Overview
Definition:
STSG (Superficial Temporal Artery to Superficial Gastric Artery) flap, or more commonly, superficial temporal artery (STA) to superficial temporal vein (STV) or other venous pedicle flaps, are used in head and neck reconstruction
Failure of such a microvascular free flap refers to the partial or complete loss of flap viability due to inadequate perfusion or venous congestion
Salvage strategies aim to restore perfusion and prevent total flap loss.
Epidemiology:
The incidence of microvascular free flap failure varies widely, reported between 1-15%, with STSG flap failure rates also falling within this spectrum
Factors influencing failure include patient comorbidities, surgeon experience, recipient vessel quality, and postoperative care
Early identification of failure is crucial for salvage.
Clinical Significance:
STSG flap failure represents a significant complication, leading to delayed reconstruction, increased morbidity, potential for disfigurement, and loss of function in head and neck defects
Prompt and effective salvage strategies are paramount to optimizing patient outcomes and avoiding re-operation with potentially compromised recipient sites.
Clinical Presentation
Symptoms:
Increasing flap pain or discomfort
Petechiae or ecchymosis on the flap surface
Fluctuating flap color (from dusky to pale)
Diminished or absent capillary refill
Complete lack of Doppler signal within the flap pedicle
Serosanguinous or hemorrhagic drainage from the wound site.
Signs:
Flap skin becomes dusky, mottled, or cyanotic
Loss of flap turgor and elasticity
Swelling of the flap
Absence of palpable pulse in the pedicle
Doppler signal changes from pulsatile to weak or absent
Signs of superficial thrombophlebitis along the pedicle course
Proximity to complete flap necrosis with dry, leathery eschar.
Diagnostic Criteria:
No specific diagnostic criteria, but failure is usually evident clinically
Objective confirmation can be obtained via intraoperative exploration, duplex ultrasound showing absent flow, or even flap angiography in select cases
A high index of suspicion based on visual and palpable changes is key.
Diagnostic Approach
History Taking:
Review of operative notes for details of pedicle dissection, anastomosis technique, and intraoperative assessment
Patient's risk factors (smoking, diabetes, hypertension, previous radiation)
Postoperative pain, color changes, or drainage
Recent trauma or infection in the flap area.
Physical Examination:
Close and serial inspection of flap color, temperature, and turgor
Palpation for capillary refill and firmness
Assessment of Doppler signal over the flap and pedicle
Examination of the recipient site for signs of infection or congestion.
Investigations:
Handheld Doppler ultrasound for immediate assessment of pedicle flow
Intraoperative exploration and revision of anastomosis if indicated
Angiography (CT or conventional) to assess patency of recipient vessels and flap perfusion
Meticulous examination of the flap itself for signs of ischemia.
Differential Diagnosis:
Early venous congestion without arterial compromise
Superficial skin necrosis from friction or pressure
Infection of the flap or surrounding tissues
Early partial flap failure due to venous outflow obstruction
Hematoma formation beneath the flap.
Salvage Strategies
Initial Management:
Immediate return to the operating room for flap exploration is the cornerstone of salvage
Avoid delays
time is critical for flap survival
Maintain meticulous sterility and handle the flap gently.
Surgical Management:
Exploration of the pedicle and anastomosis: Check for kinking, tension, or extrinsic compression
Release any obstructing sutures
Assess and revise arterial anastomosis if thrombosed, inadequate, or kinked
Assess and revise venous anastomosis if thrombosed, kinked, or demonstrating poor outflow
consider venous super-microsurgery if necessary
Consider adding a venous graft to improve outflow
If arterial inflow is compromised due to recipient vessel disease, consider revising to an alternative recipient artery if available
If flap is salvaged, meticulously check perfusion with Doppler before closure.
Medical Management:
Administer heparin (e.g., 1000 U/hr infusion) postoperatively to maintain patency, especially after revision
Aspirin (e.g., 81-325 mg daily) can also be considered
Systemic vasodilators are generally not effective for arterial thrombosis but may be used cautiously if vasospasm is suspected
Antibiotics should be administered if infection is suspected or prophylaxis post-exploration.
Supportive Care:
Strict bed rest with the limb elevated to optimize venous return
Avoid external pressure on the flap
Close monitoring of flap viability (color, temperature, Doppler) hourly for the first 24-48 hours, then as per institutional protocol
Meticulous wound care and dressing changes
Adequate pain management and nutritional support.
Complications
Early Complications:
Complete flap necrosis requiring complete debridement and re-reconstruction
Partial flap necrosis
Infection of the flap or recipient site
Hematoma or seroma formation
Anastomotic leak.
Late Complications:
Scarring and alopecia at the recipient site and flap area
Potential for donor site morbidity recurrence
Aesthetic deformities
Functional deficits if reconstruction is incomplete or fails
Recurrence of defect if flap cannot be salvaged.
Prevention Strategies:
Meticulous microsurgical technique, including adequate flap elevation, pedicle length, and vessel preparation
Careful recipient vessel selection and preparation
Avoidance of tension on the anastomosis
Use of anticoagulation/antiplatelet agents judiciously based on risk factors
Robust postoperative monitoring protocol
Patient education on early signs of flap compromise.
Prognosis
Factors Affecting Prognosis:
Timeliness of presentation and intervention
Reversibility of the cause of failure (e.g., thrombosis vs
arterial insufficiency)
Quality of remaining recipient vessels
Surgeon's experience in microsurgical salvage
Patient's overall health status and comorbidities.
Outcomes:
Successful salvage of an STSG flap can lead to successful reconstruction, but outcomes are often less predictable than primary success
Partial flap survival may require secondary procedures
Complete failure necessitates a different reconstructive approach, often with more challenging recipient sites or donor options
The goal is to restore defect coverage and function, albeit with potential compromises.
Follow Up:
Close follow-up is essential for at least 6-12 months post-salvage
This includes serial physical examinations and Doppler assessments to ensure sustained flap viability
Long-term monitoring for any signs of recurrence or late complications.
Key Points
Exam Focus:
Recognize clinical signs of flap compromise early
The primary salvage strategy for STSG flap failure is immediate re-exploration and revision of the anastomosis
Differentiate arterial vs
venous compromise based on flap appearance and Doppler findings
Management involves both surgical revision and perioperative medical support.
Clinical Pearls:
Never hesitate to explore a compromised flap
delay is the enemy
If revising a venous anastomosis, consider the use of fibrin glue to improve seal
Always have a backup plan for recipient vessels or flap viability if salvage attempts are unsuccessful
Document all findings and interventions meticulously
Postoperative heparin infusion is often used in salvage to maintain patency.
Common Mistakes:
Delaying exploration due to false reassurance from intermittent Doppler signals
Inadequate pedicle dissection or insufficient length of the anastomosed vessels
Failing to identify and address extrinsic compression or tension on the anastomosis
Over-reliance on medical management without surgical intervention for mechanical issues
Neglecting meticulous postoperative monitoring.