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
cd
1.7 Retrograde Approach
https://t.me/medicina_free
129
Fig. 1.191 Possible
combinations of
compartments containing the
two guidewires. Reverse
CART can be accomplished
relatively easily if the two
guidewires are in the same
compartment (a & b), or
when a retrograde guidewire
in the true lumen is
manipulated toward a false
lumen (c). In contrast, it is
more difcult to advance a
retrograde guidewire from a
false lumen toward the true
lumen (d) because inating an
antegrade balloon has little
impact on control of the
guidewire, as can be seen
from the transverse views of
the target vessel
ab
Fig. 1.192 Advancing a crossing guidewire for the reverse CART
technique. Ination of an antegrade balloon should make a retrograde
guidewire more deectable. You should then advance a retrograde
crossing guidewire with a higher tip load toward the center of the ante-
Table 1.10 Difculty accomplishing reverse
CART depending on the compartments
containing the tips of the two guidewires
grade balloon in the transverse section (with imaging in two orthogonal
projections) so that the wire deects the balloon and enters the space
created by balloon ination
Retrograde
Guidewire
Antegrade
True lumen +++
Subintimal space ++ ++++
True lumen Subintimal space
+−
130
abc
https://t.me/medicina_free
1 Mitsudo’s PCI Techniques forCTO
Fig. 1.193 Situations that can preclude success with the reverse CART
technique. (a) Both guidewires are blocked by hard plaque in the true
lumen and undergo deviation into the subintimal space. If the two
guidewires are present in a common compartment for only a short distance, it is difcult for the retrograde guidewire to enter a connecting
Fig. 1.194 When attempting
the reverse CART technique
is precluded. (a) It is pointless
to attempt reverse CART if
the antegrade guidewire is in
the true lumen and the
retrograde guidewire is in the
subintimal space. (b) You
should search for a true-true
route by advancing an
antegrade guidewire with
greater penetrability. (c) You
should advance a retrograde
guidewire with greater
penetrability until it comes
into contact with the
antegrade guidewire
ab c
channel to the true lumen. (b) Even after reverse CART has been
accomplished, the retrograde guidewire may continue to advance
through the subintimal space. (c) If reverse CART is performed at a
slightly more distal site, it becomes easier to alter the direction of the
retrograde guidewire
a
b
1.7 Retrograde Approach
https://t.me/medicina_free
131
1.7.15 Introducing theRetrograde Guidewire
into theAntegrade Guiding Catheter
After Crossing theCTO
1.7.15.1 If aRetrograde Microcatheter Crosses
theOcclusion Before Introducing
theRetrograde Guidewire
After a retrograde guidewire has crossed the CTO, you
should advance the retrograde wire further into the coronary artery proximal to the occlusion and introduce it into
the antegrade guiding catheter. When performing reverse
CART, a retrograde guidewire with a small curve at its tip
is better for passing through the connecting channel, while
one with a larger tip curve is better for entering the antegrade guiding catheter. Thus, it is often difcult to introduce
the retrograde guidewire that has crossed the CTO into the
antegrade guiding catheter without changing its tip curve. If
you have also been able to cross the occlusion with a retrograde microcatheter, you should withdraw the retrograde
guidewire and modify the shape of the curve at its tip. You
should then pass the wire through the occlusion again and
advance it toward the antegrade guiding catheter. To advance
a retrograde microcatheter into the occlusion and reach the
proximal true lumen, you often have to push it forward while
performing to-and-fro rotation.
To facilitate successful crossing of the occlusion with
a retrograde microcatheter, you may consider trapping the
retrograde guidewire that has crossed the CTO by inating a balloon in the artery proximal to the occlusion before
advancing the microcatheter. However, I do not use this
method because intravascular trapping of the guidewire is
unreliable and requires ination of a balloon compatible in
size to the proximal coronary artery at a very high pressure,
which may unnecessarily increase the risk of injuring the
proximal vessel. To successfully advance a retrograde microcatheter, you should instead push it forward while pulling the
retrograde guidewire back. During this procedure, be aware
that the retrograde guidewire may be abruptly released by
the anchoring balloon and withdrawn completely.
introduce the retrograde guidewire into the guiding catheter
(Fig.1.195b).
