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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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1.9 Troubleshooting
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Fig. 1.219 Coronary artery perforation by a
guidewire. (a) To control hemorrhage from a side
branch, place a balloon in the main vessel across the
branching point, and inate it at a low pressure. (b) To
control hemorrhage from the main vessel, place a
balloon in the vessel at the site of hemorrhage, and
inate it at a low pressure
149
a
b
Fig. 1.220 Hemorrhage from
the distal coronary artery
segment (a). Place a balloon
in the proximal segment, and
inate it at a low pressure.
Conrm that the distal
segment is not visualized
during balloon ination (b)
Fig. 1.221 Hemorrhage after
stenting a CTO of the LCX
(a). Hemostasis was achieved
by inating a balloon in the
lesion at a low pressure (b)
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1 Mitsudo’s PCI Techniques forCTO
1.9.3 Perforation or Laceration
ofaRetrograde Collateral Channel
Perforation or laceration of a septal channel is not so serious. Even if it leads to intramyocardial bleeding, blood will
ow into the ventricle and rarely creates a large hematoma
in the myocardium. However, if there is a hematoma showing progressive enlargement and poor clearance of contrast
medium, you should take measures to secure hemostasis. If
bleeding into the ventricle does not occur, the perforation
Fig. 1.222 Septal channel
perforation caused by
inating a balloon after a
microcatheter failed to cross
the channel (a). The
hematoma was enlarging and
showed poor washout of
contrast medium, so a coil
was implanted to achieve
hemostasis (b)
is probably large, so a coil is more reliable for stopping the
bleeding than a blood clot or a block of subcutaneous fat
(Fig.1.222). After successful hemostasis, similar measures
should be taken from the contralateral side (Fig.1.223).
If there is intramyocardial bleeding, it is difcult to estimate the size of the connection between the artery and the
cardiac chamber. In this case, coil embolization should basically not be performed (Fig.1.224) because the connection
may be too large to retain a coil that is delivered as a hemostatic plug.
Fig. 1.223 Septal channel
perforation caused by
ination of a balloon after a
microcatheter failed to cross
the channel retrogradely from
the LAD in a patient with
CTO of the RCA.The
hematoma was enlarging and
showed poor washout of
contrast medium, so a coil
was implanted from the
LAD.Angiography of the
RCA showed bleeding (a), so
a coil was also implanted
from the RCA to consolidate
hemostasis (b)
1.9 Troubleshooting
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a b c
151
Fig. 1.224 Connection to the right ventricle created by a guidewire
during retrograde tracking of a septal channel from the LAD in a patient
with CTO of the RCA (a & b). The patient was followed up without any
1.9.4 Uncontrollable Bleeding: Management
ofCoronary Perforation
Typical cases are presented below (Figs.1.225 & 1.226).
specic treatment. After 3months, CAG conrmed disappearance of
the connection to the ventricle (c)
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bc
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1 Mitsudo’s PCI Techniques forCTO
a
Retrograde
ConPro12
Antegrade
ConPro30
POBA
1.25 mm
Retrograde wire
not cross
Antegrade
Runthrough
hypercoat
POBA
1.25 mm
Retrograde
ConPro12
d
ef g
h
Covered stent
3.0×16mm，16 atm
POBA 3.0mm
POBA 2.5mm
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153
Fig. 1.225 Bleeding during PCI for CTO of the RCA (1) (a). (b) The
retrograde guidewire was parallel with the antegrade guidewire in the
proximal true lumen and followed the same route when manipulated
repeatedly. It reached a site of resistance, and the tip was deected
when the guidewire was pushed further, indicating that the tip was in
the subintimal space. Since reverse CART could not be accomplished,
CART was attempted, and antegrade crossing of the CTO was successful. Subsequent CAG showed coronary artery perforation (c), and IVUS
conrmed that the antegrade guidewire was outside the vessel wall (d).
a
b c
Antegrade
Gaia First
After the antegrade guidewire was anchored with a retrograde balloon,
a covered stent was delivered and implanted (e). To control persistent
hemorrhage (f), another covered stent was implanted, and prolonged
plain old balloon angioplasty (POBA) was performed from both directions. Simultaneously, protamine was injected intravenously (g).
