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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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1.3 Guiding Catheter
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To treat an ostial CTO for which an antegrade guiding catheter cannot provide good backup, you should also
consider crossing the lesion via the retrograde approach and forming a loop with an RG-3 to consolidate backup
(Figs.1.24 and 1.25).
Fig. 1.24 RCA originating
from the left sinus of Valsalva.
Images obtained with an SL4.
In the AP-CR view, the RCA
changes direction just beyond
the ostium. Therefore, it is
difcult to engage a guiding
catheter in the RCA and
maintain it coaxial to the
proximal part of the artery,
resulting in poor backup
19
Fig. 1.25 Anchoring technique for balloon angioplasty and stenting combined with a GuideLiner for imaging
20
1 Mitsudo’s PCI Techniques forCTO
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1.4 Anticoagulation Strategy
1.4.1 Administration ofHeparin
Performing PCI for CTO requires prolonged manipulation
of guidewires and other devices, which increases the risk
of thrombosis. In particular, thrombosis occurring in a retrograde channel is often fatal and must be prevented. For
complete thromboprophylaxis, it is necessary to ensure that
a stable effect of heparin is sustained throughout the PCI
procedure. Table 1.3 summarizes the recommended initial
dose of heparin. At 5minutes after administering the initial
dose of heparin, you should measure the activated coagulation time (ACT). If the ACT indicates inadequate anticoagulation by heparin, you should administer an additional
dose of heparin as indicated in Table1.4. Measure the ACT
every 30minutes thereafter, and, depending on the results,
administer an additional dose of heparin to keep the ACT at
≥300seconds.
Blood for measurement of the ACT is often collected
from the guiding catheter. When collecting blood for this
purpose via the guiding catheter, you should take care to
prevent contamination with even a small amount of contrast medium. If the ACT is ≥400seconds after treatment
with the standard dosage of heparin, this undoubtedly represents a measurement error arising from contamination of
the blood sample by contrast medium during collection. If
the ACT is around 300seconds due to unrecognized contamination by contrast medium, the true ACT may be at a
level associated with a signicant risk of thrombosis. To
completely exclude the risk of contamination by contrast
medium, you should take care to optimize handling of the
three-way stopcock during blood collection and pay attention to the dead space volume.
If the ACT is not prolonged at 5minutes after the initial
dose of heparin, administer a second dose, and repeat measurement of the ACT after another 5minutes. If the ACT is
still not prolonged, suspect heparin-induced thrombocytopenia/thrombosis (HIT/T), and switch heparin to argatroban.
With this anticoagulation strategy using doses of heparin
modied according to the ACT, no patient undergoing PCI
for CTO at our center has developed thrombosis during
intervention.
1.4.2 Blood Sample Collection forACT
Measurement
If venous access has been obtained with a sheath to provide
blood samples for measurement of the ACT, blood collected
via this route yields the most precise ACT values. If the sheath
is the same size as the guiding catheter, it becomes difcult to
collect blood from the side arm of the sheath. Using a sheath
that is one size larger than the catheter makes it easier to collect blood and obtain precise ACT values. If there is no other
route available, it becomes necessary to collect blood samples
via the guiding catheter while taking appropriate precautions.
1.4.3 Precautions When Collecting Blood via
theGuiding Catheter
If a blood sample is collected from the contrast injection port
of a three-port manifold, much blood will need to be discarded
rst because of the large dead space. The volume of blood
that needs to be discarded to prevent contamination with contrast medium is sometimes excessively large. At our center,
we place a three-way stopcock near a Y-shaped connector
and collect blood via the stopcock. When aspirating blood
from the three-way stopcock to eliminate the dead space, the
syringe should be kept horizontal or angled downward. Even
if a large volume of blood is aspirated into a syringe angled
upward, contrast medium always remains at the bottom of the
three-way stopcock because of its high specic gravity. Take
care to completely avoid contamination with contrast medium
because this is essential for obtaining precise ACT values.
If the ACT is longer than 400 seconds or is prolonged
without administration of additional doses of heparin, you
should suspect that contamination with contrast medium has
resulted in a falsely high ACT value and should repeat the
test with a blood sample collected more carefully to exclude
contamination.
If the ACT measured using blood contaminated with contrast medium is within the target range, the true ACT value
will be below the range and will be at a level that is associated with a signicant risk of thrombosis during PCI.It is
important to always keep in mind the necessity of completely
excluding contrast medium from blood samples collected
through a guiding catheter for measurement of the ACT.
