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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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5 Mitsudo’s Non-pushing PCI Techniques
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Fig. 5.30 LAD bifurcation lesion. Because the diameter of the proxi-
mal MB was much larger than that of the distal MB, POT was performed after stenting. When a balloon was advanced into the SB, it
caused shortening of the proximal part of the stent (arrows), making it
difcult to deliver a stent into the SB
Fig. 5.31 Stenting a calcied LAD bifurcation lesion. After stenting, a balloon was advanced into the SB and caused shortening of the stent
(arrows) due to malapposition
5.6 Stenting
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263
Fig. 5.32 CTO of the LAD successfully recanalized by reverse
CART.After a guidewire had crossed the CTO through a false lumen, a
stent was implanted in the false lumen. After stenting, a balloon was
advanced into the SB and caused shortening of the stent (arrows) at the
gap between lesion and stent. Planned SB stenting was abandoned
because shortening of the stent (i.e., strut deformation) prevented delivery of a second stent to the SB
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Fig. 5.33 Stent deformation by a balloon advanced into the SB or by
an IVUS catheter during withdrawal after stenting. A stent may be
deformed if a balloon is advanced forcibly or an IVUS catheter is withdrawn forcibly
5 Mitsudo’s Non-pushing PCI Techniques
calcied, debulking of the lesion should often be per-
formed by scoring/cutting balloon angioplasty or
rotablation.
For a bifurcation lesion, such as a distal LM bifurcation
lesion:
4. Perform POT immediately after implanting a stent.
5. If difculty is encountered when delivering a previously
used balloon into a stent, withdraw the balloon into the
guiding catheter and then rewrap it there by ination at
about 10atm.
6. and 7. To deliver a balloon into the SB for post-stenting
KBI, special techniques may be required.
1. Without using a guidewire that provides relatively strong
support, it is impossible to alleviate bias of the stent/bal-
loon toward the larger curvature of a bend in the target
vessel (Fig.
5.35). For example, the Sion guidewire is not
suitable for use when delivering a stent/balloon because it
provides insufcient support. The Sion Blue ExtraSupport wire, or another guidewire that provides equivalent support, is preferable.
2. The stent should be well apposed when it is initially
placed. If there is malapposition of any strut, the stent can
easily be deformed if the strut is hit by another device. At
a large bend in the target vessel, a strut is likely to be hit
by another device, even if the struts are all well apposed.
In a tapered vessel, a stent with a diameter as close as possible to that of the proximal segment should employed. In
a tapered vessel with a bend, a stent with a diameter that
ensures optimal apposition in the proximal segment of the
vessel should be used.
Fig. 5.34 Stent deformation by other devices at a curved bifurcation
with a large-diameter proximal MB.A stent placed at such a bifurcation
lesion is likely to show malapposition at its proximal part. When a balloon is introduced for POT, it may hit a strut and deform the stent
5.6.2.3 Practical Approach toPlacing
aConformable Stent
The following strategies can be employed when placing a
conformable stent:
1. In principle, use a guidewire that provides relatively strong
support.
2. In a tapered vessel, place a stent with a size matching the
diameter of the proximal segment of the vessel by inating the SDB at a low pressure.
3. Prepare the lesion sufciently to allow optimal stent
expansion, even by low-pressure ination of the
SDB.Particularly if the distal segment of the vessel is
In a tapered vessel, there are two methods of placing a
stent with a diameter matching that of the proximal segment. One method is to perform double stenting, while the
other is carry out low-pressure implantation of a stent with a
diameter matching the proximal segment, followed by distal
and proximal post-dilatation. I generally employ the latter
strategy. If the proximal vessel has a diameter of 3.5 mm,
I choose to implant a 3.5-mm stent even if the distal vessel
diameter is only 2.5mm. If there is no plaque at the distal
edge of the stent, there is little risk that low-pressure expansion of the stent (about 6atm) will cause dissection.
If there is plaque at the distal edge of the stent and dissection unfortunately occurs at the stent edge, this can be
overcome by implanting a short additional stent (about 8mm
long) with a diameter matching that of the distal vessel.
