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1.6.4.11 Correcting theGuidewire Route by
Using aLandmark
If there is strong evidence that subintimal deviation of the
guidewire has occurred, the next step is usually to reorient
the wire toward the true lumen by using a landmark.
In the days when I used a 0.014-inch less slippery nontapered guidewire, I could feel the resistance to its tip and
use the magnitude of resistance to decide whether the wire
was in the true lumen or had deviated into the subintimal
space. Since the recent CTO crossing guidewires create less
resistance, the interventionalist cannot rely on subjective
judgment of resistance alone to make a reliable assessment.
Currently, visual evidence is absolutely required to determine whether a guidewire is in the true or false lumen.
However, when imaging shows the interventionalist that the
tip of a guidewire is unable to advance further in a vessel, the tip
may actually have been trapped within the occlusion. Trapping,
which makes the guidewire difcult to withdraw, seems to
occur when the tip of the wire has been advanced through the
media parallel with the vessel wall for a certain distance (see
1.6.4.4 “Guidewire Trapping and Inection” [page 52]). If a
guidewire has become trapped, you still have a good chance
to correct the route of the wire and to ensure that it follows the
true lumen. However, if the guidewire remains trapped for too
long, it will become extremely difcult to withdraw. Therefore,
you should suspect guidewire trapping and attempt to correct it
at an early stage. You should promptly pull the guidewire back
slightly if it becomes impossible to advance further and check
that the tip can be pulled free and moved before attempting to
correct the route of the wire by using a landmark.
Since conrmation of guidewire trapping is a basic procedure, I will discuss here how to use a landmark to correct the
guidewire route after trapping has been conrmed. I would
like to emphasize that the methods for correction described
under [1] and [4] in “Parallel Wire Technique” (page 75) are
also applicable to retrograde PCI.
First, I would like to review the basics of correcting the
guidewire route. Under what circumstances and when should
you correct the route of a guidewire that has deviated into the
subintimal space? In general, if the tip of the guidewire is near
the distal true lumen, but collateral imaging indicates that it will
not enter the distal lumen, the wire is a candidate for correction unless you can verify that it is coaxial with the target vessel
and directed toward the distal lumen. If the guidewire has been
advanced as far as the distal true lumen, but its tip is actually
outside the lumen, it is also a candidate for correction. The tip
of the guidewire may deviate from the true lumen in various
ways. For example, it may deviate toward the larger curvature
(Fig.1.117a) or toward the smaller curvature (Fig.1.117b) of
the bend in a vessel in only one projection (Fig.1.118a) or in
both of two projections (Fig.1.118b), or it may deviate in a noncoaxial manner (Fig.1.119). The mode of guidewire deviation
from the true lumen inuences the method of correcting it.
To correct a deviating guidewire, it is recommended
to search for an inection point in the wire as the site from
which to start correction and/or use two orthogonal projections, one of which shows the guidewire outside the true
lumen (Figs.1.108, 1.118a, and 1.120). In a long CTO with
no natural internal landmarks, if the tip of the guidewire is
outside the true lumen distal to the occlusion, the wire will
not always have a denite inection point within the occlusion
(Fig.1.121). You should suspect that the guidewire is winding through the subintimal space. If the guidewire is found to
show slight deviation in a certain direction in both projections,
it is worth pursuing that direction (Fig.1.121). This is especially true if there is an obstruction in that direction.
Using monoplane angiography, most guidewires that
have deviated from the true lumen are visualized as remaining within the lumen in one projection and exhibit maximum deviation from the lumen in another projection that is
orthogonal to the rst.
