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164 Setting up the therapeutic maneuver: Crossing lesions
place along the learning curve where each operator
is working and how many tricks are at immediate
disposal. As endovascular skills and new devices are
developed, the rst category may not change much;
however, the second category should get larger as
the third category, composed of impossible lesions,
becomes smaller. In the past, occlusions were in
this third category of impossible or nearly impos-
sible lesions. Now there are many tools for crossing
occlusions, such as subintimal angioplasty, chronic
total occlusion (CTO) wires, CTO support cath-
eters, a variety of crossing devices, re-entry devices,
and distal puncture or alternative puncture sites,
and these are being used with increasing frequency.
Occlusions are discussed in Chapter 16. Incidentally,
the small third category of seemingly impossible
lesions to cross are mostly composed of very heavily
calcied lesions, which are still relatively resistant to
many of the new crossing tools available.
NEED FOR SUPPORT AND
DIRECTIONALITY
is discussion on crossing lesions presupposes
that the operator has decided that the lesion must
be treated. In this situation it is usually best to
begin the case by having the right amount of sup-
port. A guiding sheath is placed close to the lesion
and a directional catheter placed to support and
direct the guidewire intended for the lesion cross-
ing. In most cases, sheath support should be estab-
lished prior to crossing the lesion if the lesion is
going to be treated in the same setting. In general,
it is better to go ahead and set up your platform to
support the therapeutic maneuver, then cross the
lesion and, aer that, treat immediately.
CROSSING STENOSES
A stenotic lesion should be visualized with arte-
riography before attempting to cross it. Oblique
projections may be required for a full evaluation.
Sometimes, the passageway through the lesion is
only visible on a particular oblique projection and,
occasionally, it cannot be identied. If the entrance
to the lesion can be identied, this is very helpful
for beginning the crossing in the true lumen. e
guidewire is selected on the basis of the lesion’s
appearance. Asteerable, hydrophilic-coated guide-
wire is a good choice in most cases. When the lesion
also contains a critical stenosis, the steerable tip is
very helpful. Lesions near branch points are best
managed with steerable guidewires. If possible,
do not lead with a sti guidewire, a loop of guide-
wire, or a catheter tip near a lesion because of the
likelihood that this will result in dissection rather
than crossing. ere is some advantage in using
0.014-inch guidewires when crossing long diseased
segments, especially in small caliber vessels. e
0.014-inch guidewire may be supported with either
a microcatheter or a 4-Fr or 5-Fr angiographic
catheter with a Tuohy-Borst adapter. Many of the
0.014-inch guidewires have tips that can be shaped
and steered across the lesion. Since the 0.014-inch
guidewire has less than one-half the caliber of a
0.035-inch guidewire, the ability to cross a tight
lesion without stopping forward ow is much bet-
ter. Smaller caliber treatment platforms are dis-
cussed in Chapter 5.
Encounters between guidewires and lesions are
observed using uoroscopy. When a guidewire fails
to cross a lesion, its behavior as it encounters the
lesion may reveal information that will assist sub-
sequent passage using an alternative technique.
Using the shortest and most direct route between
the entry site and the arterial segment of interest
oers the operator the most guidewire control at
the site of the lesion. is approach assumes a mini-
mum adequate working room, or distance, between
the access site and the lesion (usually the length of
a standard access sheath [10–15 cm]). When dis-
tance results in poor guidewire control once it
has reached the lesion, passing a catheter over the
guidewire improves support and a selective cathe-
ter improves directionality. e key is to avoid forc-
ing the guidewire when it is not crossing the lesion.
If the guidewire damages the lesion, a critical ste-
nosis may become an occlusion. If the wire crosses
and the lesion is critical to the point where the wire
stops ow across the lesion, anticoagulation should
be administered and the lesion treated as soon as
the treatment platform is established.
