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304 Visceral and renal artery interventions
kidneys move up and down continuously with
the breathing cycle, it is frequently helpful to
have the patient hold their breath prior to angi-
ography but also prior to stent placement itself
so that accuracy of stent placement can be
achieved. Frequently, a deep breath causes too
much displacement and will help to force the
kidneys inferiorly and accentuate the angle of
origin of the renal arteries. Often it is helpful
to have the patient exhale and hold their breath
while in exhalation so that the kidneys are ele-
vated, and this tends to deaccentuate the angle
of takeoff of the renal artery.
e renal arteries tend to egress from the aorta
in a posterolateral direction so it is frequently valu-
able to use an ipsilateral anterior oblique of from 5
to 15 degrees in order to see the renal artery origin.
If the preoperative study obtained is either a CAT
scan or MRA, this can be used to assess the best
angle for visualizing the renal artery origin. Even
though many arteries will be seen in their best
projection by a slight anterior oblique, some arter-
ies do not follow that rule. If the aorta is a little
rotated, as oen occurs in the setting of infrarenal
aortic aneurysm, one artery may even originate a
little bit anteriorly.
Systemic heparin is administered. A 6-Fr
sheath or 8-Fr guide catheter is advanced over
the guidewire (Figure 22.6). A guiding sheath
or catheter is selected that best fits the angle and
curvature of the renal artery origin. There are
numerous shapes, specially designed for renal
artery intervention, which are available through
different companies (Figure22.7). The tip of the
sheath is soft and radiopaque. The transition
from dilator to sheath is smooth, and the dis-
tance that the dilator extends beyond the sheath
is very short. This permits the tip of the sheath
to be placed within the renal artery without a
long segment of leading dilator tip advancing
into the distal renal artery. A guiding sheath
with a 6-Fr or 7-Fr shaft and a 45-cm length is
adequate. If a guide catheter is selected, it may
have an IMA shape, a RDC shape, or some other
curve. The tip is curved but somewhat flexible.
A guidewire is advanced through the guide
Fig. 22.6 Balloon angioplasty
of the renal artery. (A) The
left renal artery is cannulated
with a Cobra catheter and the
guidewire is advanced across
the stenosis. (B) An angio-
plasty balloon is advanced
over the guidewire and across
the lesion. In this case, the
lesion is in the mid-renal
artery, as might be seen with
fibromuscular dysplasia or,
occasionally, with atheroscle-
rosis. (C) Balloon angioplasty
of the left renal artery is
performed. (D) A completion
renal arteriogram is obtained
by injecting contrast through
the guiding catheter or guid-
ing sheath. In this case, with a
mid-renal artery lesion, if the
result of angioplasty is accept-
able, no stent is required.
A
C
D
B
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Renal angioplasty and stenting 305
catheter. When the tip of the catheter falls into
the orifice of the renal artery, the guidewire is
advanced (Figure 22.8). If this is an unfavor-
able angle, another option is to place a C2 Cobra
catheter or other appropriate curved tip catheter
and use one of these catheters to cannulate the
renal artery. The renal artery is cannulated, the
0.014-inch guidewire advanced across the lesion
and into the distal renal artery, and the guide
catheter tip placed close to the lesion. The guide-
wire choice should be one that has a relatively
stiff body across the location of the lesion and
also a f loppy wire tip so that injury to the renal
parenchyma can be avoided. Care must be taken
to avoid inadvertently advancing the wire into
the parenchyma and causing a kidney injury.
Another option for access to the renal arteries is
the steerable sheath (Figure22.4). This is espe-
cially useful if the angle of origin of the renal
artery is acute and necessitates a more angulated
turn to achieve access.
A critical orifice lesion may make it difficult
to enter the renal artery. This is the case with
the vast majority of atherosclerotic renal artery
lesions. In this case, the steerable guidewire tip
must be used to gently probe the origin of the
artery. After the guidewire traverses the lesion,
it is advanced into a secondary branch. This is
done to maintain as much purchase on the artery
as possible. However, the guidewire should not
be forced or advanced against resistance because
it can perforate the parenchyma. Another option
is to use the “no touch” technique. The sheath is
advanced into the aorta in the proximity of the
renal artery (Figure22.9). A stabilizing guide-
wire is placed, which protrudes into the aorta
and lays against the wall of the aorta to hold the
tip of the sheath in a steady position. Through
the tip of the sheath, the renal artery lesion is
probed with a directional guidewire and crossed
with the least amount of trauma.
