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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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1.7 Retrograde Approach
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ef
Fig. 1.143 Collateral channels available for the retrograde approach to
CTO of the LAD. (a) RAO. (1) PDA → SB → LAD. (2)
PDA → Apex→LAD. (b) RAO. (1) Conus branch→Vieussens
anastomosis→LAD prox. (2) RVB → LAD distal or apex. (c)
RAO. Intracoronary collateral; LAD→SB → SB → LAD. (d)
RAO.Intracoronary collateral; (1) OM→FWEpi→rst Dg→LAD.If
the LAD is occluded between the rst and second diagonal branches,
another channel (rst Dg→FWEpi→second Dg→LAD) may be used.
(e) LAO. (1) Dg→FWEpi→LAD. (2) PL (OM)→FWEpi→LAD. (f)
If the Dg is occluded; (1) OM→FWEpi→Dg. (2) LAD→FWEpi→Dg.
(3) LAD→Apex (FWEpi)→Dg. (g) RAO. (1) RVB→Apex→Dg. (2)
PDA→Apex→Dg
b
Fig. 1.144 Collateral channels available for the retrograde approach to CTO of the LCX. (a) RAO. (1) LCX prox→ACC→ LCX distal. (2)
OM→FWEpi→PL. (3) Dg→EWEpi→PL. (b) LAO. (1) AVB→ACC→LCX main trunk. (2) AVB→FWEpi→LCX
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Fig. 1.145 Two crossing septal branches. On CAG, two septal
branches appeared to cross each other and to give rise to channels leading to the posterolateral branch of the RCA.The channel originating
1.7.3 Selection ofaCollateral Channel
Before selecting a channel, you should assess the anatomy
of all available channels. To do this, you should carefully
review the diagnostic CAG images. Using the list of channels presented in the previous subsection for reference, be
careful not to miss any of the channels that may be present.
Note that diagnostic CAG images may not be obtained at
angles that are suitable for following all possible channels
or may visualize two small vessels crossing at two levels as
if they formed one continuous channel. Therefore, immediately before starting retrograde PCI, you should obtain a
contrast image at the angle which provides the best view of
the route of the channel selected.
Then, I select the collateral channel for retrograde PCI
according to the following rules:
1. Select a septal channel before an epicardial channel: A
septal channel should be chosen rst, even if its diameter
is rather small. There is a low risk of cardiac tamponade
after perforation of a septal channel, which is the most
important reason for preferring this type of channel. Other
reasons for preferentially selecting a septal channel
include less tortuosity and easier tracking.
If the distal end of the occlusion is at a bifurcation of
the RCA, you may consider using an epicardial channel
that leads to the atrioventricular branch, if there is no
other accessible retrograde route to the distal RCA
(Segment #3) and if the posterior descending branch
comes off the distal RCA at a large angle (Fig.1.146).
from the rst septal branch is very tortuous, whereas that from the second septal branch is relatively straight. The latter channel was selected
for wiring and was tracked successfully
A collateral channel running toward the RCA from the
rst septal branch often joins the atrioventricular branch
(Fig.1.147). If such a channel is found, you can safely
advance a guidewire from a septal branch directly toward
the distal RCA through the channel and penetrate the distal cap of the occlusion.
Even if there is no visible collateral channel from a septal branch and another channel is prominent, you may still
be able to achieve successful tracking by advancing a
guidewire into a septal branch (Fig.1.148). In such cases,
the other prominent channel presumably reduced the pressure gradient between the donor artery of a relatively small
septal channel and the distal true lumen, thus preventing
visualization of the channel. Since you cannot distinguish
such invisible channels from the actual absence of channels by performing CAG, you cannot verify the absence of
septal channels without rst exploring the septal branches.
This may be a good reason for performing septal surng.
Sometimes, no collateral channels are visible even
when there is delayed visualization of the distal true
lumen, presumably via several collateral channels with a
large pressure gradient between the donor artery of the
collaterals and the distal true lumen. If this happens, it is
reasonable to consider that the collateral channel is too
small for tracking by a guidewire to reach the distal true
lumen and it is no use performing septal surng blindly.