You should leave the antegrade guidewire and balloon
used for reverse CART at the ostium because they make it
easier to introduce the retrograde guidewire into the antegrade guiding catheter by helping to keep the guiding catheter
coaxial with the ostium of the coronary artery (Fig.1.196).
It can also be effective to advance a GuideLiner “child”
catheter along the antegrade guidewire and introduce the retrograde guidewire into this catheter (Fig.1.197), because the
tip of the GuideLiner catheter can reach the distal edge of a
curve in the vessel and because its shaft and the antegrade
guidewire ensure the coaxiality with the coronary artery.
Once the retrograde guidewire has entered the antegrade guiding catheter, you should trap the guidewire
with a Kusabi or balloon catheter to form a partial loop
(Fig.1.198). Then a retrograde microcatheter can be introduced into the antegrade guiding catheter with a probability of nearly 100%. If the retrograde guidewire shown in
Fig.1.198 is pulled back too strongly relative to the force
used to advance the retrograde microcatheter, the guiding
catheter may become deeply engaged and may cause dissection at the ostium of the coronary artery. If the ostium
of an artery that is being used for the retrograde approach
is injured and this results in occlusion, shock may occur.
Therefore, you should carefully watch the position of each
guiding catheter and the retrograde pressure waveform to
avoid deep engagement.
1.7.15.2 If aRetrograde Microcatheter Fails
toCross theCTO
If a retrograde microcatheter fails to cross the occlusion,
there is no option but to introduce the retrograde guidewire
without changing the size of its tip curve. In this case, you
should slightly advance the tip of the antegrade guiding catheter to bring the larger curvature of its tip into contact with
the larger curvature of the target coronary artery near its
ostium. If you use an anchoring balloon, you should pull it
back slightly to allow for optimal positioning of the guiding
catheter (Fig.1.195a). If the antegrade guiding catheter has
become slightly wedged into the ostium as it was advanced
(based on the pressure waveform), you can often easily
Fig. 1.195 Navigating a retrograde guidewire (1). (a) The tip of the
guiding catheter should be oriented toward the larger curvature of the
artery. If an anchoring balloon is used, the retrograde guidewire should
be advanced toward the balloon and introduced into the guiding catheter. (b) Advancing the guiding catheter until it has been wedged (as
estimated from the pressure waveform) will reduce the gap between the
catheter and the vessel wall, making it easier to introduce the retrograde
guidewire into the catheter
132
Only advancing the microcatheter
https://t.me/medicina_free
Fig. 1.196 Navigating a retrograde guidewire (2). An antegrade guide-
wire and antegrade balloon should be left in situ because they make it
easier to keep the guiding catheter coaxial with the retrograde guidewire and to introduce the guidewire into the guiding catheter
1 Mitsudo’s PCI Techniques forCTO
Pulling the guidewire
back while advancing
the microcatheter
Fig. 1.198 Assisting a retrograde microcatheter to cross the CTO and
introducing it into the antegrade guiding catheter. To advance a retrograde microcatheter through an occlusion, there is no alternative but to
simply push it forward unless the retrograde guidewire has been
trapped. When pushed forward, the retrograde microcatheter trends laterally at a bend of the vessel (dotted line), losing coaxiality with the
vessel and stretching that segment. When the microcatheter is in this
position, more force is required to push it forward, and there is greater
stress on the vessel, increasing the risk of perforation. On the other
hand, if the tip of the retrograde guidewire has been trapped, the wire
can be pulled back (from the hub of the retrograde guiding catheter) in
the opposite direction to that of advancing the microcatheter. If the retrograde guidewire is pulled back while you push the retrograde microcatheter forward, the opposing forces offset each other. As a result, the
microcatheter can be kept coaxial with the coronary artery and can be
advanced without stretching the vessel while minimizing stress upon it
Fig. 1.197 Navigating a
retrograde guidewire (3). If
the retrograde guidewire
cannot be introduced into the
antegrade guiding catheter
(a), a GuideLiner “child”
support catheter should be
advanced antegradely to the
vertex of a curve of the target
vessel (b) or to the distal end
of the curve (c). The
retrograde guidewire can then
be more easily introduced into
the GuideLiner catheter
a
b
c
a
b
c
1.7 Retrograde Approach
https://t.me/medicina_free
Column 10 Selection and Rationale: Part 2
The reverse CART technique involves enlarging a proximal space by ballooning via the antegrade guidewire. After
inating the balloon, I advance the tip of a retrograde microcatheter to just beyond the tip of the antegrade balloon
catheter and exchange the retrograde guidewire for a Runthrough Hypercoat. Although any other 0.014-inch guidewire
with a low tip load is a reasonable alternative, I choose the Runthrough Hypercoat because this spring coil guidewire
has the optimal slipperiness (not too great) that produces sufcient resistance to signal entry into a proximal false
lumen and also helps it to go forward smoothly within an uneven false lumen. I tend to avoid using a polymer- jacketed
guidewire because it is too slippery and creates too little resistance when advanced into a false lumen. This may result
in the unwitting creation of a new dissection and enlargement of the false lumen toward the proximal side of the lesion.