A selective catheter is passed over the guide-
wire into the renal artery if selective arteriog-
raphy or pressure measurements are required or
if a different guidewire is desired over which to
perform stenting. Nitroglycerine may be admin-
istered through the catheter to help prevent
renal artery spasm. Attempting to assess the
hemodynamic significance of the renal lesion
by measuring pressure across it can be challeng-
ing. It is not well understood if a pressure drop
across the lesion is significant and how much of
a drop there has to be to represent a physiologi-
cally significant change. In addition, when mea-
suring the pressure using a 4-Fr or 5-Fr catheter,
there may be some decrease in pressure because
of occupation of the residual lumen of the renal
artery by the pressure measuring device. In
order to accurately measure pressure, it means
potentially crossing the lesion more than once
by placing the pressure measuring catheter
across the lesion and then withdrawing it. As the
kidney loses its ability to vasodilate distal to the
stenosis, it may become more resistive. This will
tend to equalize the pressures proximal and dis-
tal to the lesion and this may explain why some-
times an apparently significant appearing lesion
has a less than significant pressure drop across
it. Likewise, with vasodilating agents, if the kid-
ney is physically unable to vasodilate any further
than it already is, this will lead to a less dramatic
hemodynamic response than one would antici-
pate based on the severity of the lesion. Another
option for pressure measurement is to use a pres-
sure wire, since the wire itself takes up less space
and obstructs the lumen less than a 4-Fr or 5-Fr
catheter.
Aer these maneuvers, a guidewire is inserted
into the catheter and across the lesion for treat-
ment. Keeping the guidewire in the correct place is
a challenge throughout the remainder of the pro-
cedure. Every maneuver tends to move the guide-
wire and tension builds up around the sharp turn
is so close that only a short length of relatively so
A
B
C
Fig. 22.7 Access for renal artery intervention.
Renal guiding sheath tips are shown here. These
sheaths have a hemostatic valve, a side arm, and
a dilator and are used for progressively more
acutely angled renal arteries.
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306 Visceral and renal artery interventions
(atraumatic) guidewire can be maintained within
the artery.
e guiding sheath or catheter may be advanced
close to but not into the lesion over the selective
catheter and guidewire. Prior to stent placement,
predilation may be performed using a 2–4 mm
balloon to create a tract for stent delivery. e
angioplasty balloon is usually 2 cm in length and
has low-prole features with a monorail system.
Aer balloon angioplasty, the guiding sheath or
A
B C
D
G
E F
Fig. 22.8 Balloon angioplasty and stent placement through a guiding sheath. (A) A guidewire and
guiding sheath are placed in the aorta. (B) The dilator is removed. (C) A selective catheter, such as a
C2 Cobra, is placed through the sheath and into the renal artery. Guidewire access across the lesion is
obtained. (D) The balloon catheter is advanced through the guiding sheath and over the guidewire. The
tip of the guiding sheath is maintained in proximity to the renal artery origin. It is often helpful to advance
the sheath a little bit to support the passage of the balloon and stent catheter and keep the platform
stable. (E) A premounted, balloon-expandable stent is placed at the location of the lesion. (F) The stent is
placed with balloon inflation. In general, because it is usually aortic plaque that is “spilling over” into the
renal artery, it is desirable to place the stent so that its leading end protrudes into the aorta by 1–2mm.
(G) Poststent angiography is performed through the sheath while maintaining guidewire access.
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Renal angioplasty and stenting 307
guiding catheter may be gently advanced using the
angioplasty catheter for support, especially if the
sheath had to be withdrawn a little bit in order for
the balloon to be inated. e balloon catheter is
removed. Aer the stent is placed on the wire, it
is advanced into position. It is quite commonly a
challenge getting the stent across the lesion and
forceful advancement when the stent is not going
easily may force the guidewire and/or guide cath-
eter to back up in an undesirable way. is is where
system stability is important to permit the opera-
tor to push when needed and obtain acceptable
results. Contrast is pued from the sheath to reas-
sess the landmarks for correct placement. Because
the premounted stent and its catheter may ll the
lesion, there may not be any lling of contrast into
the artery past the stent until the stent is deployed.
However, the contrast should pu around the ori-
gin of the artery and give an identication of the
location of the stent at the origin of the renal artery.
