What is a femoral-femoral (fem-fem) bypass?

Femoral-Femoral (Fem-Fem) Bypass

A femoral-femoral bypass is a surgical procedure that creates a crossover graft between the femoral arteries of both legs, using one femoral artery with adequate inflow as a donor to supply blood to the contralateral limb with compromised circulation. 1

Anatomical Considerations and Technique

• The procedure involves:

  • Creating a subcutaneous tunnel across the suprapubic region
  • Placing a synthetic graft (typically polytetrafluoroethylene or polyester) from one femoral artery to the other
  • The donor side must have adequate inflow from the iliac artery
  • The graft is typically externally supported to prevent kinking

• The procedure is performed when:

  • One iliac artery has significant occlusive disease
  • The contralateral iliac artery has adequate flow
  • The patient is not a suitable candidate for direct aortic reconstruction

Indications

Fem-fem bypass is indicated in the following scenarios:

1. Bilateral iliac artery occlusive disease when the patient is not a suitable candidate for aortobifemoral bypass 1
2. Unilateral iliac occlusion in high-risk patients who cannot tolerate aortic surgery 2
3. Critical limb ischemia requiring urgent revascularization in patients with prohibitive surgical risk for direct aortic approach 2
4. After endovascular treatment of one iliac artery when the contralateral iliac artery also has occlusive disease 1

Outcomes and Efficacy

• Patency rates:

  • Primary patency at 3 years: approximately 70-82% 2, 3
  • Secondary patency at 3 years: approximately 89% 2
  • Limb salvage rates at 3 years: 85-89% 2, 4

• Mortality and morbidity:

  • Operative mortality: 5-6% overall (higher in urgent cases, lower in elective cases) 2, 4
  • Morbidity: approximately 27% 2

Comparison with Other Procedures

Fem-fem bypass is generally considered inferior to aortobifemoral bypass:

• Aortobifemoral bypass has superior long-term patency (85-87% at 5 years vs. 70% for fem-fem) 1, 4
• Hemodynamic performance is better with aortobifemoral bypass (higher ankle-brachial index) 4
• Fem-fem bypass has higher risk of late failure due to progression of disease in the donor iliac artery 5

Factors Affecting Outcomes

Several factors influence the success of fem-fem bypass:

• Graft material: Externally supported prosthetic grafts show better patency than non-supported grafts or autogenous vein 3
• Previous vascular procedures: Patency rates are lower when performed after previous vascular graft failures 3
• Outflow status: Patency is significantly reduced when the superficial femoral artery is occluded 5
• Donor iliac artery quality: Adequate inflow is essential for long-term success 4

Clinical Pearls and Pitfalls

• Always assess donor iliac artery adequacy before performing fem-fem bypass to ensure sufficient inflow
• Consider preoperative angioplasty of donor iliac artery stenosis to improve inflow 3
• Monitor for disease progression in the donor iliac artery, which can cause late graft failure
• Use externally supported grafts whenever possible to improve long-term patency 3
• Consider outflow status when selecting patients; those with superficial femoral artery occlusion may have poorer outcomes 5

Algorithm for Decision-Making

1. First-line approach for bilateral aortoiliac disease: Aortobifemoral bypass (if patient is an acceptable surgical candidate) 1
2. Consider fem-fem bypass when:
   • Patient has high surgical risk for direct aortic approach
   • Unilateral iliac disease with adequate contralateral iliac artery
   • After successful endovascular treatment of one iliac artery
3. Avoid fem-fem bypass when:
   • Both iliac arteries have significant disease
   • Patient is a good candidate for aortobifemoral bypass
   • Donor iliac artery has significant stenosis that cannot be treated

In summary, while fem-fem bypass is not the first-line treatment for aortoiliac occlusive disease, it remains an important option for selected patients who cannot undergo direct aortic reconstruction, with acceptable patency rates and limb salvage outcomes.