I rarely try to accomplish reverse CART without exchanging the retrograde CTO crossing guidewire. A guidewire
with a stiff tip is absolutely unsuitable for the delicate task of navigating a connecting channel across the intima
between the false and true lumens. If the tip of the retrograde microcatheter cannot reach the tip of the antegrade balloon, a retrograde guidewire with a non-stiff tip that has been advanced to replace the CTO crossing guidewire may
also not be able to reach the antegrade balloon. In such cases, it is sometimes unavoidable to use a CTO crossing
guidewire as the retrograde wire for reverse CART.
133
1.7.15.3 If theRetrograde Guidewire Fails
toEnter theAntegrade Guiding
Catheter
It may be impossible to introduce the retrograde guidewire
into the antegrade guiding catheter in some circumstances,
e.g., if the CTO is located at the ostium of a coronary artery
and does not have a dimple in which an antegrade guiding
After a retrograde microcatheter has been sufciently
introduced into the antegrade guiding catheter and the retrograde guidewire is no longer necessary, you should withdraw
the snare together with the guidewire. While the hard proximal part of the guidewire passes through the microcatheter
during withdrawal, this procedure only takes a short time and
rarely causes injury to the collateral channel.
catheter can be engaged, or if the CTO is in a vessel with a
large diameter ostium and it is difcult to maintain coaxiality of the antegrade guiding catheter. In such cases, capturing the tip of the guidewire with a snare (e.g., a Gooseneck
snare, Ensnare, or Soutenir NV) is an effective measure (see
Figs.1.174 and 1.175).
After you have captured the tip of the retrograde guidewire, it is pulled into the antegrade guiding catheter. After
introduction of the retrograde wire into the guiding catheter,
you should trap the guidewire at its interlocked site with a
Kusabi or balloon catheter to facilitate advancement of the
retrograde microcatheter (Fig.1.199).
If the retrograde guidewire has a non-stiff tip, it can be
retracted into the retrograde microcatheter within the antegrade guiding catheter even if the tip is bent by snaring.
In contrast, a retrograde guidewire with a stiff shaft near
the tip (e.g., a Conquest Pro) cannot be retracted into the
retrograde microcatheter as its tip cannot be completely
straightened after it is bent (Fig. 1.200). When using a
CTO crossing guidewire with a stiff shaft near the tip, you
should employ a snare with adequate stiffness and keep the
snare locked while introducing the retrograde microcatheter into the antegrade guiding catheter. You should take
appropriate measures to prevent unintentional de-snaring,
including trapping the site of interlocking with the snare
by using a balloon.
Fig. 1.199 Navigating a retrograde guidewire. If a retrograde guide-
wire cannot be introduced into the antegrade guiding catheter, a snare
should be advanced antegradely (a) to capture the retrograde guidewire
(b). After it is subsequently introduced into the guiding catheter, the
guidewire should be trapped, and then a retrograde microcatheter
should be advanced (c)
134
a
b
https://t.me/medicina_free
1 Mitsudo’s PCI Techniques forCTO
its optimal position. This is because deating the trapping
balloon will disengage the antegrade guiding catheter and
reversal of the shrunken coronary segment proximal to the
CTO will pull back the retrograde microcatheter. An RG-3
wire can be used if the retrograde microcatheter even slightly
enters the antegrade guiding catheter after withdrawal of the
retrograde guidewire.