Table 1.3 Initial dose of heparin recommended for patients undergo-
ing PCI
Characteristics
None of the characteristics listed below Full
Age>75years About 80%
Body weight<45kg (females) or<50kg
(males)
On warfarin About 80%
Initial dose
of heparin
(100%)=10,000U
About 80%
Table 1.4 Additional doses of heparin recommended for patients
undergoing PCI based on ACT values
Additional dose of heparin (U)
ACT value (sec)
120–170 5000 4000 3000
171–220 4000 3000 2000
221–270 3000 2000 2000
271–290 2000 1000 1000
290–300 1000 1000 500
300- 0
100% 80% 80%×2 (64%)
RAO+CA
1.5 Fluoroscopy andImaging Strategies
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1.5 Fluoroscopy andImaging Strategies
1.5.1 Video Imaging Equipment
andFluoroscopy Angles
Selection of the correct video imaging equipment and uoroscopy angles are among the most important considerations
when performing PCI for CTO.
1.5.1.1 Is Biplane Imaging Essential?
I think that simultaneous biplane cineangiography of the
heart is essential when PCI is performed for CTO, not only
for diagnostic imaging but also for uoroscopic guidance
during guidewire manipulation.
In order to conrm the passage of a guidewire by monoplane cineangiography, images need to be obtained in different projections. Efforts have been made to reduce the
frequency of imaging with monoplane cineangiography,
such as obtaining an image while rotating the detector after
locating the patient’s heart precisely at the center of the two
projections (isocenter). Despite such efforts, it is impossible
to conrm passage of a guidewire until the wire has been
advanced for a certain distance. Thus, more frequent imaging is needed with monoplane cineangiography to conrm
the position of the guidewire after advancing the wire for a
short distance.
Simultaneous biplane imaging allows the position and
direction of the tip of a guidewire to be checked easily after
advancing it for a short distance (Fig. 1.26). In practice,
simultaneous biplane imaging is important for PCI because
we manipulate guidewires and other devices while checking the uoroscopy screen. I strongly recommend setting the
biplane imaging equipment in the simultaneous mode since
most biplane apparatus can be set this way.
a
Fig. 1.26 Correcting the direction of the guidewire tip by simultane-
ous biplane cineangiography. (a) During PCI for a CTO in the middle
segment of the LCX, simultaneous imaging in two orthogonal projections was employed to visually check whether the direction of the wire
was correct or not. Although the guidewire appeared to be heading
LAO+CA
toward the exit point, simultaneous imaging showed that its tip was
directed to the right in both the RAO+CA and LAO+CA views. (b)
Based on this information, the direction of the guidewire tip was corrected leftward in both views, resulting in successful crossing of the
CTO through the true lumen
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RAO+CA
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1 Mitsudo’s PCI Techniques forCTO
b
LAO+CA
Fig. 1.26 (continued)
1.5.1.2 Direction oftheLongitudinal Axis
oftheTarget Vessel intheRegion
ofInterest forGuidewire Advancement
The region of interest (ROI) is dened as the occluded region
of the coronary artery from the point at the tip of the guidewire to a peripheral landmark or the site of a presumed bend
(Fig.1.27). When treating a long tortuous CTO such as the
lesion shown in Fig.1.28, the position of the ROI changes as
the tip of the guidewire is advanced and the direction of the
longitudinal axis of the target vessel in each ROI changes
as well. In principle, two projections should be used to conrm that the guidewire tip is in the true lumen, and the two
detector surfaces should desirably be set orthogonal to each
other and parallel with the longitudinal axis of the target vessel when imaging. This is because obtaining two orthogonal
projections minimizes the blind area (Fig.1.29) and provides
more accurate visual conrmation that the guidewire tip is in
the true lumen (Fig.1.30).
