Overview
Definition:
Axillary-bifemoral bypass is a revascularization procedure used to restore blood flow to the lower extremities in patients with extensive aortoiliac occlusive disease, where traditional aortobifemoral bypass is not feasible
It involves creating a conduit from the axillary artery to the superficial femoral arteries bilaterally, bypassing the entire infrarenal aorta and iliac system
The "tunneling" aspect refers to the critical technique of passing the graft material subcutaneously or retroperitoneally from the axillary incision to the groin incisions.
Epidemiology:
This procedure is typically reserved for a subset of patients with critical limb ischemia and extensive disease, often those with previous abdominal surgery, comorbidities that preclude abdominal exploration, or anatomy unsuitable for endovascular repair or axillobifemoral bypass
The exact incidence is less common than standard aortobifemoral bypass, but it remains a vital limb salvage option.
Clinical Significance:
Axillary-bifemoral bypass is a complex but life-saving procedure for patients with debilitating limb ischemia due to infrarenal aortic and bilateral iliac occlusions
Mastery of the tunneling technique is paramount for graft patency, avoiding complications, and achieving successful limb salvage, making it a key topic for surgical residents preparing for DNB and NEET SS examinations.
Indications
Indications For Procedure:
Severe critical limb ischemia (Rutherford class 4-6) with non-reconstructible infrarenal aortoiliac occlusive disease
Absence of suitable inflow from the aorta or iliacs
Inability to perform abdominal surgery due to comorbidities or prior interventions
Failed previous infrainguinal bypasses requiring proximal inflow revision
Patient amenable to a staged approach for potential contralateral limb revascularization.
Contraindications:
Extensive axillary or subclavian artery disease precluding adequate inflow
Active infection at potential graft sites
Severe coagulopathy
Limited life expectancy due to non-vascular comorbidities
Unrealistic patient expectations.
Patient Selection:
Careful assessment of inflow (axillary/subclavian artery diameter and patency) and outflow (femoral and below-knee arteries) is crucial
Assessment of comorbidities and patient's physiological status guides suitability for a lengthy bypass procedure.
Preoperative Preparation
Imaging And Assessment:
Duplex ultrasonography to assess axillary and femoral artery patency
CT angiography or MR angiography to delineate the extent of aortoiliac occlusive disease and identify potential outflow targets
Conventional angiography may be performed if imaging is equivocal or to plan for potential staged interventions.
Anesthesia And Monitoring:
General anesthesia is typically employed
Invasive arterial monitoring (femoral or radial artery line) for continuous blood pressure assessment
Central venous access for fluid administration and monitoring
Electrocardiography (ECG) and pulse oximetry are standard
Transesophageal echocardiography (TEE) can be used for detailed cardiac assessment and intraoperative fluid management.
Graft Selection:
Synthetic grafts (e.g., PTFE or Dacron) are commonly used
The graft is typically a bifurcated prosthesis with one limb extending to each superficial femoral artery
The choice of graft material and diameter depends on patient anatomy and surgeon preference
Pre-hydration and appropriate antibiotic prophylaxis are essential.
Tunneling Techniques
Axillary To Femoral Tunnel Anterolateral Approach:
The most common approach involves creating an anterolateral tunnel
An incision is made in the axilla over the pectoralis major muscle to expose the axillary artery
The tunnel is then created subcutaneously along the anterolateral chest wall, passing posterior to the pectoralis muscles and then inferiorly towards the groin
Careful dissection is required to avoid injury to the brachial plexus and long thoracic nerve
This route generally provides a relatively straight path and is less prone to kinking.
Axillary To Femoral Tunnel Retroperitoneal Approach:
An alternative involves a retroperitoneal tunnel
After exposing the axillary artery, the graft is passed through the retroperitoneum
This can be achieved by tunneling down the flank or through a separate abdominal incision to enter the retroperitoneal space, then continuing towards the groin
This approach may offer a more protected route for the graft, potentially reducing superficial infection risk, but requires more extensive dissection and carries risks of retroperitoneal injury.
Securing And Managing The Tunnel:
The graft within the tunnel must be carefully positioned to avoid angulation, kinking, or tension
The tunnel should be wide enough to accommodate the graft without compression
The graft is usually secured in the axilla and groin incisions
Attention must be paid to the integrity of the tunnel to prevent seroma formation or graft extrusion
Pulsation of the graft should be confirmed at multiple points along the tunnel during closure.