1.7.17 Switching totheAntegrade Approach
After the retrograde microcatheter has been introduced into
the antegrade guiding catheter, you should advance the ante-
Fig. 1.200 Navigating a retrograde microcatheter. (a) If the retrograde
guidewire has a non-stiff tip, it should be captured by a snare and then
introduced into the antegrade guiding catheter. Subsequently, a retrograde microcatheter should also be introduced into the guiding catheter.
(b) A retrograde guidewire with a stiff shaft near the tip cannot be
retracted into the antegrade guiding catheter because its shaft cannot be
completely folded over by a snare. Therefore, such a guidewire should
be captured by the snare, and then a retrograde microcatheter should be
advanced. The retrograde guidewire can be trapped by a balloon to prevent de-snaring
1.7.16 Introducing theRetrograde
Microcatheter into theAntegrade
Guiding Catheter
If a retrograde guidewire has successfully been introduced
into the antegrade guiding catheter, it is not difcult to
subsequently introduce a retrograde microcatheter into the
antegrade catheter. First, you should attempt to advance
a retrograde microcatheter by pushing it forward. If you
become unable to advance the microcatheter, you should trap
the retrograde guidewire in the antegrade guiding catheter
by using a balloon and pull the wire back while simultaneously pushing the microcatheter forward. An important tip is
to disengage the antegrade guiding catheter while advancing
the retrograde microcatheter, because advancement of the
microcatheter may cause deep engagement of the guiding
catheter, potentially injuring the ostium of the target artery.
If the antegrade guiding catheter is 7 Fr in size, the trapping balloon can be 2.0mm or more in diameter. Although I
inate a 2.25-mm or 2.5-mm balloon at 10atm, it should be
noted that a balloon ranging from 2.0mm to 3.0mm or larger
usually needs to be inated at 14atm. A small balloon must
be inated at a high pressure to trap a 0.014-inch guidewire as
there is a small gap between the balloon and the inner surface
of the catheter. A large balloon forms wrinkles when inated.
If the wrinkles are parallel with the longitudinal axis of the
guidewire, the guidewire may slide into one and slip through
the balloon unless it is inated at a sufciently high pressure.
When using the rendezvous technique explained in
the next subsection, a retrograde microcatheter must be
advanced into the antegrade guiding catheter far beyond
grade guidewire through the CTO to facilitate antegrade
delivery of devices to complete PCI.For this purpose, I use
either of the following techniques. The rendezvous technique is suitable in most cases (>95%), and I only use the
externalization method if the rendezvous technique seems
inappropriate.
1.7.17.1 Rendezvous Technique
The rendezvous technique involves placing the tip of the
retrograde microcatheter at the vertex of the curve of the
antegrade guiding catheter (Fig.1.201) and pulling the retrograde guidewire back to 2 to 3cm from the tip of the microcatheter. Without extruding the antegrade guidewire, you
should then advance an antegrade microcatheter and bring
its tip into contact with the tip of the retrograde microcatheter. If you then advance the antegrade guidewire slightly, its
tip will readily enter the retrograde microcatheter. Whether
the antegrade guidewire has successfully entered the retrograde microcatheter can be determined by checking if the
antegrade guidewire deviates from the radiolucent marker of
the retrograde microcatheter and/or if it retains its tip curve
when it comes out of the antegrade microcatheter. Final
conrmation is obtained when the antegrade guidewire is
blocked by the tip of the retrograde guidewire.
The tips of the two microcatheters must not be brought
into contact with each other vigorously because doing this
will deform the tip of the antegrade guidewire (Fig.1.202),
precluding successful introduction of the antegrade guidewire into the retrograde microcatheter. Making gentle contact between the two guidewires is important for achieving
success with the rendezvous technique.
This technique utilizes the very simple phenomenon that
all devices advance along the larger curvature of each bend
within a guiding catheter. You might wonder if the distance
between the tip hole of a microcatheter and the wall of the
guiding catheter on the larger curvature varies with the thickness of the microcatheter wall at its tip. However, in actual
practice an antegrade guidewire can readily enter a retrograde microcatheter whatever combination of antegrade and
retrograde microcatheters is used, even if they are very different with respect to size or wall thickness.
1.7 Retrograde Approach
https://t.me/medicina_free
135
Next, I will discuss the circumstances where it is difcult
for an antegrade guidewire to enter the retrograde microcatheter and effective countermeasures.
