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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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Stenting ofLeft Main Coronary Artery
All-cause mortality
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(LM) Lesions
As shown in Fig.4.1, the survival of patients undergoing
PCI for LM disease at my center was signicantly worse
than that of patients undergoing coronary artery bypass
grafting (CABG) in the rst-generation DES era (sirolimus-eluting stent: SES). However, survival has improved
in the second- generation DES era to a level similar to that
in patients undergoing CABG.Among several second-generation DES that are available, I use the Nobori 3.5-mm JV
stent to treat almost all LM bifurcation lesions because it
was developed with the aim of optimizing the stenting of
such lesions. Before the Nobori stent became available, I
used the Xience (an everolimus-eluting stent) for a while,
but only in patients with a small- to medium-diameter
LM.The outcomes shown in Fig.4.1 were obtained with
these stents and with other measures to solve various technical problems.
Since the second half of the SES era, it has generally
been considered that CABG is indicated for patients with
LM disease (particularly bifurcation lesions) requiring
rotablation. However, in the last few years, PCI has been
performed in some patients with LM disease that can be
adequately prepared by rotablation and scoring balloon
angioplasty (KBI with Lacrosse NSE balloons), as discussed later. If the LM lesion cannot be pre-dilated sufciently, switching to CABG to prevent acute coronary
occlusion should be considered, even if provisional stenting of the lesion is performed.
100
80
60
40
Cumulative incidence (%)
20
No. of patients at risk
st
DES (SES) 111 111 98
1
nd
2
DES (EES/BES) 58 58 42
CABG
Fig. 4.1 Survival of patients after PCI or CABG for unprotected LM
lesions with a SYNTAX score ≤32 during the period from 2003 to
2012. Comparison of all-cause mortality after PCI with secondgeneration DES (everolimus-eluting stent [Xience] or biolimus-eluting
stent [Nobori]) (n = 58) versus PCI with rst-generation DES (SES
[Cypher]) (n=111) versus CABG (n=159)
1st
DES vs. 2nd DES
nd
2
DES vs. CABG
st
1
DES vs. CABG
st
DES (SES)
1
nd
2
DES (EES/BES)
CABG
13.5
4.4
0
0 365 730
1.7
159 154 136
P=0.11
P=0.98
P=0.03
Interval (days)
16.2
8.3
6.5
4
© 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_4
211
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4 Stenting ofLeft Main Coronary Artery (LM) Lesions
4.1 Lesion Pathomorphology
andStenting Techniques
LM lesions vary with regard to anatomy and the indications
for stenting. LM lesions can be classied as follows:
1. LM ostial lesions with little or no plaque in the trunk or
bifurcation
2. Left main trunk lesions with no plaque in the ostium or
bifurcation
3. LM bifurcation lesions involving the LAD and/or LCX
ostium
4. LM lesions with severe calcication that requires
rotablation
5. LM lesions that are expected to be difcult to dilate, but
do not require rotablation
The outcome of PCI for these different LM lesions largely
depends on the choice of stents and stenting techniques. If
the lesion can be successfully recanalized by stenting of the
ostium or trunk alone, the outcome will be favorable. What
are the morphological characteristics of lesions in which
such simple stenting is likely to be achieved?
A localized stenosis without signicant plaque elsewhere
(plaque area/cross-sectional vessel area ≤ 40%), as conrmed by IVUS (Fig.4.2a or c), can be treated by implanting a short stent that covers the lesion. The LM can have
an enormous plaque burden because of its large diameter,
so post- stenting plaque shift may occur over a wider region.
Hence, the stent should be 6mm longer than the length of
the stenosis to reliably cover the artery from 3mm proximal
to 3mm distal to the lesion. For LM ostial lesions, the stent
should be positioned so that its proximal part completely
covers the entire ostium.
Left main trunk lesions with proximal plaque (Fig.4.2e)
should be treated by implanting a stent that can also cover
the affected proximal segment, which is generally the entire
ostium.
Bifurcation stenting is indicated for the left main trunk
lesions approximating the bifurcation (Fig. 4.2d). Lesions
such as those shown in this gure may be successfully
treated by stenting with KBI, while culotte stenting may be
indicated for some lesions depending on the expected extent
of plaque shift and/or carina shift.
LM bifurcation lesions with diffuse plaque extending
from the LM ostium to the proximal LAD and/or LCX
(Fig.4.2f or g) require both LM ostial stenting and bifurcation stenting.