Direct incremental advancement of a oppy tip
guidewire results in passage across long distances
of normal or mildly diseased conduit artery. If,
for some reason, passage of the oppy tip guide-
wire stalls or is unsuccessful, the wire should not
be forced. If the guidewire tip buckles, the leading
elbow of the wire loop may nd the lumen and pass
with the wire doubled over on itself (see Chapter 4,
Figure 4.1). is is a useful maneuver but it is not
advisable when crossing signicant stenoses. In this
case, the guidewire may enter a dissection plane
and act as a loop stripper. If the guidewire begins
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Crossing stenoses 165
to buckle, but continues to accumulate into several
loops and piles up proximal to the lesion, withdraw
the wire and change course and use one of several
options that may facilitate guidewire passage.
A catheter passed over the guidewire gives addi-
tional support to the guidewire sha and secures the
access site (Figure 15.2). e guidewire tip remains a
few centimeters beyond the leading end of the cath-
eter, and the wire is used to probe the lesion. Another
option is to exchange the oppy tip starting guidewire
for a hydrophilic-coated, steerable guidewire, which
may cross the lesion, even a preocclusive stenosis, on
the rst pass. Hydrophilic-coated guidewires may be
sourced with either a straight or an angled tip. e
angled tip is steerable with a torque device and may
be used to nd the entrance to an eccentric lesion
(see Chapter4, Figure 4.7). Hydrophilic guidewires
have been a tremendous advance in crossing lesions
but are more challenging to use for treatment because
of their handling diculty. Road mapping facilitates
this maneuver (see Chapter8, Figure8 .2). A 5-Fr bent
tip catheter, such as a Berenstein or aTegT catheter or
angled Glidecath
®
, may help steer the guidewire into
the desired location (Figure 15.3). e catheter may
be advanced incrementally as the guidewire makes
forward progress. e wire should lead into the lesion
and the catheter used for support and directionality.
Asthe wire enters the lesion, the catheter is advanced.
A
B C
Fig. 15.2 Stiffening the guidewire by passing
a catheter. A straight catheter passed over a
guidewire gives additional stiffness and body to
its shaft. (A) The guidewire is unable to traverse
the lesion and the floppytip guidewire piles
up proximal to the lesion. The wire is partially
withdrawn. (B) A straight catheter is passed over
the guidewire. The tip of the wire protrudes
from the catheter and probes the lesion.
(C)Theguidewire is advanced through the lesion.
A B C D
Fig. 15.3 Using a catheter to steer the guidewire. An angle tip catheter (4-Fr or 5-Fr) passed over a
steerable guidewire can help direct the guidewire tip into the desired location. (A) The guidewire
enters a collateral proximal to the lesion intended for passage. (B) A bent tip catheter is passed
over the guidewire. (C) The catheter is rotated to redirect the guidewire away from the collateral and
toward the entry to the lesion. (D) The guidewire is advanced into the lesion.
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166 Setting up the therapeutic maneuver: Crossing lesions
A special exception to this is when the guidewire
will not cross an occlusion and the lesion is crossed
in the subintimal plane. is is performed by using
the catheter at the plaque– vessel wall interface and
advancing the guidewire into it. Intentional subinti-
mal guidewire passage is discussed in more detail in
Chapter 16. Otherwise, the catheter tip itself, without
the guidewire protruding from it, should not encoun-
ter the lesion because it may disrupt plaque.
Contrast may be pued through the tip of the
catheter to ensure that its position is intraluminal
(Figure 15.4). If signicant resistance occurs, the
guidewire may have passed outside the course of the
artery lumen. Whenever a lesion is crossed, always
conrm the intraluminal position on the distal side
of the lesion before proceeding to treatment.
Crossing lesions in well-collateralized arter-
ies, such as the supercial femoral artery (SFA) or
popliteal artery, when there is a distal occlusion
can present an additional challenge. A large juxta-
posed collateral just proximal to a critical stenosis
or occlusion may be the preferential course for a
passing guidewire. e guidewire may be mistak-
enly advanced into a collateral that parallels the
treatment artery (Figure 15.5). e position of the
A B C
Fig. 15.4 Puffing contrast after crossing a lesion.
