Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3585_Библиотеки_им_академика_М_И_Перельмана
.pdf
4.6 Case Study
https://t.me/medicina_free
a
b
241
KBI :
LAD 3.0 mm×LCX 3.5mm
14 atm
LAD : POBA (3.0×20 mm)
18 atm
LCX : POBA (3.5×20 mm)
18 atm
KBI :
LAD 3.0 mm×LCX 3.5 mm
14 atm
c
Fig. 4.34 KBI after culotte stenting. (a) Rewiring of the SB (LAD) was done via the Crusade catheter. (b) A 3.0-mm balloon in the LAD and a
3.5-mm balloon in the LCX were inated alternately at high pressure, and then were inated simultaneously (KBI). (c) Final angiography
Mitsudo’s Non-pushing PCI Techniques
https://t.me/medicina_free
5
My 33years of experience with PCI have taught me much,
including the essential importance of non-pushing PCI
techniques. Pushing devices forcibly may lead to injury
in various ways because of stress on the target vessel.
Although a device cannot be advanced at all without applying some force, the maximum tolerable force should be
estimated (i.e., the force that can be applied to a device
without causing damage/deformation), and force exceeding
this threshold should never be applied. In addition, methods for advancing devices with minimum force should be
determined. For example, it may be necessary to push hard
on a device if it becomes blocked. Therefore, avoiding this
situation is one of the ways to minimize the force required
to advance a device.
5.1 When Is Pushing Allowed?
In general, I do not recommend forcibly pushing a device to
advance it. However, there is one situation in which pushing is the only option and thus is permitted. This is when it
proves difcult to advance a balloon or microcatheter across
a lesion after successful wire crossing.
5.1.1 Microcatheter
It may be possible to cross a lesion, including one requiring rotablation, with a 0.014 inch guidewire, but not with a
microcatheter. However, the microcatheter can often cross
the lesion if the guidewire is exchanged for another that provides greater support.
During PCI for CTO, it is often necessary to rotate the
microcatheter in addition to pushing it forward with minimal
force in order to advance antegradely into a lesion, to retrogradely cross a collateral channel, or to deliver the catheter
into a lesion requiring rotablation that has been crossed by a
guidewire with microcatheter support.
Unlike the Tornus catheter, microcatheters must not be
rotated excessively in the same direction because these catheters generally cannot tolerate the torque of excessive rotation. For example, the Caravel microcatheter only tolerates
up to three clockwise or counterclockwise rotations. When
more than three rotations are performed with the tip xed,
the shaft of this catheter tends to bulge and may become
deformed. If this occurs after successfully tracking a channel,
it may prevent withdrawal of the microcatheter. Therefore,
you should never perform more than three clockwise or
counterclockwise rotations of the Caravel microcatheter in
succession. Of course, it is possible to perform three counterclockwise rotations initially and then repeat alternating
cycles of six clockwise and six counterclockwise rotations.
The Corsair microcatheter is better able to tolerate rotation,
but it is safer to limit the number of successive clockwise or
counterclockwise rotations to about ten with the Corsair and
most other microcatheters.
5.1.2 Small-Diameter Balloon Catheter
If a microcatheter cannot be advanced, it should be exchanged
for a small-diameter balloon catheter. Balloon catheters from
1.0 to 1.25mm in diameter with good crossability are available. Monorail balloon catheters can only be pushed and can
hardly be rotated. Therefore, you should use a balloon catheter that is suitable for the characteristics of the lesion.
Attempting to forcibly advance balloon that had become
blocked will sometimes deform the balloon and enlarge its
prole, preventing further advancement. Most of the recently
developed balloon catheters have been modied to be more
resistant to such deformation, but this problem has not been
completely overcome. Therefore, bench testing should be
performed to determine the force that can be applied before
each balloon undergoes deformation.
A balloon with a stiffer tip is better for a hard and relatively linear lesion, since it can be advanced despite the
© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
K. Mitsudo, Non-Pushing PCI Techniques, https://doi.org/10.1007/978-981-15-7043-8_5
243
244
ab
https://t.me/medicina_free
hardness of the lesion. If the balloon has a soft tip, it will
easily become deformed (Fig.5.1), and you cannot advance
a balloon with a deformed tip no matter how hard you push
it. However, it may not be possible to advance a balloon
with a stiff tip through a tortuous lesion because it is signicantly biased toward the outer side of the vessel (Fig.5.2b).
