure.
      • Monahan T.S.
      • Owens C.D.
      Risk factors for lower-extremity vein graft failure.
      On the contrary, several authors have observed that graft patency is higher in patients with diabetes as opposed to patients without diabetes. This observation was also made in the PREVENT III study which included 900 patients with diabetes and CLI. However, on multivariable analysis when including other patient and technical variables, a direct relationship between diabetes and graft patency is not retained. Quite likely, this apparently protective association is confounded by the higher percentage of shorter, distal-origin grafts (see below) in the diabetic cohort. Although graft patency in patients with diabetes is unaffected, limb salvage and long-term patient survival are reduced in comparison to people without diabetes.
      A negative relationship between clinical outcomes of LEB and renal failure has been frequently observed. Patient survival and limb salvage after LEB are linked to degree of renal insufficiency, and both are markedly inferior for those with an estimated glomerular filtration rate of less than 30 mL/(minutes × 1.73 m2).
      • Owens C.D.
      • Ho K.J.
      • Kim S.
      • Schanzer A.
      • Lin J.
      • Matros E.
      • et al.
      Refinement of survival prediction in patients undergoing lower extremity bypass surgery: stratification by chronic kidney disease classification.
      Conversely, vein graft patency does not seem to be linked to renal disease. The distressing problem of amputation despite a patent bypass graft is seen in 10% to 15% of patients with end-stage renal disease who undergo bypass surgery for limb salvage, reflecting their poor substrate for wound healing and sepsis control.
      • Lantis 2nd, J.C.
      • Conte M.S.
      • Belkin M.
      • Whittemore A.D.
      • Mannick J.A.
      • Donaldson M.C.
      Infrainguinal bypass grafting in patients with end-stage renal disease: improving outcomes?.
      Therefore, advanced renal disease is a particular subgroup that merits careful consideration for treatment selection in CLI.

      Technical factors and developing the operative strategy

      Although clinical risk factors play a dominant role in patient survival and systemic complications after LEB, technical factors are the primary determinants of graft-related events. First and foremost among these is the availability of good quality autogenous vein conduit, recognized as a relevant limitation of lower extremity vein bypass surgery. Good quality ipsilateral great saphenous vein (GSV) may be lacking in as many as 40% of patients needing revascularization.
      • Taylor Jr, L.M.
      • Edwards J.M.
      • Brant B.
      • Phinney E.S.
      • Porter J.M.
      Autogenous reversed vein bypass for lower extremity ischemia in patients with absent or inadequate greater saphenous vein.
      Assessment of vein availability and quality is, therefore, a critical element of both preoperative planning and intraoperative decision-making. Quality of the venous conduit for bypass surgery encompasses a range of attributes including lumen diameter, wall compliance, and absence of pathologic changes such as sclerosis, calcification, and varicosities.
      • Panetta T.F.
      • Marin M.L.
      • Veith F.J.
      • Goldsmith J.
      • Gordon R.E.
      • Jones A.M.
      • et al.
      Unsuspected preexisting saphenous vein disease: an unrecognized cause of vein bypass failure.
      • Marin M.L.
      • Veith F.J.
      • Panetta T.F.
      • Gordon R.E.
      • Wengerter K.R.
      • Suggs W.D.
      • et al.
      Saphenous vein biopsy: a predictor of vein graft failure.
      Ultrasound scan vein mapping allows accurate, objective evaluation before surgery and has become standard in many centers. Vein diameter, patency, and wall thickness may be estimated noninvasively. Mapping also facilitates placement of harvest incisions to avoid wound complications. Intraoperative assessment of the vein is crucial to technical success in infrainguinal bypass surgery. The same features are evaluated by direct inspection, and gentle distension with vein harvesting solution allows the surgeon to determine venous distensibility.
      Several studies have demonstrated the strong influence of vein diameter, and graft origin (GSV vs alternative veins), on bypass graft patency. Most recently, post-hoc analysis of the PREVENT III trial, which included protocol-mandated ultrasound scan surveillance and clinical follow-up to 1 year, have highlighted the strength of these relationships.
