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_3924_Библиотеки_им_академика_М_И_Перельмана
.pdf
174 Crossing challenging lesions
and the catheter subsequently advanced in a step-
by-step fashion. If the loop is advanced too far on
its own, it will begin to spiral around the inside
of the artery. Adjuncts that may be employed for
crossing occlusions are listed in Table 16.2.
It is not clear which yields better results of revas-
cularization over the long run, a subintimal passage
or an intraluminal passage. Each has advantages
and disadvantages. e major advantage of intra-
luminal passage is that the reconstruction is as
short as possible because it only goes thelength of
the true occlusion and does not include the extra
length that is required for entering the subintimal
space and also re-entry into the true lumen. In the
intraluminal space, the lesion has been chronically
occluded. Usually this means that there has been
some core atherosclerotic lesion, sometimes highly
calcied, and in the intervening segments between
the occluded lesion and the next collaterals there
is ll-in with chronic compacted thrombus. With
current CTO guidewires and catheters it is usually
possible to cross the occlusion/lesion. Passage of
the wire is usually slower and more laborious than
with subintimal passage. Rather than forming a
loop and advancing it in a potential space such as
the subintimal space, the CTO wire is bent so that
it has a sharp angle at its tip. e wire is rapidly
rotated by hand using a torque device to achieve
a screw-type eect on the occlusion. One word
of caution is due on the concept of intraluminal
passage: if the wire passes easily in the intralu-
minal space without any hesitation or any cross-
ing of seemingly chronic lesions, the vessel may
be lled with acute or subacute thrombus. is
initiates a whole set of other concerns. e opera-
tor shouldconsider a distal lter. Also, obtain an
activated clotting time if one has not already been
performed since the patient may be hypercoagula-
ble and/or heparin resistant. ese are the patients
that are at highest risk for distal embolization dur-
ing revascularization.
Given the availability of very eective CTO
guidewires and CTO support catheters, it is usu-
ally best to at least attempt an intraluminal pas-
sage and consider a subintimal passage as a backup
plan. If the subintimal passage is the best option,
aer the subintimal space is entered, it is usually
expeditious to pass the wire and catheter through
the potential space of the subintimal plane, which
is oen relatively smooth. e wire is usually sup-
ported by a 4-Fr or 5-Fr catheter. An exception to
easy passage is in cases where a highly calcied
artery is being treated. e bulky calcic lesion
may be dicult to pass and the subintimal layer
may be very adherent to the lesion. e main chal-
lenge of subintimal passage is the need to re-enter
the true lumen. is may take time and special
equipment, such as a re-entry device, and some-
times still may not be possible. is maneuver is
discussed in more detail later.
During passage of the guidewire across the
lesion, only the wire itself is visible on the uo-
roscopic image. e outlines of the artery may be
visible if there is calcium in the wall, but the opera-
tor very oen does not know precisely whether the
wire is intraluminal or subintimal.
Once a dissection plane is raised in juxtaposition
to an occluded arterial segment, it may be dicult
to redirect the guidewire into the lumen. e sub-
intimal angioplasty procedure is more technically
demanding because of the challenge of re-entering
the true lumen at the optimal location. Although
subintimal balloon angioplasty is a second choice
to angioplasty within the true lumen of the artery,
it has gained increasing usage in the past few years.
TOOLS FOR CROSSING
OCCLUSIONS
1. CTO guidewires. ese wires are relatively sti
at the tip and have a very supportive sha.
ey may have a hydrophilic coating along
the tip for easier passage. e wire may be
advanced as it is in a straight conguration,
or the tip may be bent to create a screw device.
CTO wires are typically 0.014- or 0.018-
inch diameter. e original CTO wires were
designed for crossing coronary occlusions.
Table 16.2 Adjunctive tools for crossing occlusions
• Loop of hydrophilic guidewire pushed into
subintimal space.
• Low-profile, stiff hydrophilic catheters
(Quick-Cross
®
).
• Entry catheters (Frontrunner
®
XP CTO).
• Re-entry catheters (Outback
®
LTD™ or
Pioneer Plus IVUS-guided).
• Intravascular ultrasound (for identifying
presence in true lumen).
• Laser.