Figure 1.122 shows a typical occlusion of the proximal
LAD.When performing PCI for CTO of the proximal LAD,
the interventionalist usually advances a guidewire under uoroscopic guidance, primarily employing the AP+CR view. In this
case, the guidewire is seen to follow the LAD in the AP+CR
view, but deviates from the course of the target artery in the
LL+CR view. If the guidewire enters the distal true lumen in
one, but not in the other, of two orthogonal projections obtained
with the detector surfaces parallel to the longitudinal axis of the
occluded vessel, the latter projection is very useful for correcting the position of the guidewire. When performing the parallel
wire technique, you should advance another guidewire along
the rst guidewire using the projection in which the rst wire
seems to remain in the true lumen and should attempt to nd the
right direction to avoid deviation of the second guidewire in the
other projection (Figs.1.123 & 1.124).
If the occlusion is not so long, the inection point of the
rst guidewire can often be identied easily in the projection which displays maximum deviation of the wire from the
distal true lumen.
Fig. 1.117 Guidewire direction relative to the distal true lumen. (a)
Guidewire deviating from the distal true lumen toward the larger curvature of the vessel. (b) Guidewire deviating from the distal true lumen
toward the smaller curvature of the vessel
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Fig. 1.118 Guidewire direction relative to the distal true lumen. (a)
Guidewire deviating from the distal true lumen in only one of two
orthogonal projections. (b) Guidewire deviating from the distal true
lumen in both of two orthogonal projections
1 Mitsudo’s PCI Techniques forCTO
Fig. 1.120 Two orthogonal projections. Deviation of a guidewire
advancing along the vessel wall is difcult to identify. However, a
guidewire that is viewed as following the center of the distal true lumen
in one projection (b) is viewed as deviating from the true lumen in
another projection orthogonal to the rst (a)
Fig. 1.119 Guidewire direction relative to the distal true lumen. The
guidewire is not directed toward the distal true lumen due to loss of
coaxiality and deviates from the lumen in both of two orthogonal
projections
RAO
Fig. 1.121 Guidewire deviating into the subintimal space in a long
occlusion. If the guidewire deviates into the subintimal space and follows a winding course within a long occlusion, the inection point of
the guidewire is difcult to identify, even using two orthogonal
projections
LAO
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a
d
b c
e f
h
g
Fig. 1.122 Occlusion of the proximal LAD: the same procedure as
shown in Fig.1.106. (a) AP + CR view. (b) LL+ CR view. The rst
guidewire was manipulated under uoroscopic guidance in the AP+CR
view. In the LL+CR view, which is almost orthogonal to the AP+CR
view, the coronary artery branches overlap considerably, and precise
guidewire manipulation is impossible. Biplane angiography shows that
the guidewire reaches the distal true lumen in the AP+CR view (c), but
deviates considerably upward from the true lumen in the LL+CR view
(d). In this view, an inection point (arrow) can be clearly recognized
(e). Using the seesaw wiring technique, the second guidewire was
advanced along the rst guidewire to a site just proximal to the inection
point. In the AP+CR view, the second guidewire advanced in parallel
with the rst guidewire was seen to be crossing the occlusion through the
true lumen (f). The second guidewire was advanced in the LL+CR view
with its tip oriented downward around the inection point while applying xed point rotation to explore the site of obstruction. After this
manipulation, the guidewire was also seen to be crossing the occlusion
through the true lumen in the latter projection (g). An enlarged image (h)
clearly shows that the second guidewire has been advanced without
undergoing inection like that observed in the rst guidewire
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Fig. 1.123 Finding the route for the second guidewire with the parallel
wire technique. (a & b) Two orthogonal views. If the anatomy of the
occluded vessel is unclear, the second guidewire should be advanced
along a route that initially diverges from the rst guidewire, but then
goes parallel to it without increasing divergence between the two wires
1 Mitsudo’s PCI Techniques forCTO
Fig. 1.124 Correcting the direction of the second guidewire relative to
the landmark guidewire. The second guidewire is considered to have
been successfully corrected if it eventually becomes parallel with the
rst guidewire, even if it initially deviates considerably from the other
wire (e). If the second guidewire is not parallel with the rst guidewire
and is advanced in the wrong direction (a, b, c & d), it will not reach the
true lumen distal to the occlusion. If the second guidewire initially deviates from the rst guidewire, but then takes a parallel course, it is worth
advancing the second wire further in that direction of (e). If the two
guidewires are parallel but very close to each other in both orthogonal
projections, it may be doubtful that the second wire is in the true lumen
(f). It is often seen that the second guidewire crosses the rst wire one
or more times and then eventually goes toward the distal true lumen (g).
