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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3585_Библиотеки_им_академика_М_И_Перельмана
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a
b
Fig. 1.71 Tip curves for Gaia guidewires. (a) A custom-made curve
created with the shaping device. This curve is about 0.6 to 0.7mm. (b)
A pre-shaped curve slightly larger than 1mm
Fig. 1.72 Advancing a guidewire with a high tip load and a small
curve at the tip. (a) A guidewire with a high tip load and a small curve
at the tip will go straight through a soft lesion. (b) If it is blocked by
hard tissue in the lesion, even a guidewire with a small tip curve will
deviate medially when it is pushed forward. (c) If it is rotated at the
point where it was blocked by hard tissue in the occlusion, the guide-
Fig. 1.70 Tip curves for crossing guidewires. For some time, the tip
curves shown in this gure were recommended for the prototype
Conquest Pro guidewires. Many interventionalists complained that
these guidewires could go only straight forward, but I and others knew
that even these guidewires could be deected in an occlusion once the
tip was blocked and bent by a hard lesion. In fact, we knew that a guidewire of intermediate stiffness (the rst choice at the time) would be
trapped (“deected” according to current concepts) without going
straight forward if it was unable to cross the CTO.Absence of hydrophilic coating at 1mm from the tip made it easier for the guidewire to
catch a dimple at the CTO entrance and to be deected when penetrating a tortuous lesion. To obtain optimal deection and advance the
guidewire in the desired direction, I think that it is important to rotate
the guidewire tip clockwise and counterclockwise within the range of
90 degrees. This point was also taken into account when recommending
the shapes and angles of the tip curve. Nonetheless, guidewires with
these tip curves sometimes fail to reach the entry of a curved lesion in a
relatively large vessel
wire will go forward and force its way into the lesion
Fig. 1.73 Guidewires with a second curve. If the entry point to a CTO
is located at a bend of the target vessel, a guidewire without a second
curve will sometimes fail to reach the dimple. I used guidewires with a
gentle second curve for some time, but I found that a gentle second
curve at the tip of a Conquest Pro guidewire was straightened again
soon after starting intravascular manipulation
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a
b
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a
b
Fig. 1.74 Shaping the second curve of a Conquest Pro guidewire.
Although I knew that whipping was more frequent when the guidewire
was shaped with a more acute curve than the gentle curve shown in the
previous gure, creating an acute second curve was necessary to maintain its shape. Whipping is more likely to occur as the second curve
becomes longer (a). Therefore, the length of the second curve was
restricted to about 2.5 mm at maximum (b), leading to the currently
recommended shape for the second curve. Some interventionalists may
suspect that a guidewire with such a second curve will be difcult to
control or not have sufcient pushability. However, a guidewire with a
second curve of this size is easier to control during advancement in a
slightly tortuous lesion. In practice, I often use a guidewire with a more
acute second curve than that shown in this gure, and the curve may be
modied according to the tortuosity of the lesion
1 Mitsudo’s PCI Techniques forCTO
a
b
Fig. 1.76 Guidewires with a large curve at the tip. (a) Curve at the
guidewire tip handcrafted with a 25-G needle. A CTO crossing guidewire with a tapered tip and a higher tip load than a Gaia wire is likely to
show straightening of the tip during manipulation in a hard vessel
lumen, resulting in failure to reach the entrance of the lesion. (b) A
guidewire with multiple staggered curves (each 1 to 2mm long) at the
tip is more likely to maintain its curvature
Fig. 1.75 Tip curves for Gaia guidewires. Gaia guidewires exhibit vir-
tually the same behavior as Conquest Pro guidewires, and therefore the
second curve is shaped according to the characteristics of the lesion. I
sometimes use a Gaia guidewire with a third (or even fourth) curve
Fig. 1.77 Optimal tip curve of a guidewire for bifurcation CTO.While
exploring the entry point of the occlusion under IVUS guidance, you may
nd that the guidewire can only be advanced into the subintimal space or
the boundary between the true lumen and subintimal space (a). If you
reshape the curve at the tip so that it is slightly smaller and slightly more
acute, it will be easier for the guidewire to catch a proximal dimple (b)
a
b
c
d
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1.6.4.3 Fixed Point Guidewire Rotation
A guidewire that has entered the true lumen at the entry of
a CTO and then has been advanced through the subintimal
space on the way to the exit often shows an inection point
(refer to 4. “Guidewire Trapping and Inection” [page 52]).