3. Lesion preparation: To achieve low-pressure stent expan-
sion, it is necessary to sufciently prepare (pre-dilate) the
5.6 Stenting
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lesion. Wherever stent expansion is suboptimal, a postdilatation balloon or another device may become caught
on a strut, possibly leading to deformation of the stent.
The diameter of the distal vessel (particularly the
diameter of the distal MB at a bifurcation) may be much
smaller than the diameter of the stent implanted in the
proximal segment. An oversized stent will exert little
expansionary force after implantation. Many stents exert
a maximum force of only 2 to 3kPa when expanded to
their target diameter. If a stent is going to be expanded to
a smaller diameter than the target, sufcient lesion preparation must theoretically be performed to allow sustained
stent expansion with low-pressure balloon ination
(1.5–2.0atm).
4. POT: In a bifurcation lesion, POT should only be performed to dilate the proximal MB to the nal target diameter and thus improve apposition of the proximal struts. In
a tapered non-bifurcation lesion, POT should also be performed before post-dilatation of the distal part of the stent
if there is malapposition of the proximal struts.
5. Rewrapping: If a balloon is advanced into a stent for postdilatation or KBI after being used for pre-dilatation and
not rewrapped, considerable friction may be generated
within the stent, and it can be impossible to move the balloon forward. If this happens, the balloon should be withdrawn into the guiding catheter and inated at a relatively
low pressure of about 10atm, followed by rewrapping in
a ne covering tube. After a balloon is rewrapped in this
way, it can usually be delivered into a stent very easily.
In the era of bulky balloons, the interventionalist had
to withdraw a balloon completely and rewrap it outside
the patient. To rewrap the balloon in those days, it was
usually returned to its protective sheath and inated at
about 10atm. The abovementioned rewrapping technique
copies this old method of balloon rewrapping, but performs it inside the guiding catheter. Inating and deating a balloon in a smooth lumen with a relatively small
diameter increases longitudinal folding of the balloon,
which will then reduce friction during delivery of the balloon into a stent.
6. KBI or high-pressure MB dilatation: After wiring the SB
through the MB stent and advancing a kissing balloon
into the MB, you may sometimes encounter difculty
when advancing a kissing balloon into the SB across the
MB stent. If the stent struts have been crossed by the tip
of the balloon, but not by its shoulders, you may immediately perform KBI at a low pressure of about 6atm. This
will often facilitate advancement of the balloon into the
SB. Even if performing KBI once fails to completely
deliver the balloon into the SB, several cycles of balloon
ination/deation can lead to gradual advancement of the
SB balloon and eventually allow it to smoothly cross the
stent into the SB.To avoid over-dilation of the proximal
segment of the vessel, you must not allow the marker of
the MB balloon to protrude beyond the proximal edge of
the MB stent, and simultaneous ination of the two kissing balloons should be conned within the stent.
High-pressure ination of the MB balloon alone can
also be useful and is possible after withdrawal or sufcient advancement of the SB balloon.
As is also the case in (7) below, you should never use
the anchoring technique with the MB balloon delivered
into the distal MB or any other balloon. This is because
forcibly pushing a device that has been caught on a stent
strut is very likely to cause deformation of the stent.
7. Checking and cutting off a damaged balloon tip, using a
new balloon, or using the buddy wire/balloon techniques:
If a balloon cannot be advanced toward the SB and if the
site of obstruction appears to be distant from the balloon’s
distal marker, the tip of the balloon may be blocked by a
stent strut.
Possible reasons for this are (1) the balloon tip has become
frayed or (2) the angle between the tip of the balloon and the
stent strut/vessel wall is too small or large.
As mentioned in (6) above, high-pressure ination of the
MB balloon alone, which is possible after withdrawal or sufcient advancement of the SB balloon, can be useful and is
worth trying rst. It may also be effective to withdraw the SB
balloon into the guiding catheter or another site where it can
be rotated freely and rotate it 180 degrees before readvancement. However, it is impossible to deliver a balloon into the
SB across the struts of the MB stent if the tip has become
frayed. Therefore, you should cut off the frayed tip of the
balloon or exchange it for a new one.
