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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3840_Библиотеки_им_академика_М_И_Перельмана
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200 MURASATO
(A)
(B)
(C)
Figure 9 The style of the dilation of the cell for the SB after crush stenting followed by kissing balloon inflation.
The dotted lines in the right panels indicate maximally dilated cells of the MV stent at the SB ostium. A case with
good expansion of the cell (A) and that with poor position of the cell (B) using Bx Velocity stents are shown as
well as a case with well-apposed expansion using an Express II stent (C).
Source
: From Ref. 9.
as well as two layers of a crushed stent at the opposite side. In the cross-sectional views, the
absence of struts on the carina side and the evidence of two layers of crushed stent at the
opposite site were also clearly observed [Fig. (9B)].
2. The size of the reconstructed SB opening in the crush technique depends on the number of
layers of jailed struts over the SB ostium and on stent design (9,11,15). Inflating a 3.5 mm
balloon in the SB ostium, Ormiston demonstrated maximal stent cell size of 3.2 ×2.8 mm in
the Bx Velocity stent (Cordis Corporation, Miami Lakes, FL), 3.3 × 3.3 mm in the Express II
stent (Boston Scientific, Natic, MA), and 3.6 × 3.4 mm in the Liberte stent (Boston Scientific)
(15). As shown inFigure 9, anadequate openingof theSB was not achievable even after highpressure KBI because of the numerous struts of the Bx Velocity stent over the SB ostium that
restricted optimal balloon expansion. This observation is consistent with previous findings
suggesting that stents with a smaller cell size (<3.5 mm) had smaller opening at the SB
ostium compared to stents with larger cell size (>3.5 mm) (10).
3. Although the DK crush technique was advocated to improve the size of the SB ostium,
opening its efficacy remains questionable. In the 3-D LMCA bifurcation model, the fully
dilated SB stent strut rose up from the MV bed and deviated to one side by the LAD balloon
(Fig. 10)(9). This complexconfiguration might becaused by balloonoverlapping. The raised
SB stent strut would be crushed again after MV stenting and the advantage of the DK crush
technique would be lost.
BENCH TESTING OF CORONARY BIFURCATION STENTING TECHNIQUES 201
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(A) (B)
(C) (D) (E)
Figure 10 (A) 3-D view of the LCX stent from the nonmyocardial side after first kissing balloon inflation in DK
crush stenting. (B) 3-D view from the LAD side. The dilated strut was raised up from the MV bed and deviated
to one side by the LAD balloon. (C) The position of each balloon during kissing balloon inflation: dotted gray and
solid gray lines indicate the LAD and LCX balloons, respectively. The overlapping of the stents had some effect
on the expansion of the strut at the LCX ostium. (D) The second stent is advanced in the MV. (E) The raised strut
(
encircled part
) will be crushed again after MV stenting.
Source
:FromRef.9.
The above observations cannot be discerned using traditional clinical imaging devices
(IVUS, OCT) (Fig. 1) (9).
Modified T-stenting
In this technique, the SB stent is positioned with minimal protrusion into the MV in order to
preventor minimizethe potential fora gap atthe SBostium. In the3-D LMCAbifurcation model,
the MFCT images showed minimal protrusion of the LCX stent and a short metallic carina-like
overlap alongthe myocardialside ofthe proximal MV(8). Theoverlap was minimal ascompared
with other double stenting technique. However, the 3-D MFCT images revealed the absence of
stent coverage on the nonmyocardial side [Fig. 11(B)] (8). This nonmyocardial unstented area
was thought to be generated by the straightening of the SB stent during deployment caused the
slippage of the proximal end to the outside of the MV stent, when the 3-D curvature of the SB
is sharp.
Modified T-stenting requires redilatation of the proximal SB stent orifice after MV stent
deployment to ensure expansion of the SB ostium. This can be accomplished by guidewire
recrossing into the SB through the proximal portion of the SB orifice instead of the stent
struts, although distinguishing these two pathways on fluoroscopy may be challenging. If
the guidewire recrosses into the SB through a stent strut, the outcome with respect to SB stent
apposition to the vessel wall would be similar to that achieved with crush stenting. Although
minimizing the protruded segment of the SB stent into the MV is desirable to ensure proper
202 MURASATO
(A) (B) (C)
Figure 11 MFCT images after modified T-stenting in the 3-D LMCA bifurcation model. (A) Long axis 3-D image.