Hemostasis was achieved and the CTO was successfully recanalized (h)
Retrograde
Gaia Third
de f
Fig. 1.226 Bleeding during PCI for CTO of the RCA (2) (a). (Images
generously provided by Dr. Ryohei Yoshikawa, Sanda City Hospital)
After reverse CART appeared to be successful (b), externalization was
done, and the lesion was dilated with a 2.00-mm balloon. However,
IVUS showed that the guidewire ran outside the vessel wall in the segment where subintimal tracking occurred (c). CAG revealed coronary
artery perforation (arrow) (d). A GuideLiner catheter was advanced,
and a covered stent was delivered through the catheter at the site of
bleeding (e). The GuideLiner catheter not only facilitates smooth delivery of a difcult stent (e.g., a covered stent) but also has a physical
hemostatic effect and helps identify the site of bleeding by tip injection.
In this case, hemostasis was achieved by placing a covered stent at the
bleeding point. Then PCI was completed successfully by implanting
DES at the proximal and distal stenotic lesions (f)
Stenting ofBifurcation Lesions
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2
With regard to stenting of bifurcation lesions, the choice
between one and two stents, the need for kissing balloon ination (KBI) following implantation of a single stent, and the
optimal two-stent technique have been controversial issues.
Some recent studies have provided evidence that the proximal
optimization technique (POT) is useful for bifurcation stenting, while other reports have suggested the importance of
understanding the relationship between the diameters of the
two distal vessels and that of the proximal vessel when performing PCI for bifurcation lesions. Various dedicated bifurcation stents and balloons have been developed. The usefulness
of bioresorbable vascular scaffold (BVS) systems when performing PCI for bifurcation lesions has also been suggested.
This chapter reviews several stenting strategies and techniques that can be used for bifurcation lesions. Although
there is no evidence to support the superiority of these strategies/techniques over others, there also seem to be no data to
justify the solutions to the previous controversies.
For example, the controversy over the choice between one
and two stents appears to have been resolved with the conclusion that a single stent is better, but is this really correct?
The angiographic and clinical outcomes after bifurcation
stenting using general-purpose stents may be inuenced by
several factors, including (1) the stent design, (2) the stenting
technique (provisional T-stenting, culotte stenting, crush
stenting, etc.), (3) the details of stent implantation (point of
stent wire crossing, use of the Crusade, timing of proximal
optimization, kissing balloon ination [KBI], etc.), (4) the
extent of jailing or stent malapposition, and (5) unfavorable
stent deformation.
Some stents are not designed for bifurcation stenting,
while others are only compatible with certain stenting techniques. If a stent with an unsuitable design is selected, it may
be impossible to prevent jailing or malapposition when it is
used for a bifurcation lesion. KBI may not sufciently
expand the proximal part of some stents. The stenting technique has an inuence on the risk of jailing, stent malapposition, and stent deformation. The outcome of single versus
double stenting of bifurcation lesions should be compared
after optimization of all these factors, but it is doubtful that
previous studies comparing one versus two stents achieved
optimization of other factors. If any of these factors is undergoing clinical evolution, at least the best-available current
combination of stenting techniques and stent implantation
methods should be employed when comparing single and
double stenting. However, none of the previous studies comparing one or two stents employed a standardized (optimized) stenting protocol with regard to stent design and the
details of stent implantation.
This chapter describes the evolving state-of-the-art procedures for bifurcation stenting using general-purpose stents
and reviews the rationale for current practice.
© 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_2
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Column 12 Stent Design and Stenting Technique
2 Stenting ofBifurcation Lesions
The design of a stent often limits the choices of stenting techniques and the details of stent implantation. That is, stents
with a certain design can only be implanted by using certain techniques in certain situations.