If a balloon with an intact tip is difcult to deliver, you
may advance a very small balloon past the obstruction and
pre-dilate the stent cell.
Since the highly conformable PROMUS Element stent
is prone to proximal deformation, the design was modied
when developing the PROMUS Premier, which has four
or ve links in the three struts at its proximal edge. This
modication has made the proximal 3mm of the stent very
rigid and thus increased the risk of fracture at the interface between the rigid and more exible parts of the stent.
Hence, the PROMUS series cannot escape one of the greatest defects of the rst-generation DES.It is important for
interventionalists to consider ways of making the best use
of currently available conformable stents to achieve implantation without deformation and not to employ stents with a
new design that may apparently make stenting easier, but is
actually inferior.
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Fig. 5.35 Using a guidewire that provides strong backup. A guidewire
or balloon catheter tends to track along the larger curvature of a bend in
a vessel. Upfront use of a guidewire with strong backup may allow
advancement of a balloon catheter along a different route. It can also be
effective to rst advance a balloon with good deliverability on an outwardly biased guidewire and then advance an optimally sized balloon
along a guidewire with strong backup
5.6.3 Using aChild Catheter
After sufcient preparation of the lesion, you should repeatedly advance and pull back the balloon catheter. If you notice
any difculty in advancing or withdrawing the balloon catheter or a Crusade or IVUS catheter, you should consider
using supplementary techniques for stent delivery.
The supplementary techniques for stent delivery include
(1) the buddy wire technique (Fig.5.36a), (2) the buddy balloon technique (Fig. 5.36b), (3) the slip-through technique
(Fig.5.36c, d), (4) the balloon trapping technique (Fig.5.36e),
and (5) the child-in-mother guide technique (Fig.5.36f, g).
In recent years, use of a child catheter (the GuideLiner or
equivalents such as Guidezilla and GuidePlus) has become
5 Mitsudo’s Non-pushing PCI Techniques
widespread because a child catheter can be manipulated simply and reliably. However, the GuideLiner has a larger prole than a balloon or stent, and its tip becomes biased toward
the greater curvature of a bend as it is advanced through a
vessel, i.e., the same side where resistance to devices occurs.
In other words, pushing a GuideLiner too vigorously may
cause injury to the vessel (Fig.
5.37a). Advancing a bal-
loon catheter rst (Fig. 5.37b) or inating a small-diameter (≤2 mm) balloon so that half of it protrudes from the
Guideliner (Fig. 5.37c) may facilitate advancement of the
catheter. However, it is safer to use a balloon inated inside
a pre-dilated distal segment or in an implanted stent as a
coaxial anchor. Then the GuideLiner catheter can be advance
reliably while slightly pulling back the anchoring balloon
catheter (Fig.5.37d).
When advancing a Guideliner across a proximally
implanted stent into a distal segment, it is necessary to take
great care to prevent stent deformation by the child catheter.
A stent can readily be deformed if the tip of the GuideLiner
even slightly comes into contact with a strut. Use of a coaxial anchoring balloon enables safer advancement of the
GuideLiner.
When attempting to deliver a stent through a previously
implanted stent, it may be impossible to advance the new
stent from a GuideLiner catheter. If this happens, you should
advance the GuideLiner and just keep it at the point of
obstruction. With the support of this child catheter, you may
then be able to advance the stent by applying gentle force.
This method probably succeeds because the Guideliner lls
the gap between the two stents (Fig.
5.38a) or because repo-
sitioning the guiding catheter corrects the bias of the catheter
(Fig.5.38b).
The sleeve of the GuideLiner can block advancement
of a balloon/stent or may cause deformation of a stent.
Usually, the tip of a balloon or stent comes into contact
with the rim of the GuideLiner sleeve (Fig. 5.39a, b).
To prevent this, the GuideLiner should be pushed in a
little before advancing a device into it to ensure that the
GuideLiner passes the tip of the guiding catheter and that
the stent is advanced along the medial side of the sleeve
(Fig.5.39c).
The smallest catheter in the GuideLiner series is 5.5 Fr.