When the stent is appropriately positioned, it is rap-
idly deployed and, aer deployment, the balloon is
deated. is is usually best done with the patient
holding their breath in a manner similar to that
which allowed the best image on angiography. e
same balloon is used to expand and are both the
proximal and distal ends of the stent. Occasionally,
a slightly larger balloon is used to are the proxi-
mal end of the stent in the aorta. In doing this, it is
best to apply a little bit of forward pressure on the
sheath to support the balloon in the trajectory that
works best for the stent (Figure22.10).
e stents used for the renal arteries range
in length from 12 mm to 30 mm and in diam-
eter from 4 mm to 7 mm. e tendency by eye is
to overestimate the length of the stent required.
esestent delivery catheters are 0.014-inch com-
patible, monorail system devices. e very low
prole helps the stent to make the turn from the
aorta into the renal artery and to cross a lesion
that may have a very narrow residual lumen. e
low-prole nature of these stents also permits
administration of contrast around the stent deliv-
ery catheter while in the sheath and just prior to
deployment. In general, the shortest length stent
that will cover the lesion should be deployed. If
the renal artery has substantial tortuosity, the stent
will straighten a segment of the artery, leaving all
the curvature over a shorter segment of remaining
nonstented vessel. is can inadvertently create
an undesired kink in the artery. Eorts should be
made to avoidthis situation. e monorail system
also oers other advantages. A shorter wire is used,
usually 180cm. e operator controls the wire at
the hub of the sheath instead of at the end of the
wire, which is somewhere distant from the hub.
Since the end organ is so close to the lesion, only a
short distance is available distal to the renal artery
stenosis and proximal to the renal parenchyma. In
this setting, maximum wire control is desirable.
A nal diameter of 6 mm or more is desired.
e balloon and mounted stent are advanced
through the sheath and across the lesion. e
guiding sheath is gently withdrawn to uncover the
back end of the stent. e stent is placed so that
the aortic end is deployed to treat the aortic plaque
as it spills over into the renal artery, usually about
1 mm into the aortic ow stream. Aortic wall cal-
cium deposits oen provide a good landmark for
this deployment. Ination is observed using uo-
roscopy and may cause ank pain. Completion
arteriography is performed through the sheath.
A B C
Fig. 22.9 No touch technique. (A) The guiding sheath or guiding catheter is stabilized by passage of a
guidewire that leans on the side wall of the aorta. (B) The tip of the sheath is stable and avoids direct
encounter with juxtarenal aortic disease. A 0.014-inch guidewire is passed through the same access
and into the renal artery. (C) The premounted stent delivery catheter is advanced into position.
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308 Visceral and renal artery interventions
Aer ination of a balloon-expandable stent, the
balloon occasionally becomes stuck. If this occurs,
do not yank the catheter. Deate the balloon fully,
then advance the catheter a little to dislodge it
from the deployed stent. If the balloon is dicult
to withdraw from the stent, advance the tip of the
sheath close to the end of the stent to support the
stent during balloon removal so that its position is
not loosened by catheter withdrawal.
Smaller caliber guidewire systems have the
advantages of crossing critical lesions with lower-
prole guidewires, permitting balloon angioplasty
with a very low-prole balloon, and allowing com-
plex intervention through smaller caliber sheaths.
e disadvantages are that they are not as radi-
opaque and provide less support than a 0.035-inch
system.
At some point, it may be appropriate to perform
renal stenting with distal protection devices in
order to limit distal embolization. ere are dis-
advantages of the existing distal protection devices
as applied to renal stenting. None of the currently
available protection devices have a short enough
landing zone to be adequate for most renal arteries.
A B C
D
E
Fig. 22.10 Poststent placement balloon angioplasty. (A) The balloon-expandable renal artery stent is
placed by expanding the balloon on which it is premounted. The sheath must be withdrawn enough
to allow the balloon to expand. (B) When the balloon is deflated, it can be caught on the stent and
there may be resistance when attempting to remove it. To allow this to occur more smoothly, the
sheath tip is advanced along the wire so that the sheath itself can support the stent and prevent it
from migrating. (C) The balloon is withdrawn slightly and positioned so that it can be used to flare
the proximal end of the stent or at least perform a repeat angioplasty in the area where the disease
is typically worst, which is at the origin of the artery. In this setting, after the balloon is positioned in
the origin of the stent, the sheath must be withdrawn slightly to allow room for the balloon to expand.
The tip of the sheath is used to support the balloon. (D) In patients with a severely downsloping
renal artery, as in this situation, the wire is biased during stent placement and can significantly affect
the position of the stent and the ability to perform poststent placement balloon angioplasty. In this
example, with a downsloping left renal artery, there is significant curvature of the wire as it enters the
renal artery. When the sheath is advanced all the way to the stent, the curvature can become worse.
