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CHAPTER 3
Surgical Techniques
3.1 Introduction
Aneurysmal dilatation of the aorta is an irreversible pathological finding: the norm is
further expansion, except in some individuals where slow growth is visible by
imaging. Fascinating studies from Japan suggest that aortic aneurysms might grow
biphasically, i.e. slow initially, then rapidly and that the growth curve can be
expressed as a bi-exponential equation. These studies reiterate that an aneurysm may
rupture at any time and at any size: there is currently no exact measurement that can
precisely predict when this might occur. Size appears to be the best predictor of
rupture [Don F. du Toit, 1999].
Aneurysm formation and danger of rupture are illustrated by Laplace’s Law
Expansion of an aneurysm is demonstrated by the following equation:
T = Pr.
The larger is the vessel radius (r), the larger is the wall tension (T) required to
withstand a given internal fluid pressure (P). As an aneurysm expands, the tension on
the aortic wall increases. Studies have also shown that aortic aneurysms grow faster
shortly before rupture. Surgery for abdominal aortic aneurysms is recommended if
patient’s aneurysm is larger than 5 cm, nowadays there are two kinds of surgical
techniques, one referred as “open surgery” and the other as “endovascular surgery”.
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Although the former is a much older treatment than the latter (the first open surgery
treatment of AAA dates back to the fifties, whereas the less-invasive endovascular
treatment was performed for the first time in 1991), both of them are widely adopted
to treat the AAAs, this because the surgery team is often forced to chose rather one
than the other. For endovascular repair (EVR) the aneurysm should have suitable
anatomy. If certain anatomic characteristics are not met, open surgery is the only
option.
Endovascular treatment may seem always a better choice than the open surgery;
unfortunately only 15-30% of aneurysm patients are candidates for endograft
placement. Anatomic limitations for the placement of a common stent-graft include
aneurysms that involve the renal arteries, aneurysms with extremely short necks, iliac
vessels that are less than 7 mm or greater than 13.4 mm in diameter, densely calcified
vessels, very small femoral vessels, and severe angulations of the aneurysm neck.
These limitations make preoperative measurement and evaluation of the aneurysm
very important; consequently, both conventional angiography and CT angiography
need to be performed. These imaging procedures can be performed on an out-patient
basis. In summary, endograft placement allows 15-30% of abdominal aortic
aneurysms to be treated by a less invasive procedure that means with a decrease in
morbidity when compared to open surgical repair.
3.2 Open surgery
This method has been performed exclusively for almost 50 years and is one of the
most successful and durable operations. At operations the diseased part of the aorta is
replaced with a Dacron or Teflon graft that carefully matches to the normal aorta and
sutured in place by the surgeon. While ultimately curative, this is an operation that
requires a major abdominal incision and general anesthesia, and the hospital stay
averages 7-10 days for most patients. Even after uncomplicated surgery, it is often 6-8
weeks before patients can return to a full and normal life.
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Fig. 3.1 Differences between incisions for the open surgery (on the left)
and for the endovascular one (on the right). The length of the incision in
surgery has a great relevance for the risk of infections during the
surgery itself. On this point of view the open surgery has a completely
different approach.
Fig. 3.2 This is how an aneurysm appears to the surgeon just before clamping the
proximal part of the aorta. It is possible to see how much the sac is stretched, the diameter
is more than 5 cm and the risk of rupture is high.
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Surgery to remove an aneurysm is one of the most common vascular procedures; the
operation is usually completed in less than two hours. General anesthesia is given, so
the patient will not be awake and will not feel anything. First the surgeon exposes the
aneurysm via an incision in the abdomen of about 17 to 25 cm long (fig. 3.1, 3.2). The
aorta is clamped above and below the aneurysm to prevent bleeding. The aneurysm is
then opened (fig. 3.3). Any clots and fatty deposits that have lodged in the aneurysm
are removed. A synthetic graft-usually a straight, Dacron woven tube is sutured to the
aorta above and below the aneurysm (fig. 3.4).
Fig. 3.3
Fig. 3.4
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After the aortic graft has been sewn in place and all bleeding spots controlled, the
aneurysm sac, which has been opened along its length, is sewn back up loosely over
the new graft. This prevents the new graft from rubbing against the intestine, which
can damage the intestinal wall. When the graft is in place, the clamps are removed,
allowing blood to flow through the graft and to the legs. Patients are usually
hospitalized for seven to ten days.