When performing bifurcation stenting of the LM and
LAD/LCX, the following points should be considered
because of the unique anatomy of the LM:
1. As the LM (proximal main branch) has a large diameter,
you should choose a stent that can be expanded to a suit-
ably large diameter and should consider the possibility
that some struts may lose radial strength after LM stent-
ing with KBI (Fig.4.3).
2. The LCX ostium is often difcult to dilate because this
vessel can have a large take-off angle and because it may
have undergone signicant negative remodeling and
may have severe brosis and/or calcication of its
shoulders.
3. If the LM is severely calcied, the calcication will be
thick and may be resistant to rotablation, as well as mak-
ing the vessel difcult to dilate by POBA.
4. KBI is absolutely essential for adequate dilation of a ste-
notic LM bifurcation. In the presence of calcication, it
may be necessary to perform KBI at a reduced pressure to
prevent dissection of the LCX ostium or the LM, although
stenting with reduced pressure KBI may only achieve
suboptimal dilatation of a calcied bifurcation lesion.
5. Because the LCX ostium moves considerably during the
cardiac cycle, you should take special care when choos-
ing a stent for the LCX ostium and the technique for LCX
ostial stenting.
To prevent acute adverse events and obtain favorable
long-term outcomes, you should prepare the lesion as
carefully as possible and optimize the stenting procedure.
To achieve this objective, you should use an optimally
designed stent and the optimal stenting technique when
treating LM lesions, despite the potential for a longer
procedural time and increased consumption of healthcare
resources.
a
b
d
g
4.1 Lesion Pathomorphology andStenting Techniques
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213
c
e
h
Fig. 4.2 Pathomorphology of LM lesions. (a) LM ostial lesion with
plaque conned to the ostium (little or no or plaque elsewhere). (b) LM
ostial lesion with diffuse plaque extending toward the bifurcation. (c)
Left main trunk lesion with plaque conned to the trunk (the stent can
also cover plaque-free segments proximal and distal to the lesion). (d)
a
f
i
Left main trunk lesion that is too close to the bifurcation. (e) Left main
trunk lesion with plaque extending to the ostium. (f & g) LM lesion
involving the bifurcation. (h) LM bifurcation lesion with plaque conned to the LAD/LCX ostium. (i) Diffuse LM/LAD/LCX disease
b
c
Fig. 4.3 Treatment of LM bifurcation lesions by stenting with KBI
(a).If stenting with KBI causes partial jailing of the LCX (b), the culprit strut (red arrow) loses radial strength as it has no support at the site
of the carina. This strut cannot resist vascular recoil due to plaque on
d
e
the lateral side of the LCX (c; red arrow). Rewiring the LCX through
the most distal cell at the carina to resolve jailing before KBI (d)
results in all of the struts maintaining radial strength and resistance to
vascular recoil (e)
214
a
b
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4 Stenting ofLeft Main Coronary Artery (LM) Lesions
4.2 Stent Design
The LM often has a large diameter of about 6mm. For general
balloon-expandable stents, the maximum diameter is calculated as the diameter of the SDB plus 1.0 mm. Until 2013,
a 4.0-mm DES had not been approved in Japan, with the
maximum diameter of the available stents being 4.5mm after
expansion (3.5mm plus 1.0mm). Apart from the specications
of the manufacturer, there are no data regarding the diameter
to which a particular stent can be expanded. Currently, only
one balloon-expandable coronary stent marketed in Japan can
achieve a diameter of 6.0mm without cracking or fracturing.
This is the Nobori 3.5-mm JV stent, and it is the only stent in
the world that is denitely expandable to 6mm.
In addition to the maximum expansion diameter, the number of links is an important factor to be taken into account
when designing a stent. For the reasons described in Chap. 2,
it is desirable for a stent to have 0 to 2 links and for fracture
to occur at a link rather than at a strut.
What is the optimal design of a stent for a bifurcation where the proximal MB has a large diameter and the
SB shows extreme angulation (e.g., the LM bifurcation)? I
would like to discuss this matter from several viewpoints.
helical coil stents (no links) > one-link stents >two-link
stents >three-link stents >six-link stents.
4.2.1.2 Stent Conguration andStrut Material
Every stent strut has a zigzag structure. Stents t into two
categories according to the basic design, which are slotted tube stents and ring/coil stents. Helical coil stents formerly marketed under the brand names of Wiktor, Cordis, or
CrossFlex seem to have the greatest exibility.
