Townsend Courtney M.Jr., Evers B. Mark. Atlas of General Surgical Techniques: Expert Consult

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CHAPTER 82 • Resection of Abdominal Aortic Aneurysm 881

STEP 2: PREOPERATIVE CONSIDERATIONS

◆ A search for thoracic and iliac aneurysms and other associated anomalies, such as suprare-

nal extension, venous anomalies, horseshoe kidney, or aortocaval ﬁ stula, with computed

tomography (CT) scanning, magnetic resonance imaging (MRI), or duplex ultrasound imag-

ing should be made before repair of an abdominal aortic aneurysm. Assessment of cardiac,

respiratory, and renal function should be undertaken and any abnormalities optimized

before proceeding with aneurysm repair. A mechanical bowel preparation the night before

surgery facilitates the operation. Prophylactic antibiotics are administered 1 hour before the

incision.

Abdominal

aorta

Inferior vena

cava

Right kidney

Celiac trunk

Left renal artery

Left renal vein

Inferior mesenteric

artery

Left kidney

Superior

mesenteric

artery

FIGURE 82 –1

882 Section XII • Vascular

STEP 3: OPERATIVE STEPS

1. INCISION

◆ For elective aneurysm repair, the operative ﬁ eld is prepped from the nipples to the knees

after induction of general anesthesia and placement of central venous and arterial monitoring

lines. In the setting of a ruptured abdominal aortic aneurysm, the chest, abdomen, and

groins should be prepared and draped before the induction of general anesthesia. Additional

large-bore catheters are inserted peripherally and centrally, with the latter connected to a

rapid infusion device capable of delivering large volumes of blood and blood products.

◆ Aortic aneurysm repair can be undertaken using either a transperitoneal or a retroperitoneal

approach. With the transperitoneal approach, the patient is positioned supine on the oper-

ating table and in the right lateral decubitus position for retroperitoneal exposure of the

aorta (Figure 82-2).

◆ A midline incision extending from the xiphoid process to the pubic symphysis or a transverse

incision extending from ﬂ ank to ﬂ ank above or below the umbilicus provides excellent expo-

sure of the entire intra-abdominal aorta.

◆ The retroperitoneal exposure is particularly helpful in patients with inﬂ ammatory aneurysms,

horseshoe kidney, ostomies, or hostile abdomens. Although this approach allows exposure of

the suprarenal aorta, exposure of the right iliac vessels may be limited and a counterincision

required.

◆ The patient is placed in the right lateral decubitus position over a kidney rest, with the hips

allowed to rotate to the supine position after induction of anesthesia and placement of

monitoring lines.

◆ An oblique incision extending from the lateral border of the rectus sheath 2 cm below the

umbilicus over the tip of the 12th rib is made. Dissection is continued through the external

oblique, internal oblique, and transverse abdominis muscles. The retroperitoneal space is

entered by incising the most lateral aspect of the posterior rectus sheath. Dissection is con-

tinued toward the midline anterior or posterior to the left kidney. The retroperitoneal struc-

tures are retracted to the right of the midline, and repair of the aneurysm is undertaken in

the usual fashion.

CHAPTER 82 • Resection of Abdominal Aortic Aneurysm 883

Transverse

incision

Oblique incision

for retroperitoneal

exposure

Midline

incision

FIGURE 82 –2

884 Section XII • Vascular

2. DISSECTION

◆ The abdomen is explored to determine the presence of any other pathology.

◆ The transverse colon and mesocolon are then lifted cephalad, and the small intestine is

moved to the right side of the abdomen. The peritoneum over the aneurysm is incised from

the level of the left renal vein into the pelvis, a self-retaining retractor such as the Omni-

Tract retractor is placed, and the small bowel returned into the abdomen (Figure 82-3).

◆ Proximal control must be immediately obtained if the aneurysm is ruptured. This is best

achieved by dividing the triangular ligament and retracting the left lobe of the liver cepha-

lad and to the right. The lesser omentum is entered near the level of the esophagogastric

junction. The aorta is palpated through the ﬁ bers of the diaphragm, and the median arcuate

ligament is divided. The ﬁ bers of the diaphragm are bluntly separated, a large angled aortic

clamp is maneuvered into position, and the aorta is occluded. It is unnecessary to dissect

and encircle the aorta before clamping. Once the bleeding is controlled, the dissection can

proceed as for elective aneurysm repair.