Some interventionalists formerly used a Cypher stent to treat left main trunk (LMT) bifurcation lesions. The average diameter of the LAD ostium is 3.5mm, and it may sometimes be larger than 4mm. After expansion by KBI, the
strut cells of the Cypher stent open up to <3.5mm (Fig.2.1a). Although balloon ination in the side branch (SB)
appears to cause wider opening of the strut cells on imaging (which is two- dimensional), KBI has to produce threedimensional stent expansion, leading to insufcient strut cell opening for access to the SB when the reference diameter
is ≥3.5mm at the ostium. This inevitably results in jailing and stent malapposition. When culotte stenting is performed
by placing a stent from the LMT to the LCX after stenting from the LMT to the LAD, the main branch (LAD) ostium
is jailed instead of the SB (LCX) ostium (Fig.2.1b). A stenting technique that results in jailing of the main branch
(MB) is absolutely undesirable. Performing treatment on the basis that you do not know what is possible until you try
it is not good science or medicine.
In order to perform culotte stenting of an LMT bifurcation lesion, we need stents that are designed to prevent jailing of
the LAD after LCX stenting and KBI.If such stents are not available, research should focus on developing something suitable. In fact, an appropriate stent has already been developed in Japan (Fig.2.2). This stent can be expanded up to 6mm
and has made a signicant contribution to stenting of LMT bifurcation lesions, as well as other lesions in large coronary
arteries.
If protecting the SB is not considered important along with the risk of SB jailing or plaque shift, it may be felt that
crossover stenting (placing a stent in the MB across the SB) with or without POT is sufcient. If a Cypher stent (6-link
BX Velocity stent) is used for bifurcation stenting, it would be better to omit KBI, because this stent is likely to show
suboptimal expansion with jailing of the SB and because KBI leads to unnecessary stress on the SB.In contrast, using
a 2-link stent that permits optimal dilatation of both MB and SB will probably result in a satisfactory outcome after
KBI.If it is combined with an optimal stenting technique and optimal stent implantation, a 2-link stent can make a
two-stent strategy practicable. If stenting techniques are adopted on the basis of minimizing the risk of jailing (discussed later), culotte stenting will often be superior to crossover stenting.
When SB rewiring is done after stent implantation in the MB, I have proposed that the wire should cross the strut
through the most distal cell at the SB ostium since around the time when the Wiktor stent was introduced. This proposal
is based on the assumption that bifurcation stenting will always be performed by using coil or ring stents with 0 to 2
links (Wiktor, AVE Microstent, GFX, S-6, S-7, Endeavor [Driver], and Nobori [S-Stent]), and not with stents that have
a larger number of links.
Fig. 2.1 A BX Velocity stent (Cypher stent platform)
after expansion by ination of two 3.0-mm kissing
balloons. (a) The stent in the SB has not expanded to
3.0mm, with an indentation at the carina. Ination of two
3.5-mm kissing balloons also failed to sufciently expand
a 3.5- mm stent in the SB, which had the same design as
the 3.0-mm stent. (b) Culotte stenting with these stents
leads to jailing of the MB (arrow)
a
b
Side branch (SB)
Main branch (MB)
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157
Fig. 2.2 Nobori stent. (a) A 3.5-mm
Nobori stent expanded with two 3.5-mm
kissing balloons inated at their nominal
pressure. (b) A Nobori stent expanded to an
estimated proximal diameter of 5.8mm with
two 4.0-mm kissing balloons, leaving no
indentations
a
b
Next, I will discuss the implications of the MB stent wire crossing through the most distal cell of a Cypher stent at
the SB ostium. Figure2.3a, b shows diagrams of the structure of 2-link Driver and 6-link BX Velocity stents on the
same scale. The blue circles have a diameter of 3.5mm. In the case of the Cypher stent, a wire crossing through the
most distal cell as indicated by one red dot within the circle would cause minimal SB jailing, whereas a wire crossing
through the most distal cell as indicated by the other red dot within the circle would aggravate SB jailing. There is
no other route for the wire that minimizes the risk of SB jailing. With the Driver stent, if the wire crosses through the
cell as indicated by either red dot, it will only cause minimal SB jailing, even if jailing cannot be completely avoided.
Figure2.4a–e shows structural diagrams of currently available stents on almost the same scale. By moving the blue
circle over the view of each stent, it is possible to estimate the extent of SB jailing when the wire crosses through different cells.