2. Select a channel with fewer severe bends: Contrast imaging in two projections is useful for determining if a channel
has any severe bends. It is best to view the channel in two
orthogonal projections that are perpendicular to its longitu-
1.7 Retrograde Approach
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dinal axis. If two orthogonal projections that are not completely perpendicular to the longitudinal axis of the channel
show severe tortuosity at the same point (Fig.1.149), it will
be very difcult to track the channel with a guidewire and/
or microcatheter (Fig.1.150). A corkscrewing channel can
easily be tracked if the diameter of the spiral is small
(Fig.1.150b), but not if it is large (Fig.1.151a & b).
3. Select a larger channel: A non-tortuous septal channel
visualized by CAG can often be tracked successfully,
even if very small. On the other hand, a tortuous epicardial channel is easier to track when it has a diameter of
about 1mm than when it is a ne thread, but may conversely be rather difcult to track when the diameter is
too large. Even a large epicardial channel can be tracked
if its proximal part is straightened by advancing a guidewire or microcatheter (Fig.1.152), but will be difcult to
track if the proximal part is not straightened (Fig.1.151c).
4. Avoid a channel that joins the target vessel just distal to the
occlusion (Fig.
1.153a & b): After tracking such a channel,
a retrograde CTO guidewire is likely to create a dissection
from the distal end of the occlusion. When performing retrograde PCI, a small balloon is used to dilate the lesion. If
the diameter of the balloon is larger than that of the channel tracked, ination of the balloon can lead to dissection
of a channel that is too close to the occlusion. If dissection
occurs in the proximal segment or in a side branch, it may
be impossible to advance a guidewire to the distal true
lumen even through a Crusade® microcatheter.
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Fig. 1.147 Channel arising from the rst septal branch. A collateral
channel from the rst septal branch runs into the posterolateral branch
and not into the posterior descending branch
Therefore, it is preferable for there to be a certain distance
between the point where the channel joins the target vessel
and the distal end of the occlusion.
Fig. 1.146 CTO with its distal end at the bifurcation of the distal RCA (Segment #3). The posterior descending branch arises at too large an angle
to be tracked retrogradely, whereas the posterolateral branch is parallel and straight. An AC collateral channel arising from the LCX is visible
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a
b
c
Fig. 1.148 CTO of the LAD. There is a good collateral channel running from the atrioventricular branch (a). Tip injection in the posterior
descending branch also shows a collateral channel from a septal branch (b). Retrograde PCI was performed via this septal branch (c)
ab
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Fig. 1.149 Tracking a very
tortuous channel. (a)
RAO+CA. (b).
LAO+CA.The part of the
channel indicated by a white
line appears very tortuous in
both of two orthogonal
projections
Fig. 1.150 Tracking a
corkscrewing channel. This
channel appears very tortuous
in the RAO+CA view (a),
but is less tortuous and
partially straight in the
LAO+CA view (b). The
corkscrew spiral of this
channel has a small diameter
a b
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1 Mitsudo’s PCI Techniques forCTO
Fig. 1.151 Tracking a corkscrewing channel with a large spiral diam-
eter. The corkscrew spiral of this channel has a large diameter (a), and
it was difcult to track with a guidewire (b). Even after passage of a
Fig. 1.152 Tracking a bending channel. This bending channel was straightened by advancing a microcatheter
microcatheter/guidewire, the channel was not straightened (c). A guidewire is much less manipulable in such a channel, but attempts to forcibly straighten the channel may injure its walls
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Fig. 1.153 Optimal distance between the channel and the distal end of
the occlusion. (a) Several possible septal channels arise from a posterior descending branch. Among them, channel (1) joins the target vessel
too close to the distal end of the occlusion, so channel (2) or another
1.7.4 Guiding Catheter
channel should be tried rst. (b) Channel (2) was chosen because it
joined the target vessel at an appropriate distance from the distal end of
the occlusion
If a retrograde microcatheter advanced through a 100-cm-
long regular guiding catheter fails to reach the antegrade
A guiding catheter for the retrograde approach does not
require particularly strong backup. Like the antegrade
approach, you should only use a guiding catheter with a
shape that ensures stable coaxial engagement. To accommodate the possible need for anchoring, the guiding catheter
should be 6 Fr or larger in size. For the retrograde approach, I
usually employ a 7-Fr guiding catheter, but I use a 6-Fr catheter for introduction into the internal thoracic artery (ITA).
