Overview
Definition:
Aorto-bifemoral bypass is a surgical procedure to restore blood flow to the lower extremities in patients with severe atherosclerotic disease of the abdominal aorta and/or iliac arteries
It involves bypassing the occluded segments with a synthetic graft, typically connecting the infrarenal aorta to the common femoral arteries bilaterally.
Epidemiology:
Peripheral artery disease (PAD) affects millions worldwide, with critical limb ischemia (CLI) being a severe manifestation
Aorto-bifemoral bypass is a gold-standard treatment for severe aortoiliac occlusive disease, often seen in patients with multiple cardiovascular risk factors like diabetes, hypertension, hyperlipidemia, and smoking.
Clinical Significance:
This procedure is crucial for salvaging limbs threatened by ischemia, relieving disabling claudication, and improving quality of life
It significantly reduces the risk of amputation and mortality associated with untreated severe PAD and CLI
Understanding its indications, technique, and management is vital for surgical residents preparing for DNB and NEET SS examinations.
Indications
Primary Indications:
Severe intermittent claudication limiting quality of life
Rest pain in the lower extremities
Non-healing ulcers or gangrene of the toes or feet
Limb salvage in patients with critical limb ischemia (CLI).
Secondary Indications:
Ipsilateral iliac artery occlusion with contralateral femoral artery occlusion
Extensive aortoiliac occlusive disease not amenable to endovascular repair
Failed endovascular treatment of aortoiliac disease.
Contraindications:
Unacceptable operative risk due to comorbidities (e.g., severe cardiopulmonary disease)
Limited life expectancy
Absence of outflow to the distal arteries
Extensive distal embolization or infection that cannot be controlled.
Preoperative Preparation
Patient Assessment:
Thorough cardiovascular assessment, including echocardiogram and stress testing if indicated
Pulmonary function tests
Renal function assessment
Complete blood count, coagulation profile, electrolytes, and blood glucose monitoring
Smoking cessation counseling.
Imaging Studies:
Duplex ultrasonography to assess arterial anatomy and haemodynamics
Computed tomography angiography (CTA) or magnetic resonance angiography (MRA) for detailed visualization of the aorta, iliac, and femoral arteries, and to identify distal occlusive disease and collateralization.
Anesthesia And Access:
General anesthesia is typically employed
Epidural anesthesia may be an adjunct
Secure intravenous access
Arterial line for continuous hemodynamic monitoring
Urinary catheterization.
Procedure Steps
Surgical Approach:
A midline or slightly left-para-median abdominal incision is made, extending from below the xiphoid process to the umbilicus or lower
The abdominal cavity is entered, and the infrarenal aorta is carefully mobilized
The origin of the inferior mesenteric artery and lumbar arteries may need to be ligated and divided.
Aortic Control And Anastomosis:
The infrarenal aorta is controlled proximally using vascular clamps
Systemic heparinization is administered
An aortotomy is performed, and the bifurcated graft (e.g., Dacron or GORE-TEX) is anastomosed end-to-side to the aorta using a continuous polypropylene suture
Meticulous attention is paid to hemostasis.
Femoral Exposure And Anastomosis:
Bilateral groin incisions are made to expose the common femoral arteries
The iliac arteries are controlled, and end-to-side anastomoses of the graft limbs to the common femoral arteries are performed
Distal arteriotomy and endarterectomy may be necessary if significant intraluminal disease is present at the anastomosis site
Careful attention to hemostasis and graft limb patency is paramount.
Wound Closure:
The abdomen is irrigated, and meticulous hemostasis is reconfirmed
The abdominal fascia, subcutaneous tissue, and skin are closed in layers
The groin incisions are also closed in layers.
Postoperative Care
Monitoring:
Close monitoring of vital signs, urine output, and fluid balance
Assessment of peripheral pulses, skin temperature, color, and capillary refill in the lower extremities
Continuous cardiac monitoring.
Pain Management:
Adequate analgesia is crucial, typically with intravenous patient-controlled analgesia (PCA) or epidural analgesia initially, transitioning to oral pain medication.
Ambulation And Physiotherapy:
Early ambulation is encouraged as tolerated to prevent deep vein thrombosis (DVT) and improve pulmonary function
Physiotherapy may be initiated to aid recovery.
Medications:
Anticoagulation with heparin or low-molecular-weight heparin (LMWH) is typically continued postoperatively for a period
Antiplatelet therapy (e.g., aspirin, clopidogrel) is initiated to maintain graft patency
Beta-blockers are continued for cardiac protection
Antibiotics are administered perioperatively to prevent graft infection.
Complications
Early Complications:
Graft infection (most feared, incidence 1-5%)
Bleeding at the anastomosis sites or graft site
Graft thrombosis (occlusion)
Myocardial infarction or stroke due to systemic atherosclerosis
Paralytic ileus
Deep vein thrombosis (DVT) and pulmonary embolism (PE).
Late Complications:
Graft occlusion (due to intimal hyperplasia, thrombus, or infection)
Anastomotic pseudoaneurysm or dehiscence
Incisional hernia
Chronic graft infection
Distal embolization
Claudication due to progression of disease distal to the bypass.
Prevention Strategies:
Meticulous surgical technique with attention to hemostasis
Strict adherence to sterile protocols to minimize graft infection
Perioperative antibiotic prophylaxis
Aggressive postoperative anticoagulation and antiplatelet therapy
Careful patient selection and risk stratification
Smoking cessation and aggressive management of cardiovascular risk factors.
Prognosis
Factors Affecting Prognosis:
The severity of distal occlusive disease
The presence of comorbidities (cardiac, renal, pulmonary disease)
Graft patency rates, which are generally excellent early on but decline over time
Incidence of graft infection is a major determinant of limb loss and mortality.
Outcomes:
Successful aorto-bifemoral bypass typically leads to significant improvement in symptoms, limb salvage rates exceeding 90% at 5 years, and improved quality of life
Long-term graft patency rates are reported to be around 70-90% at 5 years and 60-80% at 10 years, depending on patient factors and graft material.
Follow Up:
Regular lifelong surveillance is essential, including clinical assessment and non-invasive vascular laboratory studies (duplex ultrasound)
Annual examinations are recommended to monitor graft patency, detect complications early, and assess for progression of PAD in other vascular beds.
Key Points
Exam Focus:
Indications for bypass vs
endovascular repair
Graft material selection
Management of graft infection
Recognition and management of early and late complications
Significance of perioperative anticoagulation and antiplatelet therapy
Graft patency rates.
Clinical Pearls:
Always suspect graft infection in any patient with fever, abdominal pain, or wound drainage weeks to months after surgery
Aggressive perioperative risk factor modification is as important as the surgery itself
Distinguish between claudication and rest pain in the assessment of PAD severity.
Common Mistakes:
Inadequate distal run-off assessment
Failure to adequately manage comorbidities preoperatively
Insufficient hemostasis at anastomosis sites
Inadequate postoperative anticoagulation and antiplatelet regimen
Underestimating the risk of graft infection and its devastating consequences.