• Approach lesion from opposite direction.
https://t.me/med1917
Tools for crossing occlusions 175
2. CTO support catheters. CTO catheters for
low-prole, usually 3-Fr, sti catheters, which
would support a 0.014- or 0.018-inch diameter
CTO guidewire. e tip of the catheter may be
angled or straight. By supporting the sha of
the guidewire with a low-prole catheter, the
wire can be exchanged at any time, and the
wire system is made stier and more supported
in passage. is results in greater pushability
and also helps to translate forward force better
from the operator’s hand to the tip of the wire.
In this case the operator leads with the wire but
then supports with the catheter.
3. Crossing devices. These are typically mecha-
nized rotating devices that rotate at high
speed and turn through occlusions, but are
intended to bounce off the wall. This helps
to avoid the subintimal space with the aim
being to remain intraluminal while crossing
the occlusion. Crossing devices have shown
reasonable effectiveness. However, they have
the same challenge that guidewire passage
does (i.e., remaining intraluminal during
passage). If the crossing device goes out of
the lumen, it very often does not find its way
back in.
4. Re-entry devices. Re-entry devices involve
the use of a needle, which is directed toward
the true lumen and then advanced into the
lumen from the subintimal space. A 0.014-inch
guidewire is then advanced through the needle
and into the true lumen. In order to do this,
the subintimal space must be quite tight and
the tip of the re-entry catheter must be wedged
into the space. is is done so that the tip of the
catheter is partly immobilized and is ableto
support a needle as it is advanced through the
arterial wall tissue and into the true lumen.
Ifthe space is too large or patulous, the needle
does not have adequate support to cross the
tissue. erefore, in opening a subintimal space
to make it more user friendly, do not perform
angioplasty of the subintimal space at the loca-
tion where re-entry is desired. e biggest fac-
tor in assessing the adequacy of a re-entry site
is the quality of the lumen. If there is calcium
or occlusive plaque, re-entry into the segment
is going to be more dicult. It may not be pos-
sible if the needle cannot penetrate the tissue
present between the subintimal space and the
true lumen.
In general, the shorter the occlusion and the less
calcied it is, the easier it is to cross. Once the guide-
wire is through the most narrowed segment with the
heaviest plaque formation, it usually slides through
the compacted thrombus. If a short but dicult
segment of occlusion remains to be crossed or the
entire lesion is short (2 cm or less) but heavily calci-
ed, a straight catheter is advanced to the base of the
J-tip on the guidewire and the guidewire–catheter
combination advanced together. Longer occlusions
may also be treated, especially in the supercial
femoral and iliac arteries, with a variety of steps,
which are detailed in Chapter 25. Endovascular
treatment cannot be achieved unless the guidewire
is completely across the occluded segment. Always
be sure that the guidewire is in the true lumen distal
to the occlusion before beginning the treatment.
Technique: Crossing an occlusion
1. Assess proximal and distal patent arter-
ies arteriographically to measure occluded
distance and to ensure that the plaque load is
small enough that a recanalized occlusion has
a reasonable likelihood of continued patency.
Digital subtraction arteriography is best for
this task.
2. If there is the option that access could be
obtained both proximal and distal to the
lesion (such as an iliac artery occlusion), keep
this in mind when planning so that this option
can be maintained. is is a good backup plan
if crossing of the lesion is not successful in the
rst go round.
3. Road map the lesion. An extended road
mapping run usually allows both ends of the
occlusion to be visualized simultaneously
(seeChapter 8, Figure 8.3).
4. Place the tip of the sheath close to the
occlusion. is permits enhanced pushability
and also allows interval arteriography with
minimal contrast.
5. Advance a relatively sti, angle tip catheter
through the sheath and into the stump of the
occluded artery.
6. Probe, drill, and push a 0.035-inch angle
tip,hydrophilic guidewire into the stump of
the occluded artery. e best place to pointthe
catheter is toward the interface between the
plaque and the artery wall that is opposite
thelargest collateral.
https://t.me/med1917
176 Crossing challenging lesions
7. When the tip of the guidewire grabs and sticks
in the plaque, the exible guidewire right
behind the tip will form a loop. e loop is
then advanced.
8. Watch the trajectory of the loop and be sure
that it is going along a pathway where the
artery should be. Clues about this can oen be
obtained using plain uoroscopy to look for
calcication.
