1. © 2007 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 1
11 REPAIR OF INFRARENAL
ABDOMINAL AORTIC ANEURYSMS
Frank R. Arko, M.D., Stephen T. Smith, M.D., and Christopher K. Zarins, M.D., F.A.C.S.
An arterial aneurysm is defined as a permanent localized enlarge- repair during the two trials: 81% of patients with 5.0 to 5.4 cm
ment of an artery to a diameter more than 1.5 times its expected aneurysms in the ADAM trial underwent surgery, and almost all
diameter. Aneurysms are classified according to morphology, eti- patients in the U.K. trial ultimately required surgical management.
ology, and anatomic site. The most common morphology is a Thus, it is likely that the reason for the low rupture risk in these tri-
fusiform, symmetrical, circumferential enlargement that involves als was that surgical treatment of the aneurysm was provided when
all layers of the arterial wall. A saccular morphology is also seen, clinically indicated. This conclusion is supported by data from a
in which aneurysmal degeneration affects only part of the arterial prospective study of patients from the VA hospitals involved in the
circumference. ADAM trial who were not eligible for randomization and did not
The most common cause of an arterial aneurysm is atheroscle- undergo operative repair. In these patients, the 1-year risk of rup-
rotic degeneration of the arterial wall.The pathogenesis is a multi- ture for slightly larger (5.5 to 5.9 cm) aneurysms was 9.4%.8
factorial process involving genetic predisposition, aging, athero- Furthermore, very close surveillance with ultrasound examina-
sclerosis, inflammation, and localized activation of proteolytic tions every 3 to 6 months did not prevent aneurysm rupture in 1%
enzymes. Most aneurysms occur in elderly persons, and the preva- of patients. Thus, the decision whether to treat an aneurysm is
lence rises with increasing age. Aneurysms also occur in genetical- based on assessment of the risk of aneurysm rupture relative to the
ly susceptible individuals with Ehlers-Danlos syndrome or Marfan risk associated with treatment rather than on an absolute size cri-
syndrome. Other causes include tertiary syphilis and localized terion or a surveillance protocol.
infection resulting in a mycotic aneurysm.
Aneurysms of the infrarenal aorta are by far the most common
arterial aneurysms encountered in clinical practice today: they are Open Repair
three to seven times more common than thoracic aneurysms and
PREOPERATIVE EVALUATION
affect four times as many men as women.1 Abdominal aortic
aneurysms (AAAs) have a tendency to enlarge and rupture, caus-
ing death. In the United States, AAAs result in approximately Identification of Risk Factors
15,000 deaths each year and are thus the 13th leading cause of For successful surgical reconstruction of AAAs, any significant
death.2,3 The only way to reduce the death rate is to identify and comorbidities that would increase the risk of operative repair must
treat aortic aneurysms before they rupture [see 6:3 Pulsatile Abdomi- be identified and managed at an early stage. Patients undergoing
nal Mass]. the procedure usually are elderly and often have coexisting car-
The relationship between aneurysm size and risk of rupture is diac, pulmonary, cerebrovascular, renal, or peripheral vascular dis-
well known.The annual risk of rupture is 1% to 2% for aneurysms ease. The major anesthetic risk factors for elective resection of
less than 5 cm in diameter, 10% for aneurysms 5 to 6 cm in diam- AAAs are similar to those for other major intra-abdominal opera-
eter, and 25% or higher for aneurysms larger than 6 cm.4 Although tions; in particular, they include inadequate cardiopulmonary and
large aneurysms are much more likely to rupture than small renal function. Patients with unstable angina or angina at rest, a
aneurysms, small aneurysms can and do rupture on occasion. cardiac ejection fraction of less than 25%, a serum creatinine con-
The exact size at which an asymptomatic small AAA should be centration higher than 3 mg/dl, or pulmonary disease (manifested
treated remains unsettled. This issue was the subject of two by arterial oxygen tension < 50 mm Hg, elevated arterial carbon
prospective, randomized clinical trials: the United Kingdom Small dioxide tension, or both on room air) are considered to be at high
Aneurysm Trial5 and the Aneurysm Detection And Management risk.9,10
(ADAM) Veterans Affairs (VA) Cooperative Study.6 Both trials Myocardial ischemia is the most common cause of perioperative
randomly assigned low-risk patients with small (4.0 to 5.4 cm) morbidity and mortality after arterial reconstruction of the aorta.