It can be difcult for an antegrade guidewire to enter the
retrograde microcatheter in the following situations:
1. If the tips of the antegrade and retrograde microcatheters
cannot be brought into contact with each other within the
antegrade guiding catheter, which may be due to the fol-
lowing factors:
• Inappropriate rendezvous point: The optimal position
of the two microcatheters is with their tips on the larger
curvature of a bend in the guiding catheter. If either
microcatheter cannot reach the larger curvature
(Fig.1.203a) or the tips of the two microcatheters are
at an acute angle to each other (Fig.1.203b), the antegrade guidewire may not be able to enter the retrograde microcatheter.
– Severe deformation of a microcatheter tip
(Fig. 1.204a): Even if the tip of a microcatheter is
severely deformed, advancing both an antegrade and
a retrograde guidewire toward the tip of the catheter
will usually straighten it and bring the tip into contact
with the tip of the other microcatheter. Advancing a
retrograde guidewire to 1.5 to 2.0cm from the tip of
a deformed microcatheter should be able to straighten
it (Fig.1.204b & c).
• Isolation by a guidewire or device within the guiding
catheter (Fig. 1.205): If a guidewire or device has
divided the lumen of the guiding catheter into two compartments and if the two microcatheters pass through
different compartments, their tips cannot come into contact with each other (Fig.1.205a). In this situation, you
should withdraw the antegrade microcatheter through
the O-ring and conrm its original position. Inserting
the antegrade microcatheter again on the opposite side
(Fig.1.206) may be a good solution to this problem.
If the two microcatheters are in the same compartment within the guiding catheter, a guidewire or
other device in the guiding catheter will tend to act as
a guide that helps the microcatheters meet each other
(Fig.1.205b).
If there is more than one guidewire in the guiding
catheter and if the two microcatheters are in different
internal compartments created by at least one guidewire, “rendezvous” cannot be accomplished.
Therefore, you should withdraw and reinsert one of
the microcatheters. If this also fails to bring the tips of
the two microcatheters into contact with each other,
you should switch to the externalization strategy.
2. If the tip curve of the antegrade guidewire is too acute to
maintain coaxiality with the retrograde microcatheter at
the rendezvous point (Fig.1.207a).
This problem occurs with a Sion guidewire that has a
small curve at its tip and when a guidewire designed for retrograde channel tracking is used as an antegrade guidewire.
The antegrade guidewire should be withdrawn and the tip
curve should be stretched with a ne (25-G) dull needle. If
you are planning to employ a guidewire with a small curve
at its tip for retrograde collateral channel tracking when performing the rendezvous technique, you should enlarge the tip
curve before use (Fig.1.207b).
Once an antegrade guidewire has entered the retrograde
microcatheter, you should immediately pull the retrograde
guidewire back into the retrograde guiding catheter and then
advance the antegrade guidewire into the retrograde catheter. Subsequently, you should inate a balloon between
the antegrade guiding catheter and antegrade guidewire to
trap the antegrade guidewire and slowly withdraw the retrograde microcatheter until it is near the entrance of the
collateral channel. During this procedure, you should take
care to prevent injury to the coronary ostium by the retrograde guiding catheter. Trapping the antegrade guidewire
allows you to reliably and denitely disengage the retrograde guiding catheter and thus safely withdraw the retrograde microcatheter.
You should then also withdraw the antegrade microcatheter.
Next, you should advance an angioplasty balloon to
near the trapping balloon and deate the latter balloon,
with the aim of bringing trapped air near to the proximal segment of the artery to reduce the time needed for
deaeration.
The externalization technique discussed in the next subsection has the advantage of permitting continuous use of a
guidewire loop involving the heart if PCI is continued with
a 300-cm guidewire. Only the antegrade guidewire is left in
situ with the rendezvous technique, so some interventionalists may be concerned about loss of the guidewire loop,
but I have no such concern for the reasons described below.
Actually, I have not had any difculty in accomplishing PCI
for CTO with this technique.
At this stage, a retrograde guidewire and a retrograde
microcatheter have already crossed the CTO through the
antegrade guiding catheter. Therefore, any device that is
advanced antegradely can almost always cross the occlusion
without such a guidewire loop.