With the open surgery it is possible to choose among quite a large class of suitable
stent, this because the surgeon always tries to find the stent that better fit for a
particular patient; the last choice about the kind of stent to be used is often made at
the moment of the opening of the sac.
Advantage of conventional surgery compared to EVR of AAA

Efficacy: elective aneurysmectomy and Dacron prosthetic engraftment is a
definitive and “one-off” operation for abdominal aneurysms despite the
dangers of surgery. The procedure is durable and the problems of
symptomatic aneurysms are cured.

Endoleaks: this problem is a specific drawback of EVR of AAA and does not
occur after following conventional, open surgery. Proximal endoleaks
following the endovascular approach result in expansion of the stented
aneurysm sac, with eventual rupture and death of the patient

Prosthesis: in the event of conventional surgery, the procedure can be easily be
accomplished by use of either woven or knitted Dacron prostheses. A
PTFE prosthesis is also highly suitable. Tissue incorporation and perigraft
healing are far superior with the use of knitted Dacron. Wound healing and
mechanical incorporation are retarded with the use of devices, as woven
Dacron is used. Endoleaks simply do not occur, as back bleeding from the
lumbar and the inferior mesenteric arteries are suture ligated and thus
sealed.
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
Prosthetic fabric: Dacron prosthesis used during open surgery has had an
excellent track record. Knitted grafts have to be preclotted because of the
high porosity before use. Woven fabric is less porous and is therefore the
fabric of choice for stent device.

Costs: although this aspect has been intensely debated, it does appear that
uncomplicated surgery is cheaper than EVR of AAA in the long run.
Despite reduced hospital stay and the need for intensive care facilities,
EVR of AAA has the following hidden costs that must be taken into
account:
1. Multiple secondary interventions will be needed in 5-10% of patients
to seal persisting endoleaks
2. Expensive imaging is needed for post-stent surveillance
3. Conventional aortic prostheses used for surgical repair are less
expensive than stent devices.

Remodeling of the aneurysm sac: following the conventional surgery, this
phenomenon has little effect on the long-term results of operation or graft
patency. May et al. of the University of Sidney, Australia, and others have
reported on the late changes in endograft and aneurysm morphology after
stent-graft treatment. Remodeling of the aneurysm sac may contribute to
prosthetic distortion following a reduction in the length of the aneurysm sac
[Don F. du Toit, 1999]. This may involve changes in the shape and position
of the device which could predispose to thrombosis in the endograft or
endoleak formation.
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3.3 Endovascular treatment
Endovascular repair (EVR) of abdominal aortic aneurysm offers the advantage of a
minimally invasive technique, a hospital stay of one to two days, a rapid return to
normal physical activity, and a reduction in the mortality and complication rate when
compared with the conventional surgical procedure.
EVR is well tolerated by elderly patients and many are able to undergo AAA repair
this way, with a reduced need for general anesthesia and blood transfusions. As EVR
of AAA is still in the investigation phase, long-term results are eagerly awaited as
regards the incidence of late endoleak formation. However, it is estimated that the
introduction of the newer, second-generation stent devices will allow between 7080% of aneurysms to be treated this way [Don F. du Toit, 1999]. Endovascular repair
of abdominal aortic aneurysm utilizes access to the vascular system, through the
femoral artery(-ies). A graft of appropriate design is positioned and deployed in the
abdominal aorta in order to exclude the aneurysm from the pathway of blood flow and
thus eliminate the risk of rupture (fig. 3.5 and 3.6). This technique uses the same graft
material, woven polyester, as that used for conventional aneurysm repair. A selfexpanding stent with hooks that engage the wall of the aorta and iliac arteries become
a substitute for suture material and is called the attachment system.
Fig. 3.5 The insertion of the stent with the delivery system (on the left) and
an endovascular stent-graft used for AAA repair(0n the right), showing the
two self-expanding Z-stents sutured to each end of the Dacron tube graft.
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Fig. 3.6 This picture shows the operative field prepared for the usage of the delivery
system. In this case two accesses have been opened using both femoral arteries (it is
possible to see the two guide-wires), but if the aneurysm does not involve the iliac
bifurcation it is enough only one of the two accesses to deploy the stent.
When the operation is completed, there is essentially the same reconstruction as
would have been achieved with conventional open repair with the exception of the
fact that a major abdominal incision is avoided with the substitution of one or two
small incisions over each femoral artery in the groin. For patients with an abdominal
aortic aneurysm that is limited to the aorta, and in whom there is both a neck between
the renal arteries and the aneurysm as well as a neck between the lower portion of the
aneurysm and the iliac bifurcation, a graft of tubular configuration is available (fig.