ab cd
XX
1.5 Fluoroscopy andImaging Strategies
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Fig. 1.27 ROIs (the ranges are indicated by arrows) during PCI for
CTO. (a) If the lesion appears to be relatively straight from the entry
point to the exit point on angiograms, the ROI is set from entry point to
exit point. (b) If there is a landmark within the lesion, the ROI is set
from the tip of the proximal guidewire to the landmark. (c) If there is a
large bend in the lesion, the ROI is set from the entry point to the presumed bend. (d) Once the tip of the guidewire has reached the bend, a
new ROI is set from the presumed bend to the next landmark, which
might be the exit point (as in this case), a second bend, or any other
feature
a
Fig. 1.28 Changes of the ROI while advancing the guidewire. (a)
When treating a long tortuous CTO, the ROI will change as the guidewire is advanced. The detector surfaces should be set orthogonal to each
other and parallel with the longitudinal axis of the target vessel inside
the ROI. When treating a long CTO of the RCA extending from
Segment #1 to the periphery of Segment #3, you would need to set four
different ROIs as shown in this gure until the guidewire reaches the
periphery. Appropriate projections for these ROIs are as follows: the
AP+CR and LAO+CA projections for ROI 1 (from the ostium of the
RCA to the bend in Segment #1); the RAO and LAO projections for
ROI 2 (from the middle of Segment #1 to just proximal to the acute
margin); the RAO (AP)+CA projection for ROI 3 (from the acute margin to the middle of Segment #3); and the AP+ CR and LAO+ CR
projections (because of the bifurcation) for ROI 4 (from Segment #3 to
the peripheral bifurcation of the RCA). (b) PCI was attempted for a
CTO of the RCA that had occurred after coronary artery bypass grafting. Since the longitudinal axis of the proximal RCA was visualized
well in the LAO+CA projection, the AP+CR projection was also chosen because it was orthogonal to the LAO+ CA projection. (c) The
longitudinal axis of the middle portion of the RCA was visualized well
in the AP + CA projection, so the LAO + CR projection was also
selected because it was orthogonal to the AP + CA projection. (d)
Imaging of the peripheral RCA bifurcation should be able to clearly
distinguish the two branches. Therefore, LAO+CR and AP+CR projections were chosen, although the detector surfaces partially
overlapped
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AP+CALAO+CR
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1 Mitsudo’s PCI Techniques forCTO
b
AP+CRLAO+CA
c
Fig. 1.28 (continued)
ab
: blind area
AP+CRLAO+CR
1.5 Fluoroscopy andImaging Strategies
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d
25
Fig. 1.28 (continued)
Fig. 1.29 Imaging in two
orthogonal projections
parallel with the longitudinal
axis of the target vessel. (a)
Even with imaging in two
orthogonal projections, a
guidewire in the blind spot
(green in the gure) may be
mistakenly thought to be in
the true lumen, but the blind
spot is extremely small. (b)
Imaging in two nonorthogonal projections creates
a larger blind area and is more
likely to cause the
interventionalist to think that
a guidewire outside the true
lumen is being advanced
along the correct route
guide wire
26
ab
: blind area
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Fig. 1.30 Navigating the
guidewire tip from a false
lumen into the true lumen. (a)
With imaging in orthogonal
projections, there is less risk
of erroneously navigating the
guidewire while inside the
blind area. (b) With imaging
in non-orthogonal projections,
the interventionalist is more
likely to remain unaware of
guidewire deviation and fail
to navigate it into the true
lumen
1 Mitsudo’s PCI Techniques forCTO
guide wire
1.5.1.3 Selecting Two Orthogonal Projections
I will discuss the rationale for empirically selecting the optimal uoroscopy angles and the angles parallel with the longitudinal axis of the target vessel, as well as how to choose
the two orthogonal projections. In general, you should rst
choose a projection that appears to be orthogonal to the longitudinal axis of the target vessel in the ROI, i.e., the projection that gives the longest view of the vessel in the ROI
(Fig.1.31). If this projection is truly orthogonal to the longitudinal axis of the target vessel (providing the longest view
of the longitudinal axis of the target vessel inside the ROI),
then the vessel must be parallel with the detector surface.
Based on this assumption, the angle of the second projection
orthogonal to the longitudinal axis of the vessel in the ROI
can be determined from the direction of the vessel on the
detector surface.
If the vessel runs vertically on the rst detector surface,
the second detector surface should be set at a right angle in
relation to the body axis, i.e., at 90 degrees in the RAO or
LAO direction (Fig. 1.32). If the vessel runs horizontally
on the rst detector surface, the second detector surface
should be angled in the cranial (CR) or caudal (CA) direction (Fig.1.33). If the vessel runs to the upper right (at 45
degrees) on the rst detector, the second detector surface
should be rotated at 90 degrees to ensure identical angles
from the LAO+CA or RAO+CR directions.
I would like to give some examples of determining the
angles of detector surfaces that are parallel with the longi-
tudinal axis of the target vessel. In practice, the longitudinal
axis of the target vessel in the ROI is often not parallel with
the rst detector surface (Fig.1.34a). In the above explanation of how to select the angle of the second detector surface, I assumed that the surface of the second detector was
always parallel with the longitudinal axis of the vessel in the
ROI (Fig.1.34b). Rotation of the rst detector surface at 90
degrees around the longitudinal axis of the target vessel on
the second detector surface will make both detector surfaces
parallel with the longitudinal axis of the vessel in the ROI
(Fig.1.34c).
