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184 Crossing challenging lesions
Popliteal artery occlusions
Popliteal artery occlusions are oen shorter than
SFA occlusions because of the short length of the
popliteal artery. However, they can be challeng-
ing. ere are numerous perigenicular collaterals
originating from the popliteal artery, which the
guidewire will attempt to enter instead of travers-
ing the lesion. Popliteal artery occlusions, which
also include the tibial trifurcation, are particularly
dicult to deal with. It is rare to be able to get the
guidewire to go into a named tibial vessel from an
antegrade direction in this setting. In this case, a
retrograde puncture of a tibial vessel is particularly
useful for access. e retrograde guidewire is much
more likely to follow the true path of the artery.
Popliteal artery lesions also frequently have so
spots. One of these is right at the knee joint at
the mortise between the femur and the tibia. e
adductor canal is particularly highly calcied and
this is frequently where an occlusion will initiate
and can be dicult to cross.
Tibial artery occlusions
Tibial artery occlusions are usually best to cross in
the intraluminal space. Using 0.014-inch diameter
guidewires with supporting CTO catheters is usu-
ally best. An angled catheter is placed at the origin
of the artery if needed to direct the wire. is is
usually required for the anterior tibial artery and
occasionally for the peroneal and posterior tibial
arteries. e CTO guidewire with a small bend
at the tip is advanced into the occlusion with the
support of the CTO catheter. e wire is rotated
rapidly by the operator to try to make its way
through the lumen, usually several revolutions in
one direction and then several revolutions in the
other direction. e wire is advanced slowly while
rotating rapidly. As the wire progresses it is usu-
ally possible to see the outline of the artery due to
the medial calcication that frequently aects the
tibial vessels. If the advancing wire gets to a point
where no additional progress can be made, there
are several options:
●
Pull the wire back slightly and then readvance
while drilling. Sometimes, it goes into a more
favorable plane.
●
Another option, which is sometimes help-
ful, is to perform a low-prole angioplasty
of the territory that has been gained so far.
Itis particularly dicult to advance through
an occluded tibial if the popliteal artery is
also occluded and there is friction along the
advancing wire for a long distance.
●
Another option is to switch to a stier wire or a
stronger support catheter.
●
Yet another option is to advance the wire until
it forms an elbow, and push it into the subinti-
mal space.
If your best maneuvers fail, consider a dis-
tal puncture of that tibial artery at the ankle or
foot level. Frequently, to achieve arteriography of
thedistal end of the occlusion the contrast must be
administered at the perigenicular level so that the
reconstituted segment will be opacied by collater-
als from other tibial vessels. It is usually not pos-
sible to recanalize a tibial artery if that particular
vessel has no visible runo. For example, if the
dorsalis pedis artery is also occluded, it may not be
worth attempting to cross the anterior tibial artery.
If the common, medial, and lateral plantar arteries
are occluded, it may not be worthwhile crossing
the posterior tibial occlusion. It should be noted
that understanding the aforementioned concept is
a work in progress, since sometimes the “appar-
ently” occluded dorsalis pedis or plantar artery can
be reopened. It is sometimes dicult to understand
the orientation of the vessels in dierent projec-
tions and it is possible to mistake a reconstituted
segment of one artery for another. It is usually best
to view the segment from the tibial artery origins
to the ankle in anterior and lateral projections in
order to visualize the unfolding of the tibial path-
way. e anterior projection is more helpful for
understanding the proximal tibial anatomy and
thelateral projection is better for understanding the
distal tibial anatomy. In the anterior projection, the
anterior tibial artery begins its course quite laterally
but then passes toward the middle. It passes over
the top of the peroneal artery. e posterior tibial
artery maintains its course medially.