On the other hand, such a lesion can often be crossed easily
by a balloon with a soft tip that has little or no gap between
its tip and the guidewire (Fig.5.2c).
It is often difcult to advance a balloon through a hard and
tortuous lesion. Therefore, it is usually better to exchange
the guidewire for another with a stiff shaft that can provide
greater support to straighten a tortuous vessel (Fig.5.3) and
then advance a balloon with a stiff tip. This can result in
successful crossing of the lesion, but the balloon might be
blocked by hard tissue within a long CTO.In this situation,
dilating the entire proximal part of the occlusion with a small
balloon will often facilitate easy advancement of the balloon
catheter. Dilating the proximal part of the occlusion presumably reduces friction between the balloon and the occluded
vessel, leading to better transmission of force, or changes the
direction of the balloon at the point of blockade (Fig.5.4).
5 Mitsudo’s Non-pushing PCI Techniques
a
b
c
Fig. 5.2 Advancing a balloon through a hard and tortuous lesion (a). It
can be difcult to advance a balloon with a stiffer tip because it is
biased toward the outer side of the vessel (b). A balloon with a very
small gap between its tip and the guidewire (providing better trackability) can often cross the lesion (c)
Fig. 5.1 Flaring of the balloon tip. If a balloon with a soft tip is pushed
forcibly into a hard lesion, the tip may become deformed and are out
(a). If the tip becomes even slightly ared, it will be more difcult to
advance the balloon through the lesion. Therefore, about 0.3mm of the
tip should be cut off (b) or the balloon should be exchanged for one
with a stiffer tip
5.1 When Is Pushing Allowed?
https://t.me/medicina_free
Fig. 5.3 Crossing a tortuous hard lesion. The guidewire should be
exchanged for one with a stiffer shaft that provides greater support and
straightens the tortuous lesion to facilitate crossing by the balloon
Fig. 5.4 Crossing a long hard lesion. If the proximal part of a long hard
lesion is dilated, this will reduce friction between the balloon and the
lesion and/or alter the direction of the balloon tip at the site of blockade
to assist with crossing the lesion
5.1.3 Tornus Catheter
After failing to advance a balloon catheter across a lesion, a
Tornus catheter should be tried. Three models of the Tornus
catheter are available (2.1-Fr, 88 Flex, and Pro 2.1-Fr),
all of which have a shaft composed of metal wires but are
slightly different with respect to structure and characteristics
(Fig.5.5). I always choose the Tornus Pro if there is no particular contraindication.
The Tornus Pro has a 2.1-Fr shaft and its tip size is 0.025
inches. The Tornus 88 Flex is slightly larger, with a 2.6-Fr
shaft and a tip size of 0.028 inches. If the entrance of the
lesion is large enough to accommodate the 0.028 inch tip
245
of the 88 Flex, its thicker shaft produces greater torque that
promotes advancement. The Tornus Pro 2.1 Fr has the smallest tip (0.024 inches) and can be used for a tight stenosis that
cannot be entered with the other Tornus models.
The Tornus cannot be advanced by rotation alone. To
advance it into a tight stenosis, you have to simultaneously
rotate the catheter and push it in quite strongly. In the RCA,
even a deeply engaged guiding catheter may not provide sufcient support for the Tornus. Therefore, an anchoring balloon is often used in combination with the Tornus for RCA
lesions.
There are several tips for manipulating the Tornus catheter. You should usually rotate a Tornus catheter counterclockwise in a stepwise fashion with the right hand while pushing
it in with the left hand (Fig.
5.6). After one or two rotations,
you should stop pushing with the left hand and return the
right hand to its original position. You should then relax
the left hand to release the Tornus and subsequently rotate
it counterclockwise again. These processes are repeated
until the catheter has received a total of 20 to 30 rotations.
You should then completely relax the left hand to release
the accumulated torque. The Tornus may advance spontaneously during torque release. Rotating it as much as possible
at once, rather than repeatedly performing small rotations,
will help the catheter to advance further.
After crossing has been achieved with the Tornus, most
calcied lesions need debulking with a Rotablator, although
some mildly calcied lesions may be treated by balloon
angioplasty. To perform rotablation, the guidewire should be
exchanged for a RotaWire after the Tornus has crossed the
lesion. It is usually quite difcult to advance the RotaWire
Extra Support guidewire through the Tornus catheter due to
strong friction. This is particularly true if the lesion is long,
hard, and tortuous (including CTOs), even if the measures
described below are tried. It is easier to pass a RotaWire
Floppy guidewire through the Tornus catheter.