Another practical example is shown in Fig. 1.35.
Figure1.35a presents the RAO+CA image that gives the
longest view of the LCX.In this patient, the axis of the LAD
ostium runs horizontally on this image (RAO+CA). When
a 90-degree turn is made to LAO+ CA, the axis of the LAD
ostium will be vertical, so LAO + CA will be the optimal
angle (Fig.1.35b).
Once the projection which gives the longest view of the
longitudinal axis of the target vessel in the ROI has been
determined, it is easy to select the second and third uoroscopy angles. Therefore, it is important to know the standard
projections that give the longest view of the longitudinal axis
of each coronary artery segment in the ROI (Table1.4). It
should be noted that this table only shows standard projections, so it is most important to estimate the optimal projections from the diagnostic angiograms. One exception to these
standard projections is treating a CTO at the bifurcation of a
1.5 Fluoroscopy andImaging Strategies
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27
large artery, when it is often important to consider whether
the two projections can clearly distinguish multiple branches
rather than focusing on orthogonality. Specically, I choose
the uoroscopy angles for visualizing the LMT bifurcating
into the LAD and LCX and the RCA bifurcating into the
4PD and 4AV as described below (Table1.5).
As shown in Fig.1.36a, the axis of the LAD ostium
runs vertically in the LAO + CA projection. After
the angle is rotated at 90 degrees toward the RAO, the
axis of the LAD ostium runs horizontally on the image
(Fig.1.36b). Based on this information, the detector surface will be parallel with the longitudinal axis of the vessel in the RAO+CR projection (angled at 90 additional
degrees in the CR direction). However, it is hard to clearly
distinguish between the LAD and LCX in the RAO+CR
projection, so I choose the two uoroscopy angles shown
in Fig.1.36c and d when performing PCI for LAD/LCX
bifurcation lesions.
When performing PCI for lesions from the middle part of
Segment #3 of the RCA up to its bifurcation, I often choose
the AP+ CR and LAO + CR projections (Fig. 1.37). The
two standard orthogonal projections that provide the longest
view of the longitudinal axis of the vessel in Segment #3 of
the RCA are the AP+CA (RAO+CA) and LL/LAO+CR
projections (Table1.5). However, the RCA bifurcation cannot be visualized clearly in these projections, so I always
change the uoroscopy angles as the guidewire approaches
the bifurcation.
Although the uoroscopy angles are basically determined
as explained above, the patient’s body or the other imaging
equipment can sometimes preclude imaging in theoretically
optimal orthogonal projections. If difcult imaging conditions prevent use of the optimal uoroscopy angles for
viewing the longitudinal axis of the vessel in the ROI, it
becomes necessary to perform PCI while using angles that
are quasi- orthogonal but achievable under the actual imaging
conditions.
When obtaining a lateral view of the LAD, the patient’s
arms positioned along the body have little inuence on
image quality, while both of the patient’s arms have to be
raised above the head to obtain a good lateral view of the
LCX.If the target lesion is located in the LCX and needs to
be viewed laterally, you should therefore avoid using the TB
or TR approaches.
Fig. 1.31 Two orthogonal projections around the midportion of the
LAD (1). The part of the LAD with the CTO runs vertically (from upper
to lower) on the detector surface in the AP+CR projection. If the LAD
is parallel with the detector surface, rotating the detector at 90 degrees
in relation to the body axis will provide orthogonal views of the vessel.
The longitudinal axis of the target vessel should run vertically on the
detector surface in the new projection
28
RAO+CR RAO+CR
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1 Mitsudo’s PCI Techniques forCTO
Fig. 1.32 Two orthogonal projections around the midportion of the
LAD (2). After rotation of the second detector by 90 degrees (LL+CR),
the target vessel does not run vertically, but instead runs rightward on
the cranial side and leftward on the ventral side. Therefore, the rst
detector should optimally be set in the AP + larger angled CR
projection
Fig. 1.33 Selecting two orthogonal projections (RAO + CR and
RAO+ CA). In the RAO+CR projection, the target vessel with the
CTO is almost horizontal. After the projection is rotated by nearly 90
degrees toward the CA, the target vessel is still horizontal. This indi-
cates that the vessel is being viewed in two projections that are orthogonal to its longitudinal axis and that the LAD of this patient runs to the
left and anteriorly from its origin while remaining perpendicular to the
body axis
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