Retroperitoneal Approach for Elective Abdominal Aortic Aneurysmectomy



Retroperitoneal Approach for Elective Abdominal Aortic Aneurysmectomy



Philip S.K. Paty and R. Clement Darling, III


The abdominal aorta, located posterior to the parietal peritoneum and adjacent to the spine, is by definition a retroperitoneal structure. The ease of aortic exposure from the supradiaphragmatic level to the iliac bifurcation makes a retroperitoneal approach an ideal option for both routine and complex aortic reconstruction. Techniques and appropriate indications vary for left-sided and right-sided retroperitoneal approaches in treating abdominal aortic aneurysms (AAA).



Indications and Contraindications


A traditional retroperitoneal exposure is the preferred approach to an AAA repair in the hostile abdomen, which includes patients with prior intraabdominal surgery resulting in adhesions, the presence of stomas, peritoneal dialysis, reoperative aortic surgery, prior abdominopelvic radiation treatment, inflammatory aneurysm, and morbid obesity. Relative contraindications to the retroperitoneal approach include limited exposure of the right renal and iliac arteries as well as the inability to fully examine the intraabdominal cavity for additional pathology at the time of surgical intervention. Most recently, this approach has been used for complex aortic reconstructions owing to the excellent exposure of the suprarenal and infradiaphragmatic aorta. It is also useful when treating pararenal aortic aneurysms as well as explanting failed endografts.



Surgical Techniques


Left Posterolateral Retroperitoneal Approach


After the induction of general anesthesia, the patient is placed on a suction bean bag (Olympic Vac Pac, Marlin Medical, Victoria, Australia) in a modified right lateral decubitus position. The patient is positioned with the table break 5 to 10 cm cephalad to the left iliac crest (Figure 1). The patient’s torso is elevated 45 to 60 degrees from the horizontal position, and the pelvis is rotated 15 to 30 degrees to allow access to both groins. The left upper extremity is brought across the chest and supported by blankets or a stand. The left thigh is elevated above the horizontal plane by means of blankets or an additional suction beanbag to relax the ipsilateral iliopsoas muscle and improve access to the distal aorta and left iliac arteries. To open the space between the iliac crest and the costal margin, the table is flexed 20 to 30 degrees in a reverse V position at the table break.


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FIGURE 1 Placement of the patient in right lateral decubitus position.



Exposure


The muscle layers of the lateral abdominal wall are divided to the lateral border of the rectus abdominis. This includes the external oblique, internal oblique, transversus abdominis, and transversalis fascia, respectively. The transversus abdominis is initially divided laterally and then medially to separate the peritoneum, which is usually thicker and more discrete laterally, from the underlying muscle. The intercostal muscles are divided on the superior margin of the underlying rib.


The retroperitoneal space is entered posterolaterally to avoid tearing the parietal peritoneum (Figure 2). The posterior peritoneum, posterior layers of Gerota’s fascia, and the left kidney are retracted anteriomedially and cephalad to expose the left psoas muscle and periaortic tissue. The fascia remains intact on the psoas, which minimizes dissection-related injury of the genitofemoral nerve and bleeding from the iliopsoas muscle. Exposure is maintained with a self-retaining retractor. Care must be taken to avoid vigorous retraction of the anterior and cephalad margin of the incision because this can result in injury to the spleen or kidney.


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FIGURE 2 Intended path in the retroperitoneal dissection to the aorta (dotted line).

Distal arterial control is obtained first to prevent embolization. If there is extensive right iliac artery disease, then a right suprainguinal counterincision is made to obtain extraperitoneal exposure of these vessels. Right iliac artery control can also be obtained with a balloon occlusion catheter at the time the aneurysm sac is incised. Alternatively, vertical groin incisions can be made to access the femoral vessels for distal arterial control.


After systemic anticoagulation with heparin, the outflow is occluded and the neck of the aneurysm is approached posterolaterally (Figure 3). The landmarks for the infrarenal neck of the aortic aneurysm are the origin of the left crus of the diaphragm, the lumbar branch of the left renal vein, and the left renal artery (Figure 4). The lumbar branch of the left renal vein, which crosses the aorta in a posterior and perpendicular fashion and caudad to the renal artery, is ligated and divided. The lymphareolar tissue is dissected to expose the proximal infrarenal aorta. The left lateral side of the aorta is dissected, followed by anterior and then posterior dissection of the aorta from the surrounding tissues.


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FIGURE 3 The aorta is approached posterolaterally.

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FIGURE 4 Lumbar branch of left renal vein and left renal artery as landmarks.

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Aug 25, 2016 | Posted by in CARDIOLOGY | Comments Off on Retroperitoneal Approach for Elective Abdominal Aortic Aneurysmectomy

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