AAAs to either open surgical repair or ultrasound surveillance. Optimization of preoperative medical management, perioperative
Patients in the surveillance groups were closely monitored with invasive monitoring, and long-term risk-factor modification are all
serial ultrasound examinations and underwent open surgical repair facilitated by an accurate preoperative cardiac evaluation. Such
if the aneurysm enlarged, became tender to palpation, or became evaluation may include transthoracic echocardiography, exercise
symptomatic. With respect to the primary end point—overall sur- stress testing, myocardial scintigraphy, stress echocardiography,
vival—the two trials came to similar conclusions: there was no dif- and coronary angiography; each test has its own merits and limi-
ference in overall survival between the surgery group and the sur- tations with regard to clinical risk assessment.
veillance group.5,6 There was, however, a late survival benefit in the There has been considerable controversy over the potential ben-
surgery group in the U.K. Small Aneurysm Trial.7 efit of preoperative coronary revascularization in this setting. This
Aneurysm rupture rates were low (1%) in both trials, leading issue was addressed by a clinical trial in which patients requiring
many clinicians to conclude that aneurysms smaller than 5.5 cm AAA or peripheral vascular surgery who had high-risk cardiac dis-
need not be treated, because the risk of rupture is so low. Closer ease were randomly assigned to undergo either vascular surgery
examination of the data, however, reveals that more than 60% of without preoperative coronary revascularization or coronary revas-
the patients in the surveillance groups underwent open surgical cularization followed by vascular surgery.11 There was no differ-

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6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 2
lower-extremity occlusive disease. There are risks associated with
aortography that place some restrictions on its use. Among these
risks are the potential renal toxicity resulting from the use of con-
trast agents. In addition, manipulation of catheters through the
laminated mural thrombus increases the risk of distal emboliza-
tion. Finally, local arterial complications may arise at the arterial
puncture site.
CT provides reliable information about the size of the entire
aorta, thereby allowing accurate determination of both the size
and the extent of the AAA [see Figure 2]. Spiral CT scanning per-
mits identification of the visceral and renal arteries and their rela-
tionship to the aneurysm. The administration of I.V. contrast
material allows assessment of the aortic lumen, the amount and
location of mural thrombus, and the presence or absence of
retroperitoneal hematoma [see Figure 3]. Overall, spiral CT is cur-
rently the most useful imaging method for evaluation of the
abdominal aorta.
Figure 1 Duplex ultrasonography may be used as a screening MRI is also useful in the preoperative evaluation of aortic
test and to determine the actual size of the aneurysm. aneurysms.18,19 It employs radiofrequency energy and a magnetic
field to produce images in longitudinal, transverse, and coronal
planes.The advantages of MRI over CT are that no ionizing radi-
ence between the two groups with respect to the incidence of post- ation is administered, multiplane images can be obtained, and no
operative MI or overall mortality.The investigators concluded that nephrotoxic contrast agents are used.
patients with stable coronary disease do not benefit from preoper-
ative coronary revascularization. Patients with unstable severe Classification of Patients for Elective or Urgent Repair
coronary disease may benefit from invasive cardiac evaluation and Patients may usefully be classified into three categories accord-
preliminary coronary intervention. ing to how they present for repair: (1) elective patients, (2) symp-
To reduce the mortality associated with resection of AAAs, it is tomatic patients, and (3) patients with ruptured aneurysms.
necessary not only to identify high-risk groups but also to institute
appropriate preoperative, intraoperative, and postoperative alter-
ations in patient care.With intensive perioperative monitoring and
support in place, resection of AAAs has been successfully per-
formed even in high-risk patients, with operative mortalities of less
than 6%.12-14
Confirmation of Diagnosis and Determination of Aneurysm Size
Physical examination suffices for detection of most large
aneurysms. To determine the exact size of the aneurysm and to
identify smaller aneurysms, however, more objective methods are
available and should be used. Determination of the size of the
aneurysm is extremely important because size is the most impor-
tant determinant of the likelihood of rupture and plays a crucial
role in subsequent management decisions. Imaging modalities
commonly employed to diagnose and measure aneurysms include
duplex ultrasonography (DUS), aortography, computed tomogra-
phy, and magnetic resonance imaging.
The main advantages of DUS are its ready availability in both
inpatient and outpatient settings, its low cost, its safety, and its
good performance; many studies have documented the ability of
DUS to establish the diagnosis and accurately determine the size
of AAAs [see Figure 1].15-17 The primary limitations of DUS are
that imaging of the thoracic and suprarenal aorta is poor, that the
quality of the images is considerably lower in the presence of obe-
sity or large amounts of intestinal gas, and that it must be per-
formed by a skilled imaging technician.
Aortography yields excellent images of the contours of the aor-
tic lumen, but it is not a reliable method for determining the diam-
eter of an aneurysm or even for establishing its presence, because
the mural thrombus within the aneurysm tends to reduce the
lumen to near-normal size. Nonetheless, aortography can be help- Figure 2 Shown is a CT angiogram providing a three-dimen-
ful in determining the extent of an aneurysm (especially when sional reconstruction of an infrarenal AAA after endovascular
there is iliac or suprarenal involvement), defining associated arter- repair. Of particular interest is the relation of the graft to the
ial lesions involving the renal and visceral arteries, and detecting renal arteries and the hypogastric arteries distally.

3. © 2007 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 3
Figure 3 CT scanning assesses the size of the aneurysm, the amount of mural thrombus present, and the rela-
tion of other intra-abdominal structures to the aneurysm.