      • Schanzer A.
      • Hevelone N.
      • Owens C.D.
      • Belkin M.
      • Bandyk D.F.
      • Clowes A.W.
      • et al.
      Technical factors affecting autogenous vein graft failure: observations from a large multicenter trial.
      Vein diameter was a strong predictor of early (30-day) graft failure; loss of primary patency within 30 days was observed in 14%, 10%, and 7% of grafts <3 mm, 3 to 3.5 mm, and >3.5 mm, respectively. More impressively, profound differences in primary and secondary patency across these diameter groupings were observed within the first year after surgery (Fig 2,A). On multivariable analysis, the strongest predictor for loss of primary, primary-assisted, or secondary vein graft patency at 1 year was vein diameter <3 mm. Because of the known relationships between vein diameter, vein origin (GSV vs alternative/spliced vein; Fig 2, B) and subsequent patency, the PREVENT III trial applied a “high-risk” designation a priori to all vein grafts that were either <3 mm or comprised of anything other than a single-segment GSV (SSGSV). In this trial of exclusively patients with CLI, 24% of the cases fell into this “high-risk conduit” category, and they demonstrated an inferior 1-year performance, with 44% primary and 69% secondary patency. Conversely, 43% of the PREVENT III study population had their limb salvage surgery completed using an SSGSV graft with diameter >3.5 mm, and these “optimal conduits” demonstrated 1.7% 30-day failure, 72% primary, and 87% secondary patency at 1 year (Fig 2, C).
      Figure thumbnail gr2
      Fig 2Vein quality is the dominant factor in determining long term outcome of LEB for CLI. Data from post-hoc analyses of the PREVENT III multicenter cohort. A, Influence of vein diameter on graft patency. B, Relationship of vein type (Composite, spliced vein segments; LSV, lesser saphenous vein; SSGSV, single segment great saphenous vein) to patency. C, Performance of “optimal vein conduits” (SSGSV ≥ 3.5mm) in the PREVENT III trial; note that distal anastomotic site has minimal influence on the patency of these grafts. (A, B, from
      • Schanzer A.
      • Hevelone N.
      • Owens C.D.
      • Belkin M.
      • Bandyk D.F.
      • Clowes A.W.
      • et al.
      Technical factors affecting autogenous vein graft failure: observations from a large multicenter trial.
      ; C, unpublished data from PREVENT III clinical trial).
      In the absence of an adequate ipsilateral GSV, the best available substitute for infrainguinal bypass is good quality, contralateral GSV if the source limb is not at near-term vascular risk.
      • Chew D.K.
      • Owens C.D.
      • Belkin M.
      • Donaldson M.C.
      • Whittemore A.D.
      • Mannick J.A.
      • et al.
      Bypass in the absence of ipsilateral greater saphenous vein: safety and superiority of the contralateral greater saphenous vein.
      The performance of alternative (arm, lesser saphenous vein) and spliced vein grafts are known to be inferior to that of SSGSV, but significantly better than prosthetic grafts for patients with CLI or those requiring bypass to infrageniculate targets.
      • Londrey G.L.
      • Bosher L.P.
      • Brown P.W.
      • Stoneburner Jr, F.D.
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      • Davis R.K.
      Infrainguinal reconstruction with arm vein, lesser saphenous vein, and remnants of greater saphenous vein: a report of 257 cases.
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      • Pulling M.C.
      • Smakowski P.
      • Rohan D.I.
      • et al.
      The use of arm vein in lower-extremity revascularization: results of 520 procedures performed in eight years.
      • Chew D.K.
      • Conte M.S.
      • Donaldson M.C.
      • Whittemore A.D.
      • Mannick J.A.
      • Belkin M.
      Autogenous composite vein bypass graft for infrainguinal arterial reconstruction.
      These grafts require intensive surveillance and have a higher reintervention rate, yet long-term patency may be gratifyingly achieved in a large percentage of cases.