WHEN TO APPROACH FROM THE
OTHER DIRECTION: RETROGRADE
ACCESS (
FIGURE 16.6)
e answer to this question varies from one type
of occlusion and anatomic location to the next.
ere are only a few areas where there is no option
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When to approach from the other direction: Retrograde access 185
for approaching the occlusion from the other
direction. e superior mesenteric artery and the
renal artery are the only examples where this is
the case. A “retrograde” approach in these vessels
would require an open exposure. is is because
they serve as an end organ. ere are options
for addressing each type of occlusion using an
approach from the direction opposite the one
that the operator rst selected. e key thing is to
obtain a high-quality angiogram prior to starting
and to look and see if one end or the other of the
occlusion can be approached simply and easily
from a direction where there is enough working
room and the possibility of a stable platform. In
the case of an iliac or SFA ush occlusion, it may
be challenging to enter proximally and remain
in the true lumen. In some cases, the distal cap
may be a lot soer than the proximal cap of the
occlusion; this is oen the case for SFA and popli-
teal artery occlusions. For tibial occlusions, if the
wire from above is subintimal, it may not be pos-
sible to re-enter the true lumen, and an approach
from the opposite direction via pedal puncture
may make traversing the occlusion possible. In
each case, approaching the occlusion from both
ends or opposite ends should be included as pos-
sible strategies. Usually, the operator picks an
approach, and when the maneuvers from that
direction are unsuccessful, the second access is
added.
A B C D
Fig. 16.6 When to approach from the opposite direction. (A) SFA occlusions are approached from
an antegrade direction. In this example, guidewire passage is not possible and the wire soon buckles
and loses directionality. (B) The operator purposely directs the angled catheter toward the inter-
face between the lesion and the wall of healthy artery and pushes the guidewire into the subintimal
space. Initially, a loop of wire forms and begins crossing the subintimal space. (C) In this example, the
guidewire again loses directionality. The sheath is advanced slightly for more support. The support-
ing angled catheter is advanced into the subintimal space for more support. Nevertheless, the wire
hits an obstruction, which cannot be crossed, and passes into the periadventitial space. Despite the
best efforts of the operator to redirect the wire, this cannot be accomplished. (D) The proximal wire
is pulled back so that it is in the lesion. A retrograde access is obtained through the distal SFA or
proximal popliteal artery or one of the tibial vessels. An angle tip CTO guidewire is supported by a
low-profile CTO catheter for an approach through the opposite direction.
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186 Crossing challenging lesions
CROSSING CALCIFIED LESIONS
(
FIGURE 16.7)
Calcication presents a major remaining signi-
cant challenge in minimally invasive peripheral
endovascular revascularization. Calcied lesions
are an issue in crossing an occlusion but also an
issue in reconstructing the occluded vessel. In
crossing a calcied artery, it usually does not take
much time to attempt an intraluminal crossing.
In an intraluminal crossing, it is quite common
for the pathway through the true lumen to be
relatively tortuous because of the irregularity
of the calcied lesion. As the guidewire passes
through each turn or bounces o each calcied
plaque, directionality and forward force is lost
as the wire winds its way through dierent turns
inthe lesion. Sometimes, the inner core will be
soer than the operator imagines aer seeing the
lesion on uoroscopy. However, if intraluminal
crossing is not successful, it is oen best to go
around the lesion in the subintimal space. When
progress stalls in crossing a calcied lesion, con-
sider a long low-prole angioplasty balloon and
treat the initial areas of crossing to create some
working room for the guidewire and decrease
friction. Severe and bulky calcication in SFA
lesions can burrow rather deep into the artery
wall, making the subintimal channel a little
more delicate and a little more likely to perforate
with the subintimal wire passage. is rarely has
clinical consequences but may prevent the pro-
cedure from being completed that day. In recon-
struction, calcied lesions of the lower extremity
arteries should be considered for atherectomy.
Directional and rotational atherectomy both
have merit. Tibial vessels seem to respond well
to rotational atherectomy, especially if the lesion
is so calcied that the operator has the impres-
sion that the balloon will not be able to reach full
expansion.