(B) Proximal to distal (a–d) cross-sectional images of the carina. In the distal carina, a hole-like gap was observed
on the nonmyocardial side of the vessel, which was generated by slippage of the proximal end of SB stent from
the MV after straightening of the stent during inflation in the 3-D structure (d,
image shows a metallic carina (
dotted arrow).Source
: From Ref. 8.
arrows
). (C) The plain horizontal
passage of the guidewire when recrossing, this approach may increase the chances of missing
the SB ostium (11,15).
Culotte stenting
Since this technique involves consecutive jailing of the SB and MV stents by the opposite stent,
optimal dilation of these jailed struts is necessary. Therefore, open-cell stents are preferable
because stent struts can be dilated to a larger diameter. As shown in Figure 12(A), the 3-D
images of Bx Velocity stents (closed-cell design) demonstrate a “napkin ring” restriction of the
ostium of the MV and the SB, because the maximal strut dilation diameter is 3.0 mm even if
>3.00 mm balloon is used (9,11). On thecontrary, the 3-D images of the Driverstent (Medtronic,
Santa Rosa, CA) and Liberte stent (open-cell stents) show good apposition to the vessel wall
[Fig. 11(B) and 12(C)]. In most segments of the bifurcation, the cross-sectional views also show
good stent apposition; however, there remains a very small gap and small metallic carina at the
distal bifurcation site (9). The density of metal overlapping in the proximal MV is one of the
disadvantages of this technique.
Simultaneous kissing stenting (SKS)
With the SKS technique, two stents are deployed in the MV and SB simultaneously, therefore
obviating the need for guidewire recrossing into either branch. Bench testing using the 3-D
LMCA bifurcation model demonstrates that stent overlap in this technique creates a wedgeshaped gapbeneath the site where the LCX stentcrosses over the LADstent, creating a substrate
for restenosis at the LCX ostium (Fig. 13) (8,12,13). When the stent overlap extends deep into
the proximal MV, two unfavorable configurations take place (Fig. 14): (i) “twisting” of the two
stents, where the LCX stent extend to the opposite side of the LCX ostium; and (ii) asymmetric
and often underexpanded lumen in one or both stents.
(A) (B) (C)
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Figure 12 MFCT images after culottes tenting. (A) Bx Velocity stents in the 2-D bifurcation model at 45◦angle
between the MV and the SB. The restriction of the stent expansion is observed in both ostium of the daughter
branches after kissing balloon inflation using 3.5 mm balloons (
bifurcation model. Middle and lower panels show the cross-sectional image corresponding the lines where the
star and the circle are located at the upper panel, respectively. (C) Liberte stents in the LMCA bifurcation model.
Both Driver and Liberte stents showed well-apposed configuration and a tiny gap was observed in the distal carina
in the experiment using Driver stents (B,
University, Japan).
lower panel
). The image of (A) was provided by Yutaka Hikichi (Saga
arrows
). (B) Driver stents in the 3-D LMCA
(A)
Figure 13 MFCT images after simultaneous kissing stenting in the 3-D LMCA bifurcation model. (A) The long
axis 3-D image shows the proximal end of the LCX stent crossing the LAD stent in the distal LMCA, rather
than being positioned lateral to the LAD stent. (B) Proximal to distal (a–c) cross-sectional images of the carina.
Proximally, the LCX stent was compressed by the LAD stent (a,
overlapped stents on the myocardial side (c,
shows compression of the LCX stent.
Source
solid arrow
: From Ref. 8.
). (C) The plain cross-sectional image at level “a” also
(B)
dotted arrow
). Distally, a gap is seen beneath the
(C)
204 MURASATO
(A) (B)
Figure 14 MFCT images after simultaneous kissing stenting with long overlapping site in the LMCA. (A) Long
axis 3D image. (B) Proximal to distal (a–e) cross-sectional images of the LMCA. The solid gray line indicates the
LCX stent in both views. The LCX stent was located over the LAD stent at the bifurcation and extended proximally
at the opposite side of the LCX ostium.
V-stenting
With the V-stenting technique, two stents are also deployed in the MV and SB simultaneously,
therefore obviating the need for guidewire recrossing into either branch. This technique, however, differs from the SKS technique in that there is minimal protrusion of both stents into the
proximal MV (or no protrusion). This technique is favorable for lesions located at the ostia of
both branches with nondiseased large proximal MV (such as ostial LAD and LCX disease sparing thedistal LMCA). In bench testingusing the 3-D LMCAbifurcation model,the proximal end
of both stents opposeeach other laterally. However, thereis often asymmetry in stent expansion
at the proximal edge based on the size and inflation pressure of the corresponding balloon
(Fig. 15).