This is probably the result of the rst guidewire winding through the
subintimal space
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Using Calcied Plaque as a Landmark
When advancing a guidewire toward the distal true lumen
by using calcied plaque as a landmark, you may obtain a
uoroscopic view of the calcied plaque like that shown in
Fig.1.125a. When performing PCI under uoroscopic guidance, the guidewire is manipulated toward the distal true
lumen that has been visualized by collateral imaging, and it
eventually appears to have reached the lumen in this view.
However, using calcied plaque as a landmark does not
allow us to determine the accurate anatomy of the occluded
vessel, which may be like that shown in Fig.1.125b or c. In
Fig. 1.125c, the guidewire appropriately follows the curve
of the vessel and appears to remain within the true lumen.
However, Fig. 1.125d displays a guidewire following the
course shown in Fig.1.125b within an occluded vessel having the same curvature as in Fig.1.125c. In this view, the
guidewire appears to deviate into the subintimal space, at
least at the midportion of the occlusion. Thus, a guidewire
that apparently follows the course shown in Fig.1.125b, c,
or d in one projection may have an unexpectedly different
course in another projection orthogonal to the rst projection.
Using the Distal True Lumen Visualized by
Contralateral Imaging as a Landmark
If the distal true lumen visualized by contralateral (collateral) imaging is the only landmark available, it can only
be seen temporarily during imaging and is not a sufcient
guide for accurate correction of the guidewire route with the
single- wire technique. However, if the inection point of the
guidewire can be clearly identied, you can withdraw the
guidewire to a site just proximal to that point and then slowly
advance it in the opposite direction to the direction of inection. If the guidewire advances along the predicted route
of the true lumen, you may continue in that direction and
advance it further while performing xed point rotation. If
favorable guidewire advancement continues, you may switch
from xed point rotation to plane rotation.
You can try to correct the guidewire route several times
using a single crossing guidewire, but if these attempts fail, it
is better to switch your strategy to parallel wiring or retrograde
PCI.If attempts at correction are repeated too often, the guidewire may deviate into the same subintimal space repeatedly
and create a large dissection. A Conquest Pro guidewire has a
stiffer tip than a Gaia guidewire and readily causes dissection
if it deviates into the subintimal space and is advanced through
that space (see Fig.1.85). To prevent creation of a large dissection, you should proceed to the next step at an early stage.
Fig. 1.125 Using calcied plaque as a landmark. In (a) CTO with
areas of calcication as shown in a, the anatomy of the occluded vessel
may be as shown in (b) or (c). It can often be predictable from the
movement of the vessel, but not until the start of guidewire manipulation. If (b) and (c) represent the predicted and actual anatomy of the
vessel, respectively, a guidewire advanced through the CTO will inevitably deviate into the subintimal space (d)
Parallel Wire Technique
As mentioned above, the parallel wire technique involves
using one guidewire as a landmark to advance another guidewire. You should bear in mind that the rst guidewire is a
secondary landmark compared to the distal true lumen visualized by collateral imaging, since the exact point where the
rst guidewire deviates into the subintimal space is unknown.
However, the following ve signs may indicate the point of
guidewire deviation:
1. Inection point: If there is an inection point, investigate
whether inection of the second guidewire can be avoided
and the wire can be advanced in an appropriate direction
from that point (Fig.1.102).
2. “Blocking” point: If there is a point where “blockage”
occurs, press the tip of the second guidewire against the
obstruction, and apply xed point rotation to identify the
direction in which the guidewire can be advanced (see
Fig.1.89).
3. Divergence point: If the tip of the guidewire is outside the
true lumen, explore a new direction by the second guide-
wire from any point of slight divergence of the two wires,
even if they are parallel with each other (Fig. 1.123).
