Evidence - Aortobifemoral bypass for peripheral arterial disease Fontaine stage IIb–III

Critical limb ischemia 

Limb ischemia can be acute or chronic. Emergent diagnostic work-up of acute ischemia is mandatory; most cases require prompt revascularization. Chronic critical limb ischemia is the most severe form of peripheral arterial occlusive disease (PAOD). It is characterized by rest pain or necrosis and gangrene.

Acute limb ischemia (ALI) refers to acute reduced perfusion of the limb not older than 2 weeks. The most common causes include embolization or local thrombosis worsening a pathology already present, such as PAOD.

Chronic limb ischemia (CLI) refers to pain at rest or ischemic skin lesions such as ulcers or gangrene (Fontaine stage III and IV or Rutherford category 4-6). The correlation with cerebrovascular and cardiovascular events is high. If the symptoms last for more than two weeks, the ischemia is regarded as chronic.

TASC II criteria

The consensus document TASC II (Transatlantic Inter-Society Consensus for the Management of Peripheral Arterial Disease) addresses aspects of revascularization in PAOD [1]. Depending on the length of the local occlusion/stenosis, the TASC criteria suggest the treatment options to be used. The length of the stenosis and the region where it is located determine the general type of management: Endovascular or open vascular surgery.

TASC II classification in aortoiliac occlusion:

TASC II classification in femoropopliteal occlusion:

There are no recommendations for morphological characterization in the infrapopliteal segments.

Guidelines

The S3 guideline of the German Society of Angiology/German Society of Vascular Medicine on the diagnosis, management, and follow-up in PAOD notes the following regarding CLI [2]:

• The primary objective in CLI is rapid and adequate revascularization regardless of the type of management used.
• The elimination of inflow obstructions in multilevel lesions has priority over the management of downstream lesions.
• In CLI, the inflow and subsequent outflow lesions should be treated by intervention if possible.
• The presence of combined high-grade stenoses or occlusions of the CFA, DFA and lesions in the aortoiliac inflow axis and/or the femoropopliteal outflow axis may call for a combination of open surgery and intraoperative endovascular treatment (hybrid surgery).
• Endovascular treatment should be preferred if the angiomorphologic findings suggest that the technical outcome will be comparable to open surgery.
• Endovascular intervention should be preferred if the respective surgical procedure carries an increased surgical risk due to comorbidity.
• Femoropopliteal lesions should primarily be treated by endovascular intervention. Bypass procedures should be preferred in TASC-D cases with no increased surgical risk, no significant reduction in life expectancy and availability of autologous vein.
• Lesions of the popliteal artery should primarily be treated by balloon angioplasty.
• In patients with critical ischemia, infrapopliteal vascular lesions should primarily be treated by endovascular techniques. Vascular surgical procedures can be considered if the surgical risk is acceptable and an autologous vein is available.

The European Society of Cardiology (ESC) in collaboration with the European Society for Vascular Surgery (ESVS)  recommends the following for patients with CI and CLI [3]:

1. Recommendations on revascularization of aorto-iliac occlusive lesions

• An endovascular-first strategy is recommended for short (i.e. <5 cm) occlusive lesions.
• In patients fit for surgery, aorto-(bi)femoral bypass should be considered in aorto-iliac occlusions.
• An endovascular-first strategy should be considered in long and/or bilateral lesions in patients with severe comorbidities.
• An endovascular-first strategy may be considered for aorto-iliac occlusive lesions if done by an experienced team and if it does not compromise subsequent surgical options.
• Open surgery should be considered in fit patients with an aortic occlusion extending up to the renal arteries
• In the case of iliofemoral occlusive lesions, a hybrid procedure combining iliac stenting and femoral endarterectomy or bypass should be considered.
• Extraanatomical bypass may be indicated for patients with no other alternatives for revascularization.
• Primary stent implantation rather than provisional stenting should be considered.