T-stenting and protrusion (TAP)
This technique is only applicable to the provisional stenting approach when stenting of the
SB becomes necessary due to a suboptimal balloon result. This technique does not require
guidewire recrossing through a distorted SB stent orifice or a crushed SB stent. In bench testing
using the3-D LMCA bifurcationmodel, stent expansion and appositionat the LCXostium were
dependent on the ability of MV stent struts to maximally dilate. When an open-cell stent isused
in the MV, optimal expansion of the SB stent at the ostium was possible [Fig. 16(A) to 16(D)].
On the other hand, when a close-cell stent is used in the MV, expansion of the SB stent at the
ostium was not optimal and a residual unstented area around the proximal edge of the stent
was observed[Fig. 15(E–H)]. Theadvantage of this technique is thatthere is minimalprotrusion
of the SB stent into the MV.
BENCH TESTING OF CORONARY BIFURCATION STENTING TECHNIQUES 205
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(A) (B) (C)
Figure 15 MFCT images after V-stenting in the 3-D LMCA bifurcation model. (A) Long axis 3D image. (B)View
from the LMCA. (C) Cross-sectional view at the distal LMCA. Lateral position of the two stents was maintained
and the distortion of the proximal side of both stents was minimal.
(A) (B)
(C)
(D)
(G)
(H)
(E)
Figure 16 (
model. Experiments were performed using Driver (
MV. (A, E) Long axis 3D image. (B, F) Cross-sectional view at the distal LMCA. Blue and red lines indicate the
LCX and the LAD stents, respectively. Wide opening of the orifice of the LCX stent was observed in the panel
(B), whereas the restriction of the stent expansion was observed in the panel (F). (C, G) Cross-sectional view
corresponding to the line “a” in the 3-D image. The squeezing of the LCX stent at the strut where the LCX stent
was protruded into the LMCA was small in the panel (C), whereas it was apparent in the panel (G)(
Cross-sectional view corresponding to the line “b.” There was a gap at the distal carina in the panel (H)(
See color insert
) MFCT images of T-stenting and protrusion (TAP) in the 3-D LMCA bifurcation
upper panels
(F)
) and Bx Velocity stents (
lower panels
arrows
)forthe
). (D, H)
arrow
).
206 MURASATO
Insights into “MV to SB” Stenting
The failureof the classical T-stentingtechnique in assuring SB ostiumcoverage and the frequent
incidence of restenosis at this site (24) led to the re-emergence of other stenting techniques.
One of these techniques is the strategy of extending the stent from the MV to the SB to ensure
SB ostium coverage with the main frame of the stent. However, recent data indicate that the
anatomy of SBs varies from that of the main epicardial vessels in two ways: (i) the SB ostium is
more often elliptical than round; and (ii) there is conical tapering of the proximal SB, and the
ratio of tapering from proximal to distal is three times of that in the MV (25). Therefore, the SB
ostium is much larger than its distal reference vessel.
We investigated the 3-D configuration of the “MV to SB” stenting technique in two 3-D
bifurcation models: a 90-degree bifurcation angle and a 45-degree bifurcation angle with the
proximal MV (Figs. 17 and 18).
Gap Formation
In the initial phase of stent balloon inflation, the stent dilated in a dumbbell shape where
the stent expanded proximally first, then distally, and finally at the mid-portion (Fig. 16A[b],
17B[b]). When the stent was inflated with maximal pressure, the guidewire position remained
at the outer side at both the proximal and distal stent segments but was positioned at the
inner side of the SB ostium (Fig. 16A[d], 17B[d]). Since the wire is located in the central core
of the balloon, this asymmetric position of the wire suggests nonuniform balloon expansion
at the SB ostium. This led to gap (unstented area) at the distal carina in both the 90-degree
and 45-degree angle bifurcations and the gap was larger in the 45-degree angle bifurcation
(17A[c], 17B[c]).
(A)
(B)
Figure 17 Experiment of the SB stenting from the MV. (A) Right-angled bifurcation. (B) Steeply-angulated
bifurcation at 45
side at the middle portion (
In the initial phase of the inflation, the middle portion was dilated finally (
changed to the dumbbell shape. (c) There was unstented area at the distal carina even after full expansion of the
stents. (d) The guidewire position had not been changed during the stent expansion. Note the biased position of
the wire, which was in the central core in the balloon.