If the guidewire is suspected to have entered the subintimal
space, you should pull it back to a site just proximal to the
inection point and explore to nd the direction in which
the guidewire can go straight forward without deviation.
If the guidewire advances in the same direction again, you
should manipulate a second guidewire with a tip load one
level higher while using the rst wire as a landmark (parallel wire or seesaw wiring technique) and attempt to nd the
direction in which it can advance without deviation. In most
cases, the rst guidewire has been blocked by hard plaque
and has deviated toward the adventitia through softer tissue.
The best solution is to advance the second stiffer guidewire
to the site where the rst wire was blocked, direct its tip in
the opposite direction to the deviation of the rst wire, and
rotate the second guidewire around a xed point. Rotation
should be performed very slowly and through a limited arc,
or the second guidewire will probably deviate into the same
subintimal space. A guidewire with a smaller curve at the
tip can be rotated more stably around a xed point, while
a guidewire with a large curve may be unsuitable for xed
point rotation (Fig.1.78).
If the occluded coronary artery is tortuous and stiff at
a bend, a guidewire with a small curve at the tip sometimes cannot be advanced in the desired direction, even
if “deection” of the tip is utilized (Fig. 1.79a). If this
happens, do not make the rst curve larger because this
will severely reduce manipulability of the guidewire. If
the second curve is made larger instead, it often becomes
possible to direct the guidewire toward a hard dimple
(Fig.1.79b). Once a dimple has been caught at the CTO
entrance, rotate the guidewire around a xed point to penetrate the lesion.
If the tip of the guidewire that has caught a dimple slips
out of the dimple when xed point rotation is initiated, you
should exchange the guidewire for another wire with a stiffer
tip. Then the new guidewire can be rotated at the xed point
without slipping out of the dimple.
Fig. 1.78 Fixed point rotation of a guidewire. (a) Rotating a guidewire
with a small curve at its tip. (b) A guidewire with a large curve at its tip
requires greater torque for rotation. When rotated, the tip of such a
guidewire will move through a curve with a large radius. If the wire
enters the subintimal space, it will create a large dissection. (c) When
rotating a blocked guidewire with a small tip curve at the point of
obstruction in order to alter its direction and help the wire to penetrate
the lesion, it is relatively easy to shift the wire from one direction (solid
line) to another direction (dotted line). (d) It is sometimes difcult to
redirect a guidewire with a large tip curve, even by utilizing deection,
because the wire is unable to effectively catch a dimple of a hard lesion
Fig. 1.79 Guidewire with a tip curve that is too small. (a) A guidewire
with a curve at its tip that is too small may be difcult to navigate to a
dimple at the CTO entrance, even by utilizing deection. (b) If the
guidewire is reshaped with a small second curve, it can readily catch a
dimple. Once the guidewire has caught a dimple, the wire should be
advanced while rotating it around a xed point and keeping the tip in
the desired direction
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Column 6 Mechanisms of Guidewire Penetration
1 Mitsudo’s PCI Techniques forCTO
In an attempt to elucidate the mechanisms involved in guidewire penetration, I will discuss the behavior of guidewires
in various types of coronary artery occlusion.
To pass through an almost normal coronary artery, it is desirable for the guidewire to have a tip curve slightly larger
than the vessel diameter. A guidewire with too small a tip curve cannot isolate a side branch for which a smaller curvature is needed, while a guidewire with too large a tip curve cannot enter a side branch arising at an acute angle. To
pass through a coronary artery that has been narrowed by plaque, the guidewire should also have a tip curve slightly
greater than the inner diameter of the vessel (see Fig.1.67).
To pass a guidewire through the main vascular trunk, it should be advanced with to-and-fro rotation, so that it will
advance without being deected against the vessel wall. This is natural in a patent blood vessel, since a moving guidewire with a soft tip can clearly distinguish between the completely open lumen and the vessel wall. What about in a
CTO?