3.7 and fig. 3.8).
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Fig. 3.7 A detail of the structure of a
tubular stent.
Fig. 3.8 Tubular stent partially opened.
The stent design shown in fig. 3.7 is just one of the available configurations, The
scientists are continually looking for the best design in order to obtain an optimal
adaptability of the prosthesis to the aorta, therefore different kinds of frame are
available: zigzag, fishing net configuration, spiral frame etc.
For those patients in whom the abdominal aneurysm extends to the iliac bifurcation, a
bifurcated or Y-shaped graft is available (fig. 3.9). For those patients who have both
an abdominal aortic aneurysm as well as an aneurysm of one or both iliac arteries, the
third option is a tapered tube graft that excludes both the aortic aneurysm and one
iliac aneurysm.
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Fig. 3.9 AneurRx® modular endovascular bifurcated prosthesis showing components (A)
The entire operation is executed
without
any chance
to observe
and complete
construction
alignment
(B). the aneurysm directly.
The surgeon works for the whole time on the basis of an X-ray image, just looking at
a screen. The images he can refer to are 2-D, so it is often difficult to know the exact
position of the stent-graft. The only reference upon which the surgeon can count is a
system of radiopaque markers on the vascular prosthesis, which are visible in the Xray image. The markers are usually three, one at the proximal part of the stent, one at
the distal part and another in the middle of the prosthesis. When radio-opaque contrast
solution is injected via a catheter an angiogram image is seen on the X-ray screen (fig.
3.10).
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B
A
C
D
Fig. 3.10 The four images show the screen and the images used by the surgical team during
a typical operation. In fig. 3.10b and fig. 3.10c the arrows indicate the aneurysmatic parts of
the aorta and it is possible to see the guide-wire that is used to insert the delivery system and
to measure the length of the aneurysm. In fig. 3.10d it is clearly visible the fabric of the
prosthesis after the deployment and the markers on the proximal part.
In aorto-uni-iliac endografting, the contralateral iliac artery aneurysm is secondarily
excluded, and blood flow to the contralateral leg and pelvic circulation is
accomplished with the placement of a subcutaneous crossover graft between the two
femoral arteries. The patient comes to the hospital in the morning of operation and is
taken to the operating room.
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Using either general anesthesia or regional anesthesia, one or both femoral arteries are
exposed depending upon the type of reconstruction that is required. A needle followed
by a guide wire is then placed in the femoral artery, and the guide wire is extended up
the aorta. An angiogram is obtained in order to provide a roadmap image for
placement of the device. The patient is then anti-coagulated with Heparin and the
femoral artery is clamped. A small transverse opening is then made in the femoral
artery through which a working sheath is inserted. The sheath then provides a bloodtype roadway for placement of the graft/catheter delivery system. If a bifurcated graft
is required or an aortoiliac with femoral-femoral crossover, the contralateral femoral
artery is also exposed. In the case of the bifurcated graft, the contralateral femoral
artery is accessed with a needle puncture followed by the placement of a sheath with a
catheter
that
has
a
snare
system.
In the case of a tube graft, the graft catheter delivery system is passed up through the
sheath, over the guide wire, and positioned across the aneurysm.
Using remote release levers, the graft is deployed with the upper attachment system
immediately below the renal arteries. Both prostheses, self-expandable and with a
balloon (fig. 3.11), are available. In particular, the self-expandable technology is
based on the use of shape memory alloys (generally Nitinol).
Fig. 3.11 Balloons on top of catheters, the balloons
are inflated with physiologic liquid in order to avoid
air outflow in the case of rupture.
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Fig. 3.12 Some models of stents available on the market.
The choice of the one to use is a matter of the experience of the surgeon; nowadays a
little has been written about the best configuration for the stents and the research is in
the hands of the manufactures that try to differentiate their own products (fig. 3.12).
Nowadays, this kind of prostheses are made by shaping a Nitinol wire to remember
what will be its final shape in the aorta, than the stent-graft is deformed to fit into the
delivery system. When the prosthesis is in place, the delivery system is opened
gradually and the graft is so exposed to the body temperature and due to this it
recovers the shape that was previously given (fig. 3.13).
Fig. 3.13 A detail of the
upper part of a delivery
system. After the hooks are
opened by the surgeon and
the hooks on the proximal
part of the graft are seated
into the wall of the aorta
there is no chance to change
the position of the
prosthesis.
