Overview
Definition:
A pedal bypass to the dorsalis pedis artery is a surgical procedure aimed at re-establishing blood flow to the foot via the dorsalis pedis artery when it is occluded or severely stenotic
This is typically performed in patients with critical limb ischemia (CLI) who have insufficient inflow to the distal arteries of the leg for conventional bypasses.
Epidemiology:
CLI affects approximately 50-100 per 100,000 people annually, with peripheral arterial disease (PAD) being the underlying cause in most cases
Patients undergoing pedal bypass often have extensive infrainguinal disease, diabetes, and other comorbidities, making them high-risk surgical candidates.
Clinical Significance:
This procedure is crucial for limb salvage in patients with CLI who would otherwise face amputation
Successful revascularization can alleviate ischemic pain, promote wound healing, and improve the quality of life
It represents a complex challenge in vascular surgery, demanding meticulous technique and careful patient selection.
Indications
Absolute Indications:
Critical limb ischemia with a patent, reconstructible dorsalis pedis artery
Failure of or inability to perform more proximal revascularization
Rest pain, non-healing ulcers, or gangrene distal to the ankle.
Relative Indications:
Prophylactic revascularization in diabetic patients with severe PAD and high risk of ulceration
Pre-operative planning for foot/ankle surgery in patients with compromised perfusion.
Contraindications:
Unreconstructible dorsalis pedis artery (occluded, absent, or diseased)
Uncontrolled infection at the target site
Uncorrectable coagulopathy
Patient unfit for major surgery.
Patient Selection:
Thorough assessment of the distal arterial tree is paramount
This includes duplex ultrasound, angiography, and often computed tomography angiography (CTA) or magnetic resonance angiography (MRA) to delineate the anatomy of the tibial arteries and the dorsalis pedis.
Preoperative Preparation
Vascular Assessment:
Comprehensive duplex ultrasound to assess the patency and quality of the anterior tibial artery and dorsalis pedis
Angiography to map the infrainguinal and pedal vasculature, identifying targets and potential conduits
Ankle-brachial index (ABI) and toe-brachial index (TBI) for objective assessment.
Medical Optimization:
Management of comorbidities: diabetes control (HbA1c < 8%), hypertension, hyperlipidemia, and renal dysfunction
Smoking cessation counseling
Optimization of cardiac and pulmonary function
Antibiotic prophylaxis (e.g., cefazolin) initiated 1 hour prior to incision.
Anesthesia Considerations:
General anesthesia or regional anesthesia (spinal/epidural) are options
Careful fluid management is critical, especially in diabetic patients
Intraoperative monitoring includes ECG, invasive arterial pressure, oxygen saturation, and urine output.
Graft Selection:
Autologous reversed saphenous vein is the preferred conduit
If unavailable, alternative options include in-situ saphenous vein, cryopreserved allografts, or synthetic grafts (less ideal for distal bypass)
The graft length is determined by the distance to the chosen pedal artery target.
Procedure Steps
Harvesting Conduit:
Careful and meticulous harvesting of the saphenous vein, ensuring minimal trauma to the vessel
Ligation of all side branches
Preservation of vasa nervorum is important.
Proximal Anastomosis:
An anastomosis is typically made to the common femoral artery or the superficial femoral artery
The choice depends on the inflow and proximal disease
End-to-side anastomosis is preferred.
Tunneling:
Creation of a subcutaneous or subfascial tunnel from the proximal anastomosis site to the foot
The tunnel should be direct and avoid kinking of the graft
Careful dissection to protect adjacent nerves and veins.
Distal Anastomosis:
Identification and isolation of the dorsalis pedis artery on the dorsum of the foot
Often, the artery is exposed between the first and second metatarsals
An end-to-side anastomosis is meticulously performed using fine sutures (e.g., 6-0 or 7-0 polypropylene).
Graft Checks:
After completion of both anastomoses, the graft is flushed with heparinized saline
Patency is confirmed by palpation of pulses distal to the anastomosis, Doppler ultrasound, and visual inspection of distal perfusion
Weaning from cardiopulmonary bypass or clamping and unclamping of inflow vessel.
Postoperative Care
Immediate Monitoring:
Close monitoring of graft patency via clinical examination (presence of distal pulses, capillary refill) and Doppler ultrasound
Fluid management to maintain adequate perfusion pressure
Pain control with analgesics.
Wound Care:
Meticulous wound care to prevent infection
Dressings are typically kept intact for 24-48 hours
Foot elevation to reduce edema
Mobilization is initiated as tolerated, often with non-weight-bearing or protected weight-bearing restrictions initially.
Medical Management:
Antiplatelet therapy is critical for graft patency, usually starting with aspirin and clopidogrel (dual antiplatelet therapy) for at least 3-6 months, followed by lifelong aspirin
Anticoagulation (e.g., heparin) may be used perioperatively in high-risk cases.
Ambulatory Care:
Gradual increase in activity
Wound checks for signs of infection or dehiscence
Strict blood glucose control in diabetic patients
Regular follow-up appointments with vascular surgery.
Complications
Early Complications:
Graft occlusion (due to thrombosis, technical error, or spasm)
Bleeding from anastomosis sites
Wound infection
Distal embolization
Compartment syndrome of the foot
Graft limb ischemia.
Late Complications:
Graft stenosis or occlusion
Pseudoaneurysm formation at anastomosis
Vein graft disease
Distal graft failure leading to recurrence of ischemia
Chronic wound breakdown.
Prevention Strategies:
Meticulous surgical technique, proper graft handling, adequate heparinization during surgery, post-operative antiplatelet therapy, aggressive risk factor modification (diabetes, smoking), and regular surveillance with duplex ultrasound.
Prognosis
Factors Affecting Prognosis:
Quality of the distal target vessel
Patency of the graft
Absence of significant comorbidities
Patient compliance with medical management and follow-up
Presence of diabetes
Severity of pre-operative ischemia.
Outcomes:
Successful pedal bypass can lead to limb salvage rates of 70-85% at 1 year and 50-70% at 5 years
Amputation-free survival is a key outcome measure
Pain relief and ulcer healing are significant improvements in quality of life.
Follow Up:
Lifelong surveillance is recommended
Regular clinical assessment and duplex ultrasound examinations are crucial to detect early graft stenosis or occlusion
This allows for timely intervention and preserves limb viability
Patients should be educated on warning signs of graft failure.
Key Points
Exam Focus:
Indications for pedal bypass in CLI
Graft material of choice (reversed saphenous vein)
Key anastomotic sites
Importance of distal run-off
Role of antiplatelet therapy.
Clinical Pearls:
Meticulous vein graft preparation is paramount
Protect the graft from trauma
Ensure adequate inflow and outflow
Consider the arterial supply of the foot when selecting the target artery
Early recognition and treatment of graft dysfunction are vital.
Common Mistakes:
Inadequate assessment of pedal arch
Poor graft handling leading to intimal damage
Suboptimal distal anastomosis
Failure to adhere to post-operative medical management
Ignoring signs of graft failure.