      • Armstrong P.A.
      • Bandyk D.F.
      • Wilson J.S.
      • Shames M.L.
      • Johnson B.L.
      • Back M.R.
      Optimizing infrainguinal arm vein bypass patency with duplex ultrasound surveillance and endovascular therapy.
      The role of modified or unmodified prosthetic grafts, or other biologic conduits remains unclear, but they may be acceptable substitutes in specific circumstances and in some series have results comparable to spliced veins.
      Surgical harvesting of the vein results in mechanical injury, endothelial disruption, and vasospasm. It has long been known that careful handling of the vein, avoiding overdistension, and minimizing ischemic time results in less endothelial loss and a reduced early inflammatory response.
      • LoGerfo F.W.
      • Quist W.C.
      • Cantelmo N.L.
      • Haudenschild C.C.
      Integrity of vein grafts as a function of initial intimal and medial preservation.
      The optimal solution for vein harvesting and storage has undergone a good deal of investigation with limited clinical translation.
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      • Adcock G.L.
      • Wheeler J.R.
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      • Snyder Jr, S.O.
      • Gayle R.G.
      Optimal techniques for harvesting and preparation of reversed autogenous vein grafts for use as arterial substitutes: a review.
      Buffered, balanced salt solutions, such as Plasmalyte, offer neutral pH in comparison to saline solutions which are acidic. The use of a vasodilator, such as papaverine, reduces reactive spasm during harvesting, and heparin (4-10 units/mL) is generally added for its anticoagulant properties.
      Lower extremity vein grafts may be implanted in reversed, non-reversed (excised), or in situ bypass configurations. Large single-center series demonstrate comparable results for midterm and long-term patency,
      • Shah D.M.
      • Darling 3rd, R.C.
      • Chang B.B.
      • Fitzgerald K.M.
      • Paty P.S.
      • Leather R.P.
      Long-term results of in situ saphenous vein bypass Analysis of 2058 cases.
      • Taylor Jr, L.M.
      • Edwards J.M.
      • Porter J.M.
      Present status of reversed vein bypass grafting: five-year results of a modern series.
      • Belkin M.
      • Knox J.
      • Donaldson M.C.
      • Mannick J.A.
      • Whittemore A.D.
      Infrainguinal arterial reconstruction with nonreversed greater saphenous vein.
      and a single, small randomized trial showed no difference in outcomes between reversed and in situ grafts.
      • Wengerter K.R.
      • Veith F.J.
      • Gupta S.K.
      • Goldsmith J.
      • Farrell E.
      • Harris P.L.
      • et al.
      Prospective randomized multicenter comparison of in situ and reversed vein infrapopliteal bypasses.
      In specific circumstances, there may be technical advantages to select one configuration over the other, such as optimizing the artery-vein size match at anastomoses and minimizing graft length. The author tends to use non-reversed grafts frequently for these reasons. Several studies have suggested that graft length is a factor that influences patency,
      • Schanzer A.
      • Hevelone N.
      • Owens C.D.
      • Belkin M.
      • Bandyk D.F.
      • Clowes A.W.
      • et al.
      Technical factors affecting autogenous vein graft failure: observations from a large multicenter trial.
      • Ascer E.
      • Veith F.J.
      • Gupta S.K.
      • White S.A.
      • Bakal C.W.
      • Wengerter K.
      • et al.
      Short vein grafts: a superior option for arterial reconstructions to poor or compromised outflow tracts?.
      • Ballotta E.
      • Renon L.
      • De Rossi A.
      • Barbon B.
      • Terranova O.
      • Da Giau G.
      Prospective randomized study on reversed saphenous vein infrapopliteal bypass to treat limb-threatening ischemia: common femoral artery versus superficial femoral or popliteal and tibial arteries as inflow.
      suggesting a benefit to shorter configurations.