Ligament of Treitz

Inferior

mesenteric vein

Inferior

mesenteric artery

Peritoneal incision

FIGURE 82 –3

CHAPTER 82 • Resection of Abdominal Aortic Aneurysm 885

Thrombus

Left renal vein

FIGURE 82 –4

◆ The aorta is dissected between the aneurysm and the renal arteries; in 5% to 10% of patients,

the suprarenal or pararenal aorta is involved. The surgeon should avoid injury to the left renal

vein, which may be ﬂ attened over the proximal end of the aneurysm. Care should be taken to

avoid injury to the iliac veins, which may be closely adherent to the arteriosclerotic arterial

wall. This is best avoided by dissecting only the anterior and lateral surfaces of the common

iliac arteries close to the arterial wall.

◆ The anterior and lateral surfaces of the aneurysm are more completely freed of overlying tis-

sue, care being taken not to interrupt the collateral arterial supply to the descending and

sigmoid colon as it descends in the arcade on the left side of the aneurysm. After the sys-

temic administration of heparin (100 U/kg) and mannitol (12.5 to 25 g), the aorta and iliac

vessels are occluded with vascular clamps. The clamps are placed on the iliac vessels ﬁ rst

and then on the aorta to minimize the risk of distal embolization. When the aorta and iliac

arteries are heavily calciﬁ ed, occlusion of the aorta at the diaphragmatic hiatus and balloon

catheter occlusion of the iliac arteries may be necessary. The anterior wall of the aneurysm

is incised with a no. 11 blade or electrocautery, and the arteriotomy is continued to the

right of the origin of the inferior mesenteric artery to avoid injury to the hypogastric auto-

nomic plexus on the left (Figure 82-4).

886 Section XII • Vascular

◆ The laminated thrombus and the atherosclerotic debris are removed from within the

aneurysmal sac, often by a sweep of the ﬁ nger. Only adventitia and some media remain

(Figure 82-5).

◆ Back-bleeding from lumbar and median sacral artery oriﬁ ces is controlled with mattress

sutures of 2-0 silk placed from within the opened aneurysm. Assessment of inferior mesen-

teric artery (IMA) backﬂ ow is then undertaken. If a large oriﬁ ce with pulsatile back-bleeding

is present, the vessel is ligated from within the aneurysm. If a large oriﬁ ce with minimal

back-bleeding is encountered, consideration should be given to reimplantation of the IMA

(Figure 82-6).

◆ The aneurysm wall is cut transversely just distal to its beginning, except for the posterior

third of the circumference if the neck is small. There is no objection to complete transection

of the aorta unless the posterior aortic tissues are thin and friable, in which case it is helpful

to have the retroaortic prevertebral fascia to aid in securing the posterior sutures. In most

cases, the proximal anastomosis can be constructed using the Creech technique, in which

the wall of the aneurysm is used to reinforce the suture line. A prosthetic graft of suitable

diameter is selected, and the body of the graft is shortened to approximately 5 cm if a bifur-

cated graft is to be used. (The aortic portion of the graft is equal, under tension, to the

length of the aortic aneurysm.) The iliac limbs of the graft are left long and appropriately

trimmed just before completion of each anastomosis.

Ligated inferior

mesenteric artery

from within

Ligated lumbar

arteries

FIGURE 82 –6

After Teoli

Laminated

thrombus

FIGURE 82 –5

CHAPTER 82 • Resection of Abdominal Aortic Aneurysm 887

Inferior vena

cava

Left renal vein

Construction of

proximal anastomosis

using Creech

technique

Aortic bifurcation

Completing distal

anastomosis

FIGURE 82 –7

◆ Suturing the graft to the aorta is begun by passing the suture ﬁ rst through the graft and

then through the aorta. Generous deep bites are taken through the aortic tissue to ensure a

strong, blood-tight anastomosis. Several suturing techniques may be used. In this instance,

a single 3-0 monoﬁ lament arterial suture is begun laterally at approximately the 3 o’clock

position, sewing the posterior wall and continuing each end of the suture laterally and ante-

riorly where it is tied. Care must be taken to ensure that the suture is pulled tight before it

is tied (Figure 82-7, A).