The situation will vary according to the mechanism underlying formation of the occlusion. Let us assume that the
CTO was formed by occlusion of a central channel in a gradually progressive stenosis (see Fig.1.44). There will be a
clear difference in hardness between the central tissue of the lesion that actually caused occlusion and the surrounding
plaque responsible for the preceding chronic stenosis. A CTO that develops in this way has a softer central region. You
will be able to penetrate such an occlusion by repeated rotation of a guidewire with a tip that is stiff enough to allow
free rotation in the soft central core without penetrating the surrounding hard plaque and with a tip curve smaller than
the diameter of the soft core. While the soft central core of the occlusion is expected to have a small diameter, the actual
diameter cannot be estimated. To allow the tip of the guidewire to move relatively freely within the central core, its tip
curve should optimally be slightly smaller than the diameter of the core. For this reason, a guidewire with a small tip
curve should be employed.
Next, consider a guidewire penetrating a homogenous CTO (see Fig.1.47). If occlusion has persisted for more
than 1year, the thrombus will be organized and will never be softer than the vessel wall; it is likely to be as hard as or
harder than the wall. To cross such a lesion, you must use a guidewire stiff enough to penetrate the organized thrombus. This type of occlusion is unlikely to have tapered ends, so the guidewire should be focused on the center of the
lumen revealed by CAG.It is often relatively easy for the guidewire to cross this type of CTO unless it is long or the
coronary artery lumen distal to the occlusion has a small diameter. However, you can easily imagine that tracking the
center of the organized thrombus becomes more difcult if the occlusion is very long and/or the arterial lumen distal
to the occlusion is too narrow. In this case, you cannot visually conrm whether the tip of the guidewire is within the
true lumen or in the subintimal space. In practice, you advance the guidewire in the direction in which it goes forward
with minimal force while rotating it, moving through the predicted central part of the lumen of the occluded vessel whenever possible. Despite performing plane rotation of the guidewire, it may deviate into the subintimal space
because the subintimal tissue is softer than the organized thrombus. In this case, a guidewire with a small curve at its
tip will create a smaller dissection when rotated and cause less subintimal injury. On the other hand, a guidewire with
a small tip curve is difcult to redirect after it enters a soft occluding plaque. A Gaia guidewire has a relatively large
tip curve of about 1.20mm because this was found to be optimal for redirection within the E-TOS model simulating
a relatively soft CTO.To penetrate harder plaque, you should use a guidewire with a smaller curve at the tip. Using
the shaping device, I create a customized curve of about 0.6mm at the tip of the guidewire by bending the point (see
Figs.1.69 and 1.70). A guidewire with a small tip curve is likely to advance straight through a relatively soft lesion. If
such a guidewire is given a small second curve (see Fig.1.76b), it becomes easier to reorient it in the desired direction,
even inside a soft lesion. This is another reason why I create a second curve at the tip of the guidewire. Under some
circumstances, a single relatively large curve (0.7mm) at the guidewire tip seems to exert an equal effect to that of a
very small rst curve plus a small second curve.
1.6.4.4 Guidewire Trapping andInection
While attempting to cross a relatively long CTO, you often
nd that the guidewire becomes trapped within the lesion.
The guidewire may be trapped by severe calcication or
deformation (kinking), but trapping is unrelated to the extent
of calcication in most cases. Although the mechanisms
involved in guidewire trapping remain to be elucidated, I
suggest that the following factors may be involved based on
insights from IVUS ndings.
To enter the subintimal space, a guidewire that was in the
true lumen at the CTO entry must cross the tunica media. I
think that the tip of the guidewire will not be trapped in the
media
intima
plaque
: guidewire
a
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media if it enters this layer at a large angle (Fig.1.80a), but
the tip can be trapped if it enters this layer at a small angle
and then is advanced for some distance parallel to the vessel
wall (Fig.1.80b).
If you nd that a guidewire can no longer be advanced
into a CTO, its tip may be trapped. If further advancement is impossible, you should withdraw the guidewire a
little to determine whether the tip is trapped. If the tip has
been trapped for a long time, the wire is difcult to withdraw and must not be pulled back directly or forcibly. If a
trapped guidewire is pulled back forcibly, its shaft core may
be ruptured, and the coil spring may be stretched. Therefore,
before attempting to withdraw a trapped guidewire, you must
rst rotate it clockwise and counterclockwise several times
with minimal force. Upon withdrawal of the guidewire, the
microcatheter holding the wire may advance to the point of
trapping. This is often unavoidable and can be rather convenient in most cases.