9. Aer the guidewire loop is a few centimeters
along the subintimal plane, advance the cath-
eter behind the guidewire. Alternate between
pushing the looped guidewire and pushing the
supporting guidewire.
10. Assess the course of the guidewire and the
distance from the other end of the occlusion
with oblique views or with continued use of
a road map. If the sheath that supports the
procedure is well placed, administration of
contrast into the sheath will opacify the col-
laterals that reconstitute the artery distal to
the occlusion.
11. Push the loop of guidewire supported by the
catheter until it reaches the location where the
artery reconstitutes. Usually the loop will re-
enter the true lumen.
12. If the loop does not re-enter, options include
using an angled catheter to attempt re-entry,
using a specially designed re-entry catheter, or
coming from the opposite direction.
13. If the guidewire will not cross the occlusion
completely, leave it in place as a marker and
approach the lesion from the opposite direc-
tion (Figure 16.4).
SUBINTIMAL ANGIOPLASTY
Subintimal angioplasty refers to passage of the
guidewire in the wall of the artery in order to get
past an occlusion and then performing balloon
angioplasty in this space (Figure 16. 3). is has
been a major advance in the treatment of occlu-
sions and it is being applied to many dierent vas-
cular beds. Because it is not always possible to pass
Fig. 16.4 Leaving a guide-
wire that will not cross an
occlusion as a marker and
then working the lesion
from both directions.
(A)A proximal subclavian
artery occlusion can be
approached either ante-
grade (transfemoral) or
retrograde (transbrachial/
transradial). (B) An unsuc-
cessful antegrade approach
results in the partial
passage of the guidewire
tip across a portion of
the occluded segment.
(C)The first guidewire is
left in place and serves as
a marker for an alternative
retrograde approach to
the same lesion. (D) Using
fluoroscopic guidance,
the distance between the
tips of the two guidewires
can be assessed. If the
approach from the arm fal-
ters, both approaches can
be used simultaneously to
help make the ends meet.
A B
C D
https://t.me/med1917
Subintimal angioplasty 177
through an occlusion from a transluminal stand-
point, techniques have been developed wherein a
guidewire–catheter combination may be passed
around the lesion. In practice, the actual location
of the guidewire passage is oen not possible to
know completely.
Subintimal angioplasty has had its broadest
application in the infrainguinal arteries including
the supercial femoral, popliteal, and tibial vessels.
Subintimal angioplasty has also been performed
in other areas such as the coronary arteries, iliac
arteries, the infrarenal aorta, and other vessels.
e adventitia acts as a fairly tough outer casing
with excellent tensile strength and it only rarely
results in perforation. In the lower extremity where
the supercial femoral, popliteal, and tibial arteries
have surrounding so tissue, muscle, and venous
structures, a perforation is usually not clinically
consequential and usually does not require treat-
ment. Subintimal passage may be created either
intentionally or unintentionally. For many years,
short occlusions of the SFA were treated by forcing
a guidewire or even a sti guidewire end across the
lumen of the artery that was occluded. It was not
known whether the pathway was intimal or sub-
intimal. At the present time, it is quite common to
enter the subintimal space intentionally and there
are specic methods for doing this.
e key technical points to consider are getting
into the subintimal space and then getting from
the subintimal space back into the true lumen.
ese are summarized in Table 16.3. It is typically
simpler to enter the subintimal space than it is to
re-enter the true lumen aer subintimal passage.
To perform a subintimal angioplasty, a solid
treatment platform is needed. Go into the subinti-
mal space with the concept that the treatment will
denitely be carried out and will require a sheath
to do so. Pick the right sized sheath for treatment
and advance it to within a few centimeters of the
origin of the artery. Use a sti-tipped angled cath-
eter, such as a vertebral catheter, to point into the
stump of the occluded artery and angle the catheter
toward the wall on the side that is opposite the best
collateral that is keeping the stump open. Advance
the Glidewire
®
through the tip of the catheter;
allow it to form a loop and then force the loop into
the subintimal space. Once the loop is formed and
advanced for several centimeters, advance the cath-
eter over the guidewire so that the catheter tip goes
into the occluded segment. Pull the guidewire back
slightly to again form an appropriately sized loop,
which is not too wide in its trajectory. In general,
it is best to have the guidewire loop no larger than
the width of the artery being treated. e catheter
is advanced close enough to the loop so that there
is adequate support. When the guidewire loop is
advanced well beyond the catheter support, the
loop tends to widen and also to wander in a cir-
cular fashion circumferentially around the artery
in the subintimal space. It is usually best for the
reconstruction if the trajectory is relatively straight.