2. Recommendations on revascularization of femoropopliteal occlusive lesions

• An endovascular-first strategy is recommended in short (i.e. <25 cm) lesions.
• Primary stent implantation should be considered in short (i.e. <25 cm) lesions.
• Drug-eluting balloons may be considered in short (i.e. <25 cm) lesions.
• In patients who are not at high risk for surgery, bypass surgery is indicated for long (i.e. ≥25 cm) superficial femoral artery lesions when an autologous vein is available and life expectancy is > 2 years In patients unfit for surgery, endovascular therapy may be considered in long (i.e. ≥25 cm) femoropopliteal lesions.
• The autologous saphenous vein is the conduit of choice for femoropopliteal bypass.

The guidelines of the  American College of Cardiology (ACC) and the  American Heart Association/AHA) recommend the following for patients with CI and CLI [4]:

• CLI patients should be revascularized whenever possible to minimize tissue loss.
• Before any amputation, an interdisciplinary team should assess the chances for revascularization.

1. Endovascular revascularization

• Endovascular interventions are recommended to restore perfusion to the foot in patients with non-healing wounds or gangrene. In ischemic rest pain, a phased approach to endovascular procedures is recommended.
• Angiosome-guided endovascular treatment may be considered in patients with CLI and non-healing wounds or gangrene.

2. Surgical revascularization

• If a bypass to the popliteal or infrapopliteal arteries is planned, it should be fashioned with autologous vein.
• Surgical procedures are recommended to restore perfusion to the foot in patients with non-healing wounds or gangrene.
• If endovascular treatment fails and no suitable autologous vein is available, an alloplastic graft can be used as a substitute.
• In patient with ischemic rest pain, a phased approach in surgical interventions is recommended. 

Results

1. Percutaneous Intervention vs. bypass surgery in CLI

The largest metaanalysis on this topic includes over 45 trials with a total of almost 21,000 patients and dates from 2018 [5]. Comparison of percutaneous vascular intervention (PVI) with open bypass surgery (BSX) revealed:

• PVI reduced the risk of 30-day mortality, major adverse cardiovascular and cerebrovascular events and wound infections, but increased the risk of long-term mortality and failure of primary patency.
• Compared to autologous bypasses, PVI also scored worse on secondary patency and in the long run resulted in more amputations.

The authors of the metaanalysis concluded that BSX is the better choice for patients with good overall state of health and reasonably long life expectancy, especially if autologous bypass conduits are available.

A 2017 Cochrane Review compared the efficacy of bypass surgery in chronic ischemia with other interventions (PTA, endarterectomy; thrombendarteriectomy; thrombolysis; exercising; and spinal cord stimulation) [6]:

• In a comparison of bypass vs. PTA, the bypasses often developed early, non-thrombotic complications, but were associated with higher technical success rates.
• One year after intervention, the primary patency in the bypass group was higher than after PTA, while four years later there was no difference.
• No differences in mortality, clinical improvement, amputation rates, and revision surgery rates were identified between the bypass and PTA groups.

The authors concluded that there is limited high-quality evidence regarding the efficacy of bypass surgery compared to other treatment methods.

2. Gender-specific outcome differences in revascularization of the lower limb

A systematic review with metaanalysis studied the effect of gender on the outcome in revascularization of the lower extremity [7]. 40 trials were considered, 15 trials reported outcomes following BSX, 19 following PVI, with the remainder involving hybrid procedures:

• Women had a significantly higher rate of 30-day mortality rate; amputation; early graft thrombosis; embolization; complications at the access site; and increased general complications (cardiopulmonary, cerebral) compared to men.
• No differences were found regarding repeat intervention and renal complications.
• When analyzing the results regarding BSX and PVI, the increased risk of postoperative mortality and complications in women remained. However, no significant differences between men and women were found in the long-term outcomes.

As reasons for the less favorable outcomes in women, the authors include patient age (women were older than men at the time of intervention) and unmet need of platelet inhibitors, statins and cardiovascular medication compared to men.