CROSSING REALLY LONG LESIONS
(
FIGURE 16.8)
Crossing long lesions in the lower extremity
(beyond 20 cm) can present new challenges. e
procedure takes longer and the distal ischemia
may be worse than the typical lower extremity
case. Flow in the patent segments of the artery may
be impeded or stopped by the sheath. e patient
should be well anticoagulated. If patients have rest
pain, it may not be possible for them to keep still for
the imaging. For long lesions it is usually not pos-
sible to have the entire lesion, including the proxi-
mal and distal ends of the target lesion, on the same
image. When crossing a long lesion, the operator
typically needs quite a bit of detail about guide-
wire behavior and so the image is usually magni-
ed. e guidewire can usually be manipulated
through the occlusion by advancing the imaging
system in step with the wire advancement. When
nearing the location of reconstitution, additional
contrast administration is performed through the
A B C
Fig. 16.7 Crossing calcified lesions. (A) The
degree of calcification can usually be assessed
using plain fluoroscopy. When a heavily calci-
fied lesion is also associated with an occlusion,
the true lumen for passage may be impossible
to find or may be so irregular, hard, and jag-
ged that no wire can cross it. In this example, a
standard catheter and CTO guidewire approach
a calcified lesion from the antegrade direction.
(B) The guidewire meets resistance and very
rapidly becomes severely kinked. The catheter
is advanced for additional support but it is not
possible to redirect the wire. (C) The wire is
withdrawn slightly to partially straighten it. Alow-
profile balloon catheter is advanced over the
guidewire and early angioplasty of a portion of
the lesion is performed in order to reduce friction
in the hope of supporting further wire advance-
ment. The need for early angioplasty is common
when crossing heavily calcified occlusions.
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What to do after the wire is across 187
sheath to help identify the desired wire trajectory.
In reconstructing these vessels the operator must
have in mind a priority list of which areas to treat,
how to treat them, and in what sequence. Follow
the guidewire with a support catheter. If the guide-
wire becomes damaged, exchange it for a new wire.
Perform angioplasty along the way as needed to
try to create an environment in which the wire can
work without being impinged by lesions through
which it has already passed. Sometimes, it makes
sense to advance a smaller sheath, such as a 4-Fr
sheath, through the initially placed 6-Fr sheath
in order to provide more support at the location
where the wire is attempting to cross the lesion.
Another important issue in dealing with long
lesions is to avoid fatigue associated with a multi-
step procedure.
WHAT TO DO AFTER THE WIRE
IS ACROSS
Very often the guidewire used to cross the lesion
and the guidewire used to treat the lesion are
different. The operator should think through the
type of reconstruction and the size and caliber
required. An adequately sized catheter should be
advanced and the crossing wire exchanged for
the treatment wire. Sometimes, a catheter can-
not be passed and the lesion must be predilated,
even before a treatment wire can be placed. Use a
catheter to place an exchange wire or other wire
that will be used during the entire treatment
phase of the procedure. It helps to understand
what the likely treatment will be prior to plac-
ing the wire. Some modified balloons, such as
scoring balloons, and some covered stents may
require a 0.014- or 0.018-inch wire. Tibial recon-
struction and carotid bifurcation stents require
a small caliber wire. The stent may be suited for
a low-profile or 0.035-inch diameter wire. Once
the guidewire is in place, mark the location of
the end of the wire outside the patient. Preserve
guidewire access across the lesion to avoid los-
ing it. If you advance a treatment device, such as
an angioplasty balloon, and it enters the lesion
but cannot advance all the way to where the
A B C
Fig. 16.8 Crossing long lesions. (A) A sheath has been advanced to near the origin of a long SFA
lesion. The guidewire has been advanced intraluminally using the rotation method. The wire has
been supported in a graduated fashion by a 4-Fr or 5-Fr catheter and a microcatheter. When the
progress of the wire across the lesion stalls, the catheters can be advanced to support the wire and
enhance the opportunity for additional advancement of the wire. (B) If the wire advancement stalls
and catheter support alone will not support further progress, a long, low-profile balloon may be used
to predilate the lesion. This results in a decrease in friction caused by the occlusion and experienced
by the passing wire and devices. (C) After dilation, the 4-Fr or 5-Fr catheter can be advanced again to
support the wire for additional progress across the lesion.
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188 Crossing challenging lesions
artery reconstitutes, begin performing angio-
plasty at the location to which the balloon has
advanced.
