Atlas of General Surgical Techniques (Courtney M. Townsend Jr., B. Mark Evers)

The left limb of the graft is routed through the lumen of the left common iliac artery, and the anastomosis is completed in a similar fashion as on the right.

After the aneurysmectomy is completed, hemostasis is secured and systemic heparin is reversed with protamine sulfate (1 mg/100 U heparin).

3. CLOSING

The aneurysm wall is closed over the graft with 0 Vicryl suture (Figure 82-9). To lessen the risk of an aortoduodenal fistula, omentum is placed adjacent to the anastomosis. The peritoneum is closed with absorbable suture, and the abdomen wall structures are reapproximated with a looped 1-0 running monofilament polydioxanone (PDS) or polypropylene suture.

Aneurysm wall closed over a

tube graft

Aneurysm wall closed over a bifurcated graft

A B

FIGURE 82–9

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STEP 4: POSTOPERATIVE CARE

Careful control of fluid volume and heart rate are essential. Swan-Ganz catheter monitoring to assess cardiac output and fluid volume status is a useful adjunct. These patients often require large volumes of fluid within the first 24 to 48 hours postoperatively. Sufficient pain medication should be administered. Beta blockade begun preoperatively should be continued throughout the postoperative period. Inotropic agents should be used to ensure adequate cardiac output. Careful monitoring for evidence of mesenteric ischemia is especially important in patients with ruptured aneurysms.

STEP 5: PEARLS AND PITFALLS

JUXTARENAL ANEURYSM

When the aneurysm involves the pararenal aorta, infrarenal clamping is unsafe. In this situation, supraceliac occlusion of the aorta and occlusion of the renal and superior mesentery arteries are necessary. The aorta and graft are appropriately beveled, and the patch of aorta with the visceral vessels is included in the repair. These maneuvers may require division of the left renal vein, which may be ligated or reapproximated at the completion of the aortic anastomosis.

HORSESHOE KIDNEY

A horseshoe kidney occurs in 1 in 600 to 1800 individuals. The lower pole is most often fused. Each half of the kidney is usually supplied by a single renal artery. Vascular anomalies are often present, and great care should be taken to preserve the aberrant vessels.

HYPOGASTRIC ANEURYSM

Although uncommon, hypogastric aneurysms usually occur deep inside the pelvis and are difficult to control with clamps. Endoluminal suture ligation of the orifice or preoperative coiling will control bleeding from the aneurysm.

AORTOCAVAL FISTULA

Rarely, an undiagnosed communication between the aneurysm and the vena cava is encountered. This should be suspected if venous blood is seen flowing into the aneurysm after the thrombus has been removed from the aneurysm sac. Finger or sponge stick control of the venous bleeding and endoaneurysm repair of the communication with pledgeted monofilament sutures will usually suffice.

INFLAMMATORY ANEURYSM

In approximately 5% of patients with abdominal aortic aneurysms, a dense fibrotic reaction involving the aortic wall and retroperitoneum is encountered. The inflammatory reaction may involve the duodenum, inferior vena cava, left renal vein, and ureters and is manifested as a thick white plaque overlying the aorta. Inflammatory aneurysm is an important cause of abdominal pain in patients with abdominal aortic aneurysms that must be distinguished from ruptured aneurysms on CT scans or MRI. These aneurysms are best repaired via the retroperitoneal approach mobilizing the aorta above the renal vein, taking care not to dissect the duodenum off the aneurysm wall. Venous anomalies such as left-sided or double inferior vena cava should be identified and preserved.

No attempt should be made to dissect the aorta or iliac arteries circumferentially to minimize the risk of venous bleeding.

Elective ligation and division of the left lumbar vein allows cephalad retraction of the renal vein, reduces the risk of bleeding, and improves exposure.

Large lymphatic vessels and the cisterna chyli are often present at the level of the renal vein and should be suture ligated to prevent the rare occurrence of chylous ascites.

Dissection of the left common iliac artery bifurcation should be undertaken by dividing the lateral peritoneal attachments of the descending colon, thus avoiding injury to the hypogastric nerves bilaterally. Routing the left limb of the graft through the lumen of the common iliac artery also minimizes the risk of this complication.

If the renal vein is not present in its usual anterior location, a retroaortic renal vein should be suspected and care taken in placing the proximal clamp.