After tracking a long collateral channel (e.g., a channel
running beyond the apex or starting from the ITA), the tip
of a 150-cm-long microcatheter may not be able to reach the
antegrade guiding catheter.
To solve this problem, I recommend using a short (85- to
90-cm-long) retrograde guiding catheter. Alternatively, you
can shorten a 100-cm-long regular guiding catheter by cutting
off the proximal part and connecting the cut ends with a sheath
(Fig.1.154). While doing this, you should keep the guiding
catheter engaged in the coronary artery to prevent excessive
guiding catheter after successful introduction of a retrograde
guidewire into the antegrade catheter, you should trap the
guidewire before withdrawing the retrograde microcatheter
and then withdrawing the retrograde guiding catheter. You
should shorten the guiding catheter, as mentioned above,
and reintroduce the shorter catheter. Before withdrawing the
guiding catheter, you should estimate the amount of shortening that is required from its engagement in the coronary
artery.
After the tip of the retrograde microcatheter reaches the
antegrade guiding catheter, you should use a 300-cm-long
guidewire (e.g., an RG-3) to introduce the microcatheter
into the antegrade guiding catheter and to push it through for
externalization.
If the tip of the retrograde microcatheter cannot reach
the antegrade guiding catheter despite your efforts, you may
also introduce an RG-3 guidewire into the antegrade guiding
catheter for direct externalization.
shortening of the catheter that may preclude its engagement.
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1 Mitsudo’s PCI Techniques forCTO
5–6 cm from
the sheath
About 1.5 cm
3
5 6
Fig. 1.154 Shortening a retrograde guiding catheter. The retrograde
guiding catheter should be cut short while keeping it engaged in the
coronary artery so as to determine the exact distance from the sheath.
You should withdraw the retrograde guiding catheter before cutting it,
if this is being done to pass a retrograde microcatheter through the
lesion after a crossing it with a retrograde guidewire (1 & 2). I use a
4
6-Fr outer sheath to connect the cut ends of a 7-Fr guiding catheter.
Using scissors, you should make two cuts about 1.5mm in length at 180
degrees apart on the rim of each end and spread the ends out (3). Then
you should tightly connect the two ends with a 0.035-inch wire and a
5-Fr inner sheath (4, 5, 6)
1.7.5 Microcatheter
A retrograde microcatheter should have a length of 150cm.
To ensure safe tip injection in a small tortuous collateral
channel, the retrograde microcatheter should have a tip that
is as small and soft as possible. Currently, a Caravel microcatheter is always my rst choice for retrograde PCI.
For advancing into a septal branch just distal to a stent in
the LAD, a tapered microcatheter with a soft tip (such as a
Corsair or Caravel) is useful.
1.7.6 Fluoroscopy andContrast Imaging
Angles
You should obtain contrast images at the optimal angles
for visualizing the branching and tortuosity of the collateral channel you intend to track, as well as to clearly distinguish between branches and the main vessel (Tables 1.7
and 1.8).
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In general, a septal channel originating from the LAD is
best separated from the LAD in the AP or RAO+CR views,
while a channel near the ostium of the PDA is often seen best
in the RAO or RAO+CA views.
To separate the atrial circumex branch from the LCX, the
AP+CA or RAO+CA view (together with the LAO+CA
view for double projection) is optimal. The midportion of
a channel running from the atrial circumex branch to the
RCA is often seen best in the LAO (RAO) view, and while
the LAO+ CR (RAO+ CR) view is often optimal for the
part of the channel near the atrioventricular branch of the
RCA.These projections may be used in a reverse order to
view channels running from the RCA to the atrial circumex
branch of the LCX.
To nd the best view of a septal channel originating from
the posterior descending branch of the RCA, you will often
have to search among the RAO, RAO+CR, and RAO+CA
projections for the optimum separation of the channel from
the branch.