(A) After a difficult guidewire passage, a cath-
eter may be placed over the wire. The catheter
maintains the position through the lesion. (B)
The guidewire is removed. (C) Contrast is puffed
through the catheter to ensure that the tip is
in the true lumen prior to initiating treatment.
Another option that avoids having to remove the
guidewire is to place a smaller caliber wire, such
as a 0.014- or 0.018-inch, and use a Tuohy-Borst
adapter to administer contrast.
A B C
D
Fig. 15.5 Determining that the guidewire is really in the lumen and not in a side branch. (A) Large peri-
genicular collaterals may be the preferential course for a guidewire attempting to cross a superficial
femoral artery or popliteal artery lesion. (B) Under fluoroscopy, the guidewire appears to have crossed the
proximal popliteal artery stenosis but is actually in a collateral that parallels the artery. (C) Arteriography
performed by administering contrast through the side arm of the sheath reveals the true course of the
guidewire and that the lesion has not been traversed. (D) The guidewire is redirected across the lesion.
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Crossing stenoses 167
guidewire must be conrmed before larger endo-
vascular devices are passed over it. A steerable
guidewire is useful for avoiding collaterals and
maintaining position in the ow stream. A direc-
tional catheter may be used to point the guidewire
away from the collaterals. Usually, the location of
the guidewire can be identied by careful obser-
vation under uoroscopy. If the guidewire tip is
moving freely and the sha of the wire has a bit of
back-and-forth mobility, it is typically in the main
conduit artery.
An oblique projection, as mentioned earlier,
may be useful not only for evaluation of the lesion,
but for opening up the entrance to the lesion
and showing the way to cross it (Figure 15.6).
Occasionally, the steerable guidewire will require
multiple manipulations to wind its way through
a highly irregular stenosis (Figure 15.7). When
the approach artery is highly tortuous, it can be
dicult to advance through a lesion aer the
guidewire has passed through several opposing
curves. Usually, there is a certain amount of wire
bias that is pushing the wire toward one side of
the vessel or the other and this may be unfavor-
able for crossing lesions. A 4-Fr or 5-Fr catheter
passed over the guidewire can lessen the curva-
ture of some of the turns through which the wire
must proceed. Sometimes, it is necessary to place
a sheath to give an advantage to the guidewire–
catheter apparatus.
Occasionally, a critically stenotic segment cannot
be crossed in the chosen direction, and a separate
puncture and an approach from the opposite direc-
tion are required (Figure 15.8). is option is more
commonly used with occlusions, especially iliac
and tibial artery occlusions. is can also be used
for SFA lesions but is less commonly required since
antegrade subintimal passage works for most SFA
occlusions. Aer guidewire passage, control of the
wire should not be relinquished until aer treatment
A B
Fig. 15.6 Magnified oblique view. (A) A complex
lesion is encountered by the probing guide-
wire. (B) The field is magnified and an oblique
projection helps to open up the entrance to the
lesion.
A
B
Fig. 15.7 Multiple maneuvers are sometimes
required. (A) A steerable guidewire probes
a complex lesion. (B) Multiple maneuvers are
required to steer the guidewire across the lesion.
With each turn and passage through a complex
lesion, the guidewire tip loses some responsive-
ness to turning and advancing.
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168 Setting up the therapeutic maneuver: Crossing lesions
is completed. When guidewire control is inadver-
tently lost, it may be extremely dicult to cross the
lesion a second time. Inexplicably, the same guide-
wire using the same technique across the same lesion
may not recross easily. When a lesion is crossed from
the opposite direction, the operator still has to decide
which access site to use to perform therapy.