The crush stenting technique (Fig.2.5a) was developed with introduction of the Cypher stent. Regarding this technique, many interventionalists have suggested the risk of the wire crossing a non-apposed stent through a cell distal to
the carina. In addition, crush stenting leads to three layers of struts overlapping in part of the proximal MB and limits
subsequent strategies if treatment of restenosis is required. Also, this technique has never been used with BMS.Due to
its closed cell design, the Cypher stent is crushed parallel to the MB wall. On the other hand, a 2-link stent is crushed
in an oblique direction to the MB wall, which may prevent introduction of a guidewire into the SB across the stent.
Moreover, overlapping of three strut layers impairs conformability of the stent. At best, the crush stenting technique is
only useful for placing Cypher stents at bifurcation lesions.
What about the V-stenting (simultaneous kissing stenting [SKS]) technique (Fig.2.5b)? Considering its principle,
SKS will cause stent malapposition and is far from the ideal method for bifurcation stenting (mentioned later). This
technique is also only practicable with multi-link stents that have a closed cell design. When it is used with stents that
have no links or a few links, the overlapping stent struts will interlock with each other, and this will gradually reduce
the diameters of stents expanded simultaneously.
The strategy for bifurcation stenting can only be optimized when a stenting technique is chosen that is compatible
with the stent design and when stent implantation is as sophisticated as possible. The feasibility of adopting a particular
stenting strategy also depends on lesion anatomy. Therefore, we should not compare the outcomes achieved with one
versus two stents or classify individual techniques as good or bad strategies without considering the various technical
aspects of bifurcation stenting.
Comprehensive evidence can only be obtained by comparison of all possible combinations of stent design and stenting techniques, but performing such comparisons is not practical. Therefore, we need to devise optimal stenting strategies on the basis of theoretical principles, as well as the results of bench tests and stent expansion experiments using
models.
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a
d
bc
a
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Fig. 2.3 Structural
diagrams of 2-link and
6-link stents. (a) Driver
stent. (b) Cypher (BX
Velocity) stent
2 Stenting ofBifurcation Lesions
1
2
9
4
5
3
6
14
7
12
10
8
13
11
21
26
19
17
15
16
24
22
20
25
18
23
e
Fig. 2.4 Structural diagrams of currently available stents. (a) Resolute Integrity stent. (b) Xience Prime stent. (c) PROMUS
Element stent. (d) Nobori stent. (e) Ultimaster stent
Fig. 2.5 Stenting techniques. (a)
Crush stenting. (b) V-stenting or
simultaneous kissing stenting (SKS)
b
2.1 Dedicated Bifurcation Stents
Various dedicated bifurcation stents have been developed
and can be classied into several categories. Many of them
can be used to achieve satisfactory outcomes if the stent is
positioned optimally so that its carina ts into the SB
ostium. However, it is often challenging, and sometimes
nearly impossible, to achieve optimal positioning of a dedicated bifurcation stent (Fig.2.6). The greatest limitation
of dedicated bifurcation stents is probably the xed distance between the proximal edge and carina. The stent
may be too short for full coverage of the proximal MB
2.1 Dedicated Bifurcation Stents
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159
including its ostium, which will then require implantation
of an additional stent for this purpose. Alternatively, the
stent may be too long to allow the proximal edge to remain
within the MB lumen, precluding its use.
Various difculties may be encountered during bifurcation
stenting with a dedicated stent. If a stent mounted on two balloons becomes blocked by an obstacle in the lumen during
delivery, it is often difcult to withdraw the stent into the guiding catheter and reattempt advancement. This is because mounting the stent on two balloons makes it very bulky and liable to
become stuck, deformed, or lost during withdrawal into the
guiding catheter. Another signicant limitation of a dedicated
bifurcation stent is that repositioning the stent to improve access
to the SB may be impossible after initial failure to place it in the
optimal position (Fig.2.7). SB rewiring through a strut cell far
from the carina may be required, resulting in loss of the original
advantage of the dedicated stent (Fig.2.8).
Thus, the dedicated bifurcation stents developed so far
have various limitations, including little exibility of indications, complexity of the stenting procedure, and difculty in
correcting the stent position/direction. These limitations
have prevented their extensive use in PCI.
Next, I will consider the designs of several of the dedicated
bifurcation stents that are currently available. Many dedicated
stents have been developed, all of which have embodied interesting concepts. However, further assessment is needed to
determine whether any of these dedicated stents is sufciently
useful for performing optimal bifurcation stenting.
