Femorofemoral (Femoral-Femoral) Bypass

Femorofemoral (femoral-femoral) bypass is a method of surgical revascularization used in the setting of unilateral common and/or external iliac artery occlusive disease. The technique is dependent upon a patent iliac arterial system without hemodynamically significant disease to supply adequate inflow of blood to both lower extremities. It is a commonly used means of extra-anatomic vascular reconstruction for patients with disabling claudication or critical limb-threatening ischemia (CLTI) in whom underlying anatomic constraints rule out endovascular means of restoring in-line flow and those who do not qualify for anatomic reconstruction because of comorbidities that preclude a more invasive open approach.

Femorofemoral bypass may also be used as a component of endovascular repair of abdominal aortic aneurysms (AAAs), ^[1] whereupon one aortoiliac system is occluded on an emergency or elective basis to ensure exclusion of the aortic aneurysm. Primary patency rates of femorofemoral bypasses are estimated to be in the range of 65-70% at 5 years. ^{[2, 3, 4]}  The bypass patency rates, however, are inferior to in-line reconstruction benchmarks set by the aortofemoral and iliofemoral bypass operations.

Indications for femorofemoral bypass are as follows:

• Symptomatic lower-extremity ischemia (disabling claudication, rest pain, tissue loss) due to acute or chronic occlusion of a unilateral iliac artery system
• Adjunct to an endovascular unilateral aortoiliac exclusion of an AAA
• Unavailability of endovascular options for management of iliac occlusive disease
• High-risk patients with significant comorbidities (cardiopulmonary disease, multiple prior abdominal operations, prior radiation therapy to the abdomen, abdominal stoma) that preclude in-line reconstruction with inflow from the proximal iliac artery or the aorta

In a retrospective study of 82 consecutive patients with CLTI from unilateral iliofemoral artery occlusion, Ma et al found that femorofemoral bypass to the deep femoral (profunda femoris) artery appeared to be safe, durable, and effective for limb salvage after attempted percutaneous endovascular intervention had failed. ^[5]

Femorofemoral bypass has also been used, in conjunction with retrograde endovascular aortoiliac intervention, as a component of a hybrid approach to bilateral lower-extremity inflow revascularization. ^[6]

Contraindications for femorofemoral bypass are as follows:

• Compromised inflow aortoiliac arterial segment
• Significant obesity that may cause unfavorable graft geometry
• Extreme medical risks for surgery

Complication prevention

The inflow aortoiliac arterial system must be thoroughly preoperatively assessed. The outflow common, superficial, or deep femoral artery must be thoroughly assessed as well.

Strict attention must be paid to sterile technique in handling prosthetic grafts. A wide sterile field is necessary to manage intraoperative bleeding or other unexpected complications that can arise during the procedure.

The geometry of the graft tunneling should be carefully assessed; the graft should be in an inverted C (or gentle S) configuration to prevent undue tension and kinking at the anastomoses.

In a study of 1602 patients who underwent suprainguinal bypass for aortoiliac occlusive disease (AIOD), Saadeddin et al compared the early and late postoperative outcomes of aortofemoral bypass (AFB; n = 872), axillofemoral bypass (AXB; n = 207), and femorofemoral bypass (FFB; n = 523). ^[7]  The authors found that FFB yielded significantly lower postoperative complication rates than AXB. They suggested that FFB may serve as the extra-anatomic operation of choice in high-risk patients with extensive disease who cannot undergo AFB, if the anatomy permits, and noted that AFB should be preferred in low-risk patients with appropriate anatomy.

In another study (N = 2612), Saadeddin et al described three models designed to predict 30-day mortality, morbidity, and major adverse limb events (MALE), respectively, after FFB (n = 1149), AFB (n = 1138), or AXB (n = 325) for AIOD and compared these models with the 5-Factor Modified Frailty Index (mFI-5). ^[8]  All three constructed models demonstrated significantly better discriminative ability on the outcomes of interest than the mFI-5 did.