There are several patterns of divergence (Fig. 1.124). If
advancement of the guidewire is blocked, also perform
xed point rotation at that point and attempt to nd the
direction in which it can go forward.
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4. Trapping point: The guidewire is usually trapped at the
boundary between the true lumen (inside plaque) and the
subintimal tissue, i.e., in a layer very close to the true
lumen (see 1.9.1 “Guidewire Entrapment”). You should
pull a trapped guidewire back by a distance of 1 to 2mm
and then advance it again while exploring to nd a direction in which it does not get trapped again.
5. Entry point: A guidewire may deviate into the subintimal
space or go outside the vessel wall via a small side branch
at the CTO entry. In this situation, try to penetrate the
entry at a different point or explore a different route for
advancement of the wire from the entrance (Fig.1.126).
If the guidewire seems to have penetrated a hard proximal
cap and then passed through the occlusion smoothly without obstruction to reach the exit, but fails to enter the distal true lumen, it may have deviated into the subintimal
space just near the entry. Subintimal deviation at the CTO
entry should also be suspected if the guidewire returns to
the distal subintimal space without being blocked while
crossing the occlusion after it has been withdrawn from
this space and advanced again in an attempt to nd the
correct route.
Deviation of the guidewire outside the vessel wall just at
the CTO entry can easily be detected by a sudden marked
reduction of resistance and unrestricted movement of the
wire after it has passed through a hard obstruction.
Contralateral Guidewire Technique (See 1.7.13 “Kissing
Wire Technique”)
If a guidewire has been advanced retrogradely into an occlusion, the guidewire will be in the true lumen at least at the
exit of the CTO.Therefore, you should advance an antegrade
guidewire toward the retrograde guidewire at the exit point,
but it is unclear how far the retrograde wire remains in the true
lumen. The antegrade guidewire should be advanced according to the abovementioned rules [1] through [5]. If it comes
into contact with the retrograde guidewire (Fig.1.127), it can
then reach the distal true lumen by being advanced to the
exit point alongside the retrograde wire. It does not matter
where the two guidewires come into contact with each other,
whether in the subintimal space or inside a plaque. In both
cases, the second (antegrade) guidewire should be able to
follow the track created by the rst (retrograde) guidewire.
To ensure this, you should use a Gaia Second or stiffer CTO
guidewire.
Fig. 1.126 Correcting the guidewire direction from the CTO entry.
Two orthogonal projections (a & b). If the rst guidewire is suspected
to have deviated into the subintimal space or outside the vessel wall,
you should explore another route from the CTO entrance (another point
of penetration) with the second guidewire
Fig. 1.127 Correcting the direction of an antegrade guidewire with a
retrograde guidewire as the landmark. Two orthogonal projections (a &
b). Using a retrograde guidewire (whether in the true lumen or subinti-
mal space) that cannot be advanced further as a landmark (kissing wire
technique), you should exchange the antegrade guidewire for another
wire with a higher tip load and attempt further advancement through the
occlusion to the distal true lumen. If the antegrade guidewire comes
into contact with the retrograde guidewire at any point on its way to the
exit, you should attempt the reverse CART technique
a
bc
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1.6.4.12 IVUS-Guided Wiring: Side Branch
Technique
A guidewire that is conrmed to be in the subintimal space
at the exit of a CTO has often gone into the subintimal space
at the entry of the occlusion. Many guidewires fail to track
the true lumen at the CTO entry and are located in the subintimal space at the exit. If you are manipulating a stiff CTO
guidewire toward the entry of an occlusion and there is a
side branch that can accommodate an IVUS catheter near the
entry, you should introduce an IVUS catheter into the side
branch to check if the guidewire tracks the true lumen at the
CTO entry.