In this discussion, I will refer to one zigzag of the stent
strut as a crown. A stent with a shorter crown has greater
local conformability (Fig. 4.4). Among metal stents, those
made of metals with greater elasticity generally have less
conformability. If the design is similar, stents made of stainless steel (less elastic) are more conformable than those
made of cobalt-chromium alloy (more elastic).
4.2.1 Conformability
The term “stent conformability” encompasses both the concept of exibility, which means the ability of a stent to ex
when implanted in a tortuous vessel, and the concept of
local conformability, which means the ability of a stent to
achieve apposition to the walls of a tortuous and branching
vessel.
4.2.1.1 Number ofLinks
Stenting of a bifurcation with a large branching angle
should be done by using a stent that possesses particularly
good exibility. Flexibility is a synonym for the tendency to
undergo longitudinal deformation. A stent with fewer links
has greater exibility, so stents can be ranked as follows in
order of decreasing exibility (increasing number of links):
Fig. 4.4 Inuence of the shape of the crowns. A stent with shorter
crowns (a) shows better conformability to the vessel. Such a stent will
rarely be affected by malapposition to the vessel wall as it maintains its
initial alignment with the vessel despite vascular recoil. A stent with
longer crowns (b) can only ex between the struts and expands discontinuously. Such a stent is more likely to develop malapposition when
compressed by vascular recoil
a
b
c
Xience
4.2 Stent Design
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215
4.2.1.3 Link Design
There are several link designs, including (1) inverse-phase
links with peak-valley interconnections (Fig. 4.5a), (2)
identical- phase links with peak-valley interconnections
(Fig.4.5b), and (3) identical-phase links with peak-peak interconnections (Fig.4.5c). Among two-link stents, the highest
Fig. 4.5 Link designs. (a)
Inverse-phase links with
peak-valley interconnections.
Adjacent struts are linked by
peak-to-valley
interconnections and are
aligned inversely. (b)
Identical-phase links with
peak-valley interconnections.
Adjacent struts are linked by
peak-to-valley
interconnections and are
aligned in the same manner.
(c) Identical-phase link with
peak-peak interconnections.
Adjacent struts are linked by
peak-to-peak interconnections
and are aligned in the same
manner
Cypher Nobori Integrity
Element
exibility is achieved by having struts linked by peak-valley
interconnections and aligned in the identical phase with fewer
longitudinal components in each link. The presence of a longer longitudinal link decreases the local conformability and
exibility of the stent.
6
Ultimaster Cypher Select
9
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4.2.2 Maximum Expansion Diameter
A stent for implantation in the ostium should be expandable
to a diameter of about 6.0mm in order to dilate the ostium to
its normal external diameter and prevent malapposition at the
lesion. To make a stent that can be expanded to such a large
diameter, the number and height of the crowns are increased.
For example, the Nobori 3.5-mm JV stent is designed with
ten crowns that are 1.24mm in height (i.e., higher than usual)
to ensure that it can be expanded up to 6.0mm in diameter.
Currently, no other coronary stent (especially with two links)
can be expanded to a diameter≥5.5mm.
4.2.3 Optimal Design oftheProximal Stent
Edge forOstial Stenting
A stent implanted in the ostium should have at least two links
at its proximal edge. Focusing on this point, some stents have
been developed with a larger number of links at the proximal
edge. The proximal edge of the GFX stent (a two-link stent)
often rolls up when it protrudes from the ostium (Fig.4.6).
The S-660 (another two-link stent) was designed with two
links only at the edges to prevent such “roll-up” of the most
proximal strut. Subsequently, the S-7 and Driver (2-link
stents) were designed with three links only at the edges to
further stabilize ostial dilatation.
However, two links at the edges is actually enough to prevent “roll-up” of the proximal edge. Even without apposition
to the vessel wall, the proximal edge of a two-link stent will
not roll up, although it may undergo slight deformation. If
the ostium of the target vessel has been stented with a twolink stent and the most proximal strut is protruding from the
ostium, you can insert a wire into the stent strut and advance
a large-diameter balloon along the wire. Ination of the balloon will never fail to dilate the ostium to its normal diameter
(Fig.4.7).
4 Stenting ofLeft Main Coronary Artery (LM) Lesions
Fig. 4.6 Strut roll-up with a one-link stent. If the guiding catheter even
comes into gentle contact with a two-link stent, its most proximal strut
is likely to roll up
Fig. 4.7 A two-link stent (Nobori stent). A guidewire was inserted into
the strut of a stent implanted in the LM ostium, and the ostium was
dilated with a balloon to its external diameter (4.0mm in this case).