3. Angiosome-guided revascularization in CLI

Angiosomes are skin and tissue units fed by so-called source arteries. The human foot has 6 such arteries (medial plantar artery; lateral plantar artery; calcaneal branches of posterior tibial artery; lateral and medial branch of fibular artery; dorsal artery of foot). According to this concept, the wound healing rate will be improved by direct revascularization, i.e. by fashioning a bypass to a vascular segment directly supplying the angiosome.

There is a systematic review with metaanalysis on angiosome-guided revascularization in CLI from 2017, which includes almost 4000 patients [8]. Compared to indirect revascularization (IR), direct revascularization (DR) significantly improved wound healing, major amputation rate and amputation-free survival. In the sensitivity analysis, however, the significance of the major amputation rate in bypass surgery was lost and there were no differences in overall survival between IR and DR.

The authors concluded that the angiosome concept is supported by their analysis, at least in endovascular management. Since the outcomes of PVI and IR are similar once collateral vessels are present, patients without collaterals are most likely to benefit from DR, rendering the angiosome concept less useful in bypass surgery.

Polytetrafluoroethylen (PTFE) Vascular Prostheses With Heparin Bonded Luminal Surfaces vs Crude ePTFE (REPLACE)

Allogeneic Mesenchymal Stem Cells for the Critical Limb Ischemia Therapy

Peripheral Registry of Endovascular Clinical Outcomes "The PRIME Registry" (PRIME)

Best Endovascular vs. Best Surgical Therapy in Patients With Critical Limb Ischemia (BEST-CLI)

Norwegian Laparoscopic Aortic Surgery Trial (NLAST)

1. Norgren L, Hiatt WR, Dormandy JA, Nehler MR, Harris KA, Fowkes FG; TASC II Working Group. Inter-Society Consensus for the Management of Peripheral Arterial  Disease (TASC II). J Vasc Surg. 2007 Jan;45 Suppl S:S5-67.

2. Lawall H, Huppert P, Rümenapf G, Deutsche Gesellschaft für Angiologie – Gesellschaft für Gefäßmedizin (2015) S3-Leitlinie zur Diagnostik, Therapie und Nachsorge der peripheren arteriellen Verschlusskrankheit. AWMF-Register Nr. 065/003

3. Aboyans V, Ricco JB, Bartelink MEL et al (2018) 2017 ESC guidelines on the diagnosis and treatment of peripheral arterial diseases, in collaboration with the European Society for Vascular Surgery (ESVS): Document covering atherosclerotic disease of extracranial carotid and vertebral, mesenteric, renal, upper and lower extremity arteries. Endorsed by: the European Stroke Organization (ESO) the task force for the diagnosis and treatment of peripheral arterial diseases of the European Society of Cardiology (ESC) and of the European Society for Vascular Surgery (ESVS). Eur Heart J 39:763–816

4. Gerhard-Herman MD, Gornik HL, Barrett C et al (2017) 2016 AHA/ACC guideline on the management of patients with lower extremity peripheral artery disease: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol 69:e71–e126

5. Wang J, Shu C, Wu Z, Zhao J, Ma Y, Huang B, Yuan D, Yang Y, Bian H, He Y, Wang Z (2018) Percutaneous vascular interventions versus bypass surgeries in patients with critical limb ischemia: a comprehensive meta-analysis. Ann Surg 267:846–857

6. Antoniou GA, Georgiadis GS, Antoniou SA, Makar RR, Smout JD, Torella F (2017) Bypass surgery for chronic lower limb ischaemia. Cochrane Database Syst Rev 4:CD002000

7. Wang J, He Y, Shu C, Zhao J, Dubois L (2017) The effect of gender on outcomes after lower extremity revascularization. J Vasc Surg 65:889–906

8. Jongsma H, Bekken JA, Akkersdijk GP, Hoeks SE, Verhagen HJ, Fioole B (2017) Angiosome- directed revascularization in patients with critical limb ischemia. J Vasc Surg 65:1208–1219