When penetrating the proximal cap with the guidewire,
you should focus attention on the uoroscopic image rather
than the IVUS image. The uoroscopy angle should be set
so that the guidewire can be viewed en face on the plane that
includes the axis of the side branch and the putative line at
the entry of the occlusion. You should advance the guidewire
toward the entry with its tip oriented in the opposite direction to the side branch and manipulate the wire to catch a
dimple at the entry by slightly altering the direction of the
tip (Fig.1.128). During manipulation, you should check the
IVUS screen to determine whether the tip of the guidewire
is oriented in the correct direction at the bifurcation and is
located at an appropriate entry point and to make ne adjustments to these parameters. If an assistant can relay the IVUS
ndings, the interventionalist can continuously focus on the
uoroscopic image without the need to alternately check the
IVUS screen.
If the tip of the guidewire cannot catch a dimple at the
CTO entry, you should create a more acute curve at the tip. If
the guidewire still fails to catch a dimple after being reshaped
in this way, you should exchange it for another guidewire
with a higher tip load.
If the tip of the guidewire goes into the subintimal space
from the main vessel distal to the entry of the occlusion, you
should make the tip curve more acute (Fig.1.128b). In contrast, if the tip of the guidewire enters the subintimal space
from the main vessel proximal to the CTO entry, you should
make the curve at the tip larger and less acute (Fig.1.128c).
While keeping the IVUS probe at the CTO entry, you should
advance the tip of the guidewire into the side branch and then
pull the wire back with its tip oriented in the opposite direction. Then you should perform ne adjustment to direct the
guidewire tip toward the true lumen at the entry of the occlusion using the IVUS image. With the tip oriented toward the
true lumen, you should push it forward slightly to nd a dimple. If the tip catches a dimple, you should check the IVUS
image to determine whether the tip is still oriented toward
the true lumen.
It is almost impossible to penetrate calcied plaque capping the entry of an occlusion (in a main branch). In this
case, you will need to nd a non-calcied part of proximal
cap that can be penetrated, but entry at such a site often
leads to subintimal tracking. If you fail to achieve reentry of
the guidewire into the true lumen, it becomes necessary to
attempt the reverse CART technique (described later).
Fig. 1.128 IVUS-guided
penetration of the entry to a
CTO at the ostium of a side
branch. This is a typical
example of a target vessel
with a CTO branching from
the larger curvature of the
patent main vessel. A
guidewire can be advanced
smoothly to the entry of the
occlusion (a). Then the
guidewire tip may be
advanced to a point distal to
the dimple, so that it enters
the subintimal space on the
distal side of the occlusion
(b). If the guidewire tip is
curved as shown in the upper
gure, it should be reshaped
with a slightly smaller and
more acute curve, as shown in
(c), to catch the dimple
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1.6.4.13 IVUS-Guided Wiring: False Lumen
Technique
When the guidewire is found to be in the subintimal space at
the exit of an occlusion, there may be no side branch available, and parallel wiring may fail. It may also be impossible
to attempt retrograde PCI because of the lack of a trackable collateral channel. In this situation, you should attempt
IVUS-guided tracking of the true lumen by introducing an
IVUS catheter into the existing subintimal space from the
entry of the occlusion (Fig.1.129). You should explore the
site of obstruction at the CTO entry with the tip of a guidewire oriented toward the true lumen and parallel with the
IVUS catheter/guidewire. In this situation, it is best to
manipulate the guidewire toward the predicted true lumen
based on uoroscopic images and to conrm the direction of
the lumen by IVUS.On uoroscopic images, the true lumen
is usually present on the smaller curvature of the occluded
vessel. In general, a guidewire deviates from the hard true
lumen into a false lumen in the direction of the larger curvature of the occluded vessel, as indicated by the nding that
an IVUS catheter or other device tends to easily run along
the larger curvature of a curved occlusion.
If there is a blocking point (obstruction), you should
patiently rotate the guidewire within ±90 degrees at that
location (xed point rotation) until it enters the occlusion.