Considerations For Tunneling In Specific Patients:
In patients with previous abdominal surgery, adhesions in the retroperitoneum may complicate the retroperitoneal approach, favoring a subcutaneous route
Conversely, patients with significant subcutaneous tissue may benefit from a retroperitoneal approach to reduce compression
The presence of previous sternotomy or chest wall interventions may influence the choice of axillary access and subsequent tunneling.
Procedure Steps And Anastomoses
Axillary Artery Anastomosis:
The axillary artery is identified and dissected
Systemic heparinization is administered
An appropriate arteriotomy is made, and the proximal end of the graft is anastomosed end-to-side to the axillary artery using fine, non-absorbable sutures (e.g., Prolene 5-0 or 6-0)
Careful attention is paid to achieve a leak-proof anastomosis.
Femoral Artery Anastomoses:
Bilateral groin incisions are made to expose the superficial femoral arteries (or common femoral arteries if necessary)
The distal ends of the graft limbs are anastomosed end-to-side to the superficial femoral arteries
Similar meticulous suturing technique is employed as for the axillary anastomosis
The graft limbs should be routed to avoid crossing each other unnecessarily.
Completion Angiography And Hemostasis:
After establishing both proximal and distal anastomoses and completing the tunneling, completion angiography is performed to assess the patency of the entire graft, the anastomoses, and the distal arterial tree
Any areas of stenosis or kinking are identified and corrected
Meticulous hemostasis is achieved at all incision sites before closure.
Postoperative Care And Monitoring
Immediate Postoperative Period:
Close monitoring of vital signs, including blood pressure and heart rate
Assessment of graft patency via palpable pulses and Doppler ultrasound
Fluid management to maintain adequate hydration and perfusion
Pain control with appropriate analgesics
Early ambulation as tolerated.
Graft Surveillance:
Regular follow-up with duplex ultrasonography to assess graft patency and identify any signs of stenosis or thrombosis
Typically performed at 1 month, 6 months, and annually thereafter
Monitoring for signs of infection or pseudoaneurysm formation at the anastomosis sites or along the tunnel.
Long Term Management:
Antiplatelet therapy (e.g., aspirin and/or clopidogrel) is crucial for maintaining graft patency
Lifestyle modifications, including smoking cessation and diabetes management, are essential
Regular clinical follow-up and surveillance.
Complications
Early Complications:
Graft thrombosis: Often due to technical errors, low flow states, or hypercoagulability
Bleeding at anastomosis sites or from the tunnel
Limb ischemia due to distal embolization or graft failure
Nerve injury during tunneling, leading to sensory or motor deficits
Wound infection, particularly around the tunnel
Seroma formation.
Late Complications:
Graft limb occlusion or stenosis
Pseudoaneurysm formation at anastomosis sites
Graft infection, which is a devastating complication requiring graft explantation
Chronic wound issues or skin breakdown over the graft tunnel
Persistent distal embolization.
Prevention Strategies:
Meticulous surgical technique, including proper graft handling, precise anastomoses, and careful tunneling to avoid kinking
Adequate heparinization and appropriate antiplatelet therapy
Prompt diagnosis and management of graft-related issues
Aggressive wound care and infection prophylaxis
Careful patient selection and optimization of comorbidities.
Key Points
Exam Focus:
Understand the indications for axillobifemoral bypass as a salvage procedure for extensive aortoiliac disease
Master the differences between anterolateral and retroperitoneal tunneling techniques and their respective advantages/disadvantages
Recognize the critical anatomical structures at risk during tunneling
Recall the importance of graft surveillance and long-term medical management for patency.
Clinical Pearls:
When tunneling, always maintain adequate graft length to avoid tension, especially with patient position changes
Consider a staged approach for contralateral limb revascularization if significant stenosis is present on the initial side
Always confirm pulsatile flow in the graft limbs with Doppler before closing
Document the course of the tunnel clearly in the operative notes.
Common Mistakes:
Overly tight tunneling leading to graft compression or kinking
Inadequate dissection leading to nerve or vascular injury
Failure to achieve good inflow/outflow at anastomoses
Insufficient graft surveillance leading to late graft failure going unnoticed
Ignoring comorbidities that predispose to graft thrombosis.