If an even smaller child catheter is needed, a 4-Fr Heartrail
Kiwami OTW catheter can be used.
a
b
c
d
e
f
g
a
b
c
d
a
b
a
5.7 IVUS
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267
Fig. 5.38 Failure to advance a stent through a previously implanted
stent. After advancing a child catheter to the point of obstruction, it can
be easier to advance the other stent through the previously implanted
stent, probably because the wall of the child catheter lls the gap
between the two stents (a) or because repositioning the guiding catheter
corrects the direction of the stent (b)
b
c
Fig. 5.39 Obstruction of a balloon/stent (a) or stent deformation (b)
Fig. 5.36 Supplementary techniques for stent delivery. (a) Buddy wire
techniques. (b) Buddy balloon technique. (c, d) Slip-through technique.
(e) Balloon trapping technique. (f, g) Child-in-mother guide technique
overcome by using a GuideLiner catheter. As it is advanced, the
Guideliner catheter deviates outward in the guiding catheter and orients
the device inward, thereby overcoming the obstruction (c)
5.7 IVUS
It is well-known that an IVUS catheter must not be forcibly
pushed forward if it becomes difcult to advance. An IVUS
Fig. 5.37 Advancing a child catheter. (a) If there is a lesion on the
larger curvature of a bend in the target vessel, attempts to forcibly
advance a child catheter may injure the vessel, necessitating additional
intervention. (b) Advancing a balloon rst can reduce luminal irregularity and ensure smooth advancement of the child catheter. (c) Advancing
and inating a small-diameter (≤2.0 mm) balloon rst can facilitate
advancement of the child catheter. (d) Inating a balloon in the stent
landing zone and then pulling the balloon catheter back slightly will
change the orientation of the child catheter toward the smaller curvature
of the bend, helping the catheter to advance beyond the lesion
catheter typically has a short OTW region and the shaft is not
stiff. Accordingly, the shaft can easily be bent by pushing the
catheter, leading to disconnection of the inner wiring.
If it becomes impossible to advance an IVUS catheter,
you should suspect that its tip has been trapped by an irregularity on the larger curvature of the vessel wall. Therefore,
you should pull the catheter back slightly and then immediately push it forward a little. Like a blocked stent or balloon
catheter, this maneuver may allow the IVUS catheter to slip
past the obstruction and advance again. If it becomes almost
impossible to advance an IVUS catheter further after progressive escalation of difculty in moving forward, it should be
pulled back enough to eliminate deection and then slowly
advanced again. You should check whether the tip of the
catheter can move forward even slightly, as is the case with a
stent. If the tip moves forward a little, you should continue to
push it with the same force until the shaft becomes deected
slightly in the proximal coronary artery. Then the maneuvers
of pulling back and pushing forward are repeated.
If the hard transducer of the catheter becomes caught at a
bend in the vessel, you should slide the core shaft back slightly
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a
b
c
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5 Mitsudo’s Non-pushing PCI Techniques
to increase the exibility of the catheter tip and then follow the
above procedure (Fig.5.40a, b). After the catheter tip has passed
the bend, you should slide the core shaft (i.e., transducer) forward again to restore the backup of the catheter (Fig.5.40c).
If all of these attempts fail, it is necessary to enlarge the
lumen by (1) balloon angioplasty (upfront or repeated) or
(2) by debulking the lesion with a Rotablator. After failing to deliver the IVUS catheter although the lesion is sufciently dilated or stented, supplementary techniques can be
employed, such as (1) the buddy wire technique, (2) the buddy
balloon technique, or (3) the trapping technique. I prefer to
use a Guideliner to increase the backup of the IVUS catheter.
5.8 Anchoring Technique
The term “anchoring technique” covers several different
concepts, which are reviewed here in relation to non-pushing
PCI. “Anchoring” means taking measures to stabilize a guiding catheter or another device or to ensure smooth advancement by inating and xing a balloon in the artery lumen.
In contrast, xing a guidewire by inating a balloon and
then advancing a device along the xed wire is referred to
as “trapping.”
Anchors can be non-coaxial or coaxial (Fig.5.41). When a
non-coaxial anchor is used, the device can only be advanced
by pushing it forward (Fig.5.41a). With a coaxial anchor,
it is not always necessary to push the device forward, and
it may be advanced almost spontaneously if the obstruction
can be overcome by advancing a child catheter while pulling
the anchor balloon back slightly (Fig.5.41b).