      A fundamental principle of bypass surgery is the requirement for unimpeded proximal arterial inflow. In the ideal circumstance, the proximal anastomosis is performed to a disease-free vessel with a widely patent native system upstream. However, treatment of inflow disease by either endovascular or surgical means has been a successful strategy in infrainguinal bypass surgery. The durability of these interventions for aortoiliac disease is generally as good if not superior to that of isolated distal bypass, although more liberal use of endovascular treatment for diffuse iliac disease must be considered carefully. Distal origin grafts, defined as bypasses originating at the superficial femoral, popliteal, or distal vessels, have performed well in selected patients. Short bypasses are particularly applicable to patients with diabetes (Fig 3)
      • Reed A.B.
      • Conte M.S.
      • Belkin M.
      • Mannick J.A.
      • Whittemore A.D.
      • Donaldson M.C.
      Usefulness of autogenous bypass grafts originating distal to the groin.
      because of the pattern of arterial occlusive disease that develops in a distinct subset of patients with diabetes, with sparing of the common and superficial femoral arteries and severe disease of the trifurcation vessels. More recently, the use of infrainguinal angioplasty to support inflow of a distally placed vein graft has also shown success, albeit in small numbers of very selected cases.
      • Schanzer A.
      • Owens C.D.
      • Conte M.S.
      • Belkin M.
      Superficial femoral artery percutaneous intervention is an effective strategy to optimize inflow for distal origin bypass grafts.
      This approach is reasonable for patients with favorable (TransAtlantic InterSocietal Consensus A/B) lesions in the superficial femoral, and may also be useful when conduit length is a major constraint. In these cases, postoperative surveillance should also include the upstream area of intervention.
      Figure thumbnail gr3
      Fig 3Distal origin vein grafts (DOGs; inflow from superficial femoral or popliteal arteries) are particularly useful and effective in diabetic patients. A, Secondary patency and B, Limb salvage rates for DOGs in a series of 190 diabetic and 90 non-diabetic subjects (P < .04; from
      • Reed A.B.
      • Conte M.S.
      • Belkin M.
      • Mannick J.A.
      • Whittemore A.D.
      • Donaldson M.C.
      Usefulness of autogenous bypass grafts originating distal to the groin.
      ).
      Selection of the outflow artery requires considerable surgical judgment, correlating several anatomic and hemodynamic factors. In general, the most proximal vessel that provides continuous runoff to the foot is selected as the primary target. Extensively calcified tibial and pedal arteries should be avoided if possible, but can be used with success. For patients with extensive tissue loss, there is controversy regarding the choice between peroneal, pedal, and plantar targets.
      • Pomposelli Jr, F.B.
      • Jepsen S.J.
      • Gibbons G.W.
      • Campbell D.R.
      • Freeman D.V.
      • Miller A.
      • et al.
      Efficacy of the dorsal pedal bypass for limb salvage in diabetic patients: short-term observations.
      • Raftery K.B.
      • Belkin M.
      • Mackey W.C.
      • O'Donnell T.F.
      Are peroneal artery bypass grafts hemodynamically inferior to other tibial artery bypass grafts?.
      • Bergamini T.M.
      • George Jr, S.M.
      • Massey H.T.
      • Henke P.K.
      • Klamer T.W.
      • Lambert Jr, G.E.
      • et al.
      Pedal or peroneal bypass: which is better when both are patent?.
      Some have advocated an “angiosome” approach, selecting the target artery based on location of the area of tissue loss on the foot.
      • Neville R.F.
      • Attinger C.E.
      • Bulan E.J.
      • Ducic I.
      • Thomassen M.
      • Sidawy A.N.
      Revascularization of a specific angiosome for limb salvage: does the target artery matter?.
      In patients with diabetes, excellent long-term results have been achieved with bypass to the dorsalis pedis artery.
      • Pomposelli Jr, F.B.
      • Jepsen S.J.
      • Gibbons G.W.
      • Campbell D.R.
      • Freeman D.V.
      • Miller A.
      • et al.
      Efficacy of the dorsal pedal bypass for limb salvage in diabetic patients: short-term observations.