Elective aneurysm repair is recommended for asymptomatic aneurysm repair. Consideration of endovascular aneurysm repair
patients who have aneurysms 5.0 cm in diameter or larger, who (EVAR) does introduce certain morphologic criteria into the
have an acceptable level of operative risk, and who have a life process of patient selection, in that stent grafting is appropriate
expectancy of 1 year or more. Furthermore, elective operation only for patients in whom the infrarenal neck and the iliac arteries
should be considered for patients with aneurysms smaller than 5.0 are suitable.
cm who are not at high operative risk if they are hypertensive or live Given that the long-term outcome of endovascular grafting is
in a remote area where proper medical care is not readily available. currently unknown, younger patients who are at low operative risk
Repair is also appropriate for aneurysms that are between 4.0 and and are expected to survive into the long term are typically better
5.0 cm in diameter and have shown growth of more than 0.5 cm served with open surgical repair. In addition, patients who require
on serial images in less than 6 to 12 months. Peripheral embo- additional abdominal or pelvic revascularization procedures, who
lization originating from the aneurysm is an indication for repair, have small or diseased access vessels, or who have short (< 10 mm)
regardless of the size of the aneurysm. or tortuous infrarenal necks are not candidates for endovascular
Urgent operation is indicated for patients with symptomatic grafting and should undergo open surgical repair instead.
aneurysms, regardless of the size of the aneurysm. Such patients Preoperative preparation to optimize cardiopulmonary function,
typically present with abdominal or back pain. Sometimes, the administration of preoperative antibiotics, and intraoperative hemo-
back pain radiates to the groin, much as in ureteral colic; this pain dynamic monitoring with appropriate fluid management can sig-
may be elicited by palpating the aneurysm. In most cases, DUS, nificantly reduce the risks associated with AAA repair. Before aortic
CT, and MRI will reliably detect the presence of periaortic blood; cross-clamping, appropriate volume loading, combined with vaso-
however, the absence of this finding should not delay operation, dilatation, is carried out to help prevent declamping hypotension.
because actual rupture of the aneurysm can occur at any time.
OPERATIVE TECHNIQUE
Emergency operation is indicated for almost all patients with
known or suspected rupture of an aneurysm.
Step 1: Initial Incision and Choice of Approach
OPERATIVE PLANNING
Open surgical repair of infrarenal AAAs is performed through a
Preoperative planning is essential for a successful outcome after transperitoneal or retroperitoneal exposure of the aorta with the
repair of an infrarenal AAA. Like the choice between elective and patient under general endotracheal anesthesia.The aneurysm may
urgent or emergency repair, operative planning is governed by the be exposed through either a long midline incision (for the
presentation of the patient. In patients with ruptured aneurysms, transperitoneal approach) or an oblique flank incision (for the
diagnosis is immediately followed by operative repair. In patients retroperitoneal approach) [see Figure 4a]. An upper abdominal
with symptomatic aneurysms, the amount of preoperative imaging transverse incision may also be used for either retroperitoneal or
done is balanced against the risk of impending rupture. In patients transperitoneal exposure. The results with the two exposures are
presenting for elective repair, it is generally possible to perform equivalent. The transperitoneal approach is preferred when expo-
extensive imaging to determine whether the repair is best done via sure of the right renal artery is required and when access to the dis-
an endovascular approach [see Endovascular Repair, below] or a tal right iliac system or to intra-abdominal organs is necessary.The
standard open approach. Current preoperative imaging methods retroperitoneal exposure offers advantages when extensive peri-
utilizing CT angiography (CTA) obviate several common pitfalls. toneal adhesions, an intestinal stoma, or severe pulmonary disease
The availability of endovascular techniques for excluding an is present and when there is a need for suprarenal exposure. Use
aneurysm should not alter the patient selection criteria for of the retroperitoneal approach has been associated with a shorter

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6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 4
a
Renal Vein
b
Inferior
Mesenteric Vein
Inferior
Mesenteric
Artery
Ureter
Iliac Vein
Figure 4 Open repair of infrarenal AAAs. (a) For the transabdominal approach to the abdominal aorta, a
midline or transverse incision is appropriate. For the retroperitoneal approach, an oblique flank incision
may be used. (b) The small intestine (including the duodenum) is retracted laterally after the ligament of
Treitz is mobilized, and the retroperitoneum is incised in the midline. The left renal vein is the landmark
for the infrarenal neck.
Step 2 (Retroperitoneal Approach): Exposure and Control of
duration of postoperative ileus, a lower incidence of pulmonary
Aorta and Iliac Arteries
complications, and a reduction in length of stay in the ICU.