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In the prosthesis with balloon (fig. 3.14) the balloon is coaxial with the graft within
the delivery system, it is positioned across the attachment site and inflated by the
surgeon to expand the stent against the aortic wall. The lower attachment system is
then deployed immediately proximal to the bifurcation of the iliac arteries. The
balloon is positioned across that attachment site, and the hooks are seated at that
point.
Fig. 3.14 Two steps of the inflating procedure of a stent with balloon; configuration of the
stent at the moment of insertion (left), inflated configuration (right).
It is even possible to find prostheses that use both shape memory alloys and balloons;
the latter to better adapt the stent-graft to the aortic wall in the attachment sites.
A completion angiogram is then obtained to make certain that the graft is properly
seated and there is no evidence of flow between the graft and the aneurysm.
In the case of the bifurcated graft, initially a wire that is connected to the contralateral
limb of the graft is passed up the ipsilateral side, captured with a snare, and drawn
into the contralateral side. The graft/catheter delivery system is then advanced over a
guidewire, and a jacket that covers the graft is retracted, thus allowing the two limbs
of the graft to separate. The graft is then brought down and appropriately positioned
with the proximal attachment system immediately below the renal arteries and each
iliac graft limb in their appropriate ipsilateral and contralateral iliac arteries. The
attachment systems are then sequentially deployed, and each attachment system is
seated with inflation of a balloon catheter. Once completed, the opening of the
femoral artery(-ies) is repaired.
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The femoral incision sites are closed, and the patient is returned to the recovery room
for initial observation. Following that, the patient is sent to a regular hospital bed for
an overnight stay. The following morning the patient is discharged from the hospital.
A return visit is accomplished within the first week, when a repeat CT scan and plane
abdominal films are obtained in order to make certain that the graft is functioning
properly. The femoral incisions are usually well healed within one to two weeks, and
the patient returns to normal physical activity.
Step by step EVR procedure
Here a step-by-step explanation of the implantation of a stent-graft is given. The
example is based on the use of the AneuRx stent-graft, but with the exception of
few details (for instance the configuration of the radiopaque markers) the procedure is
absolutely general.
1. Insertion of the primary stent
graft delivery catheter into the
vessel, maintaining continual
fluoroscopy for proper
positioning above the renal
arteries. Traction or a slow pull
on the wire is essential to
facilitate device tracking.
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2.This kind of stent has a special
cone shaped part to help the
surgeon during the deployment.
The catheter’s nose cone has to
be placed at, or immediately
above, the renal arteries. The
crosshole of the nose cone
should appear fully round when
aligned. The top three
radiopaque markers have to be
positioned towards the
contralateral side.
3. In this phase the graft cover
is retracted 2-3 cm until it is
possible to see the four
proximal radiopaque markers.
It is essential to watch for
possible movement via
fluoroscopy.
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4. Small rotational adjustments
with the delivery catheter can
still be made in this phase to
align the radiopaque markers.
An angio check via the
contralateral straight catheter
should be performed in order
to confirm the position of the
stent graft relative to the
lowest artery. After the
adjustments the straight
angiographic catheter has to be
pulled back into the abdominal
aortic aneurysm.
5. The retraction of graft cover
continues until this is just
below the distal radiopaque
marker. This position is crucial
and must be carefully checked
with fluoroscopy to assure safe
deployment.
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6. Insertion of the cotralateral
delivery catheter into the
sheath. This phase requires
good experience, actually the
delivery catheter has to be
inserted well into the gate area
and this is an area that is
perpendicular to the images’
plane (the area is seen as a line
on the video).
7. The delivery catheter must
be aligned within the four
radiopaque markers of the pant
leg in the mid- or upper
portion of the gate.
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8. The deployment of the stent
graft has to be executed under
continuous fluoroscopy, watching
carefully for any position changes.
Deployment of the iliac leg
continues until the graft cover is
just below the distal radiopaque
marker on the iliac leg.
9. Deployment completed.
Accurate and secure proximal
and distal attachment must be
ensured to prevent endoleak
formation.
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3.4 Drawbacks and follow up
Open surgery
The main drawbacks of the classic operation are the need for laparotomy, general
anesthesia, a hospital stay of 7-10 days, intensive care facilities and blood
transfusions. Despite the use of risk-factor determination, surgical repair of AAA is
still associated with unexpected peri- and post-operative complications.
