Overview
Definition:
Axillo-bifemoral bypass is a surgical procedure performed to revascularize the lower extremities when femoropopliteal or aortofemoral bypass is not feasible due to anatomical limitations or previous interventions
It involves creating a bypass graft from the axillary artery, through the chest and abdominal wall, to the superficial femoral arteries (or common femoral arteries) bilaterally.
Epidemiology:
This procedure is typically reserved for patients with severe aortoiliac occlusive disease, extensive infrainguinal disease, or those who have undergone previous failed infrainguinal bypasses and have a patent axillary artery
It is relatively uncommon compared to standard aortofemoral bypasses, indicated in a select group of complex cases.
Clinical Significance:
Axillo-bifemoral bypass is a life-saving procedure for patients suffering from critical limb ischemia (CLI) and disabling claudication due to extensive atherosclerotic disease that precludes other bypass options
Successful revascularization can prevent limb loss, improve quality of life, and reduce amputation rates.
Indications
Indications For Bypass:
Severe limb-threatening ischemia (Rutherford classification 4-6)
Disabling claudication unresponsive to conservative management and less invasive interventions
Distal embolization from an aneurysm
Failed previous infrainguinal bypasses with patent axillary artery
Absence of suitable inflow from the aorta or iliac arteries
Patients with hostile abdomen precluding aortofemoral bypass.
Contraindications:
Unfavorable anatomy (e.g., severely diseased or absent axillary artery)
Patient factors (e.g., extreme obesity, severe comorbidities that contraindicate major surgery)
Active infection at the graft site
Life expectancy less than 1-2 years due to other medical conditions.
Preoperative Assessment:
Detailed vascular assessment including ankle-brachial index (ABI) and toe-brachial index (TBI)
Imaging studies like digital subtraction angiography (DSA) or CT angiography (CTA) to delineate the extent of disease and assess the patency of the axillary and femoral arteries
Assessment of comorbidities and cardiac status.
Surgical Technique
Anesthesia And Positioning:
General anesthesia is typically used
The patient is positioned supine, with arms abducted to facilitate axillary artery exposure and access to the abdominal wall and groin.
Graft Selection:
Synthetic grafts, such as polytetrafluoroethylene (PTFE) or Dacron, are commonly used
A bifurcated graft is typically employed, with the single limb arising from the axillary artery and bifurcating to supply both common femoral arteries.
Anastomosis Sites:
The proximal anastomosis is performed end-to-side to the ipsilateral axillary artery
The limbs of the graft are tunneled subcutaneously or retromuscularly across the chest and abdomen to reach the common femoral arteries
Distal anastomoses are typically end-to-side to the common femoral arteries
Careful attention is paid to avoid kinking of the graft.
Tunneling And Closure:
The graft is tunneled to avoid compression and to ensure adequate blood flow
Subcutaneous tunneling is common but carries a higher risk of infection
Retromuscular tunneling may offer better protection against infection
Meticulous hemostasis and wound closure are crucial.
Postoperative Care
Immediate Postoperative Management:
Close monitoring of vital signs, graft pulsation, and distal perfusion
Pain management
Intravenous fluids and electrolyte balance
Early ambulation as tolerated.
Pharmacological Management:
Anticoagulation (e.g., intravenous heparin) may be used temporarily in the immediate postoperative period
Long-term antiplatelet therapy (e.g., aspirin, clopidogrel) is essential to maintain graft patency
Antibiotic prophylaxis for 24-48 hours.
Monitoring For Complications:
Regular physical examination to assess distal pulses and signs of ischemia
Doppler ultrasound or duplex scanning to evaluate graft patency and flow
Monitoring for signs of infection, bleeding, or graft occlusion.
Complications
Early Complications:
Graft occlusion (acute thrombosis)
Bleeding or hematoma formation
Wound infection
Lymphocele
Graft limb thrombosis
Myocardial infarction or stroke due to patient comorbidities.
Late Complications:
Graft pseudoaneurysm formation
Distal embolization
Infection of the graft (late-onset)
Stenosis at the anastomoses or within the graft
Limb swelling (lymphedema).
Prevention Strategies:
Meticulous surgical technique to ensure adequate flow and avoid kinking
Careful graft selection and tunneling
Prophylactic antibiotics
Aggressive management of comorbidities
Long-term antiplatelet therapy
Patient education on wound care and early symptom reporting.
Prognosis
Factors Affecting Prognosis:
Graft patency rates are generally lower than aortofemoral bypasses
Factors influencing patency include patient comorbidities, quality of distal vessels, graft material, and surgical technique
The success of limb salvage is a primary determinant of long-term outcome.
Outcomes:
Graft patency at 1 year is typically around 70-80%, decreasing to 50-60% at 5 years
Limb salvage rates can be as high as 80-90% for selected patients
However, reintervention rates are higher compared to more distal bypasses.
Follow Up:
Regular clinical assessment with emphasis on distal pulses, skin changes, and symptom recurrence
Non-invasive vascular studies (e.g., duplex ultrasound) at regular intervals (e.g., 3, 6, 12 months, then annually) to monitor graft patency and identify early signs of failure.
Key Points
Exam Focus:
Understand the indications for axillo-bifemoral bypass as a salvage procedure when aortofemoral bypass is not possible
Differentiate from femorofemoral bypass
Recall common graft materials and tunneling techniques
Recognize key early and late complications.
Clinical Pearls:
Careful patient selection is paramount
Thorough preoperative imaging is essential to identify contraindications and plan the optimal graft configuration
Subcutaneous tunneling offers easier access but increases infection risk
retromuscular tunneling provides better protection
Monitor distal pulses closely postoperatively.
Common Mistakes:
Failure to consider alternative bypass options before proceeding with axillo-bifemoral bypass
Inadequate assessment of axillary artery suitability
Poor graft tunneling leading to kinking or compression
Inadequate anticoagulation/antiplatelet management postoperatively
Neglecting to monitor for graft infection.