Because of its structural characteristics, a two-link stent does not induce
SB jailing since the cells on the SB and MB sides can be enlarged to a
similar extent. The most proximal strut of a two-link stent protruding
into the sinus of Valsalva has gone outside the ostium so that the ostium
is very accessible
4.2 Stent Design
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Column 19 Promus PREMIER Stent
Here, I will make some comments about the Promus PREMIER stent, which is currently available. It would be correct
to say that I want to give candid feedback to the interventionalists who assisted in the development of this product. As
stated above, the Promus Element is a well-designed stent with high exibility, which makes it prone to longitudinal
deformation. If not manipulated carefully when performing ostial stenting, the Promus Element can be shortened when
a guiding catheter, a balloon, or another stent comes into contact with its proximal edge.
Therefore, Boston Scientic Corp. developed the Promus PREMIER stent, in which the three most proximal struts are
connected with four or ve links to make the proximal part more resistant to deformation (Fig.4.8). Despite advocating use
of the Promus Element, I have never used the Promus PREMIER (as of September 2015), and I do not intend to use it in the
future.
There are several reasons for this decision. First, the proximal part (4mm long) of the Promus PREMIER is too
rigid and its distal part is too exible. The stent is likely to be fractured at the abrupt transition from the rigid part to
the exible part, applying excessive stress on the vessel. Second, there will be a greater difference in rigidity at the
site two Promus PREMIER stents overlap with each other (four links plus two links). Third, during future intervention after ostial stenting has been done with a Promus PREMIER so that the proximal edge protrudes slightly into the
sinus of Valsalva, POBA following wiring through a cell may not sufciently dilate the cell. On the other hand, there
are various effective interventional measures for preventing stent deformation.
For these reasons, I think that the 4-mm Promus Element stent should be approved for coronary ostial stenting. In
Japan, the Nobori 3.5-mm JV stent is available and can meet the need for this indication. However, the 4.0-mm Promus
Element may be sufcient for stenting a medium-sized coronary ostium (diameter≤5.5 mm). Outside Japan, only
3.5- or 4.0-mm BioMatrix (9-crown and two-link) stents are available and not the Nobori 3.5-mm JV, so I have used
the 4.0-mm Promus Element stent for a large coronary artery ostium. After stenting, CAG and IVUS generally show
sufcient dilation and successful recanalization of the coronary ostium.
Although the Promus Element is not prone to fracture, it will undergo fracture at a strut more often than at a link (see
Chap. 3 regarding the disadvantages of fracture at a strut). Better outcomes will be obtained with a modied stent that
fractures at a link and minimizes vascular stimulation by the stumps of the broken link.
217
Fig. 4.8 Design of the Promus PREMIER
stent
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4 Stenting ofLeft Main Coronary Artery (LM) Lesions
4.3 Lesion Preparation
It is essential to perform IVUS before PCI for LM lesions.
As stated in Sect. I of this chapter (page 212), IVUS should
be used to estimate the diameter of the target vessel and the
overall plaque burden. In addition, IVUS is essential for
assessing the extent and distribution of calcication and for
quantifying plaque attenuation.
4.3.1 Preparation oftheLM Ostium
andTrunk
Most isolated LM ostial or trunk lesions are relatively soft
and are not associated with severe calcication. Rotablation
should be considered if there is circumferential calcication,
while scoring balloon angioplasty (e.g., a Lacrosse NSE) or
cutting balloon angioplasty should be considered when calcication is not circumferential. It is also important to perform scoring or cutting balloon angioplasty after rotablation
in order to lessen vascular recoil.
The luminal diameter may be ≥2.25 mm at a calcied
lesion in a large coronary artery (e.g., the LM or RCA).
Since large-diameter (≥9 Fr) guiding catheters are no longer used, rotablation using a 2.38-mm or 2.5-mm burr is not
feasible, which means that scoring or cutting balloon angioplasty should be considered.
4.3.2 Preparation oftheDistal LM Bifurcation
It is well-known that an LAD ostium with plaques on the
roof is difcult to dilate by POBA. Considering that the
carina, the LCX ostium, and the distal LM are present on the
contralateral side, ination of a balloon that is sized to match
the LAD diameter can easily displace the carina toward the
LCX. Therefore, even if the balloon appears to have been
inated fully without indentations, it is unlikely to apply
pressure to the roof of the LAD ostium (Fig.4.9). Placing a
stent from the LM to the LAD across the LCX ostium after
POBA always causes carina shift and induces vascular recoil
at the roof of the LAD ostium.