If the tip of the guidewire has been trapped within the
tunica media, it is likely to return to the true lumen at a site
1 to 2mm proximal to the point of trapping. Therefore, you
should pull the guidewire back slightly and advance it in a
new direction (Fig.1.81). If the guidewire was in the true
lumen at the entry of the CTO and it reaches the lumen distal
to the occlusion without being trapped again, it will probably
have crossed the occlusion through the true lumen.
However, a trapped guidewire does not always return to
the true lumen at a point just proximal to the site of trapping.
For example, the tip of a guidewire that has been advanced
outside the media may be directed medially and then become
trapped in the media (Fig. 1.82), but the interventionalist
cannot distinguish this scenario from the one mentioned
above. In the latter case, if the guidewire is pulled back from
the point of trapping and advanced in a new direction, it will
eventually return to the subintimal space and advance outside the media. This emphasizes the importance of targeting
the true lumen at the entry of a CTO.
Guidewire trapping is almost the only information other
than uoroscopic images that suggests deviation from the
true lumen into the media and provides the interventionalist
with a chance to redirect the wire into the true lumen under
uoroscopic guidance. Tight trapping of a guidewire may
result in fracture of the wire and/or intracoronary retention.
If you feel even a little difculty in advancing the guidewire
when crossing a CTO, you should pull the wire back to check
if it has become trapped. If it is not pulled back carefully,
a guidewire that is trapped will be freed abruptly and will
jump out. If there is even slight resistance when withdrawing a guidewire that may have become trapped in a lesion,
you should advance a microcatheter over the wire toward the
entry of the occlusion and then slowly pull the wire back
while rotating it. If you try to pull back a tightly trapped
guidewire while advancing a microcatheter, the catheter will
often enter the lesion as far as the point where the wire is
trapped and then also become trapped itself (Fig. 1.81a).
In this situation, forcible withdrawal of the guidewire will
lead to dissection of its tip. Instead, you should slowly pull
the guidewire back while rotating it, but note that excessive
rotation in one direction will lead to fragmentation of the
guidewire core. Therefore, it is important to free the tip of
the guidewire by performing several alternating clockwise
and counterclockwise rotations (to-and-fro rotation) until
unforced withdrawal becomes possible.
A guidewire that has gone outside the media without
being trapped often moves smoothly. If the guidewire penetrates the media at a large angle and abruptly enters soft
subintimal tissue, it tends to advance through the adventitia
toward the larger curvature of a curved vessel. A guidewire
taking such a course will often show an inection point at
the curve, if viewed in a lateral image. If you try to correct
the direction of a guidewire that has advanced through the
adventitia based on imaging in a single projection, the guidewire will remain in the adventitia and take a spiral course
along the vessel wall. On CAG, the inection point is where
the guidewire begins this spiral course. If an inection point
cannot be recognized in one projection, it is often seen in
another projection that is orthogonal to the rst one.
adventitia
vessel lumen of occlusion site
b
Fig. 1.80 Trapping of the guidewire tip. (a) A guidewire does not
encounter much resistance when it crosses the media at a large angle.
Once it enters the subintimal space, the guidewire can be advanced with
minimal force, easily creating a dissection. (b) If a guidewire enters the
tunica media at a small angle, it will remain within the media and will
become trapped after it has been advanced for a certain (long) distance
media
intima
a
: microcatherer
adventitia
media
intima
: guidewire
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adventitia
vessel lumen of occlusion site
b
c
: guidewire
Fig. 1.81 Countermeasures for guidewire trapping. Slightly with-
draw the trapped guidewire, and advance it in a new direction where
trapping does not occur. (a) If the tip has been trapped, a guidewire is
often difcult to withdraw. Efforts to withdraw the trapped guidewire
will cause the microcatheter holding the wire to advance to a point at
least 2 to 3 mm proximal to the guidewire tip. While keeping the
microcatheter at this point, perform to-and-fro rotation of the guidewire, and attempt to pull it back slowly. It may take several minutes to
withdraw a guidewire that has become tightly trapped. Never pull the
trapped guidewire forcibly or rotate it excessively in one direction
because this will lead to fragmentation of the shaft core and stretching
of the coil spring. (b) After retracting the guidewire into the microcatheter, pull the wire back together with the catheter for a distance of
2 to 3mm. The tip of the microcatheter is likely to remain in the true
lumen. (c) While keeping the microcatheter at this point, slowly
advance the tip of the guidewire, and nd the direction in which the
wire can cross the CTO through the true lumen without being trapped
again
vessel lumen of occlusion site
Fig. 1.82 Guidewire advanced outside the media while crossing a
CTO.The guidewire can be advanced easily while creating a dissection.