When the retroperitoneal approach is taken, a transverse left
Step 2 (Transperitoneal Approach): Exposure and Control of abdominal or flank incision is made, and the peritoneum is reflect-
Aorta and Iliac Arteries ed anteriorly. The left kidney usually is left in place but may be
When the transperitoneal approach is taken, the small bowel mobilized anteriorly to expose the posterolateral aorta. Exposure
(including the duodenum) is retracted to the right, and the of the right iliac system can be achieved by dividing the inferior
retroperitoneum overlying the aneurysm is divided to the left of the mesenteric artery early in the course of dissection. The aorta and
midline [see Figure 4b].The duodenum is completely mobilized, and the iliac arteries are controlled in essentially the same fashion
the left renal vein is identified and exposed. The normal infrarenal regardless of the type of incision used.
neck, which is just below the left renal vein, is then exposed and
encircled for proximal control. Both common iliac arteries are Step 3: Opening of Aneurysm and Creation of Proximal
mobilized and controlled, with care taken to avoid the underlying Anastomosis
iliac veins and ureters that cross over at the iliac bifurcation [see Systemic anticoagulation with I.V. heparin is then performed.
Figure 5]. If the common iliac arteries are aneurysmal, then both the After sufficient time (3 to 5 minutes) has elapsed to permit ade-
internal and the external iliac arteries are controlled. The inferior quate circulation, the infrarenal neck and the iliac arteries are
mesenteric artery is then dissected out and controlled for possible clamped. To prevent distal embolization, the distal clamps should
reimplantation into the graft after the aneurysm has been repaired. be applied before the proximal aortic clamp.The aneurysm is then

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6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 5
opened longitudinally, the mural thrombus is removed, and back- clamping may be required for performance of the proximal anasto-
bleeding lumbar arteries are oversewn. Depending on its degree of mosis. If suprarenal clamping is necessary, the security of the prox-
backflow and on the patency of the hypogastric arteries, the inferi- imal anastomosis should be verified, and the clamp should then be
or mesenteric artery may be either ligated or clamped and left with moved onto the graft below the renal arteries as soon as possible to
a rim of aortic wall for subsequent reimplantation [see Trouble- minimize renal ischemia. If the aorta is especially weak or friable,
shooting, below]. the anastomosis may be supported with Teflon-felt pledgets.
The aortic neck is then partially or completely transected, and an
appropriately sized tubular or bifurcated graft is sutured to the aorta Step 4: Creation of Distal Anastomosis
with a continuous nonabsorbable monofilament suture [see Figure When the aneurysm is confined to the aorta, the distal anasto-
6]. When the proximal aortic neck is very short, suprarenal aortic mosis is performed by suturing a straight tube graft to the aortic
a
b
c
Figure 5 Open repair of infrarenal AAAs. (a) Once the aneurysm is exposed, proximal control is obtained by encir-
cling the proximal neck with an umbilical tape or heavy Silastic. The inferior mesenteric artery is identified and then
either clamped or ligated for possible reimplantation at the end of the procedure. (b) The iliac arteries are dissected
free, systemic heparin anticoagulation is instituted, and distal control is obtained, followed by proximal control to
prevent distal embolization. The aneurysm sac is then opened longitudinally. (c) All mural thrombus is removed, and
the proximal and distal necks of the aorta are incised.

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6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 6
a c
b
Figure 6 Open repair of infrarenal AAAs.
(a) Back-bleeding lumbar arteries are
oversewn with figure-eight sutures to con-
trol bleeding. (b, c, d) The proximal anasto-
mosis is sewn to the back wall of the aorta
d e with a continuous nonabsorbable monofila-
ment suture. (e) If the aorta is weak or fri-
able, Teflon-felt pledgets may be used for
additional support.
bifurcation [see Figure 7]; straight tube graft reconstructions are Every effort should be made to ensure perfusion of at least one
used about 30% of the time. Distally, the dissection should avoid hypogastric artery to help minimize the risk of postoperative left
the fibroareolar tissue overlying the left common iliac artery colon ischemia.
because this tissue contains branches of the inferior mesenteric Declamping hypotension may occur after reperfusion of the
artery and the autonomic nerves that control sexual function in lower extremities. It is essential to maintain communication with
men. the anesthesiologist so that blood and fluid replacement can be
When the aneurysm extends into the common iliac arteries, the adjusted in anticipation of lower-extremity reperfusion. Even
distal anastomosis is accomplished by suturing a bifurcated graft to though the graft and vessels are flushed and back-bled before dis-
the distal common iliac arteries or, in the case of significant occlu- tal flow is reestablished, it is preferable first to establish flow into
sive disease, to the common femoral arteries. In these situations, one of the hypogastric arteries so as to minimize the chances of dis-
control of the iliac arteries is best achieved by mobilizing the exter- tal embolization to the legs.
nal and internal arteries and clamping them individually [see Figure Before the abdomen is closed, adequate perfusion of the lower
8]. It is sometimes easier to control iliac artery back-bleeding by extremities and the left colon should be ensured via either direct
using intraluminal balloon catheters and oversewing the common inspection or noninvasive monitoring. The open aneurysm sac is
iliac arteries from within the opened aortic or iliac aneurysms. then sutured closed over the aortic graft to separate the graft from
Care must be taken not to injure the accompanying venous struc- the duodenum and the viscera [see Figure 9].This step reduces the
tures or the ureters, which cross anterior to the iliac bifurcation. risk of aortoenteric fistula.