This is to ensure penetration of the guidewire into the true
lumen because previous guidewires presumably deviated
into the subintimal space at this point. After penetration
into the lesion, you should advance the guidewire within
the true lumen if there is no intimal calcication and if the
lumen is clearly visible on IVUS.If there is intimal calcication, you cannot use IVUS to conrm that the advancing guidewire remains within the true lumen. In the rst
window without calcied plaque that is found as the IVUS
catheter is advanced, you should conrm the position of
the true lumen and estimate the course for the guidewire
to follow. Then you should advance the guidewire toward
the predicted point parallel with the IVUS catheter/guidewire to nd a direction in which it can easily go forward.
When the guidewire is about to reach the plaque window,
you should check if it is still in the true lumen. If it is, you
should further advance the IVUS catheter/guidewire and
repeat your IVUS check until the guidewire is advanced
into the true lumen at the exit.
If the guidewire is found to be outside the true lumen at
the window, you should pull it back to the previous window
where it was conrmed to be in the true lumen and then try
to advance it through the true lumen up to the next window.
For IVUS-guided wiring by the false lumen technique,
it is better to use an IVUS catheter with a short nose. The
Eagle Eye (Volcano) was commonly used at one time, and
the double R type NaviFocus WR (Terumo) has also become
popular in recent years (Fig.1.130). Currently, I also use the
latter catheter.
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a
e
Proximal
bc d
IVUS
Distal
IVUS-Guided True Lumen Tracking
f
Tru GW
Fig. 1.129 IVUS-guided wiring: False lumen technique. (a & b) CTO
of the RCA (Segment #3), with reattempted IVUS-guided wiring by the
false lumen technique. (c & d) Antegrade PCI resulted in deviation of
the guidewire into the subintimal space, so the strategy was switched to
retrograde PCI, but attempts at collateral channel tracking failed. A second antegrade guidewire manipulated by the parallel wire technique
also failed to reach the true lumen. (e) IVUS showed that the guidewire
was in the subintimal space. (f) While the position of the true lumen
was checked by IVUS, a guidewire was advanced along the predicted
correct route. (g) After the guidewire reached the exit, it was conrmed
to be in the true lumen, and PCI was completed by stent implantation
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Proximal
Distal
g
Fig. 1.129 (continued)
9mm
distal marker Transducer
Fig. 1.130 Photograph of the NaviFocus WR.The NaviFocus WR has
a short nose, with a distance of only 9 mm between the tip and the
transducer
1.6.4.14 Conrmation ofCrossing theTrue
Lumen andPoints toBeConsidered
After Crossing
As mentioned above, crossing the true lumen with a guidewire is rst recognized by a sudden reduction of resistance
and almost spontaneous advancement of the wire. However,
this also occurs when the guidewire has gone outside the
vessel wall. These two different situations can usually be
distinguished easily on the basis of the movement and route
of the guidewire, but sometimes may be confused. Crossing
through the true lumen has to be conrmed by collateral
(usually contralateral) imaging.
After a stiff tapered CTO guidewire enters a relatively
soft false lumen, resistance to advancing the wire is reduced
considerably, which may lead to the misunderstanding that
the guidewire has entered the true lumen. The guidewire is
tracking the true lumen if it does not show deection when
advanced slowly without rotation and with the tip oriented
medially to the curve of the occluded vessel. However, subintimal tracking must be suspected if there is even slight
deection of the tip when the guidewire is advanced a little.
To check whether the guidewire is in the true or false lumen,
it must be advanced without rotation, since a guidewire that
is advanced with tip rotation may move forward in a false
lumen without showing deection in response to even light
pressure.
After the guidewire has reached the exit of the occlusion,
you should perform collateral imaging to determine whether
it is inside or outside the true lumen. If the guidewire has
crossed the CTO in a false lumen, you should choose from
the following strategies: (1) attempt to cross the occlusion
through the true lumen with the same guidewire, (2) attempt
to cross through the true lumen with a second guidewire
(parallel wiring or seesaw wiring), or (3) switch the strategy
to the retrograde approach.
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