A typical step-by-step approach is to advance the
wire, then the catheter, then the wire again. As the
Table 16.3 Technical points concerning using the subintimal space
• How to get into the subintimal space:
• Use a braided catheter with a stiff angled tip.
• Aim the tip of the catheter at the plaque/artery interface.
• Point toward the stump of the occluded artery or, if there is no stump, opposite the largest end
collateral.
• Advance an angled Glidewire
®
until it catches and forms a loop.
• Follow the loop of guidewire with the catheter.
• How to get back into the true lumen:
• Advance the guidewire loop into the reconstituted stump of the distal artery.
• Keep the loop narrow and well supported by the catheter.
• If the loop does not pop back into the true lumen:
• Perform balloon angioplasty along the subintimal space to decrease friction and increase
pushability. Do not perform balloon angioplasty of the actual intended site of re-entry.
• Direct a stiff, angle tip catheter toward the reconstituted artery segment and probe with a guidewire.
• Use a re-entry catheter.
• Approach from the opposite direction.
https://t.me/med1917
178 Crossing challenging lesions
guidewire loop approaches the reconstituted distal
true lumen, make sure the catheter is close behind
the loop to support it and keep the loop as narrow
as possible. Keep in mind that the most eective
loop with which to re-enter the true lumen is if the
bend in the wire that forms the loop is located at the
junction of the so part of the wire where the tip
starts with the stier sha of the wire.
Oen, the loop pops into the true lumen. When
the advancing loop does not pop into the true
lumen, it is usually due to severe calcication or a
heavy plaque burden of the reconstituting artery.
e more diseased the re-entry site, the more likely
that adjunctive measures will be required, such as
a re-entry catheter or an approach from the oppo-
site direction. If the advancing catheter and guide-
wire in the subintimal space reach an area where
there is heavy calcication, which can be seen on
uoroscopy, and/or where the catheter cannot be
adequately advanced because of the constriction of
the tight subintimal space onto the catheter, then
a balloon angioplasty catheter may be passed to
start to break the plaque a little bit. is frequently
helps to create a space through which to re-enter
into the true lumen. If the progress of the support-
ing catheter is impeded in a very tight subintimal
space, passing a lower prole angioplasty catheter
and performing angioplasty is reasonable. Do not
perform angioplasty of the intended re-entry site;
it is likely that a re-entry catheter will be used.
Re-entry catheters are explained in later chapters,
but they all function by throwing a needle from the
false lumen to the true lumen and they need a tight
subintimal space to support the catheter.
Subintimal angioplasty has also provided a new
method of managing occlusions, which has sub-
stantially improved the entire eld but, specically,
has changed lower extremity revascularization.
Subintimal angioplasty in the aorta and the iliac
and lower extremity arteries is discussed in more
detail in Chapter 25.
CROSSING OCCLUSIONS IN VARIOUS
VASCULAR BEDS (
FIGURE16.5)
Subclavian artery occlusions
Subclavian artery occlusions may be crossed either
from the origin of the artery at the arch or using
a retrograde brachial or radial approach. Factors
that help to decide this are the following. If there
is a stump of open subclavian artery at the arch,
this is usually the preferred method of approach
and a transfemoral approach would be indicated.
If the subclavian artery stump is adequate in size,
a 6-Fr sheath tip can be directed into the stump.
If a 0.035-inch diameter guidewire and angled
catheter can be placed into the origin of the artery,
this is a reasonable platform. Oblique views may
be obtained of the lesion to see if there is a hint
as to which way to pass the wire into the occlu-
sion. A slight craniocaudal angulation is usually
best to show the origin of the vertebral artery.