      • Pomposelli F.B.
      • Kansal N.
      • Hamdan A.D.
      • Belfield A.
      • Sheahan M.
      • Campbell D.R.
      • et al.
      A decade of experience with dorsalis pedis artery bypass: analysis of outcome in more than 1000 cases.
      The relationship between runoff and graft performance is somewhat unclear. Although some studies have suggested that poor runoff is a major factor,
      • Seeger J.M.
      • Pretus H.A.
      • Carlton L.C.
      • Flynn T.C.
      • Ozaki C.K.
      • Huber T.S.
      Potential predictors of outcome in patients with tissue loss who undergo infrainguinal vein bypass grafting.
      many others have not found strong correlations and measurement of graft runoff is not straightforward. The implication from such data is that conduit quality, graft length, and adequate inflow are stronger predictors of vein graft patency than level of the distal anastomosis. However, such retrospective data are intrinsically flawed by careful selection, and the technical challenges associated with anastomoses to small, diseased vessels with poor runoff can be a significant cause of early and late graft failure.
      Lower extremity bypass grafts using excised veins may be tunneled in either a deep, anatomic position or be placed superficially. There are no data to suggest that graft location influences patency. In situ GSV grafts have demonstrated excellent long-term durability in the subcutaneous location. In addition, superficial location facilitates Duplex scan surveillance and greatly simplifies surgical revisions when needed. The primary advantage of placing the graft in a deeper position is improved soft tissue coverage, greatly reducing the chance that a wound complication will threaten the bypass. When there are concerns about acute or chronic skin conditions, soft tissue quality, or increased likelihood of wound breakdown or infection, deeper tunneling of the graft is preferred.
      Careful preoperative LEB planning involves assessment of conduit availability and selection of arterial anastomotic sites based on imaging studies. There are few “short-cuts” of value in the performance of lower extremity vein bypass surgery; however, errors in planning, judgment, and technique can greatly lengthen the operation, increase the risk of complications, and reduce the long-term benefit for the patient. Few operations in vascular surgery are as technically demanding, or require as much creativity. As in all surgical procedures, minimizing intraoperative surprises and having well-thought-out primary and secondary strategies correlate directly with success. The major unknown and the most critical element is the conduit. If there is concern about the GSV from either clinical evaluation or preoperative vein mapping, the next best available vein should be identified before starting the operation, and that extremity prepared. When an issue of vein quality is unexpectedly encountered, the surgeon must weigh the options carefully based on knowledge of alternative veins available and other factors. In general, a spliced vein graft made of good quality segments is preferable to retaining a segment of poor/marginal quality within the bypass. Small diameter, sclerotic, or non-distensible vein segments are the source of both early failure and subsequent reinterventions, and are best excised. Intraoperative, completion imaging using Duplex ultrasound scan facilitates conduit assessment and can also identify unsuspected problems which should be treated aggressively. A normal intraoperative scan is highly predictive of early technical success, whereas abnormalities associated with increased velocity (ratio >2) or low flow (velocity <45 cm/second) should be addressed pre-emptively.
      • Bandyk D.F.
      • Mills J.L.
      • Gahtan V.
      • Esses G.E.
      Intraoperative duplex scanning of arterial reconstructions: fate of repaired and unrepaired defects.
      • Johnson B.L.
      • Bandyk D.F.
      • Back M.R.
      • Avino A.J.
      • Roth S.M.
      Intraoperative duplex monitoring of infrainguinal vein bypass procedures.
      Contrast arteriography is complementary in that it demonstrates the runoff bed more completely; however, duplex scan is likely more sensitive for abnormalities within the conduit, especially for conduits in which valve lysis has been used. The use of completion imaging, incorporating one or both of these modalities, is highly recommended.