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6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 7
Troubleshooting
If the inferior mesenteric artery is small and back-bleeding is ade-
quate, it may be ligated [see Figure 10a]; however, if the vessel is large
or back-bleeding is meager, it should be reimplanted. Reimplan-
tation of the inferior mesenteric artery can be accomplished with rel-
ative ease by using the Carrel patch technique. After the graft has
been completely sewn to the aorta, a partial occluding clamp is
placed on the main body of the graft or on one of the limbs. An
opening in the graft is then created, and an end-to-side anastomosis
[see Figure 10b]—with an interposition graft added if necessary [see
Figure 10c]—is used to reconstruct the inferior mesenteric artery.
This anastomosis is created with a continuous monofilament suture.
SPECIAL CONSIDERATIONS
Concurrent Disease Processes
At times, a concurrent disease process complicates repair of an
AAA.The most common problems encountered are hepatobiliary,
pancreatic, gastrointestinal, gynecologic, and genitourinary disor-
ders. Careful evaluation of the situation is necessary to determine
whether to treat the two disease entities concurrently. As a rule, the
more life-threatening disorder is treated first.
There are three key points that should be remembered in the
management of patients with AAAs and concurrent diseases. First,
a careful preoperative diagnostic workup usually detects any con-
Figure 7 Open repair of infrarenal AAAs. When the aneurysm
comitant disease processes. Second, in emergency situations such as
does not extend into the iliac arteries, a straight tube graft is
used. The distal anastomosis is completed with a continuous
ruptured or symptomatic aneurysms, the aneurysm always takes
suture. Before completion of the anastomosis, the graft is flushed priority unless the other condition is life-threatening and the
by back-bleeding the iliac arteries and flushing the proximal aneurysm clearly is not the cause of the critical symptoms. Finally,
anastomosis. many concomitant intra-abdominal problems can be avoided by
taking an endovascular approach.
a b
Figure 8 Open repair of infrarenal AAAs. When the common iliac arteries are aneurysmal, both the internal and the
external iliac arteries must be clamped individually (a), and a bifurcated graft is sewn to the iliac arteries bilaterally (b).

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6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 8
incidence is quite low. Left renal vein variants, such as retroaortic
left renal veins and circumaortic venous rings, are the most com-
monly seen venous anomalies.22 Azygous continuation of the infe-
rior vena cava and bilateral inferior vena cava have also been noted.
Unnecessary bleeding can be prevented by means of careful dis-
section and meticulous technique.
Inflammatory Aneurysm
Approximately 5% of infrarenal AAAs are inflammatory.23 These
AAAs have a dense fibroinflammatory rind that typically adheres to
the fourth portion of the duodenum; they may also involve the infe-
rior vena cava, the left renal vein, or the ureters. Patients with
inflammatory AAAs typically experience abdominal or flank pain
and may present with weight loss. The erythrocyte sedimentation
rate is usually elevated as well. Inflammatory aneurysms rarely rup-
ture, because most are symptomatic and consequently are treated
before rupture can occur. Repair of inflammatory aneur-
ysms poses technical problems because of the involvement of adja-
cent structures. A retroperitoneal approach is usually advocated for
these aneurysms.
Ruptured Aneurysm
Infrarenal AAAs can rupture freely into the peritoneal cavity or
into the retroperitoneum. Free rupture into the peritoneal cavity is
usually anterior and is typically accompanied by immediate hemo-
dynamic collapse and a very high mortality. Retroperitoneal rup-
tures are usually posterior and may be contained by the psoas mus-
cle and adjacent periaortic and perivertebral tissue. This type of
rupture may occur without significant blood loss initially, and the
patient may be hemodynamically stable.
When an aortic aneurysm ruptures, immediate surgical repair is
indicated. If the patient is unstable and either an abdominal aortic
Figure 9 Open repair of infrarenal AAAs. Once the anastomoses aneurysm was previously diagnosed or a palpable abdominal mass
have been completed and adequate flow to the lower extremities
is present, no further evaluation is necessary and the patient should
and the left colon has been confirmed, the open aneurysm sac is
sutured closed over the aortic graft.
be taken directly to the OR. If the patient is stable and the diagno-
sis is questionable, CT scanning may be performed to confirm the
presence of an aneurysm and determine its extent, the site of the
Anatomic Variants rupture, and the degree of iliac involvement. Bedside ultrasonogra-
Several anatomic variants may be encountered during repair of phy may also be used for quick confirmation of the presence of an
AAAs, including horseshoe kidney, accessory renal arteries, and AAA.
venous anomalies. Surgical repair of ruptured aneurysms is performed via a
transperitoneal approach. In cases of contained rupture, supraceli-
Horseshoe kidney The incidence of horseshoe kidney in the ac control should be achieved before infrarenal dissection; once the
general population is less than 3%. Most patients with horseshoe neck of the aneurysm has been dissected free, the aortic clamp may
kidneys have between three and five renal arteries.20 To preserve be moved to the infrarenal level. In cases of free rupture, efforts to
renal function, renal arteries arising from the aneurysm should be obtain vascular control may include compression of the aorta at the
reimplanted. In patients with horseshoe kidneys who have more hiatus and infrarenal control with a clamp or an intraluminal bal-
than five renal arteries, there often are multiple small accessory loon. Once proximal and distal control have been achieved, the
arteries, some of which originate from the aneurysm, the iliac arter- operation is conducted in much the same way as an elective repair.
ies, or both.