ANATOMIC MANIPULATIONS CAN
ASSIST IN GUIDEWIRE OR DEVICE
PASSAGE
External anatomic ma nipulation can be performed
in order to move the orientation of an artery to
obtain a better arteriogram or to pass guidewires
or devices. e carotid artery is particularly sus-
ceptible to this type of manipulation by having
the patient extend the neck or turn the head from
one side to the other. e orientation of the bifur-
cation and the trajectory of its access or eerent
arteries can change signicantly. Whenobtaining
an arch aortogram, if the patient’s head is turned
slightly to the right, this usually helps visualize
both carotid arteries and both vertebral arteries
as separate vessels. When passing a lter capture
catheter through a carotid stent, the catheter may
catch on components of the stent. is can oen
be released by turning the head toward the oppo-
site side. When the arm of the patient lays gently
at the patient’s side in the anatomic position, the
subclavian and axillary arteries usually progress
in a gentle curve from the thoracic cage toward
the arm. When the arm is abducted on an arm
board, the subclavian and axillary arteries may
be quite tortuous and redundant. When advanc-
ing a device over a guidewire through a femoral
A B
C D
Fig. 16.9 Anatomic manipulations that can help in crossing occlusions. (A) When performing upper
extremity access through either the radial artery or the brachial artery, the left arm is typically
abducted at the patient’s side for easy access to the operator. In some patients this position causes
significant tortuosity of the subclavian and axillary arteries as the artery is bunched up in this position.
(B) By adducting the arm and placing the position closer to the patient’s side, this usually stretches
out these tortuous segments into a gentle curve. (C) A distal posterior tibial and common plantar
artery occlusion is demonstrated. With the foot and ankle in the neutral position, the angle of egress
from the occlusion is quite sharp and may be impossible to traverse. (D) Aggressive dorsiflexion of the
ankle into a steep position creates a much more gentle curve of the plantar artery.
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Anatomic manipulations can assist in guidewire or device passage 189
approach and into a tortuous iliac artery, it usually
makes sense to put pressure on the lower quad-
rant or ank of the patient to try and help direct
the passage of the device, especially if it is a large
device such as an aortic stent–gra. By bending
the knee or putting pressure on the popliteal fossa,
the popliteal artery can change conguration sig-
nicantly. If the artery has a signicant plaque
burden, with some segments of the artery being
stier than others, bending of the knee creates
points of more signicant exion along the course
of a diseased popliteal artery. Plantar exion and
dorsiexion can signicantly alter tibial artery
anatomy. Steep plantar exion usually decreases
the angle of origin of the anterior tibial artery. If
the posterior tibial artery is redundant near the
ankle, or there is a lesion with a tortuous segment
leading into it, dorsiexion usually stretches the
artery a bit and makes the trajectory less tortuous.
e same is true for plantar exion that assists in
crossing from the anterior tibial artery into the
dorsalis pedis artery.
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191
17
Balloon angioplasty: Minimally invasive
autologous revascularization
BALLOON DILATION CAUSES
DISSECTION
e force exerted by the angioplasty balloon
mainly enhances the lumen by fracturing the
plaque and changing its shape and the shape of
the vessel. Very little lumen gain comes from
plaque compression. e radial force of the angio-
plasty balloon causes plaque fracture and dis-
section where the heterogeneous plaque forms a
circumferential ring or at locations in the plaque
where there is a junction between soer plaque
and harder plaque (Fig u re 17.1). e pressure
within the balloon is increased until it over-
whelms the tolerance of the plaque that is being
treated. is tolerance depends on the amount
of calcium. When the plaque gives way to over-
whelming pressure, the energy is propagated
along the plaque and tends to create dissec-
tions. ere is usually evidence of dissection on
completion images immediately following the
angioplasty, and the more thorough the investi-
gation, the more dissections that can be found.
Contrast lls cracks in the plaque, most of which
are longitudinal. Oblique angiographic views or
cross-sectional imaging with IVUS or optical
coherence tomography (OCT) generally show
signicant disruption of the surface. Experience
with balloon angioplasty before the develop-
ment of stents indicates that some of these dis-
sections heal without treatment. However, they
do represent tissue hanging into the ow lumen
and may lead to acute occlusion or serve as a
nidus for restenosis. e availability of stents has
made it possible to treat most dissections safely
and quickly but has prompted a dilemma. How
aggressively should mild-to-moderate postangio-
plasty dissections be stented? is will gradually
be solved in each vascular bed. However, there are
downsides to stent placement since they are per-
manent implants and have continuous interaction
with the vessel wall.