      Anastomotic techniques vary widely among surgeons and have not been directly correlated with outcome. My strong preference is to perform the proximal anastomosis first in all cases. This allows the graft to be tunneled while under arterial pressure, minimizing the chance of kinks or twists. Furthermore, it allows for greater flexibility in case of unsuspected issues arising at the distal target artery, leaving excess distal vein length in place until after the artery is opened and prepared for anastomosis. Calcified arteries pose a technical challenge particularly for the distal anastomosis. Tourniquet control in the thigh or calf is often an excellent adjunctive method, minimizing manipulation of the target artery, and greatly facilitating re-do bypass surgery. In cases of extensive arterial calcification, it may or may not be adequate. In such cases, intraluminal balloon control or microvascular clamps are the remaining options. Sometimes circumferential (“egg-shell”) calcification can be gently cracked with forceps without producing extensive intimal disruption, but this must be done with great care and any loose debris removed from the lumen. Limited endarterectomy is sometimes needed and if a longer arteriotomy is required, then a primary vein patch angioplasty is recommended. In all cases, direct visualization of an unobstructed downstream lumen is required to execute the distal anastomosis with precision. “Parachuting” at the distal anastomosis is an excellent technique for tibial/pedal bypass, allowing full visualization of all of the sutures placed at the critical heel and toe areas.

      Postoperative management

      Long-term success after LEB is the benchmark of excellence, and necessitates diligent postoperative care and compliance with medications and surveillance. More so than many other surgical procedures, sustained benefit after lower extremity revascularization requires long-term commitment on the part of both provider and patient.
      All patients with advanced limb ischemia should be treated with cardioprotective, anti-atherosclerotic medications in accordance with guidelines; including the use of antiplatelet agents, statins, and treatment of hypertension and diabetes to accepted goals.
      • Hirsch A.T.
      • Haskal Z.J.
      • Hertzer N.R.
      • Bakal C.W.
      • Creager M.A.
      • Halperin J.L.
      • et al.
      ACC/AHA 2005 Practice Guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic): a collaborative report from the American Association for Vascular Surgery/Society for Vascular Surgery, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, Society of Interventional Radiology, and the ACC/AHA Task Force on Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Peripheral Arterial Disease): endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation; National Heart, Lung, and Blood Institute; Society for Vascular Nursing; TransAtlantic Inter-Society Consensus; and Vascular Disease Foundation.
      The beneficial impact of these therapies on performance of the lower extremity bypass graft is less clear, but the benefit on overall survival and cardiovascular events has been well demonstrated. In PREVENT III, statin use in patients with CLI undergoing bypass surgery was associated with reduced 1-year mortality.
      • Schanzer A.
      • Hevelone N.
      • Owens C.D.
      • Beckman J.A.
      • Belkin M.
      • Conte M.S.
      Statins are independently associated with reduced mortality in patients undergoing infrainguinal bypass graft surgery for critical limb ischemia.
      Recent data also strongly suggest that statin drugs markedly reduce perioperative events in vascular patients.
      • Schouten O.
      • Boersma E.
      • Hoeks S.E.
      • Benner R.
      • van Urk H.
      • van Sambeek M.R.
      • et al.
      Fluvastatin and perioperative events in patients undergoing vascular surgery.
      There has been some data to suggest that statins may impact on graft failure
      • Abbruzzese T.A.
      • Havens J.
      • Belkin M.
      • Donaldson M.C.
      • Whittemore A.D.
      • Liao J.K.
      • et al.
      Statin therapy is associated with improved patency of autogenous infrainguinal bypass grafts.
      and restenosis in various circumstances; further work in this area is required.
      Management of foot and extremity wounds in the patient with dysvascular diabetes is beyond the scope of this review; however, it is clearly critical to overall clinical success. Recent technology, such as negative pressure wound therapy, has made a major impact on inpatient and outpatient care of patients with CLI before and after bypass surgery. Special attention must be paid to wounds in proximity to grafts. An aggressive approach to debridement, re-closure, graft repositioning, and skin and muscle flaps is preferred in all cases of questionable bypass graft coverage, and may require a team effort with plastics and reconstructive specialists.