If the guidewire is redirected medially and enters the tunica media, its
tip can become trapped
1 Mitsudo’s PCI Techniques forCTO
1.6.4.5 Does aSti Guidewire Only Advance
Toward theLarger Curvature inaCurved
Vessel?
Interventionalists often complain that a stiff guidewire is not
very useful because it can only advance toward the larger
curvature at a bend in a curved vessel. If the interventionalist is well-known, this comment is accepted as the truth and
becomes a widespread belief, but it is a “myth.”
In fact, a guidewire with a high tip load relative to the
hardness of the occlusion and the wall of the target vessel
(i.e., a guidewire with a small curve at its tip that can be
advanced within the lumen or soft tissue with little force
while maintaining the shape of the curve [Fig. 1.83a]) will
go straight forward and then will follow the larger curvature at a bend of the vessel after being blocked by the harder
adventitia. However, if the guidewire is only slightly stiffer
relative to the tissue of the lesion so that its tip is deected
when blocked, the wire can take a course medial to the larger
curvature at the bend of the vessel (Fig.1.84). Of course, the
guidewire has to be stiff enough to penetrate the lesion. If the
guidewire does not have sufcient stiffness, its tip will deviate into the soft subintimal tissue and go toward the adventitia despite being advanced carefully. Thus, the stiffness (tip
load) of a CTO crossing guidewire should be adequate to
cope with the hardness of the lesion, but it should not be stiff
enough to maintain the shape of its tip curve during advancement. In other words, the guidewire should have a tip load
that is well balanced between penetrability and deection.
This balance largely depends on the hardness of the target
occlusion. Penetration of softer tissue is more sensitive to
changes in the tip load of the guidewire, while altering the
tip load will have little inuence if the hardness of the target
lesion is above a certain threshold. In that situation, you will
need to carefully manipulate the guidewire while making the
best use of deection and xed point rotation.
Anyway, please bear in mind that the tendency of a guidewire to go straight forward does not only depend on its tip
load. For this reason, if you expect the hardness of the tissue
in a CTO to show signicant heterogeneity, you should consider exchanging the guidewire as required to maintain the
optimal tip load for each part of the occlusion. For example,
if a guidewire with a relatively high tip load (e.g., a Conquest
Pro 12) is needed to penetrate the very hard entry point of a
CTO, but the distal segment of the occlusion is not so hard, it
is safer and reasonable to exchange the guidewire for another
with a lower tip load after entering the lesion. If the exit of
the occlusion is hard, you may want to exchange the guidewire again for another with a higher tip load.
This is the basic concept of selecting a guidewire based
on its tip load relative to the hardness of the target lesion.