You must never push a RotaWire forward strongly when
advancing it through the Tornus catheter because the wire
is likely to become kinked at the hub of the Tornus, making it impossible to advance further. Even if you manage
to successfully pass a kinked RotaWire through the Tornus
catheter, the kinking will make it difcult to deliver the
RotaBurr and will affect debulking. To pass a RotaWire
through the Tornus catheter, you should advance the wire
carefully while rotating it. Do not use the attached clip for
advancing the guidewire, but use a torquer to apply sufcient rotation to the wire. You should slide the torquer forward from the proximal edge of the RotaWire to near the
hub of the Tornus. Advancing the RotaWire successfully
may require many rotations, but you must never hurry or
push it in forcibly. Instead, step-by-
step advancement of the
guidewire while rotating it provides the key to successful
delivery through the Tornus catheter.
246
a
ab
https://t.me/medicina_free
b
c
Fig. 5.5 The three Tornus models. (a) Tornus Pro. (b) Tornus. (c)
Tornus 88 Flex
5 Mitsudo’s Non-pushing PCI Techniques
5.1.4 Backup fortheGuiding Catheter
As explained in Chap. 1, a guiding catheter should be
selected that has a tip of the optimal size and curvature to
maximize backup in the target coronary artery. That is, when
the guiding catheter is engaged in the ostium of the target
coronary artery, its tip should be parallel with the ostium and
its shaft should be supported by the contralateral wall of the
sinus of Valsalva so that it provides sufcient support when
delivering devices.
If there is no guiding catheter with the optimal tip size/
curvature and if greater back-up is needed, the following
methods can be employed to enhance the back-up provided
by any guiding catheter.
1. Anchoring technique (see Chap. 1 [p. 14])
2. Deep engagement
Deep engagement of the guiding catheter is an effective
method of enhancing backup if the coronary artery ostium
has a sufciently large diameter and the vascular anatomy
allows the catheter to be positioned coaxially in relation to
the ostium (Fig.5.7a). It is relatively easy to achieve deep
engagement of a guiding catheter with a small diameter (e.g.,
5-Fr) (Fig.5.7b).
However, deep engagement of the guiding catheter is associated with a risk of coronary artery injury.
Therefore, this method should only be used if the guiding
catheter can easily be advanced by rotation alone without
pushing it in.
Fig. 5.6 Technique for advancing the Tornus. First, attach a torquer to
the guidewire. Then rotate the Tornus catheter counterclockwise with
the right hand while pushing it in with the left hand
Fig. 5.7 Deep engagement of a guiding catheter. (a) To achieve deep
engagement of an Amplatz guiding catheter in the RCA, the catheter
should be pulled back slightly while rotating it clockwise so as that the
tip is coaxial to the ostium. (b) It is easier to achieve deep engagement
of a guiding catheter with a small diameter because its tip has a small
radius of curvature
5.2 Guidewire
https://t.me/medicina_free
247
3. Deep engagement with assistance from an over-the-wire
child catheter or GuideLiner
The child-in-mother technique can a useful supplemen-
tary method. However, the over-the-wire child catheter or
Guideliner is not always suitable, and you may be unable
to use either of them some circumstances. In that situation,
you should exchange the current guiding catheter for another
catheter with a tip designed to enhance backup. At many centers, it is difcult to always have access to all kinds of guiding catheters. Therefore, a guiding catheter can be heated
and reshaped with an optimal curve or tip size or any additional three-dimensional changes that maximize backup (see
Chap. 1 [Page 12]).
5.2 Guidewire
5.2.1 Fundamentals ofAdvancing
aGuidewire
If the tip of a guidewire is deected by an obstruction, excessive force must not be applied to advance it. If a guidewire
becomes stuck in a severe stenosis or CTO and if the proximal part of the wire shows deection, too much force must
not be applied either. This is my absolute rule for guidewire
manipulation. About 90% of procedural problems related to
guidewires are attributable to using excessive force when
attempting to advance the wire in various situations.
5.2.2 Guidewire Manipulation
A guidewire can be manipulated in four ways, which are
pushing it forward, pulling it back, rotating it, and xing its
tip. These four manipulations should be combined appropriately to achieve the optimal wiring strategy for various
purposes, such as (1) tracking a clearly visible channel, (2)
exploring and tracking an accessible channel, and (3) crossing an occlusion.