Lesions at the orice of major branch arteries,
such as occur in the subclavian, renal, or visceral
arteries, may also be a challenge to cross. Selective
catheters and steerable guidewires are routinely
used to cross these arteries. e tip of the selective
catheter must provide substantial support to the
guidewire despite being perpendicular to the aor-
tic ow stream. Selective catheters appropriate for
these arteries are described in Chapter 9. e usual
intent in crossing a lesion in one of these loca-
tions is intervention. Before the lesion is crossed,
appropriate planning should be undertaken so that
access for endovascular therapy with a guiding
catheter or guiding sheath is prepared. Chapter 14
contains further discussion of appropriate access
options for endovascular therapy. Once the branch
artery lesion has been crossed, subsequent place-
ment of a guiding sheath may pull the guidewire
from its location and back into the aorta. Aer
an orice lesion has been crossed in one of these
arteries, care must be taken to prevent dislodge-
ment of the guidewire during other maneuvers.
is is especially true in the renal artery, where
the distance to the renal parenchyma is relatively
short and the length of guidewire across the lesion
is limited. is is combined with a sharp turn,
oen more than 90 degrees, from the aorta into the
branch artery, and oen a critical lesion providing
resistance. e visceral arteries typically permit
more guidewire length distal to the lesion, but the
acute angle of origin of these vessels makes them
just as challenging.
Aer the guidewire is in place across the lesion,
the chosen catheter is advanced (see Chapter 4 for
a detailed discussion of techniques for catheter
placement). If there is a minimal lumen diameter at
the site of the lesion, the guidewire– catheter com-
bination may occlude it. Heparin should be admin-
istered to prevent thrombosis or the lesion should
be dilated without delay so that ow resumes.
Technique: Crossing a stenosis
1. Do not raise a dissection plane. is can be
done easily by using excessive force, pushing a
hydrophilic-coated guidewire, or attempting
to advance the catheter without the guidewire.
A B
Fig. 15.8 Approaching the lesion from the opposite direction. After attempting various maneuvers
to cross a lesion, it is sometimes better to approach the lesion from the other end rather than force it
and cause a complication. (A) Ipsilateral retrograde passage of a guidewire is unsuccessful at cross-
ing an external iliac artery stenosis. (B) A second puncture is performed in the contralateral femoral
artery, a catheter is passed over the aortic bifurcation, and the guidewire is advanced antegrade
through the iliac stenosis.
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Crossing stenoses 169
2. Buckle the guidewire to form a leading edge
across a mild stenosis, a long segment of artery,
healthy or mildly diseased vessel, or a previ-
ously placed stent. Do not force the elbow.
3. Use a catheter to confer directionality or sti-
ness to the guidewire (Figure 15.2).
4. If a standard steel guidewire will not cross the
lesion easily, use a hydrophilic-coated guidewire.
5. Exchange for a steerable guidewire (Figure15.7;
see also Chapter 4, Figure 4.7).
6. Obtain oblique views of the lesion to provide
more information, especially if it is an eccen-
tric or posterior wall lesion or located at a
bifurcation or branch point (Figure 15.6).
7. Road map the lesion to provide real-time
guidance (see Chapter 8, Figure 8.3).
8. Use a selective catheter to provide additional
directionality and to steer the guidewire
(Figure 15.3).
9. Once across the lesion, pu contrast to ensure
that the guidewire has not passed through a
dissection plane or into a collateral juxtaposed
to the lesion (Figure 15.4). Make sure that the
catheter is in the artery distal to the lesion.
10. If the guidewire impedes ow, administer
heparin.
11. If endovascular therapy is planned, advance
an exchange catheter and place a stier guide-
wire to maintain control of the lesion.
12. If the lesion still cannot be traversed, approach
from the opposite direction and repeat these
maneuvers (e.g., if a retrograde approach to
an iliac artery lesion is not successful, try an
antegrade approach) (Figure 15.8).
Strategy: Avoiding subintimal
guidewire dissection, unless a
subintimal course is intended
1. Most stenoses can be crossed with the guide-
wire maintained in the true lumen, even long
and challenging stenotic lesions with multiple
preocclusive stenoses. A possible exception to
this is a severely calcied, complex, and criti-
cally stenotic lesion in which the guidewire
will not follow the true lumen and seems to
prefer the subintimal space.