Debulking may be the optimal intervention to ensure
sufcient dilation at the roof of the LAD ostium if a sufcient volume of plaque can be removed. At present, three
debulking methods are available (Rotablator, excimer laser
coronary angioplasty [ELCA], and directional coronary
atherectomy [DCA]).
1. A Rotablator is used for debulking calcied tissue or other
very hard tissue. Since it has become uncommon to use
guiding catheters larger than 8 Fr, the maximum diameter of
the Rotablator burr cannot exceed 2.25mm. Consequently,
the reduction of plaque volume after rotablation is relatively
small compared to the LM diameter, and the residual thick
layer of calcied plaque may resist POBA.
Although some use can be made of the effect of guidewire bias, this method cannot completely ablate calcied
plaque because the plaques are not always concentric
with the vessel. Hence, complete debulking is difcult.
However, even if debulking is not complete, subsequent
KBI can apply pressure to plaques on the roof, thereby
dilating the stenotic lesion to some extent (Fig.4.9), and
proper stent placement after KBI can optimally dilate the
lesion. Thus, strategically adding rotablation to DES stenting with KBI will considerably improve the medium- to
long-term outcome of PCI for LM disease.
2. ELCA may be effective for ablating thrombotic plaques
in coronary arteries, but generally it cannot effectively
ablate plaques in large vessels.
3. It has been suggested that DCA may achieve optimal debulking if performed by experienced interventionalists.
However, we general interventionalists often nd it difcult to sufciently ablate plaques in the LM by DCA to
avoid the need for stenting. This is because the LM arises
in a leftward direction from the sinus of Valsalva and then
runs almost straight until it branches into the LAD and
LCX with extreme (left) anterior and posterior angulations, respectively. It should be noted that plaques which
require debulking at the LM bifurcation exist in these
extremely angulated vessels. It is almost impossible to
accurately locate plaques at this angulated bifurcation by
IVUS or to ablate plaques in such angulated vessels by
using a linear debulking device.
Even when using DCA, I only expect to achieve a modest
debulking effect with this device before implanting a DES.
Thus, the different debulking devices each have their own
points. I regard them all as useful tools for lesion preparation
to optimize stenting, and I think you should aim to achieve
better long-term outcomes by combining optimal debulking
and DES stenting with KBI.
Some interventionalists may recommend POT, i.e., dila-
tion of the proximal vessel by a single large-diameter balloon, before stent implantation. However, it is very difcult
to dilate the distal LM near the bifurcation to its normal
diameter by inating a single balloon (Fig.4.10). Also, en
face observation of the distal LM bifurcation by CAG is
problematic due to the different angulations of the LAD and
LCX.Taking these points into account, it is almost impossible to reliably dilate the distal LM bifurcation by using a
single large balloon. In fact, a large balloon often fails to
dilate an LM bifurcation lesion if it is inated insufciently
a
4.3 Lesion Preparation
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219
to prevent over-dilation of the distal MB (LAD) or if it slides
back into the left main trunk or ostium.
This may occur not only during POBA but also during
scoring or cutting balloon angioplasty. Even alternating ination of balloons matching the diameters of the LAD and LCX,
respectively, will fail to sufciently dilate the LM bifurcation.
KBI is eventually necessary, and high-pressure POBA often
fails to dilate the bifurcation, even with KBI.In the rst place,
high-pressure KBI is not recommended at the distal LM bifurcation because it is associated with a risk of causing dissection
in the LM bifurcation/trunk or in the LAD/LCX.When performing high-pressure KBI (≥14atm) at the LM bifurcation,
you must use balloons that are one quarter size smaller for
both the MB and SB and slowly increase the pressure.
KBI cannot be done with cutting balloons, but can be
performed with two scoring balloons (Fig.4.11). To prepare
a calcied lesion or some other hard lesion, I perform KBI
with Lacrosse NSE balloons. Neither of the kissing Lacrosse
NSE balloons will burst, even if inated simultaneously at
pressures up to the RBPs. Therefore, performing KBI with
slightly undersized Lacrosse NSE balloons inated sufciently to remove indentations can crack calcication and
achieve adequate dilation of the LM bifurcation, even by
low-pressure ination.
even in the absence of calcication. If these devices can be
employed effectively to minimize the plaque burden, such
preparation should lead to greater dilation of the lesion.
Nonetheless, the following points need to be considered
before using either of these two devices. Regarding the
Rotablator, can this device be optimally directed toward a
non-calcied plaque by utilizing guidewire bias, and can a
sufcient volume of plaque be ablated?