(E) When performing poststent placement balloon angioplasty in this setting, the balloon can be
advanced so that it is positioned to dilate the proximal end of the stent. The sheath is advanced so
that it can support the tilting of the balloon to accommodate the downsloping left renal artery and
the left renal artery stent during balloon dilation.
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Renal angioplasty and stenting 309
Most of the existing devices are based on guide-
wires that are not sti enough to be stable in the
setting of the acute turn from the aorta into the
renal artery, as is required.
Recurrent renal artery stenosis is dicult to
assess on plain angiography. e best way to evalu-
ate the degree of stenosis in this situation is with
IVUS. Treatment options for recurrent renal artery
stenosis are standard balloon angioplasty, repeat
stenting, cutting balloon angioplasty, drug-coated
balloon angioplasty, or a combination of these.
Covered stents may also be used if the caliber of
the artery is adequate to accept the slightly higher
prole of the covered stent.
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311
23
The infrarenal aorta, aortic bifurcation,
and iliac arteries: Advice about balloon
angioplasty and stent placement
INTRODUCTION
Stents have had a profound impact on the man-
agement of atherosclerotic occlusive disease of the
aortoiliac segment and open surgery for aortoiliac
occlusive disease has decreased signicantly over
the past 10 years. e long-term results of endo-
vascular intervention are not quite as good as with
open surgery, but they are reasonable and continue
to improve. At the same time, morbidity and mor-
tality appears to be much less with endovascu-
lar procedures than with open procedures of the
aortoiliac segment. Endovascular approaches are
being deployed for many patients with TASC D
lesions. e long-term success of aortoiliac inter-
vention is closer to the results of open surgery than
with any other endovascular intervention. In addi-
tion, the short-term risk of percutaneous interven-
tion is so much less than with open surgery that
endovascular approaches have become the treat-
ment of choice for most patients. Open surgery is
reserved only for patients who have failed endo-
vascular intervention or in whom a percutaneous
approach is not technically feasible. Chapter 9 pro-
vides a step-by-step approach for crossing the aor-
tic bifurcation. Chapter 11 provides information
about aortoiliac arteriography. Supplies for aortoil-
iac intervention are listed in Table 23.1. Aortoiliac
occlusive disease is usually treated with coaxial
catheters on a 0.035-inch platform. Most aortoiliac
lesions can be treated using 6-Fr or 7-Fr sheath
access. Covered stents may require an 8-Fr access.
Stent–gra components, such as those needed to
treat aneurysmal disease, require sheaths in the
range of 12-Fr to 16-Fr.
AOR TA
Lesions of the aorta that are indicated for treat-
ment are usually treated with a stent. Isolated,
focal stenoses of the infrarenal abdominal aorta
oen respond to balloon angioplasty alone, and
this approach has reasonable long-term success,
but stent placement has even better results over the
long run (Figure 23.1). e availability of stents
has also permitted the treatment of more complex
lesions with endovascular intervention. If the aorta
is suspected as a source of emboli, a covered stent
or stent–gra should be considered. Stents provide
an opportunity to approach lesions that would
not be expected to respond to balloon angioplasty
alone. Aortic lesions that extend to the bifurcation
also require kissing stents placed through each
iliac artery. Ideas, concepts, and tools are currently
being developed for complete reconstruction of the
aortoiliac segment with stents or covered stents or
a combination of these.
Lesions that are limited to the infrarenal aorta
may be accessed through a unilateral femoral
approach on either side. Lesions of the aorta that
extend near or into the aortic bifurcation should be
accessed with a guidewire placed through each iliac
artery. is is discussed in more detail in the next
section. If there is coincidental, nonbifurcation,
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312 The infrarenal aorta, aortic bifurcation, and iliac arteries
unilateral iliac disease that also requires treat-
ment along with a separate aortic lesion, the access
should be ipsilateral to the iliac lesion. is per-
mits treatment of both the aortic and iliac lesions
through the same approach without passing guide-
wires and sheaths over the aortic bifurcation.
Retrograde passage of the guidewire is per-
formed from the femoral puncture site and an
aortogram is acquired using a ush catheter.