Whatever wiring strategy is employed, it is of paramount
importance to apply minimal force to the guidewire and to
nd a route that allows the wire to be advanced without pushing hard. If you cannot nd a suitable route, the shape of the
guidewire tip should be modied. If even a guidewire with a
reshaped tip cannot be advanced, it should be exchanged for
another wire that is appropriate for the circumstances, such
as a guidewire with greater slipperiness, a guidewire with a
tapered tip, a CTO crossing wire with a 0.014″ tip, or a CTO
crossing wire with a tapered tip. Then you should search
for a route along which the new guidewire can be advanced
without pushing it hard by bypassing obstructions.
5.2.3 Rotating andPushing aGuidewire
As explained in relation to PCI for CTO (see Chap. 1), a
guidewire can be rotated in two ways, which are (1) xed
point rotation and (2) to-and-fro rotation.
To perform to-and-fro rotation of a guidewire, the entire
(curved) tip is rotated around its axis (shaft) (Fig.5.8). This
method of rotation is often used to advance a guidewire to
the entrance of a lesion or through the normal vessel lumen
distal to a lesion. The wire is advanced while rapidly rotating it alternately clockwise and counterclockwise. Rotation
of the tip is utilized to free the guidewire from irregularities
of the vessel wall that have temporarily caught it and thus to
minimize the force required to advance it.
If the guidewire becomes stuck while to-and-fro rotation is being performed, its tip stops rotating. If this happens, you should immediately stop advancing and rotating
the guidewire, because forcible attempts to push the wire
forward may cause intimal injury or deviation into the subintimal region. In this situation, you should pull the guidewire back slightly and then try to advance it again. If the
guidewire is blocked by a hard lesion, the shaft should be
rotated while keeping the tip xed at the point of obstruction
(xed point rotation; Fig.5.9), in order to cross the obstruction. This technique is typically used during SB wiring in
bifurcation stenting when the guidewire targeting the SB
becomes blocked by a stent strut. To assist the guidewire to
bypass the obstruction, rotation of ≤90 degrees should be
performed using the torquer without moving the tip of the
wire. If the guidewire is advanced with even slightly stronger force than optimal during rotation, the tip will easily
deviate from the obstruction. If the tip of the guidewire is
deected, you should pull it back slightly to straighten the
tip. Combining this manipulation with xed point rotation
often helps to pass the obstruction.
Fig. 5.8 To-and-fro rotation. A guidewire may be caught by irregulari-
ties of the vessel wall as it is pushed forward, leading to intimal injury
if forcible attempts are made to continue advancing it. Performing toand- fro rotation aims to free the guidewire from such irregularities by
alternately rotating it clockwise and counterclockwise
248
https://t.me/medicina_free
Fig. 5.9 Fixed point rotation. For wiring the SB during bifurcation
stenting, the guidewire is advanced to the distal MB and then is pulled
back with its tip oriented in the direction of the SB until the tip enters
the branch. Applying xed point rotation of ≤90 degrees to the guidewire at this stage will help to bypass obstruction by a stent strut so that
it enters the SB.If the tip of the guidewire is deected and does not
enter the SB, the wire should be pulled back slightly to straighten the tip
and xed point rotation should be repeated to bypass the obstruction
5.2.4 Exploration withaGuidewire
If a channel across a CTO is thought to exist but it cannot
be conrmed visually, you should try advancing a guidewire
with a tapered soft tip in several directions to nd a route
along which the wire can go forward without deection.
If the guidewire deviates into a subintimal space while you
are attempting to cross a CTO and you can see an inection
point, the wire should be pulled back until it is just proximal
to that point to bypass the obstruction that led to deviation.
While exploring to nd a route to the SB at a bifurcation
after reshaping the tip curve of a guidewire, slight rotation
of the wire may be performed. However, such rotation only
aims to orient the tip in the desired direction and should be
considered as part of exploration.
5 Mitsudo’s Non-pushing PCI Techniques
1. Techniques for wiring a very tortuous vessel are described
in detail in Chap. 1.7.8 (see p. 111). Although tortuous vessels with target lesions differ from the tortuous collateral
channels used in retrograde PCI because of having a larger
diameter and fewer bends, a similar approach to wiring is
employed. That is, you should reshape a guidewire with a
slippery soft tapered tip or non-tapered tip (polymer jacketed guidewire) to create a very acute (hairpin) tip curve
and then should slowly advance the wire while applying
nearly xed point rotation (Fig.5.10).