Regarding DCA, is it possible to denitely ablate plaques
extending from the LM into the angulated proximal LAD or
LCX with a DCA cutter, which can only be advanced linearly? In addition, it is doubtful whether CAG can accurately
locate plaques that have been identied by IVUS, and it may
be difcult for CAG to display the true take-off angle of the
LCX. Accordingly, will the branching angle of the LCX
observed in the RAO caudal view always correspond to the
direction of the artery on IVUS? Is DCA a safe and effective
debulking measure for LM bifurcation lesions, in principle?
Convincing answers to these questions are required before
commencing rotablation or DCA at the LM bifurcation.
Considering the risk/benet ratio, it seems reasonable to
think that it is not necessary to try such difcult debulking
procedures as part of lesion preparation since the goal is to
ensure optimal stent implantation.
Performing additional KBI with two optimally sized balloons seems to ensure optimal stent deployment. This is
probably because a stent cannot be deployed evenly if it is
implanted after a single KBI procedure that has only cracked
the calcication, since some of the struts may be blocked by
calcied plaque(s) and may be deformed or deployed suboptimally. It is highly probable that post-dilatation, even at a
high pressure, will fail to optimize stent implantation under
such circumstances. In contrast, additional KBI with high-
b
pressure balloons will temporarily dilate the vessel lumen
to as cylindrical a shape as possible. Therefore, the pressure
applied to the struts during implantation will be smaller,
even if vascular recoil occurs subsequently. Accordingly, it
is reasonable to think that performing additional KBI with
high- pressure balloons will reduce the risk of uneven stent
c
implantation compared with a single KBI procedure using
Lacrosse NSE balloons.
The primary goals of lesion preparation are (1) to prevent
plaque shift and carina shift after stent implantation in the
MB (LM-LAD) and (2) to reduce the pressure of vascular
recoil to ≤2.0atm by dilating the (LM) bifurcation to its normal diameter.
I think that all interventionalists prepare LM lesions for
PCI with these goals, although this cannot be veried objectively and the degree of commitment to the goals may vary.
Those who have a particularly high commitment with a logical background may use a Rotablator or DCA for debulking,
Fig. 4.9 KBI for bifurcation lesions. At a bifurcation stenosis (a), alter-
nating balloon ination appears to have sufciently dilated the MB and
the SB, as evidenced by the lack of indentations in either balloon (b).
However, alternating balloon ination has actually caused carina shift
and deformation of the SB shoulder, which have transiently eliminated
the indentations in the body of the SB balloon. During KBI, one or more
indentations may reappear in the SB balloon, but can be eliminated by
increasing the pressure to 8atm. Accordingly, both the MB and SB will
be dilated sufciently and optimally prepared for stenting by KBI (c)
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Column 20 Carina Shift
4 Stenting ofLeft Main Coronary Artery (LM) Lesions
About 10years ago, I participated in a live demonstration of PCI when I had not yet used IVUS, and I saw an opera-
tor protecting the SB during PCI of a non-LM bifurcation lesion after checking the IVUS ndings. A commentator
suggested that SB protection was unnecessary because plaque only existed on the contralateral side to the bifurcation.
When consulted by the operator, I recommended that SB protection should be done because plaque on the contralateral
side, if not effectively compressed by a stent implanted thereafter, might push the carina toward the SB, potentially
causing SB stenosis or occlusion. SB occlusion did not occur after stent implantation, leading to the conclusion that
this case did not require SB protection, although there was persistent mild stenosis of the SB.We understood the con-
cept of “carina shift” in those days, although we had not coined the term, and we thought it was natural to take this
phenomenon into account when performing bifurcation stenting. Several years ago, someone suddenly proposed the
term “carina shift” as if it were a new concept, so we were initially somewhat confused, but we admired the term for
its appropriateness. Our efforts to remind colleagues of the need for countermeasures against “carina shift” might have
made a signicant contribution to the coining of this term.
a
b
c
Fig. 4.10 Dilation of an LM lesion with a large-diameter balloon (POT).
It is best to inate a large-diameter balloon with the distal end just proximal to the carina (a). If the balloon slides back into the left main trunk, it
cannot effectively dilate the lesion (b), while the balloon may injure the
distal vessel if its distal end enters the distal MB (LAD) (c)
Fig. 4.11 KBI with Lacrosse NSE balloons. KBI can be performed
with Lacrosse NSE balloons aligned so that they will not damage each
other by their external scoring elements
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