A B C D
Fig. 17.1 Balloon dilation causing plaque fracture. (A) A cross-sectional view of an atherosclerotic
lesion. (B) A balloon catheter is placed in the lesion. (C) The radial force generated by the dilation is
applied to the lesion. (D) Plaque fracture causes dissection, which is often observed during comple-
tion studies. Most significant dissections are longitudinal in orientation.
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192 Balloon angioplasty: Minimally invasive autologous revascularization
ABOUT BALLOON CATHETERS
Every balloon angioplast y catheter has two lumens.
One lumen lls the balloon and the other lumen is
used for placement over a guidewire. Fig u r e 17. 2
demonstrates a coaxial angioplasty catheter in
which the guidewire lumen runs the whole length
of the catheter. In Chapter 5, Figure5.1, the coax-
ial catheter is compared with a monorail or rapid
exchange catheter in which the lumen for the wire
only runs for a portion of the length of the leading
end of the catheter. e balloon is not preinated
because aer ination it assumes a higher prole
and may be dicult to advance into the lesion.
e balloon is wrapped tightly around the catheter
when it is manufactured. Aer ination, it can-
not be wrapped quite as tightly and it has “wings”
where the folds of the balloon are located and
assumes a higher prole. e catheter is irrigated
and wiped with heparin–saline solution. Balloon
catheters with inated diameters of 3–12 mm may
be obtained on 5-Fr shas and can be placed over
0.035-inch guidewires. Balloon diameters as small
as 1.5 mm are available on low-prole (0.014) plat-
forms. Balloons for low-prole systems generally
have a 3-Fr sha and can be obtained in sizes up
to 8 mm in diameter. Balloon lengths of 2–20cm
are available. Nominal pressure is the ination
pressure at which the balloon takes its specied
diameter. is is usually around 6–8 atm of pres-
sure. Balloon construction dictates that there is
a certain degree of compliance in the balloon’s
inated diameter. A balloon may have very little
compliance (additional ination pressure does
not increase the diameter of the balloon) or it may
be fully compliant (additional pressure translates
directly into a larger balloon diameter). Most bal-
loons intended for peripheral vascular indication
are semicompliant. is means that additional
ination pressure can achieve a larger lumen, but
within a fairly narrow range. Balloons used for
securing an aortic stent–gra are fully compliant
and are able to reach large diameters of 20mm or
more, at a relatively low pressure of 2 atm. Burst
pressure specications usually range from 12 to
20atm, but thicker polymer balloons have a burst-
ing pressure of up to 30 atm. Radiopaque mark-
ers on the catheter at each end of the balloon,
placed to ensure the balloon is in the correct loca-
tion, are observed using uoroscopy. e catheter
sha length varies depending on the intended
purpose of the balloon catheter. A short sha of
40 cm is used for dialysis access angioplasty. An
intermediate length sha of 80 cm is used for iliac,
renal, and visceral treatment using a transfemoral
approach. Longer shas (120–150 cm) may be used
for carotid, subclavian, upper extremity, or cere-
brovascular interventions using a transfemoral
approach or, for lower extremity or tibial proce-
dures, using an up-and-over approach.
Desirable features for angioplasty balloon
material are rupture resistance and low prole
Prole
Shoulder
Balloon diameter
Balloon length
Balloon port
Guidewire port
Shaft length
Shaft size
Fig. 17.2 Balloon angioplasty catheter. The width of the folded balloon over the catheter is the pro-
file. The shaft size depends on the size and type of the balloon. A wide range of balloon diameters is
available on a 5-Fr shaft. The shoulder is the distance from the radiopaque marker, where the balloon
is filled out to its specified diameter, to the actual end of the balloon. The balloon diameter is the fully
inflated diameter of the balloon. The length is the distance between the radiopaque markers. The
shaft length provides a working distance between the operator and the angioplasty site. The balloon
port is used to inflate the balloon, and the guidewire (or distal) port extends the length of the cath-
eter and is used for passage over the guidewire.