2. Wiring the SB at a bifurcation can be difcult in two situations. One is where the SB is located after a bend in the
proximal MB (Fig.5.11a). In this situation, you should
follow the steps stated above when choosing and reshaping the guidewire for a tortuous vessel. Then you should
twist the tip of the guidewire in the opposite direction to
orient it toward the SB (Fig.5.11b) and advance the wire
slowly. This technique may require considerable experience with PCI.If another guidewire is advanced through
the MB rst, it will straighten the vessel and decrease the
take-off angle of the SB, which may make it easier for the
wire to enter the SB (Fig.
5.11c). A Crusade catheter can
also be used to straighten a tortuous MB (Fig.5.11d).
The other situation that makes wiring the SB difcult is if
the branch arises with reverse angulation (Fig.5.12). While
you may follow the same advice for choosing and reshaping
the guidewire given in (1) above, the wire will often fail to
enter the SB.In this situation, the reverse wire technique can
be very useful.
Fig. 5.10 Wiring a very tortuous
vessel. To pass a guidewire through
a vessel that is too tortuous to be
crossed by a wire with a 0.014inch tip, a slippery polymer
jacketed guidewire should be
reshaped to create a hairpin curve
at the tip and then advanced while
rotating it
5.2.5 Guidewire Selection
andSupplementary Wiring Techniques
(Crusade Microcatheter, Scoring Balloon
[Lacrosse NSE Balloon] Angioplasty,
Reverse Wire Technique, etc.)
It may be difcult to advance a guidewire through a very tortuous vessel, the SB of a tortuous vessel, a highly angulated
SB, an SB distal to a coronary artery aneurysm, or an SB
that is just distal to a stenosis. I have summarized the optimal
guidewires and wiring strategies for these situations below.
ab
cd
5.2 Guidewire
https://t.me/medicina_free
249
Fig. 5.11 Wiring a side branch (arrow in a). The guidewire is advanced
into the distal MB and then slowly pulled back while orienting its tip
toward the SB. To prevent the guidewire from slipping out of the
ostium, the wire should be slowly advanced into the SB while applying
rotation (b). Advancing another guidewire or a Crusade catheter into
the MB may assist with isolation of the SB (c, d)
250
a
b
c
d
e
https://t.me/medicina_free
5 Mitsudo’s Non-pushing PCI Techniques
5.3.1 Bifurcation Lesions
Entanglement of multiple guidewires in a bifurcation lesion
may prevent delivery of a balloon catheter (Fig.5.13). This
is most commonly encountered when advancing a previously used balloon catheter to perform post-stenting KBI
after rewiring an SB (Fig.5.14). In such a situation, forcibly
advancing the balloon catheter will dislocate the entangled
guidewires and prevent guidewire crossing or even cause
guidewire deformation. If it is difcult to advance a balloon
catheter, you should always consider the possibility of guidewire entanglement.
If a Crusade catheter is used for SB rewiring, guidewire
entanglement, if any, will be limited to several millimeters
distal to the guidewire exit port of the catheter and entanglement is unlikely. Nonetheless, guidewire entanglement can
occur even if SB rewiring is performed with a Crusade catheter, probably due to exion or torsion of the guiding catheter.
Two guidewires can become entangled even if their proximal
topological relationship is always kept constant outside the
body.
Therefore, interventionalists need to know countermeasures for guidewire entanglement. If entanglement of two
guidewires prevents advancement of a balloon, the two
guidewires should be kept in place and the balloon catheter
should be withdrawn. You should then correct the torsion of
the two guidewires by rotation in the correct direction (in
practice, it can be hard to determine which direction this is)
at the O-ring. Subsequently, re-advancing the balloon may
Fig. 5.12 Wiring a side branch with reverse angulation. The reverse
wire technique is used for isolation of the branch
5.3 Balloon Angioplasty (POBA)
To pre-dilate a tight stenosis, it may sometimes be necessary to push a balloon catheter into the lesion, but this must
not be done with too much force. Pushing a balloon catheter strongly into the lesion will deect the proximal shaft
of the catheter and apply stress to the vessel wall. Although
the extent to which such catheter deection contributes to
dissection of the coronary artery proximal to the lesion or
progression of stenosis is unclear, I have encountered progression of coronary stenosis that was possibly due to forcible advancement of a balloon catheter. Therefore, following
the principle of “avoiding potential causes of adverse events
whenever possible,” measures should be taken to improve
the crossability of a balloon catheter for pre-dilation, such as
exchanging the balloon for one with a smaller diameter and
inating the new balloon.
resolve guidewire entanglement, although this is not always
successful. Another method is to withdraw the guidewire
from the distal MB into a balloon catheter that has been
advanced to the site of entanglement and then readvance
the guidewire for a short distance. This method can resolve
guidewire entanglement and allow the balloon to pass into
the stent (Fig.5.14c, d).