Aer appropriate arteriography is completed and
the decision made to proceed with treatment,
50–75 U/kg of heparin is administered. e opera-
tor may consider a larger bolus of heparin when
treating very complex or embolizing lesions or
preocclusive stenoses, or if longer indwelling cath-
eter times are anticipated. e catheter is removed
and an appropriately sized sheath placed through
the femoral entry site (Figure 23.2). If there is sig-
nicant tortuosity, the lesion is very complex, or
a large sheath is anticipated, the operator should
consider placing an Amplatz Super Sti
®
exchange
guidewire to provide extra support during the
intervention. Standard length hemostatic access
sheaths of 10–13 cm may be used for simple balloon
angioplasty and placement of stents. However, it is
also useful to consider a 30- or 45-cm sheath with a
radiopaque tip to treat aortic lesions. Interval arte-
riography may be performed through this type of
sheath, with contrast administered in proximity to
the target lesion site. e size of the sheath depends
on the intended diameter to which the aorta is to be
dilated and whether a stent will be placed. Balloon
angioplasty may be performed up to 10-mm
diameter using a 5-Fr catheter sha through a
6-Fr sheath. Self-expanding nitinol stents up to
14 mm in diameter can also be placed through a
6-Fr sheath. Dilation to 12 or 14 mm is performed
using a 5-Fr catheter sha through a 7-Fr sheath.
A 9-Fr sheath is required for 16–20-mm balloons.
Balloon-expandable stents up to 9 or 10 mm in
diameter may be placed through 7-Fr sheaths.
A9-Fr sheath is required for balloon-expandable
Table 23.1 Supplies for aortoiliac intervention
Length Diameter
Guidewire Starting guidewire Bentson 145 cm 0.035 inch
Selective guidewire Glidewire
®
150 cm 0.035 inch
Exchange guidewire Amplatz Super Stiff
®
180 cm 0.035 inch
Catheter Flush catheter Omni
®
Flush 65 cm 4-Fr
Selective catheter Angled glide catheter 65 cm 5-Fr
Exchange catheter Straight 70 cm 5-Fr
Sheath Access sheath Standard hemostatic access 12, 13 cm 6-Fr, 7-Fr, 9-Fr
Straight sheath Long straight with radiopaque tip 30, 35 cm 7-Fr, 9-Fr
b
Selective sheath Over bifurcation 45, 55 cm 6-Fr, 7-Fr
Balloon Balloon angioplasty
catheters
Balloon diameter 6, 7, 8, 10, 12,
14, 16, 18 mm
Balloon length 4–10 cm
Catheter shaft 75 cm 5-Fr
Stent
a
Balloon-expandable Stent diameter 6–22 mm
Stent length 25–50 mm
Delivery on 75-cm-length
angioplasty balloon catheter
Self-expanding Nitinol stent diameter 8–14 mm
(covers most)
Stent length 40, 60, 80,
100 mm
Delivery catheter length 80 cm
a
A 9-Fr or 10-Fr sheath is used to introduce large diameter balloons for aortic angioplasty (>12-mm diameter) or a
Wallstent
®
larger than 14 mm.
b
A 9-Fr sheath is used to introduce a large Palmaz™ stent (P308) for diameters of 10–12 mm.
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Aor ta 313
stents up to 12 or 14 mm. Larger diameters require
10-Fr or 12-Fr sheaths. Self-expanding stents larger
than 14 mm require 9-Fr sheaths. Sheaths for cov-
ered stents vary from 6-Fr to 9-Fr in caliber. It is
best to place the sheath or sheaths required for
treatment as soon as the decision is made to pro-
ceed with treatment.
Aortic angioplasty is performed with balloons
ranging from 8 to 18 mm in diameter. Sizing the
intended diameter of the aorta may be challeng-
ing because of the broad range of potential sizes,
but there are several options. A ush catheter with
1-cm markers may be used for the aortogram, and
the known distance between markers may be used
to calculate the desired diameter of the aorta for
angioplasty. If IVUS is available, this probably
provides the most accurate representation of ves-
sel diameter. IVUS requires an 8-Fr sheath for a
large diameter vessel probe. Another method is to
proceed with balloon angioplasty using a balloon
that is an underestimation of the probable aortic
diameter and compare the inated balloon prole
with the preintervention aortogram. e selected
balloon is advanced over the guidewire and into
position using externally placed or bony markers.
e balloon is inated under uoroscopy.
e aorta may rupture at lower pressure than
smaller diameter vessels, so ination is performed
A B
C D E
Fig. 23.1 Endovascular approaches to aortic lesions. (A) A significant but focal lesion is isolated within
the infrarenal abdominal aorta. (B) Balloon angioplasty of the aortic lesion is performed. (C) This more
extensive lesion involves the infrarenal aorta and its bifurcation. (D) The lesion is approached by plac-
ing a guidewire retrograde through each femoral artery. (E) Balloon angioplasty is performed in the
aorta and kissing balloons are used to dilate the bifurcation.
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