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Balloon selection 193
(enhances trackability and crossability). Most angio-
plasty is currently performed with balloons con-
structed ofpolyethylene terephthalate or a similar,
semicompliant polymer.
Reinforced high-pressure polymer balloons
exert very high pressures (e.g., Dorado
®
PTA
Dilatation Catheter) and are useful for resid-
ual, recurrent, calcied, or intimal hyperplastic
lesions. ese are mounted on slightly larger shas
and assume a higher prole due to thicker bal-
loon material. Larger balloons (from 14 to 28 mm
inated diameter) are available for use in endo-
vascular aortic gra placement, large-vessel work,
and cardiac valvuloplasty. ese are on shas that
range from 5.8-Fr to 7-Fr, and the redundancy of
the balloon material requires that substantially
larger sheaths be used.
Smaller platform balloons for branch vessel
treatment, such as carotid or tibial angioplasty, are
available on a 3-Fr sha that travels over a 0.014-
inch guidewire. (See Chapter 5 for a discussion of
monorail balloon catheters. e monorail system
has several advantages for managing small-vessel
angioplasty and stenting.)
THE ANGIOPLASTY PROCEDURE
Percutaneous balloon angioplasty functions by
causing dissection of the atherosclerotic plaque.
Since this is an injury and is somewhat unpredict-
able, it is amazing that balloon angioplasty works
so well and that it is applicable to so many vascu-
lar beds and situations. It is best to approach this
procedure with the same diligence and careful
attention to technique as one would any surgical
procedure. In the case of balloon angioplasty, spe-
cic technical maneuvers do make a dierence to
results. One brief but pertinent comment about the
evolution of balloon angioplasty: the development
of stents that can be used in various vascular beds
was a signicant step in extending the use of mini-
mally invasive vascular procedures to a wide vari-
ety of disease morphologies. However, with that
major development, angioplasty technique became
less important and somewhat of a second thought.
Now that the downsides of stents are becoming
more apparent and the advantages of drug delivery
are emerging, there has been a renewed interest in
angioplasty technique.
Aer patient selection and preparation, the
next most important factor in success is a stepwise
game plan that proceeds methodically, with con-
tingencies available for managing any untoward
events that may occur. e general steps include:
(1) identifying the lesion and conrming that it
is a reasonable lesion for endovascular treatment
(arteriography); (2) securing percutaneous access
(sheath placement); (3) gaining control of the
lesion (by passing a guidewire across the lesion);
(4) selecting and preparing the balloon catheter;
(5) placing the balloon; (6) dilating the lesion; and
(7) conrming an acceptable result (completion
arteriography). Steps 1 to 3 were covered in earlier
chapters. Steps 4 to 7 are described in this chapter.
BALLOON SELECTION
Choosing the optimal balloon diameter is more
art than science and experience really helps with
this process. It is unlikely that immediate trouble
will be caused by selecting a balloon with a diam-
eter that is a little too small. Indeed, in the case of
drug-coated balloon angioplasty, predilation with
a balloon 1 mm smaller in diameter is indicated.
Underdilation in the short term results in an extra
step, since the smaller diameter balloon must be
exchanged for a larger size to nish the procedure.
If underdilation is not recognized, it may result in
a residual lesion that requires treatment at some
later date. Conversely, signicant overdilation
can cause immediate problems such as rupture.
Balloon angioplasty in its early stages was taught
as a situation that was performed best with approx-
imately 10% oversizing of the balloon.
ere are two choices for balloon diameter
sizing: (1) the eyeball method, and (2) digital
measurement:
1. Eyeball method. Can be performed using
educated and experienced estimating based
on the appearance of the artery on arteriogra-
phy. Aer performing arteriography, choose a
static image for analysis (Table 17.1). Assess the
likely diameter of the “normal” artery proximal
or distal to the lesion. Sizing the balloon to a
segment of poststenotic dilation will result in
choosing a balloon diameter that is too large.
Choose a balloon with the same or slightly
smaller than anticipated diameter and dilate
the artery without moving the image intensier.
When the balloon diameter is selected conserva-
tively, the likelihood of signicant overdilation
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