Occlusions may be crossed using 0.014-, 0.018-, or
0.035-inch diameter wires. If there is no stump of
artery and there is a ush occlusion, one may still
attempt to engage this artery originating from the
arch because usually there is a calcic outline of
the location of the artery. However, it is extremely
dicult to get support for the platform in this set-
ting as the sheath is bobbing around in the arch of
the aorta. A percutaneous approach to a subclavian
artery occlusion can also be made from the ipsilat-
eral brachial or radial artery, especially when it is a
ush occlusion or there is some reason why it is not
possible to cannulate the origin of theartery. Most
of the time the brachial artery andthe radial artery
will tolerate a 6-Fr sheath. Since the puncture site is
in a relatively ischemic bed that is underperfused,
and because the upper extremity arteries are some-
what prone to spasm, administer anticoagulation
early in the procedure and administer vasodilating
agents into the brachial or radial artery. ere is no
closure device for the brachial artery and this will
require manual compression to control the punc-
ture site.
One major concern with the subclavian artery
is the location of the origin of the vertebral artery.
Usually in the setting of subclavian occlusion, the
vertebral artery ow is reversed and this helps to
protect the vertebral circulation from emboliza-
tion. However, this is not a guar antee that emboliza-
tion can be avoided. Give plenty of anticoagulation
in this setting. Evaluate the vertebral circulation
before starting so that it is clear which vertebral
artery is the dominant one and also whether both
vertebral arteries connect to the basilar artery. If
the vertebral artery ipsilateral to the subclavian
occlusion ends in the posterior inferior cerebel-
lar artery (PICA), rather than the basilar artery,
patients tend to present with more upper extremity
ischemic symptoms. ese patients are at higher
https://t.me/med1917
Crossing occlusions in various vascular beds 179
A B C
D E F
Fig. 16.5 Crossing occlusions in various vascular beds. Some features of crossing occlusions
in a variety of vascular beds are highlighted here. (A) When considering approaching a sub-
clavian artery occlusion, one of the key strategic questions is the proximity of the origin of the
left vertebral artery and whether the artery can be safely revascularized without encroaching
on the vertebral origin. (B) Axillary artery occlusions are uncommon. If an axillary artery occlu-
sion presents that is in proximity to the first rib, a CT angiogram should be obtained to assess
whether this is a thrombosed aneurysm resulting from damage caused by first rib crossing due
to thoracic outlet syndrome. (C) Visceral artery occlusions are usually associated with significant
calcific plaque formation along the anterior aspect of the aorta and spilling over into the origins
of the celiac and superior mesenteric arteries. In this example, a lateral view under fluoroscopy
helps to identify the approximate location of the origin of an occluded superior mesenteric
ar ter y. (D) A left renal artery occlusion is approached using a mechanically directable sheath to
support a probing guidewire. The sheath has rotational levers on its handle that allow adjust-
ment of the trajectory and shape of the tip of the sheath. (E) Occlusions of the infrarenal aorta
are often shorter than anticipated because of patent lumbar arteries that support the patency of
some length of the diseased artery. In this example, the occlusion is approached through both an
upper extremity access and a femoral access in the hope of having the wires rendezvous along
the occluded length. (F) A left common iliac artery occlusion may be approached from any one
of three directions or a combination of these. An upper extremity access may be used to probe
the proximal end of the occlusion. If there is an open beak of patent artery in which to seed a
catheter from the contralateral side, an up-and-over approach with a hook-shaped catheter may
be undertaken. Likewise, the left common femoral artery can be accessed under ultrasound
guidance and the distal end of the occlusion may be approached from a retrograde direction.
(Continued)
https://t.me/med1917
180 Crossing challenging lesions
risk for stroke with subclavian stenting. If the
subclavian artery lesion encroaches on the origin
of the vertebral artery, one must consider, prior to
crossing, which stent it might be possible to use. It
is not acceptable to jail the origin of the vertebral
artery. e operator must be ready to perform ver-
tebral artery reconstruction in conjunction with
subclavian reconstruction. If the lesion encroaches
on the vertebral artery origin, the patient may be
better served with a carotid–subclavian bypass.
Axillary and brachial artery occlusions
Axillary and/or brachial artery occlusions are
unusual. An occlusion might occur as a result
of trauma (humerus fracture or dislocation) or
extrinsic compression from the rst rib. e
approach is usually antegrade with the sheath tip
placed in the subclavian or axillary artery. Stents
are used sparingly due to the highly mobile nature
of the artery.