Now let us consider a tortuous occlusion near the origin of
the RCA, in which the guidewire is likely to enter the adven-
a
b
c
Intermediate tissue
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titia at the larger curvature of the bend in the vessel. In this
case, the balance between the tip load of the guidewire and
the hardness of the target lesion will not solely determine
the likelihood of guidewire deviation toward the larger curvature and the risk of vascular dissection. When performing
PCI for a hard tortuous occlusion, as shown in Fig.1.84, a
CTO crossing guidewire with a small curve at its tip will
enter the subintimal space despite every effort to achieve
deection. Once it enters the subintimal space, a guidewire
with a higher tip load will create a larger subintimal dissection (Fig.1.85), based on the assumption that a wire with a
higher tip load will have a stiffer shaft. Naturally, a guidewire with a stiffer shaft will advance more laterally toward
the adventitia. To penetrate the entry point of such a CTO,
you should use a guidewire with a larger curve at its tip
and nd the optimal entry point. Optimizing the size and
Fig. 1.83 Effect of tissue
hardness on the course of the
guidewire. When pushed
forward without rotation into
a heterogeneous occlusion, a
guidewire with a small
shallow curve at its tip will
advance in a straight line if
the tissue composing the
lesion is soft (a). If the tissue
is so hard that it prevents
advancement of the guidewire
after entry is achieved, the
wire will curve back in the
wrong direction (c). If the
tissue is of intermediate
hardness, the guidewire will
show behavior between these
two extremes (b)
shape of the guidewire curve provides the key to successfully entering such a lesion. The tip of the guidewire should
have a very small rst curve with a small angle, and the second curve should be located about 2mm from the rst curve
(see Fig.1.75), so that the shaft is pressed against the larger
curvature of the vessel wall when the tip catches a dimple
at the CTO entrance (Fig.1.84b & c). The optimum angle
of the guidewire tip relative to the surface of the occlusion
is slightly less than 90 degrees. As mentioned above, you
should ensure the correct direction of the guidewire tip by
performing biplane cineangiography and then apply xed
point rotation for successful entry into the CTO.
Employing these techniques and optimizing the curve
of a stiff CTO crossing guidewire can allow it to be navigated in the appropriate direction along the curve of the
target vessel.
Soft tissue
Hard tissue
a
Gaia
Conquest Pro
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b
c
Fig. 1.84 Effect of the tip curve on the course of the guidewire. If the
entry of a CTO is located at a bend in the target vessel, a guidewire with
a single curve at the tip cannot reach the dimple at the entrance (a). If
forcible penetration of the occlusion is attempted, the guidewire will
inevitably be deected outside the media. To catch the dimple at the
entrance, a guidewire should be designed with second and third curves
at the tip (b), so that the tip can reach the dimple when the shaft of the
wire is running along the larger curvature of the vessel (c)
Fig. 1.85 Risk of dissection after a guidewire enters relatively soft
subintimal tissue. A Gaia guidewire is less likely to cause dissection
because the shaft is exible near the tip, allowing it to follow a tortuous
vessel. In contrast, the shaft of a Conquest Pro guidewire is stiff even
near the tip, and this wire straightens as it is advanced, creating a large
dissection. Therefore, once a Conquest Pro guidewire has entered the
subintimal space of a relatively soft vessel, you would usually hesitate
to retry wiring with the same guidewire because it would be expected to
enlarge the dissection. If a second wire is manipulated parallel to the
rst wire, it is also likely to enter the subintimal space and cause narrowing of the vessel lumen distal to the occlusion, which can prevent
imaging. On the other hand, a Gaia guidewire does not create a large
dissection, so repeated attempts with the same wire are feasible
1 Mitsudo’s PCI Techniques forCTO
1.6.4.6 Straightening oftheGuidewire Tip
A guidewire may gradually become uncontrollable as it
is advanced through a relatively long and hard CTO.The
usual reason is that the curve at the tip of the guidewire
(Fig.1.86a) has been lost because the tip has been stretched
and straightened (Fig.1.86b). It is natural for a guidewire
to become difcult to control once the tip is straightened.
If this problem is suspected, you should advance a microcatheter over the guidewire to an appropriate point and
then withdraw the wire to check the tip. If the tip has lost
its curve, you can reshape the curve or replace the guidewire with a new one. Fluoroscopy can also help to determine whether the tip of a guidewire has lost its curve. If
neither biplane angiography nor multidirectional imaging
can conrm a curve at the guidewire tip, or if monoplane
angiography does not show rotation of the tip during rotation of the wire, it should be concluded that the curve has
been lost.
As mentioned above, I used to bend the tip of a Conquest
Pro guidewire with an original shaping device because it was
difcult to manually produce a small curve at the tip and
because a curve created manually was easily lost. However,
even a curve shaped using the device can be straightened. As
it is advanced and withdrawn through a very small channel
that only just permits the passage of the guidewire through
a hard occlusion, the curve at the tip of the wire will gradually become shallower, and the wire will eventually be
straightened.