OUTCOME EVALUATION
The presence of a horseshoe kidney may complicate—but does
not preclude—an anterior approach to repair of an infrarenal The mortality associated with repair of AAAs has been greatly
AAA.21 In such cases, the left retroperitoneal approach provides reduced by improvements in preoperative evaluation and perioper-
excellent exposure of the infrarenal aorta. This approach requires ative care: leading centers currently report death rates ranging from
that the surgeon dissect the space between the aneurysm and the 0% to 5%.24 Mortality after repair of inflammatory aneurysms and
left portion and isthmus of the kidney; the kidney can then be after emergency repair of symptomatic nonruptured aneurysms
reflected to the right and the aneurysm fully exposed. The left continues to be somewhat higher (5% to 10%), primarily as a con-
ureter crosses the iliac arteries from the right in this position, and sequence of less thorough preoperative evaluation.
duplication of ureters may be noted. Overall morbidity after elective aneurysm repair ranges from
10% to 30%. The most common complication is myocardial
Venous anomalies A number of different venous anomalies ischemia, and MI is the most common cause of postoperative
may be observed in the course of AAA repair; however, the overall death. Mild renal insufficiency is the second most frequent com-

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6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 9
a c
b
Figure 10 Open repair of infrarenal AAAs. (a) A small, adequately back-bleeding inferior mesenteric artery may be lig-
ated. (b) A large or meagerly back-bleeding inferior mesenteric artery should be reimplanted. A side-biting clamp is
applied to the graft, and an end-to-side anastomosis is created with a fine monofilament suture. (c) If the inferior mesen-
teric artery is not long enough for a direct anastomosis, an interposition graft—either a segment of a vein or a prosthetic
graft—may be used for added length.
plication, occurring after 6% of elective aneurysm repairs; howev- graft or graft limb thrombosis, and graft infection) may occur but
er, severe renal failure necessitating dialysis is rare in this setting. are extremely rare. Graft infection may be associated with graft-
The third most common complication is pulmonary disease; the enteric fistula and is notoriously difficult to diagnose and treat.
incidence of postoperative pneumonia is approximately 5%. Long-term survival in patients who have undergone successful
Postoperative bleeding may occur as well. Common sources of AAA repair is reduced in comparison with that in the general pop-
such bleeding include the anastomotic suture lines, inadequately ulation. The 5-year survival rate after AAA repair is 67% (range,
recognized venous injuries, and coagulopathies resulting from 49% to 84%), compared with 80% to 85% in age-matched control
intraoperative hypothermia or excessive blood loss. Any evidence of subjects, and the mean duration of survival after AAA repair is 7.4
ongoing bleeding is an indication for early exploration. years. Part of the difference in survival can be attributed to associ-
Lower-extremity ischemia may occur as a result of either emboli ated coronary disease in patients with aneurysms. Late deaths
or thrombosis of the graft and may necessitate reoperation and result primarily from cardiac causes.
thrombectomy. So-called trash foot may also develop when diffuse
microemboli are carried into the distal circulation.
Colon ischemia develops after 1% of elective aneurysm repairs. Endovascular Repair
Patients usually present with bloody diarrhea, abdominal pain, a Endovascular repair was introduced during the 1990s as a less
distended abdomen, and leukocytosis. The diagnosis is confirmed invasive approach to treating infrarenal AAAs. In this approach, a
by sigmoidoscopy, which reveals mucosal sloughing. In cases of stent-graft is placed endoluminally via bilateral groin incisions;
transmural colonic necrosis, colon resection and exteriorization of thus, there is no need for a major abdominal incision and aortic
stomas are warranted. clamping. The results to date have been promising: blood loss is
Paraplegia is rare after repair of infrarenal AAAs: the incidence is decreased, hospital stay is shortened, and earlier return to function
only 0.2%. Most instances of paraplegia occur after repair of a rup- is achieved. Not all patients are candidates for endovascular repair,
tured aneurysm or when the pelvis has been devascularized. The however. In September 1999, the Food and Drug Administration
majority of patients recover at least some degree of neurologic approved two stent-graft devices for use in surgical management of
function. AAAs: the Ancure device (Guidant, Indianapolis, Indiana), which
Late complications (e.g., pseudoaneurysms at the suture lines, is a balloon-expandable one-piece bifurcated stent-graft, and the

10. © 2007 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 10
a b
c d
Figure 11 Endovascular repair of infrarenal AAAs. (a) The main bifurcated stent-graft
is advanced through the aortoiliac system under fluoroscopic guidance. (b) The sheath
over the stent-graft is retracted under fluoroscopic guidance. Controlled deployment
allows the graft to be gradually positioned directly below the renal arteries. (c) With the
main body of the stent-graft deployed, the contralateral limb is cannulated. Once this is
done, the contralateral limb is positioned within the junction gate and the common iliac
artery. (d) Shown is proper deployment of the stent-graft within the aortoiliac system,
with good proximal and distal fixation of the stent to the arterial wall.