G H I
Fig. 16.5 (Continued) Crossing occlusions in various vascular beds. Some features of crossing occlu-
sions in a variety of vascular beds are highlighted here. (G) An SFA occlusion is usually approached
from the proximal direction, either through an up-and-over approach or an ipsilateral antegrade
access. If this is not successful, the operator has a choice of using a re-entry device from the subinti-
mal space and re-entry into the true lumen, or a retrograde access of the above-the-knee popliteal
artery, or a retrograde access site more distally placed. (H) A popliteal artery occlusion is usually
approached antegrade through an ipsilateral antegrade femoral access. If this is not successful, ret-
rograde access from one of the tibial vessels should be considered. Re-entry catheters may also be
considered but are not approved for usage this distally in the infrainguinal vasculature. (I) Tibial artery
occlusions are usually approached through an antegrade access. The sheath tip is placed distally into
the popliteal artery if possible. An angled catheter is used to direct a CTO guidewire into the appro-
priate tibial vessel. If true lumen crossing is not possible, a retrograde access of the appropriate tibial
artery should be obtained.
https://t.me/med1917
Crossing occlusions in various vascular beds 181
Visceral and renal artery occlusions
Visceral and renal artery occlusions are oen spill-
over lesions of aortic plaque occluding the entry of
the branch artery. It is extremely helpful if there is
a stump of artery to help direct the operator. As in
the example of subclavian artery occlusion when
the occlusion is ush with the aorta and there is no
stump of artery, there is usually a calcic outline
visible on uoroscopy when the projection is opti-
mized. For visceral lesions, this is usually a lateral
projection. For renal lesions, this is usually an ipsi-
lateral anterior oblique projection. Unlike subclavian
artery occlusions, there is no convenient method of
approaching a visceral or renal artery occlusion from
the opposite direction, since these are end organs and
not available for access. If the occlusion is somewhere
in the mid-segment of the branch artery, and the ori-
gin of the artery is patent, the sheath is directed into
the origin of the vessel and this is used as a platform.
ese occlusions may be approached from either
a femoral or an upper extremity access, with the
approach being determined by the angle of the artery
from the aorta and also the pathway from the access
to the vessel origin. One very helpful tool in a femo-
ral approach is a Destino™ sheath. is is a sheath
Table 16.4 Crossing occlusions in various vascular beds
Platform Approach Considerations
Subclavian 035 or 018 Antegrade/
retrograde/
bidirectional
Usually a stump from the aortic arch where the sheath
tip can be placed to work; usually attempt antegrade
first; proximity of distal end of occlusion to vertebral
artery is a concern
Axillary–
brachial
035 or 018 Antegrade Place sheath deep into the subclavian or axillary artery;
occlusion in the region of the first rib could be
thoracic outlet syndrome; stent the brachial artery
sparingly due to high mobility of vessel
Visceral 018 or 035 Antegrade Antegrade approach may be performed from femoral or
from upper extremity access; check trajectory of
artery on CTA; calcific plaque usually indicates vessel
location on fluoroscopy
Renal 018 or 035 Antegrade Antegrade approach may be performed from femoral or
from upper extremity access; check trajectory of
artery on CTA
Aortic 035 Antegrade/
retrograde/
bidirectional
For a long aortic occlusion, a bidirectional approach is
usually helpful; beware occlusions that initiate in close
proximity to renal arteries
Iliac 035 Antegrade/
retrograde/
bidirectional
Direction of approach usually determined by location of
occlusion; potential for iliac rupture is an issue;
attempt to preserve internal iliac artery; retrograde
approach limited in external iliac occlusions that
extend to inguinal ligament
Superficial
femoral
artery
035 or 018 Antegrade/
retrograde/
bidirectional
Attempt antegrade in all cases, either from ipsilateral or
contralateral femoral access; re-entry catheter may be
useful; avoid a retrograde access
Popliteal 018 or 035 Antegrade/
retrograde/
bidirectional
Attempt antegrade in all cases, either from ipsilateral or
contralateral femoral access; make sure occlusion is
not due to thrombosis of popliteal aneurysm
Tibial 014 or 018 Antegrade/
retrograde/
bidirectional
Attempt antegrade in all cases, either from ipsilateral or
contralateral femoral access; retrograde access very
helpful for tibial chronic total occlusions that cannot
be crossed from an antegrade direction
https://t.me/med1917
182 Crossing challenging lesions
that allows the operator to shape the tip of the sheath
in real time and direct the catheter and/or wire in
the chosen direction. e big challenges with renal
and visceral occlusions are developing a platform
by which any sort of force can be delivered into the
vessel, and breaking back into the true lumen if the
wire has gone into the subintimal plane. e platform
usually consists of a standard access sheath, with a
shaped guide catheter or shapeable sheath going
through it. A CTO catheter and CTO guidewire are
used to probe the lesion in an attempt to cross it.