If the occlusion is relatively soft, the guidewire will
retain the curve at its tip. If the tissue of the occlusion is
hard enough to straighten the guidewire tip as it crosses
the CTO, it is unavoidable for the curve to be straightened
to some extent. Increasing the frequency of forward and
backward movements of the guidewire and performing
more to-and-fro rotations will increase the risk of straightening the tip.
While manipulating a guidewire, you should always be
thinking about whether the tip has retained its curve or not.
The following events or ndings during guidewire manipulation suggest straightening of the tip: (1) loss of contact with
a hard object that was previously caught by the guidewire
tip, (2) loss of control of the guidewire tip and a tendency
for it to go straight forward, (3) no detectable curve at the
tip with imaging in two orthogonal views, and (4) failure to
rotate the guidewire tip or change its direction even when
rotating the torquer. If any of these events occurs, you should
advance a microcatheter over the wire to an appropriate
point and then withdraw the guidewire to check the shape
of its tip. Fluoroscopy does not always conrm straighten-
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ing of the guidewire tip. Passing the guidewire through a
relatively small and hard occlusion may cause straightening
of the tip, but the curve can reform if the tip has only been
stretched within the limit of its deformability. Even if uoroscopy shows that the tip of the guidewire appears to have
been straightened, you may continue PCI with the same wire
if you can optimize its direction through blocking by hard
tissue.
If there are many risk factors for guidewire tip straightening and if the wire is trapped, there may be no good
solution other than replacing it. When pushed forcibly, a
guidewire with a straightened tip becomes hard to control
and eventually enters the subintimal space. Under the same
circumstances, a guidewire with a higher tip load is less
likely to undergo straightening than a wire with a low tip
load. Prompt crossing of a hard lesion without repetitive
forward and backward movement of the guidewire prevents
straightening of the tip. For these reasons, it is useful to
replace the guidewire with a new one having a tip load one
level higher.
a
b
Fig. 1.86 Loss of the curve at the guidewire tip. After the tip of a
guidewire has been shaped into a curve (a), the tip may become straightened again as it is advanced through a relatively hard lesion (b). If the
guidewire becomes difcult to control, it should be withdrawn to check
the curve at its tip
1.6.4.7 Basic Techniques forManipulating aCTO
Guidewire
A CTO guidewire can only be manipulated actively in three
ways, i.e., it can be “pushed,” “pulled,” or “rotated.” There
is also one important guidewire manipulation that does not
involve active movement, which is xing the tip.
Pushing (Advancing) the Wire
The purposes of pushing a guidewire forward include (1)
advancing the guidewire tip toward a distal segment of the
vessel, (2) penetrating the entry point of an occlusion or penetrating hard plaque/thrombus, (3) deecting the guidewire
tip, and (4) advancing the guidewire tip to nd a route that
can bypass hard plaque/thrombus.
You should only advance a guidewire without rotation
before it has reached the entrance of the CTO or after it has
entered the vessel lumen distal to the occlusion, or with the
intention of just advancing it slightly while orienting the tip
medially to a bend in the target vessel (Fig.1.87).
A guidewire can easily be advanced through the softer
core of a relatively hard occlusion if you apply minimal force
while performing to-and-fro rotation of the tip. This mimics
the situation where a guidewire with a soft tip can easily pass
through a non-occluded vessel while avoiding plaques on the
walls if it is advanced with to-and-fro rotation. If the guidewire is blocked by hard plaque on the vessel wall, continuous
rotation of the tip helps to return the wire to the lumen (soft
core) and allows it to be advanced with little force.
Of course, many CTOs do not have a soft core due to
the mechanism underlying formation of the occlusion. A
guidewire may be able to cross a short CTO that lacks a soft
core if it is advanced in the right direction. However, many
CTOs are long, and their precise anatomy cannot be determined. To cross such occlusions, the guidewire should be
advanced with minimal force when its tip is oriented in the
desired direction while continuously performing to-and-fro
rotation of the tip (“plane rotation”; see “Rotation” in this
subsection).