Rectal bleeding in the early postoperative period should prompt careful sigmoidoscopy and prompt return to the operating room if significant ischemia is present or acidosis persists.

SELECTED REFERENCES

1. Standring S (ed): Gray’s Anatomy: The Anatomical Basis of Clinical Practice, 39th ed. Philadelphia, Churchill Livingstone, 2005.

2. Lederle FA, Johnson GR, Wilson SE, et al: Prevalence and associations of abdominal aortic aneurysm detected through screening. Ann Intern Med 1997;126:441-449.

3. Sicard GA, Reilly JM, Rubin BG, et al: Transabdominal versus retroperitoneal incision for abdominal aortic surgery: report of a prospective randomized trial. J Vasc Surg 1995;21:174-181.

C H A P T E R 83

AORTOFEMORAL BYPASS GRAFT

FOR OCCLUSIVE DISEASE

Charlie C. Cheng and Michael B. Silva, Jr.

STEP 1: SURGICAL ANATOMY

SURGICAL ANATOMY OF THE FEMORAL REGION

The inguinal ligament defines the transition from the external iliac to the common femoral artery. The common femoral artery and vein are encased in the femoral sheath in the proximal thigh bounded by the femoral triangle (Figure 83-1). The lateral boundary of this triangle is formed by the sartorius muscle, the medial boundary by the adductor longus muscle, and the cephalad base by the inguinal ligament.

Just proximal to the inguinal ligament, the external iliac artery has two branches: the inferior epigastric and the deep circumflex iliac arteries. Just distal to the inguinal ligament, the common femoral artery has three branches: the superficial epigastric, the superficial circumflex iliac, and the superficial external pudendal arteries.

The common femoral artery divides into the superficial and the deep femoral arteries as it crosses the pectineus muscle. The superficial femoral artery traverses the thigh between the quadriceps and adductor muscles in the adductor, or Hunter’s, canal. The origin of the deep femoral artery is 3 to 5 cm distal to the inguinal ligament. This artery is crossed by the lateral femoral circumflex vein (see Figure 83-1).

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SURGICAL ANATOMY OF THE ABDOMINAL AORTA

The abdominal aorta has three large, unpaired midline branches that supply most organs: the celiac, superior mesenteric, and inferior mesenteric arteries (Figure 83-2). The celiac and superior mesenteric arteries arise at the level of the first lumbar vertebra. The inferior mesenteric artery arises at the third lumbar vertebra.

The renal arteries arise at the level of the disc between the first two lumbar vertebrae from the lateral walls of the aorta (see Figure 83-2). The left-sided artery is usually slightly more cephalad than the right. The renal arteries lie posterior to the corresponding veins on each side. The left renal vein usually passes anterior to the aorta, whereas the right renal artery passes behind the inferior vena cava. A retroaortic left renal vein is a relatively common venous variant with an incidence of approximately 3%.

The left renal vein serves as a landmark for cephalad dissection of the abdominal aorta. Beneath this vein, the origins of the right and left renal arteries can be located.

STEP 2: PREOPERATIVE CONSIDERATIONS

Indications for aortobifemoral bypass are symptomatic atherosclerotic occlusive disease of the infrarenal aorta and both iliac systems, and peripheral atheromatous embolization (blue toe syndrome). Symptoms of occlusive disease include claudication, rest pain, and tissue loss. The presence of rest pain or tissue loss usually results from multilevel occlusive disease involving both the aortoiliac segment and the infrainguinal segment. Seventy-five percent to 80% of these patients can initially be managed with treatment of the inflow aortoiliac disease without treatment of the distal infrainguinal disease. This is usually adequate for patients with claudication or rest pain. However, in patients with tissue loss, the distal disease should also be treated to provide pulsatile flow to the foot. Embolization from atherosclerotic plaques in the aortoiliac system requires exclusion of the native aortoiliac arteries, even if the plaque lesions are not associated with hemodynamically significant stenoses.

Up to 50% of patients with aortoiliac disease may have clinically evident coronary artery disease. The 30-day operative mortality for this bypass has decreased from 5% to 8% in the early 1970s to 2% in the past decade as a result of improved preoperative management of coronary artery disease. Patients should routinely be evaluated preoperatively for the presence of coronary artery disease and pulmonary, renal, and coagulation disorders.