2. Staying in the true lumen, when possible, obvi-
ates the need to re-enter the true lumen. is
would be the case when the subintimal plane
isentered.
3. Crossing a lengthy and challenging stenosis
with multiple critical areas is facilitated by
the following maneuvers: place the tip of the
sheath close to the lesion, use a 0.014-inch
directional guidewire, and support the wire
with a catheter, either a microcatheter or a
4-Fr directional, hydrophilic catheter with a
Tuohy-Borst adapter.
4. A guidewire-induced subintimal dissection
may occur at the leading edge of a lesion at the
interface with the wall of the artery. Care must
be taken during the initial encounter with the
lesion. Occasionally, even innocuous appear-
ing lesions will dissect.
5. Pu contrast as oen as is required to see
where you are going. Make sure there is blood
return before administering contrast.
6. “Dance” through the stenosis with a steerable-
tip guidewire.
7. Use continuous uoroscopy while the guide-
wire is in motion through a lesion.
8. Go fast with the guidewire until you get close
to the lesion and then make small incremental
and deliberate movements aer that.
9. Be aware that a hydrophilic-coated guidewire
may pass eortlessly along a dissection plane.
If the guidewire tip catches on a lesion, do not
keep pushing to form a loop unless you intend
to go into the subintimal space. is is a good
way to enter the subintimal space.
10. Anticipate where cleavage planes might be in
the plaque, such as bifurcations and branch
origins, and be extra careful around these
areas, especially if they are also calcied and/
or tortuous.
11. If a dissection plane placement is suspected,
twirl the guidewire to be certain that it behaves
as a free guidewire should in the vasculature
distal to the lesion. When the guidewire
encounters unexpected obstructions or appears
constrained, it may be in the wall of the artery.
When a guidewire is passing freely and easily
along a dissection plane, usually the tip of the
wire comes to an abrupt stop at the end of the
dissection plane. If you withdraw and pass
thewire a couple of times, it typically goes to
the same place and forms the same shape.
12. A suspected guidewire dissection may be
evaluated by advancing a 4-Fr straight cath-
eter over the wire and pung a tiny amount
of contrast. If it is subintimal, the contrast will
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170 Setting up the therapeutic maneuver: Crossing lesions
be stationary in the arterial wall. Usually, the
operator can tell from the look and feel of the
wire behavior whether or not it is subintimal.
13. If a dissection occurs, remove the guidewire
and start again, unless of course the procedure
is intended to be performed in the subintimal
space aer that.
14. Subintimal angioplasty is oen best for treat-
ing occlusions. is is discussed in the next
section and in Chapter 16.
Strategy: When is road mapping
useful to cross lesions?
1. Road mapping is a helpful adjunct for treating
occlusions. Both ends of the occlusion may be
visualized simultaneously. e progress of the
guidewire across the occluded segment may
be monitored in real time, using the distal
reconstituted segment as the target.
2. Road mapping may not be as useful for
crossing stenoses. Most operators use other
tricks before going to the effort to construct
a road map.
3. Consider a road map for approaching complex
lesions that could not be crossed aer many
dierent maneuvers have been attempted. e
road map provides another option for attack-
ing the lesion.
4. Road mapping simplies the approach to
lesions near the origins of branch arteries
since it permits simultaneous visualization of
the location of the branch that must be entered
and the lesion that must be crossed.