◦
angle between the proximal MV and the SB. (a) Initial position of the guidewire is in the inner
black triangle
) and in the outer side at both ends of the stents (
arrow
). The stent configuration was
white triangles
). (b)
BENCH TESTING OF CORONARY BIFURCATION STENTING TECHNIQUES 207
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(A)
(B)
Figure 18 MFCT images of the SB stents deployedfrom the MV (a: view from the inner side, b: anterior–posterior
view, c: view from the outer side). Experiments were performed using Bx Velocity (A) and Driver stents (B). There
were restrictions of the stent expansions in both stents (A[a], B[a];
stent were stretched (A[c];
outer side (B[b], B[c];
dotted arrow
white triangles
), whereas the Driver stent had the wide opening between the coils at its
).
arrows
). The outer struts of the Bx Velocity
Stent Distortion
In this experiment, we used the Bx velocity stent [Fig. 18(A)] and the Driver stent [Fig. 18(B)]
in the 45-degree angle bifurcation model. Restricted stent expansion was observed at the bifurcation in both stents (18A[a], 18B[a]; arrows). The stretch of the struts at the outer side and
concentration of the struts at the inner side were also observed in both stents. The S-link of the
Bx Velocity stent was extremely stretched (18A[c]; dotted arrow) and the distance between the
coils of the Driver stent was widened to generate the gap at the outer side (18B[b], 18B[c]; white
triangles).
These experiments closely simulate the potential problems related to stenting from the
LMCA to the LCX artery, namely, stent expansion is less uniform than that in a straight vessel;
the restricted stent expansion at the LCX ostium leads to gap formation; and the hinge motion
at this point may cause stent fracture (Fig. 19).
ARE THE FINDINGS FROM BENCH TESTING APPLICABLE TO CLINICAL PRACTICE?
The decision to use provisional stenting or elective double stenting technique should be based
on a careful analysis of the patient’s bifurcation anatomy (as discussed in previous chapters). If
a decisionhas been made touse elective double stenting,the choice of whichtechnique to utilize
has been largely based on the individual operator experience due to the lack of strong evidence
favoring one technique over another. Anyhow, optimal technique is critical to ensure optimal
results, particularly in LMCA bifurcation disease where elective double stenting is utilized in
20% to50% of patients (26–28). Althoughbench testing cannottake into account all thepotential
anatomic variations that can be present in a given patient, it is the best method we have to gain
better insights into the 3-D behavior of stents in bifurcation lesions.
208 MURASATO
(A.)
(B.)
Figure 19 These experiments evoke thepotential problem withstenting fromthe LMCAto theLCX. Theguidewire
remained in the inner side at the LCX ostium and in the outer side at both ends of the stents during the entire
inflation (B). The stent expansion is less uniform than that of the straight vessel (comparison between A[b] and
B[b]). The restricted stent expansion at the LCX ostium leads to a gap formation (B[b];
hinge motion at this point may cause fracturing of the structure of the stretched struts.
dotted arrows
) and the
Key findings from bench testing that proved useful for bedside technical decision making
are as follows:
1. The effect of bifurcation angle on selection of the appropriate double stenting technique: We learned
that the crush and culotte stenting techniques perform favorably (from stent configuration
perspective) in Y-shaped bifurcations, whereas T-stenting is more favorable in T-shaped
bifurcations. The effect of stent configuration on clinical outcome has been suggested (29),
but a convincing proof requires more dedicated clinical studies to answer this specific
question.
2. The importance of stent platform in optimizing the technical results: We learned that the maximal
achievable strut diameter, conformability at angulations, and the degree of distortion after
KBI are all important attributes for results optimization particularly at the SB ostium.
3. The importance of the site of guidewire recrossing into the jailed SB: With most double stenting
techniques, guidewire recrossing should be through the distal portion of the SB ostium to
provide the most optimal scaffolding of the SB ostium and least deformation of the MV
stent. However, with crush stenting, the optimal recrossing site is the middle portion of the
SB ostium. Recrossing through the distal portion of the SB ostium would lead to partial
crushing of the proximal SB stent.
4. The importance of the pattern of balloon overlap during KBI on final configuration of the proximal
MV stent: We learned that an x-shaped balloon overlap in wide-angle bifurcations is associated with the suboptimal stent configuration. Optimal balloon positioning for KBI involves
advancing the two balloons distally and then pulling them back to where the proximal
markers are in the same position. KBI should be performed with minimal overlap or with
the balloons positioned lateral to each other.