In this setting, if the tip of the balloon is used to put
slight pressure on the site of guidewire entanglement in the
MB, withdrawal of the entangled guidewire into the balloon will not have much inuence on the balloon’s direction. If the guidewire is subsequently advanced a little from
the tip of the balloon, the balloon will usually go forward
smoothly into the MB.After withdrawal of the guidewire
into the balloon, the balloon may sometimes become oriented toward the SB.If this happens, you should pull the
balloon back a little and give its tip some freedom. Then
you should readvance the balloon while avoiding guidewire advancement toward the SB or blocking of the wire
by stent struts.
a
b
c
d
5.3 Balloon Angioplasty (POBA)
https://t.me/medicina_free
251
5.3.2 Balloon Size, Ination Pressure,
andInation Speed
It is often said that high-pressure balloon ination causes
dissection, but is this true? It is completely incorrect if dissection is taken to mean direct injury of an intact part of the
vessel by the balloon (Fig.5.15). The most common causes
of dissection after balloon ination are oversizing of the bal-
Fig. 5.13 Guidewire entanglement at a bifurcation lesion. Guidewire
entanglement prevents delivery of a balloon
Fig. 5.14 Guidewire entanglement after SB wiring, precluding deliv-
ery of a previously used balloon to the MB
Although SB rewiring may be performed while avoiding
guidewire entanglement, it is recommended to overcome
entanglement by withdrawing the guidewire into a balloon
that has been advanced to the site of entanglement in the
MB and then advancing the balloon to the distal MB.This
maneuver can resolve guidewire entanglement and permit
smooth delivery of the balloon. As the tip of the balloon is
oriented toward the MB, you can smoothly pass the balloon
and the guidewire through a stent in the MB if the stent has
been well apposed.
loon and excessively rapid ination.
Assume that a balloon is inated in a straight vessel to
exactly the luminal diameter so that the vessel wall comes
into contact with the balloon but does not undergo expansion
(Fig.5.15b). Then balloon ination will not injure the vessel
regardless of the pressure employed. In this case, even if the
balloon is inated more rapidly, it will never injure the vessel.
However, what will occur after ination of a balloon with a
larger size than the luminal diameter (Fig.5.15c)? One can easily imagine that ination could cause increasingly severe injury
of the vessel as the balloon is inated to a larger size and/or
at a higher speed. In a curved vessel, vascular injury due to
inating an oversized balloon at excessive speed will predominantly occur at the edges of the balloon where the vessel wall
undergoes greater excursion (Fig.
5.15d, e). In a curved vessel,
high-pressure ination of a balloon with low conformability
can cause marked vessel wall excursion, and this increases the
risk of dissection at the balloon edges. The risk of dissection
also largely depends on the speed of balloon ination after vessel wall excursion occurs at the balloon edges.
In general, insufcient preparation of the lesion (leading
to suboptimal stent expansion) is associated with a high rate
of restenosis and with an even higher rate of re-restenosis
after repeat PCI for in-stent restenosis. You should remember
that there are no satisfactory interventions for treating restenosis due to suboptimal stent expansion. Therefore, suboptimal expansion is an event that must be avoided. Because
PCI is performed on this basis, it will often be necessary to
increase the balloon ination pressure to avoid suboptimal
stent expansion. On the other hand, it is not always easy to
predict the need for high-pressure balloon angioplasty. If a
safe method of performing high-pressure balloon angioplasty
is known, it should be employed routinely. I will explain my
own method of high-pressure balloon angioplasty next.
To dilate a stenosis (Fig. 5.16a), a balloon (3.0-mm)
that matches the luminal diameter of the vessel (3.05-mm)
is selected and is inated at its nominal pressure (6 atm).
To remove an indentation in the balloon (Fig. 5.16b) and
thus avoid insufcient lesion preparation, the pressure is
increased to 18atm (RBP plus 4atm), achieving a nal balloon diameter of about 3.3mm (Fig.5.16c). There is a risk
Соседние файлы в папке Библиотека им академика М.И. Перельмана