Intraluminal passage of CTO wires is almost always
the best way to proceed. e subintimal approach
should be avoided.
Occlusions of the infrarenal aorta
Before doing anything, check to see if the occlu-
sion is a thrombosed aortic aneurysm. is can
be determined with CTA. If it is a thrombosed
aneurysm, this will inuence your approach, your
aggressiveness, and your choice of repair. Detailed
arteriography of the proximal and distal ends of
the occlusion will assist the operator in deciding
which way to approach the lesion and which direc-
tion might accept the entry of a guidewire. is may
be approached from either a proximal direction or
a distal direction, or both. e key issue is whether
the occlusion is ush at the renal arteries or begins
more distally. If there is any runo through patent
lumbar arteries, the patent segment typically tapers
beyond the renal arteries. If the occlusion initiates
distal to the renal arteries, this is a lot safer than if
there is a ush occlusion at the renal arteries. All
occlusions, but especially ush occlusions, have the
possibility of liberating chronic compacted throm-
bus into the renal and visceral vessels. e other
key issue regarding infrarenal aortic occlusion is
to assess how far distally the occlusion extends. If
the bilateral common and external iliac arteries are
also occluded, recanalizing and stenting the entire
segment may be a waste of time and energy. If, on
the other hand, the infrarenal aortic occlusion is
isolated and the iliac arteries are patent, the care
is signicantly more straightforward. Iliac artery
occlusion is discussed in the next section. Very oen
the approach to recanalizing is both from a proxi-
mal direction using brachial access and from a dis-
tal direction using femoral access. If the guidewires
can be made to meet in the middle, especially if they
meet in the occluded segment, this is usually best.
e aortic wall is thicker than the wall of other ves-
sels and if the wire goes into the subintimal space,
it may travel a long way before it can be made to re-
enter into the true lumen. Re-entry devices can be
used in this setting; however, this has not been stud-
ied and may be dangerous. If the wire is directed
outside the vessel wall, it is essentially an aortic
perforation. e lumbar arteries are frequently a
place where the wire will attempt to follow. Do not
advance a loop of wire into a lumbar artery as this
could potentially cause a disruption of that small
vessel. In general, aggressive subintimal approaches
in the infrarenal aorta should be avoided until fur-
ther studies have been undertaken. If in doubt about
the integrity of the wall, consider reconstruction
using covered stents.
Iliac artery occlusion
Most iliac artery occlusions can be crossed using
current techniques. There are three potential
approaches: (1) ipsilateral retrograde femoral;
(2) contralateral femoral using an open over
approach; or (3) a proximal approach using a
brachial access. Detailed arteriography will help
the operator assess which end of the occlusion is
most likely to accept a guidewire and provide a
foothold into the occlusion. Very often it helps
to approach an iliac occlusion from two direc-
tions. An example is to approach a common
iliac artery occlusion using both a contralateral
femoral up-and-over approach and an ipsilateral
femoral retrograde approach. Most external iliac
occlusions are approached using a contralateral
femoral up-and-over approach. If the occlusion
extends to the aortic bifurcation, and especially
if it is bilateral, one might consider a proximal
approach. If the occlusion extends to include
the common femoral artery, then an ipsilateral
femoral approach is less useful and may not be
possible due to a lack of working room, but a
retrograde approach through the ipsilateral SFA
can be considered. Either an intraluminal or
subintimal approach may be used to cross iliac
artery occlusions. A word of caution on the sub-
intimal approach. If an occlusion is approached
using ipsilateral retrograde femoral access and
the guidewire enters the subintimal space, as the
wire approaches the aortic bifurcation, the cal-
cification and occlusive disease is usually worse
and it can be extremely difficult to re-enter in
https://t.me/med1917
Crossing occlusions in various vascular beds 183
this setting. If an iliac artery occlusion has been
approached using an ipsilateral retrograde femo-
ral access and the guidewire has gone subintimal,
usually a proximal approach must be established
to recanalize the artery. In this case, if it is a
flush occlusion at the iliac artery origin, go to
the brachial artery. If it is a common iliac artery
occlusion with an open beak at the entry site, go
to the contralateral femoral and use the up-and-
over approach with a hook-shaped catheter. If
an up-and-over approach is taken to access an
external iliac artery occlusion and the guidewire
remains subintimal after it is pushed beyond
the occlusion, pull the wire back and puncture
the femoral artery on the side of the occlusion
using a retrograde approach to the lesion. Work
to make the two wires meet in the occluded seg-
ment. Whenever two different approaches are
taken, it is usually best to have the wires meet in
the occlusion itself so that no length of nonoc-
cluded artery is given up in the process.