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171
16
Crossing challenging lesions
ARTERIOGRAPHY OF OCCLUDED
ARTERIES
Very oen, the occlusion is shorter than it seems
on rst glance. It is quite common for there to be
a distal segment just beyond the occlusion that is
not lling immediately. Typically, when a segment
occludes, it does so from one collateral above to
another collateral below. If the collateral below
does not ll immediately with opacied blood
during angiography, the occlusion will appear to
include that segment. Vice versa, if the contrast
injection is preferentially lling the main collateral
source for ow beyond the occlusion, the proximal
portion of the occlusion may not be well delineated
and may appear longer than it is. Since occlusions
in most situations can be considered for crossing, it
is also helpful to look at the origin of the occlusion
in dierent projections to see where the guidewire
might approach in order to achieve entry into the
occlusion and possible intraluminal passage. It is
usually best to place a catheter close to the origin
of the occlusion and perform selective arteriogra-
phy in order to understand best how to approach
the lesion. e operator benets by knowing if it
is a ush occlusion or whether there is an open-
ing into the vessel. It is also useful to consider how
the contrast will make it to the point of reconsti-
tution. For example, with a supercial femoral
artery (SFA) occlusion, the origin of the occlusion
is best seen by administering contrast into the SFA
or, if it is a ush occlusion, close to the origin of
the SFA (Figure 16.1). e distal end of the occlu-
sion is best seen by administering contrast into the
profunda femoris artery, since this is typically the
main collateral carrying blood beyond the occlu-
sion. Occlusions in the tibial vessels can be confus-
ing because of overlying images from the dierent
tibial arteries and also the long segment between
the origin of the vessel and the ankle. When work-
ing on an occlusion in this segment, the operator
must isolate the tibial artery of interest, identify
the reconstitution point, and aim for that point on
the uoroscopic screen.
CROSSING OCCLUSIONS
Crossing occlusions is more challenging and less
reproducible than crossing stenotic lesions. e
only reason to cross an occlusion is in preparation
for an attempt at recanalization. It is not advisable
to put a guidewire into the occlusion “just to see”
if it is easy to cross. It is better to have your plat-
form all set for crossing and your plan set all the
way through reconstruction. An ill-fated attempt
at crossing and recanalizing an occlusion that
results in distal embolization can be one of the
most costly complications of endovascular inter-
vention because of the potential that relatively
stable chronic ischemia will be converted to acute
ischemia. Acute ischemia due to embolization may
also be untreatable if it is caused by plaque contents
occluding the distal runo of the organ system in
question. Along the length of an occluded arterial
segment, there is usually an underlying critical
stenosis from a progressive atherosclerotic plaque
that went on to thrombose and occlude. ere is
usually an accumulation of compacted chronic
thrombus proximal and distal to the lesion, which
extends to the next substantial collateral. ere are
usually substantial collaterals just proximal and
just distal to the occlusion that maintain ow to
the distal reconstituted segment and also help to
prevent the occlusion from propagating.
ese collaterals come into play in several
ways when managing occlusions. An approaching,
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172 Crossing challenging lesions
probing guidewire usually passes preferentially
into the large collateral immediately preceding the
occlusion, rather than into the lesion itself. When
the occlusion is crossed in the subintimal plane, an
attempt is made distal to the occlusion to re-enter
the true lumen close to where it reconstitutes. is
is in an eort to maintain the patency of the distal
reconstituting collaterals and to make the length
of the reconstruction no longer than necessary.
In addition, when reconstructing aer subintimal
passage and true lumen re-entry, any stent or stent–
gra should be placed such that the distal collateral
is preserved, if possible. When the occluded artery
is tortuous or the underlying atherosclerotic lesion
is diuse or heavily calcied, the likelihood of pass-
ing a guidewire along the true lumen is decreased
and the risk of perforation increased. A dual ante-
grade and retrograde approach to a lesion is more
oen required for occlusions than for stenoses.
