What are the indications for femoral-popliteal (fem-pop) bypass?

Indications for Femoral-Popliteal Bypass

Femoral-popliteal bypass is indicated for patients with lifestyle-limiting or vocational-disabling claudication who have failed conservative management (exercise therapy and pharmacotherapy) and are unsuitable for or have failed endovascular intervention, as well as for patients with chronic limb-threatening ischemia (CLTI) requiring limb salvage. 1

Primary Indications

Intermittent Claudication

• Bypass is appropriate for patients with vocational or lifestyle-disabling symptoms who remain symptomatic despite optimal medical therapy and supervised exercise programs 1
• Patients must have a reasonable likelihood of symptomatic improvement and acceptable surgical risk 1
• Surgical intervention is NOT indicated solely to prevent progression to limb-threatening ischemia in claudicants 1
• An endovascular-first strategy is recommended for short lesions (<25 cm), with bypass reserved for longer lesions (≥25 cm) when autologous vein is available and life expectancy exceeds 2 years 1

Chronic Limb-Threatening Ischemia (CLTI)

• Bypass is indicated for patients with ischemic rest pain, non-healing ulcers, or gangrene when limb salvage is the goal 1
• This represents the most common indication for fem-pop bypass, with 17 of 21 patients in one series undergoing the procedure for limb salvage 2
• CLTI encompasses ischemic rest pain (typically with ankle pressure <50 mmHg or toe pressure <30 mmHg), diabetic foot ulcers, non-healing ulceration ≥2 weeks duration, or gangrene 1

Patient Selection Criteria

Anatomic Considerations

• Bypass is most appropriate for superficial femoral artery occlusions with adequate inflow from the common femoral artery and suitable outflow through the popliteal artery 1
• For combined inflow and outflow disease, inflow lesions should be addressed first before considering fem-pop bypass 1
• The procedure can target either above-knee or below-knee popliteal artery depending on disease extent 1

Conduit Availability

• Autologous saphenous vein is the conduit of choice for all fem-pop bypasses, both above-knee and below-knee 1
• When above-knee bypass is indicated and no autologous vein is available, prosthetic conduit (PTFE) should be considered as an acceptable alternative 1
• Synthetic grafts to below-knee popliteal artery are reasonable only when no autogenous vein from ipsilateral or contralateral leg or arms is available 1

Surgical Risk Assessment

• A preoperative cardiovascular risk evaluation must be undertaken in all patients planned for major vascular surgical intervention 1
• Patients younger than 50 years may have less durable results due to more aggressive atherosclerotic disease, making the benefit unclear for claudication alone 1
• Patients unfit for surgery may be considered for endovascular therapy even for long lesions 1

Contraindications

Absolute Contraindications

• Fem-pop bypass should NOT be performed solely to prevent progression to limb-threatening ischemia in patients with stable claudication 1
• Femoral-tibial artery bypasses with synthetic graft material should not be used for claudication 1

Relative Contraindications

• Patients with claudication who have not undergone adequate trial of exercise therapy and pharmacotherapy 1
• Patients with short lesions (<25 cm) amenable to endovascular intervention who have not had endovascular therapy attempted 1
• Absence of adequate conduit (autologous vein) in patients requiring below-knee bypass, particularly for claudication 1

Expected Outcomes by Indication

Claudication

• Primary patency rates for above-knee vein grafts: 73% at 4 years 1
• Primary patency for above-knee PTFE: 47-58% at 4-5 years 1, 3
• Below-knee vein grafts: 66% at 5 years 1
• Below-knee PTFE: 33% at 5 years 1

Limb Salvage (CLTI)

• Limb salvage rates: 100% at 1 year, 90% at 2 years, and 77% at 5 years for combined procedures 2
• Primary patency: 73.2% at 1 year for TASC D lesions treated with endoscopic vein harvest 4
• Below-knee bypass target and tissue loss are independent predictors of major adverse limb events 5

Common Pitfalls

• Performing bypass for claudication without adequate trial of conservative therapy violates guideline recommendations and exposes patients to unnecessary surgical risk 1
• Using prosthetic grafts below the knee when vein is available significantly reduces patency rates (33% vs 66% at 5 years) 1
• Failing to address inflow disease first in patients with combined aortoiliac and femoral-popliteal disease leads to poor outcomes 1
• Attempting bypass in patients with inadequate outflow without considering tibial vessel revascularization compromises graft patency 1