If a loop should become necessary, you can easily create
a loop by trapping the antegrade guidewire within the retrograde guiding catheter. When doing so, you should always
keep in mind the fact that the 0.014-inch antegrade guidewire is directly in contact with the coronary artery wall in
the segment between the tip of the antegrade device and the
tip of the retrograde guiding catheter. This means that the
antegrade guidewire can cause coronary perforation if you
apply too much force.
136
ab
ab
a
b
c
https://t.me/medicina_free
1 Mitsudo’s PCI Techniques forCTO
Fig. 1.201 Optimal position
of the “rendezvous” point.
The rendezvous technique
should be performed at the
vertex of the bend in the
guiding catheters (a, b, c are
different catheters)
Fig. 1.202 Advancing a
guidewire for the rendezvous
technique. (a) Advance a
guidewire while keeping
gentle contact between the
two microcatheters. (b)
Pushing the guidewire
forward too hard may deform
its tip, preventing entry into
the retrograde microcatheter
ab c
Fig. 1.203 Major impediments to achieving “rendezvous.” (a) The
tips of the two microcatheters are not at the vertex of the bend in the
guiding catheter. (b) The two microcatheters are at an acute angle to
each other, leaving a gap between their tips even after they come into
contact
Fig. 1.204 Impediment to achieving “rendezvous” and the solution. (a)
The retrograde microcatheter is deformed and is not oriented toward the
larger curvature of the bend in the guiding catheter. (b & c) Advancing a
retrograde guidewire to near the tip can straighten the microcatheter
GW, DV MC for the Rendezvous
ab
1.7 Retrograde Approach
https://t.me/medicina_free
137
Fig. 1.205 Potential positions of the two
microcatheters inside a guiding catheter that also
contains a guidewire (GW) or other device (DV)
introduced antegradely. (a) If the antegrade and
retrograde microcatheters (MC) are in different
compartments of the guiding catheter created by the
GW (or DV), their tips cannot meet each other,
preventing “rendezvous.” (b) On the other hand, if the
antegrade and retrograde MCs are in the same
compartment created by the GW (or DV), the GW (or
DV) will act as a guide that helps the tips of the two
MCs meet
Fig. 1.206 Position of the
antegrade microcatheter
relative to an antegrade
guidewire (or device) seen
from the Y-connector. If the
antegrade microcatheter (MC)
is on the opposite side relative
to an antegrade guidewire
(GW) or device (DV) when
you attempt to use the
rendezvous technique (a), you
should conrm the position of
the MC relative to the GW/
DV (on the right side in this
example) at the Y-connector
and then completely withdraw
the MC.Then you reintroduce
the MC on the opposite (left)
side (b)
O–ring
GW, DV
a
retrograde MC
b
GC
antegrade MC
a
b
Fig. 1.207 Further major impediments to achieving “rendezvous.” (a)
A guidewire with an acute curve at its tip for collateral channel tracking
should not be used as the antegrade guidewire, since it may not be able
1.7.17.2 Externalization Using anRG-3Wire
Externalization using an RG-3® wire is most commonly performed to revisit the antegrade approach. This technique is
very simple, since it just involves advancing the RG-3 wire
after withdrawing the retrograde guidewire. After completely
to enter the retrograde microcatheter. (b) The guidewire should be
reshaped with a less acute tip angle before it is used as an antegrade
“rendezvous” guidewire
withdrawing all balloons and other devices from the antegrade guiding catheter, you should carefully push the RG-3
wire forward without needing CAG conrmation. Once the
tip of the wire has reached the radiolucent part near the hub
of the Y-connector attached to the antegrade guiding catheter,
138
https://t.me/medicina_free
1 Mitsudo’s PCI Techniques forCTO
you should disconnect the Y-connector and pull the tip of the
RG-3 wire out of the O-ring by using an inserter.
While leaving the wire in this way, you could advance a
balloon and/or other device from its soft tip to accomplish
PCI.However, I always trap the RG-3 wire with a balloon
and advance a microcatheter antegradely to exchange the
wire for a 0.014-inch guidewire. As mentioned above, I do
not think that it is difcult to advance a device antegradely
without a guidewire loop. If the microcatheter is unable to
reach the distal end of the CTO even using a guidewire loop,
it needs to be exchanged for a Tornus catheter. After the
catheter has crossed the lesion, you should consider using
a Rotablator.