Preoperative imaging is needed in the evaluation of the entire abdominal aorta, the bilateral iliac arteries, and down to the origins of the deep femoral arteries. Arteriography has historically been the main imaging modality. Other contemporary alternatives include magnetic resonance imaging and computed tomography angiography. Complete bilateral lower extremity arteriography is also recommended.

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STEP 3: OPERATIVE STEPS

1.INCISION

The patient is placed supine, and the abdomen, groin, and thighs are prepared and draped. A narrow perineal towel is used, ensuring that it does not extend laterally to the groins. The perineum should remain excluded from the surgical field throughout the procedure. A povidone-iodine (Betadine)–impregnated self-adherent drape can be used to cover the abdomen, perineal towel, and groin areas to prevent the towel from becoming loose on the medial side of the femoral incisions.

The groins are opened through vertical incisions directly over the femoral pulse, crossing the inguinal crease to expose the femoral arteries (Figure 83-3). The incision is made with one third of the incision above the inguinal ligament, and two thirds below it. If femoral pulse is not palpable, the vertical incision is made slightly medial to the midpoint of the inguinal ligament.

The abdomen is opened through a full midline incision from the xiphoid process to the symphysis pubis. The peritoneal cavity is entered through the linea alba, and the abdominal aorta is exposed (see Figure 83-3). Alternatively, a retroperitoneal incision may be used. This may be the approach of choice in patients with a hostile abdomen from previous abdominal or aortic surgeries and poor pulmonary function. This incision is started from the lateral border of the rectus muscle, 2 cm below the level of the umbilicus, and is extended laterally to the tip of the 12th rib.

2.DISSECTION

Femoral artery exposure

The groin incisions are deepened and extended proximally to the inguinal ligament. The fascia lata is opened along the medial margin of the sartorius muscle to expose the femoral sheath underneath. This sheath is opened to access the common femoral artery, and the artery is easily dissected free by separating the areolar tissue.

The common femoral artery branches into the superficial and deep (profunda) femoral arteries. The superficial femoral artery is exposed by dissecting distally from the common femoral artery on its anterior surface. The deep femoral artery often originates 3 to 5 cm distal to the inguinal ligament on the posterior lateral surface of the common femoral artery. The lateral femoral circumflex vein crosses anteriorly to the deep femoral artery, and caution should be used during dissection of this artery to avoid venous injury (see Figure 83-1).

The femoral arteries are examined for atherosclerotic occlusive disease and their suitability for distal anastomosis. The common, superficial, and deep femoral arteries are each encircled with tapes or vessel loops for control.

Abdominal aorta exposure

Following the exploration of the abdomen for any incidental pathology, the transverse colon and the omentum are retracted upward toward the chest and protected from retraction injury. The small bowel is gathered and retracted to the patient’s right side and wrapped in a moist laparotomy towel.

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The peritoneum is opened over the upper part of the aorta, and the ligament of Treitz is divided to mobilize the fourth portion of the duodenum and the first part of the jejunum. The patency of the celiac axis and the superior and inferior mesenteric arteries are confirmed by palpation.

The aorta is exposed proximally to the left renal vein and distally to the inferior mesenteric artery using both sharp dissection and electrocautery of the small veins in the retroperitoneal tissue (Figure 83-4).

The aorta is dissected free using blunt finger dissection or a curved instrument just below the left renal vein. The left renal vein is usually anterior to the aorta but can occasionally be retroaortic. Failure to accurately identify the left renal vein may result in iatrogenic injury during aortic cross-clamping.

Aortofemoral bypass tunnel

The tunnel is used to connect the exposed aorta from the abdomen and the femoral arteries in the groins. It follows the course of the iliac and femoral arteries, lying anterior to the arteries and posterior to the ureter. This prevents compression of the ureter by the graft. The graft is protected in the retroperitoneal tissues.

Tunneling is started from the groin incision, with blunt finger dissection along the anterior surface of the common femoral artery. The inferior epigastric and deep circumflex iliac veins course anterior to the external iliac artery, and caution is used. These veins are routinely divided and ligated under direct vision to preclude inadvertent avulsion.

In the abdomen, tunneling is started on the anterior surface of the aortic bifurcation and continued onto the common iliac artery. The finger is passed blindly to meet with the finger advancing from the groin incision (Figure 83-5). The tunnel tract is maintained with passage of umbilical tape. The patient is systemically treated with anticoagulants, usually with unfractionated heparin, after the tunnel has been dissected and inspected for hemostasis.