An occlusion may be crossed in the true lumen
or in the subintimal plane (Table 16.1). When
crossing an occlusion, it is oen possible to keep
the guidewire in the intraluminal space and per-
form a true lumen crossing (Figure 16.2). If the
occlusion can be crossed intraluminally, there is
no true lumen re-entry required and the shortest
possible reconstruction can be performed. True
lumen crossing can be attempted in most situa-
tions and is usually initiated with a low-prole
hydrophilic wire (0.014-inch or 0.018-inch). e
tip is purposely bent in order to use it as a drill-
ing device. e wire is supported by a chronic
total occlusion (CTO) catheter. A CTO catheter is
a low-prole catheter with a straight or an angled
tip with a 0.014-inch or 0.018-inch lumen. e
catheter adds sha strength and pushability to the
guidewire passage and helps reduce the friction of
the wire within the occlusion. e wire is rotated
360 degrees for several revolutions in one direc-
tion and then 360 degrees in the other direction
in rapid succession. Gentle forward pressure is
applied and the wire tip visualized under magni-
ed uoroscopy. If the wire buckles, less pressure
is applied and stationary drilling is performed for
a few moments before advancing the wire again.
e trajectory of the wire is carefully monitored to
ensure that the directionality is correct. If the wire
loops or goes o in the wrong direction, it is pulled
back a short distance and the process started again.
e CTO catheter is intermittently advanced to
support the wire.
A
B C
D E
Fig. 16.1 Arteriography of occluded arteries.
(A)Contrast is administered at the proximal
femoral level to fill the profunda femoris artery
and its collaterals. (B) Contrast fills the true
lumen distal to the occlusion. (C) Retrograde
passage of contrast demonstrates the true
length of the occlusion. (D) On a flush aor-
toiliac arteriogram, it appears that the entire
left iliac system is occluded, including both
the common and the external iliac arteries.
(E) On delayed imaging, it is apparent that
the common iliac artery is occluded and that
the external iliac artery has low flow due to
severe iliac artery stenosis. Delayed imaging
permits opacified blood to enter the external
iliac artery via retrograde flow from the internal
iliacartery.
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Crossing occlusions 173
Oen the guidewire nds its way into the sub-
intimal plane regardless of what the operator does
(Fig ure 16.3). Many specialists seek this out at
the beginning of the case and do not worry about
it, especially when treating a long occlusion. e
most common approach is to use a hydrophilic-
coated guidewire in the shape of a loop and pass
it in the subintimal plane. A relatively sti, angled
catheter is used to back up the guidewire. e cath-
eter tip is pointed into the stump of the occluded
artery. e hydrophilic guidewire is used to jab
and probe until the tip catches and the guidewire
forms a loop. e loop is advanced for a few centi-
meters. e catheter is advanced a few centimeters
up to the beginning of the loop but the loop is not
straightened out. en the loop is advanced again,
Table 16.1 True lumen versus subintimal wire passage
True lumen Subintimal
Advantages Preserves all collaterals Easy wire passage
Shortest reconstruction Good fallback if true lumen passage not possible
Likely to fail slowly if it does fail,
due to preservation of branches
Disadvantages More difficult to cross Re-entry is a challenge
If there is thrombus in the lesion,
it may cause embolization
When it fails, often occludes the whole length
A B C
Fig. 16.2 Crossing an occlusion in the true lumen.
(A) A low-profile hydrophilic tip guidewire with a
bent tip approaches the occlusion. The guidewire
tip enters the thrombus but advancement stops.
The wire is supported by a CTO catheter. (B) The
CTO catheter is passed over the guidewire and
up against the lesion to support the wire. The
guidewire is then advanced gently while its tip is
rotated vigorously. (C) The catheter is advanced
gradually and intermittently over the guidewire
as the wire tip is advanced.
A B
C D E
Fig 16.3 Method of subintimal recanalization.
(A) A sheath is placed close to the origin of the
occlusion and a braided catheter with an angled
tip is pointed opposite to the largest proximal
collateral. (B) The Glidewire
®
tip probes the inter-
face between the plaque and the artery wall until
the wire tip buckles and forms a loop. (C) The
loop in the guidewire is maintained and pushed
forward until the knuckle of wire pops back into
the true lumen. (D) The catheter is advanced to
support the guidewire and advance into the true
lumen. (E) The position of the catheter in the true
lumen is always confirmed with arteriography
prior to initiating reconstruction.
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