1.8 Antegrade Approach Revisited
After a retrograde guidewire has crossed the CTO through
the antegrade guiding catheter, PCI is accomplished by performing a series of procedures from ballooning to stenting as
is done with the antegrade approach.
1.8.1 Balloon Ination
If a CTO has been easily crossed by the antegrade approach,
it may be possible to advance an IVUS catheter into the lesion
without performing balloon dilation, but it is difcult to do
so in most CTOs that have been crossed by the retrograde
approach. In particular, if reverse CART has been accomplished via the false lumen, the false lumen has a remaining
blind distal end. To prevent distal enlargement of this false
lumen, you need to create a channel leading to the distal true
lumen as soon as possible. Ballooning is considered successful if you can use a 1.0- to 1.5-mm balloon to create such a
channel, in order to reduce the pressure in the false lumen
and permit advancement of an IVUS catheter.
1.8.2 IVUS
You should introduce an IVUS catheter into the space
enlarged by the balloon for the following purposes: (1) to
determine how the CTO has been crossed (through the true or
false lumen), (2) to estimate the external and internal diameters of the target vessel proximal and distal to the occlusion,
(3) to estimate the luminal diameter and the characteristics
of plaques at the occlusion, (4) to characterize plaques in the
entire target vessel, (5) to assess side branches at the occlusion, and (6) to assess a bifurcation distal to the occlusion.
1. Mode of guidewire crossing lumen: You should deter-
mine the extent to which the CTO has been crossed
through the true and false lumens. Even if the lesion has
been crossed through a false lumen, the standard procedure is to dilate the lumen and place one or more stents.
However, if the false lumen is long, you may reattempt
tracking the true lumen in parallel under IVUS guidance
(see 1.8.3 “Retry for Tracking the True Lumen”).
If the proximal part of a previously stented CTO cannot be crossed through the true lumen, the rst antegrade
guidewire may not be able to pass through the stent. Also
in this case, you may reattempt tracking the true lumen
through the stent from the proximal true lumen under
IVUS guidance.
2. Diameter of the target vessel proximal and distal to the
occlusion: If there is no plaque in the proximal or distal
stent landing zone, you should dilate these parts of the vessel using a balloon compatible with the external vessel
diameter in these zones. For post-dilatation, I use a balloon
at least 0.25mm smaller than the external vessel diameter
estimated by IVUS.To obtain sufcient dilation, I inate
the high-pressure balloon at an average of its rated burst
pressure (RBP) plus 4 to 6atm. Inating a balloon of the
optimal size at 14–16 atm may effectively dilate hard,
plaque-rich lesions such as CTOs, as indicated by
IVUS.Even so, better dilation of such lesions (as indicated
by IVUS) is obtained by inating a high- pressure balloon
that is a quarter size smaller to its RBP plus 4–6atm. To
avoid creating a dissection at the edge of the stent by highpressure dilatation, I increase the pressure more slowly as I
get closer to the nal target pressure. If there is plaque at
the distal end of the stent or the vessel may be over-dilated
by high-pressure dilatation, I perform high-pressure dilatation by placing the distal end of the balloon 2–3mm proximal to the distal end of the stent and dilate the vessel at the
edge of the stent by inating a balloon at 14–16atm.
The coronary artery lumen distal to a CTO often shows
negative remodeling (shrinkage). In this case, you should
administer intracoronary nitrate before performing IVUS,
although this treatment cannot promptly dilate the remodeled vessel completely. IVUS after stenting often conrms dilation of the distal true lumen. If a marked
vasodilatory response of the distal true lumen occurs, you
should dilate the vessel with a balloon of the optimal size.
3. Luminal diameter and characteristics of plaques at the
occlusion: The occluded segment of a coronary artery
often undergoes positive or negative remodeling. In particular, if plaques are scattered through the remodeled
part of a long occlusion, you must not overlook calcied
plaques or plaques showing attenuation because their
presence inuences the technique to be used in the next
step. A CTO with severe calcication that has been
crossed through the true lumen is a good indication for
using a Rotablator or scoring balloon, while the presence
of plaques with attenuation may require protection of the
coronary artery distal to the CTO, depending on the properties and volume of the plaque in question.
Соседние файлы в папке Библиотека им академика М.И. Перельмана