AneuRx device (Medtronic AVE, Santa Rosa, California), which is the Endologix Powerlink System (Endologix Incorporated, Irvine,
a self-expanding bifurcated modular device that is fully supported California), in November 2004. The Ancure device is no longer
externally by a nitinol stent. Subsequently, the FDA approved available.
three more devices for endovascular repair of AAAs: the Excluder
PREOPERATIVE PREPARATION
Bifurcated Endoprosthesis (W. L. Gore and Associates, Flagstaff,
Arizona), in November 2002, the Zenith AAA Endovascular Graft Precise preoperative evaluation that yields accurate measure-
(Cook Incorporated, Bloomington, Indiana), in May 2003, and ments will result in proper planning and effective prevention of

11. © 2007 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 11
problems. Both CTA and contrast biplane angiography are used and 0.035-in. guide wires are placed bilaterally under fluoroscop-
for this purpose. Of the two, spiral CTA is currently preferred.This ic guidance; 10 French sheaths are then placed over the two guide
imaging modality is capable of obtaining high-quality images of wires and advanced into the aneurysm under fluoroscopic guid-
the vascular anatomy and reconfiguring them into detailed three- ance. A superstiff 0.035-in. guide wire 260 cm in length is insert-
dimensional images. For optimal evaluation, images should be ed into the thoracic aorta, usually from the right limb. In the con-
obtained at 1.5 to 3 mm intervals from the celiac artery to the tralateral iliac artery, a pigtail catheter is placed just above the level
femoral arteries. Spiral CTA accurately defines the proximal and of the renal arteries, and an initial roadmapping aortogram is
distal characteristics of the AAA, as well as detects any significant obtained.The 10 French sheath in the right femoral artery is then
renal, visceral, or iliac occlusive disease. It is particularly helpful in exchanged for the device, which is placed over the superstiff guide
defining the infrarenal neck between the renal arteries and the wire and carefully advanced into the proximal infrarenal aorta
proximal portion of the aneurysm. under fluoroscopic guidance, then into the perirenal aorta [see
Angiography is employed as a complement to spiral CTA in this Figure 11a]. A second aortogram is performed to verify the posi-
setting. An arteriogram is useful in that it helps define renal, tion of the renal arteries. Under fluoroscopic guidance, the stent-
mesenteric, and distal arterial anatomy; helps characterize tortu- graft is then gradually deployed by retracting the outer sheath and
osity, calcification, and stenoses in access arteries; and helps deter- allowing the graft to expand, and it is positioned directly below the
mine the angles between the aorta, the proximal neck, and the level of the renal arteries [see Figure 11b].
aneurysm. Once the main bifurcation module has been deployed, the 10
Intravascular ultrasonography (IVUS) is a useful intraoperative French sheath in the contralateral iliac artery is pulled back, and a
imaging adjunct in the process of sizing and selecting endograft 0.035-in. angled hydrophilic wire and a guide catheter are insert-
components. It can be used to measure vessel diameters and land- ed into the contralateral limb of the bifurcation module.The hydro-
ing zone lengths, as well as to determine the amount of mural philic wire is then exchanged for a superstiff guide wire, over which
thrombus in the aneurysm neck. In patients with severe renal the contralateral limb is then advanced through the sheath into the
insufficiency, IVUS is used primarily to identify the renal and contralateral vessel and deployed [see Figure 11c]. A final aorto-
hypogastric arteries, allowing the endograft to be deployed with gram is then performed to confirm that a satisfactory technical
minimal or no resort to angiography. result has been achieved [see Figure 11d]. Proximal and distal ex-
Proper patient selection is mandatory for successful outcome. tender cuffs may be placed if necessary.The femoral arteriotomies
The common femoral arteries must be large enough to accept a are repaired, and lower-extremity perfusion is reestablished.