Some of the reasons why the classical operation of resection and prosthetic
engraftment are associated with a significant morbidity in high-risk patients include
the following:
 Aortic aneurysmectomy is a major surgical intervention requiring extensive
retroperitoneal dissection
 Blood loss may be significant during the procedure
 Access is needed through a full-length laparotomy incision extending from
the xiphisternum to the pubis. This predisposes to important fluid losses and
hypothermia during the procedure
 Clamping and declamping of the aneurysm neck result in hypo tension
associated with major haemodynamic disturbances
 Respiratory problems associated with general anesthesia and major surgery.
The results of conventional surgical repair of AAA are durable and the danger of
rupture is eliminated, these aspects are fundamental to understand why this kind of
operation is still performed and is often preferred to the endovascular procedure.
Moreover EVR of AAA is currently still considered an investigational technique
under validation worldwide and results of long-term studies and outcome are slowly
becoming available.
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EVR
The Achilles heel of EVR is the development of procedural, peri-procedural or late
endoleaks and endotension (when aneurysms grow even in absence of any detectable
endoleak) due to anatomical factors. An endoleak refers to incomplete sealing of the
stent allowing back bleeding into the paraprosthetic space. The incidence varies from
7-10% in major series, unfortunately the need for additional interventions to seal the
leaks increases the cost \ benefit ratio of EVR of AAA [Don F. du Toit, 1999].
Before analyzing these important drawbacks of the endovascular procedure, it is
useful to distinguish four different types of endoleak.

Endoleak Type I: flow between the stent-graft and the wall of the aneurysm
related to the graft device itself (fig. 3.13).

Endoleak Type II: retrograde flow from collateral branches, this leak appears
to have a greater tendency to seal by spontaneous thrombus (fig. 3.14).

Endoleak Type III: due to fabric tears, graft disconnection or disintegration
(fig.3.15).

Endoleak Type IV: flow through the graft presumed to be associated with
graft wall “permeability\porosity” (fig. 3.16).
Type Ia
Blind
end to
end
Type Ib
With
drainage
Fig. 3.13 Perigraft-leaks
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Type IIa
Type IIb
Blind
end to
end
With
drainage
Fig. 3.14 Collateral leaks
Type III
Fig. 3.15 Mid-graft leak
Type IV
Fig. 3.16 Graft-porosity leak
Endoleaks
The definition of initial technical success with endovascular techniques in the
management of aneurysms includes complete exclusion of the sac, reduction of intraaneurysm pressure, restoration of normal blood flow and prevention of rupture. The
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fixation points at the ends of a stent-graft must be in complete apposition with the
normal vessel wall without thrombus interposition to achieve these goals. If this is not
achieved, sealing at the fixation points will be incomplete or temporary [J. C. Parodi
et al., 2001]. Endoleaks have been reported in 7% to 37% of endovascular aortic
aneurysm repair [B. Marty et al., 1998].
An endoleak involves the failure of complete exclusion of the aneurysm with the
persistence of elevate pressures within the aneurysm sac. The flow due to an endoleak
may be caused by an incomplete seal at the graft ends or, between segments, by
thrombus interposition, by incomplete deployment, or by inappropriate sizing.
Finally, endoleaks that are not graft related may be seen with retrograde flow from
patent lumbar or inferior mesenteric arteries.
The presence of endoleaks without enlargement and, conversely, enlargement without
demonstrable endoleaks allow us to justify the concept of aneurysm sac
pressurization as a real cause of enlargement, ultimately leading to aneurysm rupture
[J. C. Parodi et al., 2001].
Two factors produce pressurization inside the sac:
1.
pressure inside the endograft that is transmitted by pulsation inside a semi-
rigid container (the aneurysm sac);
2.
the intra-abdominal pressure.
The presence of an endoleak causes a significant increase in aneurysm pressure (mean
pressure and diastolic pressure), the extent of which is directly proportional to the
endoleak size, even a small size endoleak causes considerable pressure in the sac,
which in the clinical settings could lead to aneurysm rupture.
La Place’s law dictates that the wall stress of an artery is proportional to the radius
and intraluminal pressure and inversely proportional to wall thickness. This concept
predicts that increasing blood pressure or sac diameter should increase wall tension
and also the risk of rupture.
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Endoleaks are usually situated at the proximal stent attachment site and produce a
small perigraft channel with outflow through a partially thrombosed aneurysm sac [J.
C. Parodi et al., 2001]. The pressure in the thrombus remains low, but at the distal
end, the pressure level suddenly increases up to systemic level and pulsatility
immediately.
The addition of extra human fibrinogen into the aneurysm sac prohibits the formation
of thrombus inside the aneurysm.
