Overview
Definition:
Open transperitoneal abdominal aortic aneurysm (AAA) repair is an open surgical procedure to replace a weakened, bulging segment of the abdominal aorta with a synthetic graft
The transperitoneal approach involves accessing the aorta through an incision in the abdominal wall, passing through the peritoneal cavity.
Epidemiology:
AAAs are most common in men over 65 years old, smokers, and individuals with a family history of aneurysms
The prevalence varies, with estimates ranging from 2-5% in men aged 65-75
Rupture is a catastrophic event with a high mortality rate, making timely repair crucial.
Clinical Significance:
AAA repair is a cornerstone of vascular surgery, aiming to prevent rupture, which is often fatal
Understanding the open approach is critical for surgical residents preparing for DNB and NEET SS examinations, as it forms the basis for comparison with endovascular techniques and is still performed in specific scenarios.
Indications
Indications For Repair:
Surgical repair is generally recommended for AAAs that are symptomatic (e.g., causing pain, rupture) or asymptomatic with a maximum diameter > 5.5 cm in men or > 5.0 cm in women
Rapid expansion rate (> 0.5 cm in 6 months or > 1 cm in 1 year) also warrants repair
Patients with infrarenal AAA amenable to open repair and a suitable surgical risk profile are candidates.
Contraindications:
Absolute contraindications are rare but include prohibitive surgical risk (e.g., severe comorbidities, poor life expectancy) and active systemic infection
Relative contraindications may include extensive hostile abdomen from previous surgeries, severe coagulopathy, or inability to tolerate major surgery.
Risk Assessment:
Preoperative risk assessment involves evaluating cardiovascular, pulmonary, renal, and hepatic function
Tools like the Revised Cardiac Risk Index and assessment of forced expiratory volume in 1 second (FEV1) are important
Multidisciplinary discussion, including anesthesia and cardiology, is often beneficial.
Preoperative Preparation
Imaging:
A contrast-enhanced computed tomography angiography (CTA) is essential for detailed anatomical assessment, including aneurysm diameter, length, neck below renal arteries, iliac artery anatomy, and presence of calcification or thrombus
Duplex ultrasound may be used for initial screening and follow-up but is insufficient for surgical planning.
Medical Optimization:
Optimization of comorbidities is crucial
This includes management of hypertension, diabetes, and cardiac or pulmonary issues
Smoking cessation is strongly advised
A thorough review of medications, especially anticoagulants and antiplatelets, is necessary.
Anesthesia Considerations:
General anesthesia is typically employed
Hemodynamic monitoring is essential, including arterial line and central venous pressure monitoring
Fluid management and blood product readiness are paramount due to potential for significant blood loss.
Procedure Steps
Surgical Approach:
A midline or paramedian laparotomy incision is made to gain access to the retroperitoneum
The abdominal contents are retracted to expose the aorta proximal and distal to the aneurysm
Careful dissection is required to identify and preserve visceral and renal arteries.
Aortic Control:
Proximal control is achieved by clamping the infrarenal aorta
Distal control is obtained by clamping the iliac arteries
This isolates the aneurysm sac
Adequate lengths of healthy aorta and iliac arteries are essential for graft anastomosis.
Graft Implantation:
The aneurysm sac is opened longitudinally, and thrombus and atheromatous debris are removed
The synthetic graft (typically Dacron or PTFE) is then sutured to the infrarenal aorta proximally and to the iliac or common femoral arteries distally using appropriate suture material (e.g., polypropylene).
Completion Angiography:
After declamping, meticulous inspection for hemostasis is performed
A completion angiogram may be performed to assess the patency of the graft and distal vasculature and to identify any leaks or technical issues
The abdomen is then closed.
Postoperative Care
Intensive Care Monitoring:
Patients are typically admitted to an intensive care unit (ICU) for close monitoring of hemodynamics, urine output, respiratory status, and potential complications
Invasive monitoring lines are usually maintained.
Pain Management:
Effective pain control is essential using a multimodal approach, including intravenous analgesics, patient-controlled analgesia (PCA), and epidural anesthesia if appropriate
Early mobilization is encouraged.
Fluid And Hemodynamic Management:
Strict fluid balance and hemodynamic monitoring are crucial to prevent hypovolemia or fluid overload
Management of blood pressure is key to prevent graft stress or leakage.
Gastrointestinal Recovery:
Nasogastric tube decompression may be necessary postoperatively
Gradual reintroduction of oral intake as bowel function returns is important
Monitoring for signs of ileus or other gastrointestinal complications is vital.
Complications
Early Complications:
Early complications include bleeding from suture lines, graft infection, myocardial infarction, stroke, renal failure, bowel ischemia, pancreatitis, and pneumonia
Graft occlusion or thrombosis can occur
Acute limb ischemia can result from distal embolization.
Late Complications:
Late complications include graft infection, pseudoaneurysm formation at suture lines, aortoenteric fistula or enteric erosion, graft occlusion, and distal embolization
Incisional hernia is also a common late complication.
Prevention Strategies:
Meticulous surgical technique, meticulous hemostasis, prophylactic antibiotics (given preoperatively and continued postoperatively), careful graft handling, and vigilant postoperative monitoring are key to preventing complications
Selection of appropriate graft material and size is also important.
Prognosis
Factors Affecting Prognosis:
Prognosis is significantly influenced by whether the aneurysm ruptures before repair
Operative mortality for elective repair is generally low (around 1-5%), but increases substantially for ruptured aneurysms (up to 50-80%)
Patient comorbidities, age, and graft-related complications also impact long-term outcomes.
Outcomes:
Successful elective open AAA repair leads to durable prevention of rupture and can significantly improve long-term survival compared to untreated aneurysms
Long-term patency rates for infrarenal grafts are generally high.
Follow Up:
Regular lifelong surveillance is recommended to monitor for graft complications and potential new aneurysms
This typically involves duplex ultrasound and/or CTA at intervals determined by the surgeon and the presence of any postoperative issues
Annual follow-up is common for asymptomatic patients.
Key Points
Exam Focus:
Understand the indications for open vs
endovascular repair
Know the critical anatomical landmarks for aortic and iliac control
Be aware of the key steps of graft implantation and suture techniques
Remember common and life-threatening complications.
Clinical Pearls:
Adequate proximal and distal neck lengths are crucial for graft sealing
Careful preservation of the hypogastric and visceral arteries is important, especially when considering bifurcated grafts or preserving one hypogastric artery in cases of aortoiliac aneurysms
Judicious use of aortic clamps minimizes ischemic time.
Common Mistakes:
Inadequate proximal neck length for clamp placement, insufficient distal landing zones, failure to identify and preserve critical visceral or hypogastric arteries, inadequate hemostasis leading to postoperative bleeding, and insufficient graft oversizing or undersizing
Underestimation of operative risk is also a significant pitfall.