Figure 2.9 shows the dedicated bifurcation stent developed
by Advanced Stent Technologies. Although this stent has an
extendable petal that is a very interesting idea, the design
raises important questions such as whether its carina can
always reach the vascular carina between the MB and the SB
and whether the center of the petal can be positioned precisely
at the center of the SB lumen (Fig.2.7). In addition, this stent
may show poor conformability with the SB at its origin.
Figure 2.10 displays Abbott’s dedicated bifurcation stent.
It has a simple design and is intended for simultaneous stent
implantation and KBI.This attractive stent mimics a generalpurpose stent suitable for provisional stenting that has been
applied to a bifurcation lesion. However, it also has limitations, including difculty in achieving optimal positioning
and proper alignment of the carina (i.e., the distance from the
vessel carina and orientation relative to the SB). Also, the
position of this stent cannot be corrected. If the stent is positioned wrongly, SB rewiring has to be performed through a
different strut cell, followed by KBI, resulting in loss of the
original functionality of a dedicated stent (Fig.2.8).
Figure 2.11 illustrates the dedicated stent system devel-
oped by Advanced Bifurcation Systems. This system is
designed to deliver a stent to the SB rst so as to automatically achieve optimal alignment. Although it is interesting,
this stent does not appear to conserve dynamic conformability with the SB origin and thus may not ensure optimal alignment if guidewire entanglement occurs.
Figure 2.12 illustrates the Y stent developed by
Medtronic, which joins two Driver stents into a “Y” shape.
If it can be implanted at a bifurcation lesion without deformation, its design appears to ensure optimal bifurcation
stenting. However, optimizing the carinal position and alignment remain challenging with this stent, while inability to
correct suboptimal carinal position and alignment is another
limitation.
The Tryton stent is displayed in Fig.2.13. This stent is
based on a unique concept and may be practical, with the
stent being composed of three zones (Fig.2.13a). The distal
zone (SB zone) is implanted in the SB, while the proximal
zone for the MB (MB zone) consists of a wedding band and a
triple linkage to the middle zone, which is referred to as the
transit zone. Two types of stent delivery balloon are available,
a stepped balloon and a straight balloon. The Tryton stent can
be implanted by a “simplied” culotte stenting technique,
which involves implanting the SB stent, inserting the SB
guidewire into the MB, implanting the MB stent, reinserting
the guidewire into the SB, and nal KBI (Fig. 2.13b).
However, it cannot be used for provisional stenting. Also, the
transit zone has very little radial strength, so it may not be
able to provide an adequate scaffold at the carina.
The STENTYS stent is shown in Fig.2.14. It has a unique
self-expanding mesh linked by small interconnections
between the struts, which can be disconnected by KBI.This
structure will ensure almost optimal bifurcation stenting plus
KBI if the SB take-off angle from the proximal MB is
medium to small. If the SB take-off angle is large, conformability of this stent is insufcient to ensure excellent apposition in the SB and possibly in the MB on the contralateral
side. Also, its self-expanding nature prevents correction of
malapposition by KBI.
The AXXESS stent is displayed in Fig.2.15. It is a self-
expanding stent designed to treat bifurcation lesions of the
LMT or other large coronary arteries. Although they cannot be seen in this gure, the stent has one and three markers at the proximal and distal edges, respectively, for
optimizing its position. As its distal end expands into an
elliptical bell, the strut edge becomes orthogonal to the
longitudinal axis of each branch. This results in little or no
overlap between it and the stent implanted in one branch
and also minimizes jailing of the other branch. The bell at
the distal end of the stent can expand to a diameter as large
as 8–12mm. This allows conformity to a bifurcation with
a large SB take-off angle, but possibly not to a distal LMT
bifurcation with a large SB take-off angle versus the
LMT.In addition, if the proximal LMT has a large diameter (either anatomically or due to progressive dilatation
after CTO), the distal end of this self-expanding stent will
open to a smaller extent, and stent malapposition will
occur at the lateral wall of the branch, especially the LCX
because of its extreme take-off angle. A similar phenomenon may occur when the SB take-off angle becomes progressively larger year after year.
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