◆ The graft should lie within the aortic lumen to allow better hemostasis and to prevent dis-

section beneath an atherosclerotic plaque at the suture line.

◆ The integrity of the aortic anastomosis is assessed by temporarily releasing the aortic clamp

while the graft is occluded digitally or with a shod clamp. This is the time to be certain that

the posterior suture line is secure, because it is difﬁ cult to expose this area later in the oper-

ation. A shod clamp is placed across the aortic tube graft or each limb of a bifurcated graft.

◆ Liquid blood, clots, and loose debris are aspirated from within the graft before proceeding

with the distal aortic or iliac anastomosis. When a tube graft is used, the aorta above the

bifurcation is partially divided transversely, leaving the posterior wall intact. The anastomo-

sis is constructed using 3-0 polypropylene suture beginning at approximately the 3 o’clock

position, taking deep bites of the posterior wall. Before placement of the ﬁ nal sutures, the

graft and iliac arteries are ﬂ ushed and the anastomosis completed (Figure 82-7, B).

888 Section XII • Vascular

◆ When the distal anastomosis is to the iliac arteries, each iliac bifurcation is dissected, isolat-

ing the external and internal iliac arteries. The common iliac artery is divided 1 cm proximal

to its bifurcation. If the common iliac artery is aneurysmal or otherwise unsuitable for anas-

tomosis, the common iliac artery is oversewn or stapled and the external iliac or femoral ar-

teries used for the distal anastomosis. The external iliac artery is allowed to back-bleed to en-

sure the absence of clot or debris and then ﬂ ushed with heparinized saline. The limbs of the

bifurcated graft are routed within the aneurysm bed to the iliac arteries.

◆ The proximal clamp on the right limb is removed with the distal end occluded digitally to

assess the appropriate length of the graft so that it is long enough to allow for a tension-free

anastomosis but not so long that kinking occurs.

◆ The distal anastomosis on the right is constructed ﬁ rst with a running 4-0 polypropylene

suture. Before ﬂ ow is reestablished, the iliac arteries are allowed to back-bleed, the iliac

limb of the graft is ﬂ ushed, and the remaining sutures are placed (Figure 82-8).

◆ The order of clamp removal is important in preventing of air or atheromatous debris material

from passing into the legs. The clamps on the right internal iliac artery, the right limb of the

graft, and the external iliac artery are removed in sequence and ﬂ ow is reestablished.

Inferior vena

cava

Left renal

vein

Aortic aneurysm

Iliac aneurysms

Completed aortoiliac

bypass

Aortic wall

FIGURE 82 –8

CHAPTER 82 • Resection of Abdominal Aortic Aneurysm 889

◆ 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 ﬁ stula, omentum is placed adjacent to the anastomosis. The perito-

neum is closed with absorbable suture, and the abdomen wall structures are reapproximated

with a looped 1-0 running monoﬁ lament polydioxanone (PDS) or polypropylene suture.

Aneurysm wall

closed over a

tube graft

Aneurysm wall

closed over a

bifurcated graft

FIGURE 82 –9

890 Section XII • Vascular

STEP 4: POSTOPERATIVE CARE

◆ Careful control of ﬂ uid volume and heart rate are essential. Swan-Ganz catheter monitoring

to assess cardiac output and ﬂ uid volume status is a useful adjunct. These patients often

require large volumes of ﬂ uid within the ﬁ rst 24 to 48 hours postoperatively. Sufﬁ cient pain

medication should be administered. Beta blockade begun preoperatively should be contin-

ued throughout the postoperative period. Inotropic agents should be used to ensure ade-

quate 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 situ-

ation, 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 anoma-

lies 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

difﬁ cult to control with clamps. Endoluminal suture ligation of the oriﬁ ce or preoperative

coiling will control bleeding from the aneurysm.

AORTOCAVAL FISTULA

◆ Rarely, an undiagnosed communication between the aneurysm and the vena cava is encoun-

tered. This should be suspected if venous blood is seen ﬂ owing 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 monoﬁ la-

ment sutures will usually sufﬁ ce.