Table 1.7 Optimum projections for en face viewing of collateral
channels
Donor Recipient Angle
Conus branch LAD AP+CR
RV branch LAD
RCA distal
RSA 4-AV LAO
4-PD (Sept) LAD RAO
4-AV (AC) LCX prox
LCX distal
Table 1.8 Optimum projections for en face viewing of collateral chan-
nels (continued)
Donor Recipient
Septal branch 4-PD
LAD distal
RV branch RCA distal
LAD distal
Diagonal LAD distal
LCX PL
LAD apex 4-PD LAO+CA RAO (+CR)
LCX prox AC RCA 4-AV AP+CA LAO (+CR)
LCX distal AC RCA 4-AV RAO
LCX PL RCA PL
LCX PL
RAO— AP+CR
LAO (+CR)
LAO+CR
Angle
Entry Channel
AP—RAO
+CR
AP—RAO
+CR
AP—RAO
+CR
(+CA—CR)
RAO (+CR) RAO (+CR)
RAO
RAO—AP
+CR
LAO (+CR)
LAO+CR
1.7.7 Tip Injection
For successful tracking of a collateral channel, you should
introduce a guidewire into the channel from the donor vessel
and advance it with minimal force to see whether it passes
into the channel. If the guidewire enters the channel but cannot pass through it smoothly to reach the lumen of the artery
distal to the occlusion, you should advance a microcatheter
into the channel and perform tip injection to conrm that
the channel reaches the distal true lumen and whether it is
tortuous or branched. You should use a syringe with a Luer
lock connector for tip injection and should always conrm
backow of blood into the syringe under negative pressure
before injecting contrast medium. Note that if there are multiple collateral channels and if the tip of the microcatheter
is kept coaxial with the channel to be tracked, backow of
blood will be noted even if the catheter has wedged the target
channel and blocked antegrade blood ow.
The backow volume indicates the size of the lumen distal
to the microcatheter that can accommodate contrast medium.
This means that, when the backow volume is small, vigorously injecting contrast medium will increase the peripheral
intraluminal pressure and cause leakage of contrast into the
surrounding tissue or create vascular dissection and/or perforation. Conversely, if the backow is very large, it is necessary to inject contrast medium more rapidly to obtain good
images of the channel.
As with radiographic assessment of the occlusion, the
uoroscopy angles should be selected to provide the longest possible view of the channel to be tracked, especially
its most tortuous part, or to allow the tortuous part to be
viewed en face so that the bends of the channel are opened up
most widely. When viewed in a projection orthogonal to the
rst, the tortuous part of the channel will appear to be either
straight (Fig. 1.155a) or corkscrew-like (Fig. 1.155b). You
should manipulate the guidewire while looking at images
obtained in the projection which opens up the bends most
widely. If a side branch originates from the most tortuous
part of the main vessel and/or if such a side branch is subsequently tracked, it may be difcult to separate the branch
from the main vessel, and you may be unable to track the
channel with a guidewire until separation becomes possible.
After failing to isolate the channel at a branching point, you
should search for a projection perpendicular to the course of
the main vessel that provides the best separation of the side
branch (Fig.1.156).
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It is sometimes difcult to isolate a channel from the
main vessel, e.g., to isolate a septal branch from the posterior descending artery. This may occur under the following
circumstances:
1. The channel originates from a branch of the main vessel,
and the channel and the branch overlap on CAG images
(Fig.1.157).
2. Despite actually communicating with the proximal part of
the channel, it appears that two independent branches
arise from the main vessel due to overlapping (Fig.1.158).
3. The channel branches in a direction that is not always the
same as the course of its distal segment (Fig.1.159).
a
4. A branch from the main vessel does not actually connect
to another vessel, but appears to do so because of overlapping another channel (Fig.1.160).
5. The main vessel is very tortuous, and the channel branches
in the direction where the tortuosity is most severe, precluding isolation of the channel.
If you fail to enter a visible channel, you should perform
tip injection in the main vessel with imaging at an appropriate angle to obtain more insight into the anatomy of the
channel.
b
c
AP–RAO–CAU
Fig. 1.155 Contrast imaging of an epicardial channel from the LCX to the RCA. (a) RAO. b. LAO. (b) The LAO projection provides the longest
view of the target channel. (c) Views of a tortuous channel in two projections
LAO–LL
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