I refer to inating a balloon in a coronary artery or inside
a guiding catheter for the purpose of xing a parallel guidewire as “trapping.” Trapping may be used to push forward
a device or to avoid an obstruction and allow spontaneous
advancement of the device (Fig.5.41c, d).
Fig. 5.40 Failure to deliver an IVUS catheter. (a, b) It can be difcult
to deliver an IVUS catheter into a hard and tortuous lesion. If this problem is encountered, slide back the core shaft and then slowly advance
the entire catheter. This will increase the exibility and trackability of
the catheter tip and may facilitate successful delivery of the catheter. (c)
After the catheter tip has passed a bend in the vessel, slide the core shaft
forward and then slowly advance the entire catheter
ab
Fig. 5.41 Anchoring technique. (a) Ination of a balloon in the SB to
facilitate advancing a device. (b) Ination of a balloon in the distal vessel to facilitate advancement of a child catheter. (c) Trapping with a
balloon to avoid an obstruction and allow spontaneous advancement of
a device. (d) Trapping a guidewire to facilitate advancement of a
microcatheter
ab
5.8 Anchoring Technique
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5.8.1 Anchoring technique
The original anchoring technique (Fig.5.41a) employs ination of a balloon in the SB to obtain strong backup for a
guiding catheter when advancing a device into the MB.This
technique is not required if the tip of the guiding catheter
remains coaxial to the coronary artery ostium and if the shaft
of the catheter can be brought into close contact with the
contralateral wall of the aorta or aortic sinus or if the catheter
can achieve the optimal power position.
Due to the vascular anatomy, it is sometimes impossible
for any guiding catheter to achieve the optimal power position
(Fig.5.42). Under such circumstances, it is often very difcult to engage a guiding catheter in the target coronary artery
ostium, and the catheter may become disengaged and slide out
of the ostium during PCI.If an SB is available, you should
advance a guidewire into the SB for anchoring along with
engaging a guiding catheter at the coronary artery ostium. The
anchoring technique is very useful to obtain strong backup for
a device, as well as for stabilizing a guiding catheter.
The anchoring balloon should have a diameter one size
(0.5 mm) larger than the lumen and a length of 15 mm,
and it should be inated at a low pressure of about 4atm.
Conversely, an undersized balloon inated at high pressure
often fails to be an effective anchor.
When using the anchoring technique to increase backup
for a device, it is important to be focused on pushing the
device carefully to advance it. As stated in Sect. 5.1 of this
chapter (page 243), the anchoring technique is useful for
advancing a balloon into a severe native stenosis. However,
a device should never be advanced with the aid of an anchor
when pushing is not allowed. For example, the anchoring
technique is typically contraindicated when delivering a balloon into the SB after stenting of the MB.
1
2
Fig. 5.42 Optimal power position. A guiding catheter achieves the
optimal power position when the tip is coaxial with the coronary artery
ostium and the shaft is brought into close contact with the contralateral
wall of the aorta (a). If a coronary artery shows extreme angulation at
the ostium (b), the guiding catheter cannot achieve the optimal power
position. This is because keeping the tip of the catheter coaxial to the
ostium decreases backup from the aortic wall (1), while ensuring sufcient backup from the aortic wall results in loss of coaxiality between
the catheter tip and the ostium (2)
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5 Mitsudo’s Non-pushing PCI Techniques
5.8.2 Coaxial Anchoring
Coaxial anchoring with an OTW or monorail balloon catheter is often used to advance a child catheter (Fig.5.41b). If
the guiding catheter has a small diameter, coaxial anchoring
can be a very useful technique to assist stenting after deep
engagement of the catheter. However, you should not use
coaxial anchoring to push in a guiding catheter and instead
should pull the shaft of the anchoring balloon back slightly
to avoid the obstruction to catheter advancement. A balloon
that has been used to pre-dilate the distal lumen is generally
employed for coaxial anchoring. The distal end of the balloon should not be located beyond the distal edge of the stent.