5. The importance of the pattern of stent overlap during stent deployment on vessel wall coverage:
We learned that when the plaque is primarily localized in the myocardial side of the SB
BENCH TESTING OF CORONARY BIFURCATION STENTING TECHNIQUES 209
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ostium, the use of the crush or SKS technique with the SB stent overlapping the MV stent
should be avoided because that will lead to a gap at the lesion site. On the other hand,
when the plaque is located in the nonmyocardial side of the SB ostium, the use of these
techniques with the MV stent overlapping the SB stent should be avoided for the same
reasons. The most optimal stent positioning should involve minimal overlapping or lateral
positioning.
Of course, illustrating the value of these observations does not negate the need for significant improvement on the current bifurcation phantom models with regard to a variety of
factors such as: bifurcation angle, 3-D structure, vessel size, tortuosity, vascular elasticity, and
atherosclerotic changes. Also, the addition of physiological assessment parameters (coronary
flow, wall shear stress, and the durability against the cardiac motion) will be a welcome development in future bench testing.
TAKE HOME MESSAGE
r
Bench testing allows direct and detailed inspection of stent configuration in bifurcation
phantom models using high-quality cameras, microscopy, and microfocus X-ray computed
tomography (MFCT) with resolution of 0.06 mm.
r
Although significant insights have been gained through these techniques, one should not
lose sight of the numerous limitations of these techniques resulting from the lack of good
coronary bifurcation models.
r
The insights derived from bench testing can be summarized as follows:
b
Every double stenting technique has its own set of technical advantages and limitations.
b
Bifurcation angle is an important anatomic element in making a decision as to which
double stenting technique to use.
b
In elective double stenting, excessive overlap should be avoided during simultaneous or
consecutive stent deployment.
b
Guidewire recrossing into the jailed SB should take place through the distal portion of
the SBostium (except forthe crush technique where recrossingshould take placethrough
the middle portion of the SB ostium).
b
Proximal balloon overlap should be minimized during KBI.
REFERENCES
1. Al Suwaidi J, Yeh W, Cohen HA, et al. Immediate and one-year outcome in patients with coronary
bifurcation lesions in the modern era (NHLBI dynamic registry). Am J Cardiol 2001; 87:1139–1144.
2. Tsuchida K, Colombo A, Lef`evre T, etal. The clinicaloutcome of percutaneoustreatment of bifurcation
lesions in multivessel coronary artery disease with the sirolimus-eluting stent: insights from the
Arterial Revascularization Therapies Study part II (ARTS II). Eur Heart J 2007; 28:433–442.
3. Steigen TK, Maeng M, Wiseth R, et al.; Nordic PCI Study Group. Randomized study on simple versus
complex stentingof coronary artery bifurcation lesions:the Nordic bifurcation study. Circulation2006;
114:1955–1961.
4. Ferenc M, Gick M, Kienzle RP, et al. Randomized trial on routine vs. provisional T-stenting in the
treatment of de novo coronary bifurcation lesions. Eur Heart J 2008; 29:2859–2867.
5. Colombo A, Bramucci E, Sacc`a S, et al. Randomized study of the crush technique versus provisional
side-branch stenting in true coronary bifurcations: the CACTUS (Coronary Bifurcations: Application
of the Crushing Technique Using Sirolimus-Eluting Stents) Study. Circulation 2009; 119:71–78.
6. Hildick-Smith D. The British bifurcation coronarystudy: old, newand evolving strategies(BBC ONE).
Transcatheter Cardiovascular Therapeutics (TCT) Conference. Lecture 2008.
7. Erglis A, Kumsars I, Niemel¨a M, et al. Randomized comparison of coronary bifurcation stenting with
the crush versus the culotte technique using sirolimus eluting stents: The Nordic Stent Technique
Study. Circ Cardiovasc Intervent 2009; 2:27–34.
8. Murasato Y, Horiuchi M, Otsuji Y. Three-dimensional modeling of double-stent techniques at the left
main coronary arterybifurcation usingmicro-focus X-raycomputed tomography. Catheter Cardiovasc
Interv 2007; 70:211–220.
9. Murasato Y, Hikichi Y, Horiuchi M. Stent deformation and gap formation after complex stenting of
left main coronary artery bifurcations using micro focus computed tomography. J IntervCardiol 2009;
22:135–144.
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