delivery system larger than 21 French. The proximal infrarenal
OUTCOME EVALUATION
aortic neck must be suitable for device implantation—that is, its
diameter must be between 16 and 28 mm, and its length should EVAR is significantly less invasive than open surgical repair and
be at least 15 mm. The common iliac artery implantation should consequently is associated with a significant reduction in major
be carried out as close to the iliac bifurcation as possible to procedure-related morbidity. Prospective clinical trials comparing
increase the columnar strength of the implanted device. The iliac open AAA repair with EVAR have consistently found that patients
artery diameter must be between 8 and 20 mm. In patients with undergoing the latter experience less intraoperative blood loss,
iliac artery aneurysms, it is possible to land the end of the stent in need less postoperative ICU care, have shorter lengths of stay, and
the external iliac artery and thereby exclude one internal iliac regain normal function earlier.25,26 Procedure-related mortality
artery. Exclusion of both internal iliac arteries should be avoided after EVAR is 1% to 2%, which is essentially equivalent to that
so as to prevent ischemic sequelae (e.g., buttock claudication, reported after open repair in prospective clinical trials but lower
colon ischemia, and erectile dysfunction). Coil embolization may than the 5% mortality reported after open repair in most multi-
be performed in conjunction with EVAR to treat internal iliac center studies.27,28
aneurysms. However, a waiting period of several weeks between In the past few years, two randomized, controlled trials com-
coil embolization of a hypogastric artery on one side and the same paring EVAR with open AAA repair have been published. The
procedure on the other side should be considered to allow recruit- Dutch Randomized Endovascular Aneurysm Management
ment of collateral vessels and reduce the incidence of pelvic (DREAM) trial found EVAR to have a significant advantage in the
ischemia. first 30 days, with reduced mortality and a lower incidence of
severe complications.29 This survival advantage was not sustained,
TECHNIQUE
however, and at 1 year, there was no difference between EVAR and
The methods and technical principles we briefly describe here open AAA repair. The EVAR 1 trial, carried out in the United
derive from the personal experience of two surgeons (F.R.A and Kingdom, found EVAR to yield a similar reduction in 30-day mor-
C.K.Z) with more than 1,000 modular implants. The ensuing tality.30 Again, this survival advantage was not sustained, and at 4
technical description is not intended to be exhaustive, nor is it years, there was no difference between EVAR and open repair in
meant as a substitute for the instructions provided by any of the terms of overall mortality or health-related quality of life. EVAR
manufacturers. did, however, have a significant advantage over open AAA repair
The patient is placed under epidural or general anesthesia. with regard to 4-year aneurysm-related mortality. The impact of
Bilateral femoral artery cutdowns are performed through trans- this advantage will continue to be assessed as this trial’s follow-up
verse groin incisions to allow exposure of the common femoral period lengthens.
artery from the inguinal ligament to the femoral bifurcation. On occasion, EVAR fails to exclude blood flow from the
Proximal control of the femoral arteries is obtained with umbilical aneurysm sac completely.This condition, known as endoleak, may
tapes. Systemic anticoagulation with I.V. heparin is instituted to arise from an incomplete seal at the site where the endograft is
prolong the activated clotting time (ACT) to greater than 250 sec- affixed to the aortic neck or the iliac arteries (type I endoleak),
onds.The ACT is monitored and maintained at this level through- from retrograde flow into the aneurysm from the inferior mesen-
out the procedure, and additional heparin is given as needed. teric artery or the lumbar arteries (type II endoleak), or from the
The femoral arteries are cannulated with an 18-gauge needle, graft or modular junction site (type III endoleak).Type I and type

12. © 2007 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice
6 VASCULAR SYSTEM 11 REPAIR OF INFRARENAL ABDOMINAL AORTIC ANEURYSMS — 12
III endoleaks call for secondary treatment to prevent possible or, possibly, open surgical repair). New endovascular devices are
aneurysm rupture.The significance of type II endoleaks is less cer- currently being designed and evaluated in clinical trials, and
tain. There is no clear evidence that type II endoleaks lead to endovascular treatment strategies continue to evolve and improve.
aneurysm rupture; however, most such endoleaks are treated if Clinical follow-up of patients treated during the initial prospec-
they are associated with aneurysm enlargement. tive clinical trials now extends to more than 7 years, and EVAR
Although numerous studies have shown that endovascular AAA continues to show favorable results. The largest multicenter
repair results in less morbidity and perioperative mortality than endovascular clinical trial to date, involving 1,193 patients who
open repair,31-34 reports describing endograft migration over time, were followed for as long as 6 years, found that prevention of
aneurysm enlargement, and occasional aneurysm rupture have aneurysm rupture (the primary objective) was achieved in 99% of
raised questions about the long-term durability of the proce- patients, whereas procedure-, aneurysm-, or graft-related death
dure.35,36 These adverse events, though uncommon, serve as was avoided in 97%.37,38 These results are consistent with the
reminders that EVAR is still a new technology, one whose long- favorable overall outcomes reported from a European registry of
term outcome is unknown. Accordingly, close patient monitoring EVAR using a variety of endovascular devices.39 Thus, the midterm
and follow-up surveillance are warranted, and secondary treat- results of EVAR are favorable and support the consideration of this
ments may be required (e.g., additional endovascular procedures approach for most patients who are candidates for the procedure.
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