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1 Mitsudo’s PCI Techniques forCTO
Pulling the Wire
The guidewire is pulled back in preparation for the next
manipulation (i.e., pushing), and this may be done for two
purposes. One is to withdraw the guidewire and change the
position of its tip (Fig.1.88a), while the other is to reduce
stress on the tip without moving it in order to eliminate or
attenuate deection (Fig.1.88b).
A guidewire is withdrawn if its tip has entered the subintimal space. In this situation, the guidewire should be withdrawn to the point just before it entered the subintimal space,
and exploration should be performed to nd a new direction for the wire. When the tip of the guidewire is blocked
by hard tissue in the occlusion, you should push the tip forward slightly to check whether it can be advanced. The tip
of the guidewire will be deected by hard tissue and will
be deected further when the wire is pushed forward. If the
guidewire will not advance any further, you should just pull
back on it slightly while keeping the tip at the same position
to lessen its deection. Then you should redirect the guidewire with minimal force at an angle within 90 degrees of the
desired direction while performing slow to-and-fro rotation
to nd a route that can bypass the hard tissue in the occlusion.
Fixing the Tip
If the guidewire is blocked by hard tissue in the lesion and it
enters a side branch or the subintimal space when advanced,
you should x the tip at the point where it was blocked and
push the wire forward slightly with the tip oriented in the
desired direction. The guidewire should be rotated within
±90 degrees of the right direction. It is important to keep
the tip at the point of obstruction while pushing and rotating the wire (xed point rotation; see “Rotation”). In both
of the situations illustrated in Fig. 1.89, the guidewire is
blocked by hard tissue in the lesion and deviates rightward
into the subintimal space or a side branch. If you feel the
guidewire tip change direction after being blocked by hard
tissue in the occlusion, you should rotate the wire within
±90 degrees in the opposite direction with the tip xed at
the point of obstruction (see “Rotation”). This manipulation is aimed at increasing the penetration force of the
guidewire (so as to cross the lesion without pushing the
wire) and nding the direction in which the wire can easily
be advanced. If the guidewire slips to the right and its tip
cannot be oriented to the left, you may increase the angles
of the rst and second curves at the tip to enhance its abil-
ity to remain at the point, but it is better to exchange the
wire for another with a higher tip load. A guidewire with
a higher tip load can be expected to cross the hard part of
the occlusion when advanced with a force that is not strong
enough to deect its tip.
Rotation
The tip of the guidewire can be rotated by rotating the
attached torque device. It should be noted that rotation of
the guidewire tip includes xed point rotation (rotation of
the extreme tip; Figure1.90a) or plane rotation (rotation of
the entire rst or second curve at the tip; Figure1.90b). For
example, xed point rotation is performed when attempting
to catch a dimple and penetrate the CTO entry point, while
rotating a guidewire within a soft lesion is plane rotation.
In practice, the interventionalist can advance a guidewire
by making optimum use of these maneuvers as appropriate. If the target CTO is a soft occlusion surrounded by hard
brosed/calcied tissue, you should intentionally employ
plane rotation of the guidewire to ensure safe crossing of the
lesion with minimal force. If the CTO is a soft occlusion surrounded by soft tissue, a guidewire that is not advanced in
the correct direction is likely to enter the subintimal space, so
you should rotate the guidewire within ±90 degrees to obtain
the effect of xed point rotation.
Rotating a guidewire in a lesion composed of somewhat
harder tissue than its tip will generate stronger xed point
rotation. This can be understood from the fact that even a
guidewire with a high tip load (stiff tip), such as a Conquest
Pro, can lose its tip curve while being advanced through a long
hard occlusion. As mentioned above, if the tip of the guidewire is straightened (especially the rst curve), it becomes
impossible to change direction within the occlusion, and the
wire should therefore be reshaped with an appropriate curve
at the tip. If straightening of the reshaped guidewire occurs
easily, it should be exchanged for a new wire.
I would like to re-emphasize here that a CTO crossing
guidewire must not only be rotated in a single direction.
As mentioned above, to-and-fro rotation is important, so if
ve clockwise rotations have been performed, the guidewire must then be given ve counterclockwise rotations. If
a guidewire is rotated too much in a single direction, it will
easily be damaged when its tip becomes trapped. With regard
to withdrawing a guidewire after its tip has been trapped,
please refer to 1.9: “Troubleshooting.”
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