An open endoleak produces a mean pressure inside the aneurysm identical to that in
the systemic circulation. This level of aneurysm pressure is independent of the size of
the endoleak. As soon as the endoleak thromboses, the mean aneurysm pressure
declines to zero.
The belief that large endoleaks are more dangerous than small ones might be
explained not by the higher pressure but by the presence of pulsatile pressure [G. W.
H. Schurink et al., 2000].
In conclusion, an open endoleak results in systemic mean pressure inside the sac. If
the aneurysm is not thrombosed, pulse pressure is present within the sac, but the
magnitude depends on the diameter of the endoleak.
Pulse pressure is absent within the sac when it is completely or partially thrombosed.
A thrombosed endoleak (endoleak in presence of thrombus that occludes the
bleeding) results in a decrease in mean pressure and the absence of pulse pressure in
the sac. The pressure decrease is more evident for small endoleaks.
Successful embolization of an endoleak by Histoacryl glue or Gelfoam reduces the
mean pressure in the sac and may be a useful therapeutic option when there is
progressive aneurysm growth [G. W. H. Schurink et al., 2000].
Endotension
Endotension has been recently described and defined as a persistent or recurrent
pressurization of the aneurysm sac after endovascular repair.
Transmission of pressure through thrombus or artheroma at the proximal attachment
site is a possible mechanism of endotension.
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It has been proposed that endotension may account for cases of aneurysm rupture in
the absence of endoleak and that aneurysms that enlarge or fail to decrease in size
may remain pressurized [C. S. Skillern et al., 2002].
Although the concept of endotension seems logical, it has not yet been shown
experimentally.
The mechanism for the endotension appears to be the transmission of aortic pressure
to the aneurysm sac through the attachment site failure.
The presence of endotension within the aneurysm sac after endovascular AAA repair
may signify treatment failure and risk of aneurysm rupture. Rupture may not lead to
catastrophic haemorrhage if the proximal and distal stent graft attachment sites
remain secure. However, endotension may also be the result of a sealed Type I
endoleak, and rupture could have disastrous consequences in that situation.
Pressure transmission may be related to porous graft fabrics. Also, graft materials
have previously been responsible for the local production of serous fluid by
transudation through a polytetrafluoroethylene (PTFE) graft used at open AAA
repair.
The mechanism for aneurysm enlargement remains unclear, but it is postulated to be
due to pressure transmission through thrombus after endoleak thrombosis [C. S.
Skillern et al., 2002].
Anatomical factors
Because of peculiar aneurysm anatomy detected in 70-80% of cases [Don F. du Toit,
1999], not all aneurysms can be safely treated by the elective endovascular route.
Moreover, the requirement to customize the device to specific aneurysm dimensions
precludes the use of current devices to large extent in the urgent or emergency
situation. In order to obtain a leak-free attachment, besides a correct sizing of the
prosthesis, it is important to ensure a secure anchorage; two are the critical landing
zones: the proximal and the distal necks. In fig. 3.17 and 3.18 the different
geometrical limitations are shown [Don F. du Toit, 1999].
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Fig. 3.17 Neck region. (A): Renal ostia originating at different levels. (B):
Aneurysmal dilatation at the neck wit suprarenal extension. (C): Short conical
neck. (D): Short neck. (E): Reverse conical neck. (F): Aberrant renal arteries. (G):
Angulated neck and aberrant arteries. (H): Concomitant renal artery stenosis. (I):
Juxtarenal aneurysm formation. (J): Juxtarenal thrombus formation. (K, L, M, N,
O, P): Degree of angulations. (Q): Large aneurysm with intramural thrombus. (R):
Posterior plaque. (S): Ulceration. (T): Thrombus.
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Fig. 3.18 Distal region. (A): Stenosis. (B): Hypoplastic segment. (C): Ipsilateral
occlusion. (D): Intraluminal thrombus, tortuosity. (E): Bilateral angulations. (F):
Thrombus. (G): Unilateral iliac ectasia. (H): Unilateral stenosis, contralateral estasia. (I):
Bilateral common iliac aneurysms. (J): Aorto-iliac stenosis and angulations. (K):
Hypogastric artery occlusions and stenosis. (L): Unilateral short iliac segment and
contralateral angulations. (M): Concomitant iliac aneurysms. (N) : Common iliac
aneurysm and contralateral angulations. (O): Isolated internal iliac artery aneurysm. (P):
Catheter perforation of iliac vessel during intubation.
53