Superficial femoral artery occlusion
Managing SFA occlusion is now a staple of mod-
ern endovascular therapy. Usually, a SFA occlu-
sion is approached from the proximal direction. It
can also be approached from the distal direction
using tibial or pedal artery access if necessary, but
this is not the rst choice. is maneuver is usu-
ally reserved for patients with critical limb isch-
emia who are not candidates for open surgery and
in whom the SFA occlusion could not be crossed
from an antegrade direction. Detailed arteriogra-
phy of the proximal and distal ends of the occlu-
sion is helpful. If the lesion begins in the proximal
SFA, then up-and-over access from the contra-
lateral femoral artery is indicated. If it is a ush
occlusion at the origin of the SFA, multiple oblique
angles may be viewed to get hints as to where the
occlusion begins. If the lesion initiates in the mid-
SFA, either an up-and-over access or an antegrade
femoral access can be considered. If there is a ush
occlusion of the SFA, the operator has to decide
whether to protect the proximal profunda femo-
ris artery with a buddy wire during reconstruc-
tion. e usual approach to an SFA occlusion is to
place a 6-Fr or 7-Fr sheath close to the proximal
origin of the occlusion. Introduce an angled cath-
eter or a low-prole CTO catheter. Consider using
a 0.018-inch CTO guidewire with hydrophilic
coating on the tip. e tip of the wire is bent 1 or 2
mm from the tip. Once the wire is introduced into
the occlusion it is spun rapidly, but it is advanced
slowly in an attempt to make progress through
the occlusion but within the occluded true lumen.
e backup plan is usually a subintimal approach.
As the guidewire is advanced, every few centi-
meters the CTO catheter can also be advanced
to support the wire. If the wire begins to take a
meandering course and especially if it begins to
angulate to form a bend or elbow, or if it progresses
beyond the location of the probable trajectory of
the artery, then you know that the wire has le
the true lumen and a subintimal approach may be
required. e subintimal approach is usually best
with 0.035-inch diameter hydrophilic guidewires
backed up with 4-Fr or 5-Fr catheters. When using
the subintimal approach, aer the guidewire and
catheter are deeply embedded into the occlusion
and the operator has the sense of where the true
lumen reconstitution may be located, it is usually
best to refocus the image intensier so that the
wire is visible at the upper end of the screen and
the reconstitution site is visible at the lower end of
the screen. e reconstitution usually shows best
through contrast placed into profunda femoris
collaterals. If the sheath tip is well into the SFA, a
larger bolus of contrast may be required to reux
toward the femoral bifurcation. is is because
the contrast must reux backward up the SFA and
into the profunda femoris in order to come around
through the collateral circulation and into the
reconstitution site. If during the course of guide-
wire and catheter passage across the occlusion
everything stalls, which is sometimes the case with
heavily calcied lesions, it is appropriate to use a
long low-prole balloon and perform angioplasty
along the wire of the territory that has been gained
so far by dilating that space, either true lumen or
subintimal, to 3 or 4mm in diameter. is helps
to decrease friction and allow working space. Do
not perform dilation of the subintimal space at the
location of intended re-entry. A tight subintimal
space is required in order for re-entry to occur. If
the guidewire remains subintimal from an ante-
grade direction and re-entry cannot be achieved,
then a distal access site is appropriate. In this case,
the wires should meet somewhere along the occlu-
sion. If the wires meet distal or proximal to the
occlusion, usually some collateral vessels could be
excluded, which would be undesirable.
https://t.me/med1917
Соседние файлы в папке Библиотека им академика М.И. Перельмана