      Vein graft stenosis will occur in 30% to 50% of patients within the first 3 to 5 years, at least half of which takes place in the initial postoperative year. Although still debated in some corners, duplex ultrasound scan surveillance of lower extremity vein grafts has become the standard of care in most vascular practices. Surveillance allows detection of asymptomatic lesions that may lead to graft failure. Because durable restoration of a thrombosed vein graft is not common, identification of graft lesions before thrombosis is critical to maintain long-term patency. We advocate close surveillance during the first year, with duplex ultrasound scanning following the protocol suggested by Bandyk and others at 1, 3, 6, and 12 months post-bypass.
      • Tinder C.N.
      • Chavanpun J.P.
      • Bandyk D.F.
      • Armstrong P.A.
      • Back M.R.
      • Johnson B.L.
      • et al.
      Efficacy of duplex ultrasound surveillance after infrainguinal vein bypass may be enhanced by identification of characteristics predictive of graft stenosis development.
      If there are abnormal findings, additional observation points may be warranted. Beyond 1 year, scans are done twice a year at least until year 3, and annually thereafter. Criteria for angiography and potential reintervention are those consistent with a critical (>70%) stenosis by ultrasound scan, or low velocities suggestive of impending failure. These criteria have been reviewed extensively by others.
      • Tinder C.N.
      • Bandyk D.F.
      Detection of imminent vein graft occlusion: what is the optimal surveillance program?.

      Expected outcomes after LEB

      Five-year patency rates for vein bypass grafts to infrapopliteal targets range from 50% to 70% from retrospective series. Limb salvage rates for the CLI population undergoing LEB are generally greater than 80% at 5 years. As mentioned above, conduit factors such as vein diameter and quality exert dominant effects on graft patency and specific clinical risk factors for graft hyperplasia remain to be determined. An interesting finding has been the documentation of inferior outcomes in certain racial and ethnic groups.
      • Morrissey N.J.
      • Giacovelli J.
      • Egorova N.
      • Gelijns A.
      • Moskowitz A.
      • McKinsey J.
      • et al.
      Disparities in the treatment and outcomes of vascular disease in Hispanic patients.
      • Robinson 3rd, W.P.
      • Owens C.D.
      • Nguyen L.L.
      • Chong T.T.
      • Conte M.S.
      • Belkin M.
      Inferior outcomes of autogenous infrainguinal bypass in Hispanics: an analysis of ethnicity, graft function, and limb salvage.
      In particular, the PREVENT III data demonstrated notably inferior graft patency and limb salvage for African-American women in an analysis that included multiple covariates inclusive of technical determinants.
      • Nguyen L.L.
      • Hevelone N.
      • Rogers S.O.
      • Bandyk D.F.
      • Clowes A.W.
      • Moneta G.L.
      • et al.
      Disparity in outcomes of surgical revascularization for limb salvage: race and gender are synergistic determinants of vein graft failure and limb loss.
      Therefore, it remains unclear if specific patients have an enhanced propensity to develop vein graft disease which would place them under more aggressive surveillance. Clearly, grafts constructed using alternative veins, spliced veins, or other high-risk conduits should be monitored more closely.
      As mentioned above, several studies have confirmed that diabetes is not a risk factor for vein graft failure; however, diabetes does portend an increased risk for both long-term mortality and limb loss in the patient with CLI. The issues regarding the postoperative limb are multifactorial and include infection, wound healing and management, associated comorbidities such as renal failure, nutritional/metabolic derangements, and microvascular dysfunction. Therefore, aggressive management of the systemic milieu and the limb is mandatory to achieve a successful outcome after revascularization for CLI. Series from centers of excellence have demonstrated the efficacy of aggressive revascularization to tibial/pedal targets, multidisciplinary wound and foot care, and long-term surveillance in management of the patient with diabetes with a dysvascular limb. Such efforts should be led by dedicated vascular specialists with broad expertise in these areas, and promulgation of such teams would likely reduce the burden of CLI and amputation for all patients at risk.

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