Sometimes, slightly pushing the anchoring balloon together
with the child catheter for the last few millimeters cannot be
avoided. If the child catheter still cannot be advanced, you
should slightly push the tip of the child catheter into the site
of obstruction and then gently insert a stent. The stent can
often be delivered smoothly in this manner (Fig.5.43).
5.8.3 Trapping
Trapping is a method of advancing a device by the same
mechanism as coaxial anchoring. For trapping, a parallel
guidewire is xed and used to facilitate advancement of a
device such as a stent (not a child catheter), which differentiates trapping from coaxial anchoring.
Usually, a trapping balloon has passed through the lumen
and thus reduced the space available for advancing the
device. If a retrogradely advanced balloon is used to trap a
guidewire, the available space will become larger, permitting
smoother advancement of the device.
A retrograde guidewire that has crossed a CTO is difcult
to trap stably in the lumen proximal to the lesion. To advance
a retrograde microcatheter, the retrograde guidewire often
needs to be trapped very tightly. If it is not trapped, the retrograde guidewire may move back through the CTO into the
distal coronary artery segment, necessitating another attempt
to retrogradely cross the lesion.
After a retrograde guidewire has successfully crossed a
CTO to reach the lumen proximal to the lesion, it should
be introduced into the antegrade guiding catheter and
trapped there, allowing a retrograde microcatheter to be reliably advanced across the CTO into the antegrade guiding
catheter.
Fig. 5.43 Failure to advance a child catheter with coaxial anchoring.
The child catheter should be advanced to the site of obstruction, after
which it will ll the gap and facilitate delivery of a stent
5.9 Guidewire Loop
A guidewire loop can be created by trapping, snaring, or
externalization (Fig.5.44). When snaring is used, the guidewire may escape from the snare, leading to the loss of the
loop. It is safer to combine trapping with snaring (Fig.5.44d).
In most cases, a guidewire loop is created after a retrograde
guidewire has crossed a CTO (see Chap. 1).
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5.10 Removing anIVUS Catheter
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271
Fig. 5.44 Making a guidewire loop. (a) Trapping. (b) Snaring. (c) Externalization. (d) When snaring is employed, the guidewire may escape from
the snare, so it is safer to combine trapping with snaring
5.10 Removing anIVUS Catheter
pulling harder on the catheter can also lead to it becoming
tightly stuck. What happens when an IVUS catheter is caught
You should not forcibly push a wire/catheter/device to
advance it. Likewise, you should not use excessive force to
withdraw an IVUS catheter or another device if difculty is
encountered when withdrawing it.
during withdrawal? Is it reasonable to pull the catheter if
there only seems to be a little difculty in withdrawing it?
One way that an IVUS catheter can be caught during
withdrawal is illustrated in Fig. 5.45. Advancement of a
device or balloon may be blocked when the gap between the
tip of the device and the guidewire or between the balloon
5.10.1 If theIVUS Catheter Becomes Stuck
during Withdrawal
tip and balloon membrane results in the tip being caught by
irregularities on the larger curvature of a bend in the ves-
sel (Fig.5.45a). Conversely, a device may become stuck on
After stent implantation, it is usual practice to employ IVUS
to conrm stent apposition. After completing observation,
the IVUS catheter can usually be withdrawn easily by slowly
pulling it back after rst sliding its imaging core forward to
the limit. If the guidewire used with the IVUS catheter has
a low tip load, it is better to push slightly on the guidewire
while slowly withdrawing the IVUS catheter.
During withdrawal, the IVUS catheter may sometimes
become stuck on the stent. In some cases, the catheter can
still be withdrawn by exerting a slightly stronger force, but
irregularities on the smaller curvature of a bend during withdrawal (Fig.5.45b).
During withdrawal of an IVUS catheter, it may be caught
at the exit port (Fig.5.46a). To stop the exit port from colliding with the vessel wall during withdrawal of the IVUS
catheter, you should push the guidewire while pulling the
catheter back, in order to direct the catheter toward the larger
curvature at a bend in the vessel. It is important to conrm
that the IVUS catheter has not been caught by irregularities
of the vessel wall (Fig.5.46b).
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