Overview
Definition:
Open exposure of the infrarenal aorta involves surgically accessing the abdominal aorta below the level of the renal arteries
This is a crucial step in various vascular surgical procedures, most commonly for the repair of abdominal aortic aneurysms (AAAs) and occasionally for occlusive disease or trauma requiring aortic control.
Epidemiology:
Abdominal aortic aneurysms are prevalent, particularly in older men with risk factors like hypertension, smoking, and atherosclerosis
The incidence of symptomatic AAAs requiring emergent repair is lower but carries high mortality
Open repair is performed in selected cases, often influenced by patient anatomy, surgeon preference, and availability of endovascular options.
Clinical Significance:
Adequate exposure of the infrarenal aorta is paramount for achieving proximal control of hemorrhage and for facilitating safe anastomosis during aortic repair
Complications arising from inadequate exposure or control can be catastrophic, including uncontrolled bleeding, injury to surrounding structures, and systemic hypotension
Proficiency in this technique is therefore a cornerstone of vascular surgical training.
Indications
Primary Indications:
Repair of infrarenal abdominal aortic aneurysms (AAAs) when endovascular repair is not feasible or contraindicated
Management of ruptured AAAs requiring emergent surgical control
Treatment of aortoiliac occlusive disease where open bypass is indicated
Repair of aortoenteric fistulas or prosthetic graft infections.
Relative Indications:
Exposure for aortic clamping in complex abdominal surgeries with high bleeding risk
Certain cases of traumatic aortic injury in the infrarenal segment
Rare congenital abnormalities of the aorta.
Contraindications:
Patient factors precluding major surgery (e.g., severe comorbidities, poor anesthetic risk)
Presence of favorable anatomy for endovascular repair in elective AAA cases
Active infection at the surgical site may necessitate delaying elective repair.
Preoperative Preparation
Patient Assessment:
Comprehensive cardiovascular, pulmonary, and renal assessment
Risk stratification using scoring systems like ASA
Detailed review of imaging studies (CTA, ultrasound) to delineate aneurysm anatomy, involvement of visceral arteries, and iliac vessels.
Imaging Review:
Thorough evaluation of aneurysm diameter, neck length and angulation, thrombus burden, and involvement of renal and visceral arteries
Assessment of iliac artery anatomy for suitability of distal anastomoses.
Anesthesia Considerations:
General anesthesia is typically required
Invasive hemodynamic monitoring (arterial line, central venous catheter) is essential
Anesthetic agents and fluid management should aim to maintain adequate organ perfusion and minimize blood loss.
Surgical Planning:
Selection of appropriate graft material and size
Planning for potential intraoperative complications such as bleeding or unexpected anatomy
Preoperative antibiotics are crucial to reduce the risk of graft infection.
Procedure Steps
Incision:
A midline laparotomy is the most common incision, extending from the xiphoid process to the pubis
Alternatively, a supra-umbilical incision may be used if visceral artery involvement is suspected, or a left flank approach for specific situations.
Aortic Dissection:
The peritoneum is opened, and the small bowel is mobilized superiorly and laterally to expose the retroperitoneum
Dissection proceeds along the anterior and lateral aspects of the aorta
Care must be taken to identify and preserve the left renal vein, which often crosses anterior to the aorta and may need to be retracted or divided.
Proximal Control:
The aorta is dissected proximally to identify the origin of the renal arteries
Identification and ligation of the left renal vein if necessary
Careful blunt and sharp dissection is used to free the aorta from surrounding structures, including lymph nodes and lymphatic tissue
Exposure of the aorta just distal to the superior mesenteric artery origin (if necessary) and just distal to the renal arteries is achieved.
Distal Control:
The aorta is further dissected distally into the bifurcation and extending into the iliac arteries as needed for adequate anastomosis
The bifurcation and distal aorta are freed from surrounding tissues, and appropriate-sized vascular tapes are passed around the aorta for temporary occlusion.
Aneurysm Repair Or Bypass:
Once adequate proximal and distal control is achieved, the aneurysm sac is opened longitudinally, and thrombus is evacuated
The graft is then anastomosed to the healthy aorta proximally and to the iliac or femoral arteries distally
In cases of occlusive disease, bypass grafts are sutured to the infrarenal aorta and the distal iliac or femoral arteries.
Postoperative Care
Icu Monitoring:
Close monitoring of hemodynamics, urine output, and oxygenation in the intensive care unit
Management of pain and fluid balance is critical
Regular abdominal examinations to assess for distension or signs of ischemia.
Hemodynamic Management:
Maintenance of adequate blood pressure and perfusion is essential to prevent graft thrombosis and organ dysfunction
Vasopressors or inotropes may be required
Blood loss replacement and vigilant hematocrit monitoring.
Renal Function:
Monitoring of serum creatinine and electrolytes
Adequate hydration is crucial to maintain renal perfusion
Avoidance of nephrotoxic agents
Early recognition and management of acute kidney injury.
Graft Surveillance:
Postoperative imaging (ultrasound, CTA) to assess graft patency and exclude endoleaks (in endovascular repairs, but relevant for complications in open repairs like pseudoaneurysm)
Long-term surveillance may be required for open repairs, especially concerning for infection or anastomotic issues.
Complications
Early Complications:
Hemorrhage from the aorta or graft
Injury to adjacent structures (e.g., vena cava, ureter, bowel)
Myocardial infarction or stroke
Acute kidney injury
Graft infection
Aortic stump blowout
Reperfusion injury.
Late Complications:
Graft occlusion or stenosis
Pseudoaneurysm formation at the anastomosis
Graft infection
Aortoenteric fistula
Incisional hernia
Chronic mesenteric ischemia
Spinal cord ischemia (rare with infrarenal exposure).
Prevention Strategies:
Meticulous surgical technique, careful dissection to avoid injury to adjacent structures
Adequate proximal and distal control
Appropriate graft selection and secure anastomoses
Prophylactic antibiotics
Meticulous hemostasis
Careful perioperative fluid management and hemodynamic support
Judicious use of intraoperative imaging if available.
Key Points
Exam Focus:
Understanding the surgical anatomy of the retroperitoneum
Key steps for achieving proximal and distal control of the infrarenal aorta
Common indications and contraindications for open repair of AAA
Differentiating between early and late complications.
Clinical Pearls:
The left renal vein is a critical landmark
be prepared to mobilize or, rarely, ligate it
Maintain meticulous hemostasis throughout the dissection
Always confirm proximal and distal control with vascular tapes before opening the aneurysm
Consider the impact of aortic clamping on systemic hemodynamics.
Common Mistakes:
Inadequate exposure leading to difficulty in achieving control
Injury to the left renal vein or other adjacent structures
Failure to adequately assess iliac artery anatomy for distal anastomosis
Insufficient hemostasis leading to postoperative bleeding
Not suspecting or managing graft infection promptly.