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
154 Access for endovascular therapy
A B C
Fig. 14.3 Placing the sheath tip as close to the target lesion as possible. (A) When treating infragenic-
ulate lesions, getting the sheath tip in the proper position can be helpful during treatment but can be
challenging to place. (B) The sheath is advanced as far as it will go and then the exchange guidewire is
advanced a little further, but not into the lesion. The sheath can then be advanced into proximity with
the lesion planned for treatment. (C) When the exchange guidewire and the dilator are removed, the
tip of the sheath is within a few centimeters of the target lesion.
A
B
C
Fig. 14.2 Principles of sheath placement. (A)The stiff exchange guidewire is directed away from the
lesion to be treated in the superficial femoral artery and into a safer anchoring location in a branch
artery nearby, namely the profunda femoris artery. (B) The sheath is advanced until its tip is in the
common femoral artery. (C) The exchange guidewire and the dilator are removed and the treatment
guidewire is advanced to cross the superficial femoral artery lesion.
https://t.me/med1917
When do you use a guiding sheath versus a guiding catheter? 155
pathway to the lesion, all factors that are best man-
aged by selecting the smallest caliber sheath that
will do the job. Use a sti enough guidewire for the
size of the sheath and the tortuosity of the path-
way. Do not cross the lesion intended for treatment
with a sti guidewire if it can be avoided. When
advancing the sheath, keep an eye on landmarks so
that the exchange guidewire or sheath is not inad-
vertently placed across the lesion. If when placing
the sheath the advancement is slow and dicult,
it will also be dicult to remove the sheath. If the
iliac arteries are tortuous proximal to a femoral
access site, the iliac artery can sometimes be par-
tially straightened by placing the nonsheath hand
into the retroperitoneum and pushing on the iliac
system during advancement.
As the pathway to the treatment site becomes
more remote or more complicated, each area of
impingement becomes a point of friction that
impedes progress for sheath arrival at the next
location. ese friction points include: the skin and
so tissue (especially if it is a scarred groin); the
access point in the artery (especially if it is calcied
or a redo); and any tortuosity along the way, and
the negative eects of tortuosity are worse when it
is calcied. ere are several maneuvers that can
be performed to alleviate some of these. Make
sure there is an adequate sized skin incision for
the sheath. If the artery is scarred, consider dilat-
ing the hole to one size larger than the intended
sheath (e.g., use an 8-Fr dilator for a 6-Fr sheath).
Sometimes, with severe tortuosity of calcication
it is useful to use a “sheath-within-a-sheath”. In
this setting a larger sheath is placed to mitigate one
or more of these points of friction, as described.
e treatment sheath is placed through the rst
sheath. To place a “sheath-within-a-sheath”, the
larger sheath must be 2 French sizes larger. For
example, a 5-Fr sheath ts within a 7-Fr sheath.
Another important adjunctive technique that is
useful for dicult sheath placement is the use of
“telescoping” or gradual stiening of the access
system to allow it to pass through dicult ter-
rain, such as over a hostile aortic bifurcation. Some
examples of this are provided in sections below.
WHEN TO AVOID USING YOUR
INITIAL ACCESS SITE FOR THERAPY
ere are several situations in which the opera-
tor may consider that the initial access site should
be used for arteriography only and should not be
used for therapy. As described in Chapter2, if the
puncture site turns out to be suboptimal, includ-
ing being in a particularly calcied area or near a
signicant lesion in the access artery or near a ste-
nosis either just proximal or distal to the access site,
this situation is a setup for puncture site throm-
bosis if the larger sheath is placed. is holds true
at the puncture site itself, where ow around the
sheath and through the nearby lesion may be poor.
It also holds true in areas distal to where the sheet
has created an obstruction. It is rare, but possible,
for a patient to develop ischemic rest pain distal to
an obstructive sheath. Another situation where the
operator may decide not to use the access site for
therapy is when the pathway from the puncture
site or access site to the target lesion is more hos-
tile than anticipated. Another situation where an
initial access may be abandoned is when it turns
out that the initial approach selected is not ideal in
terms of directionality. An example of this is with
iliac artery occlusions, which may be approached
from the ipsilateral or contralateral femoral, or
from a proximal approach. e location of the iliac
occlusion and the appearance of the leading edge
of the lesion will aect the approach. Another situ-
ation where the initial access site may not be used
for therapy is when an up-and-over approach is
chosen for contralateral inguinal intervention and
it turns out that the devices are not long enough
or the disease is more complex or more distal than
anticipated. If it turns out that the patient needs
extensive tibial treatment, it may make more sense
to use an ipsilateral antegrade femoral approach.
ere are also situations in this category of remote
access where certain devices will reach the target,
for example a balloon catheter, but perhaps a stent
delivery catheter may not reach. e operator then
has to decide how best to proceed.
WHEN DO YOU USE A GUIDING
SHEATH VERSUS A GUIDING
CATHETER?
Whenever endovascular therapy is required to
treat a side branch lesion, a guiding sheath or guid-
ing catheter helps deliver the devices, maintains
access, and permits interval arteriography. As more
treatment is being rendered to major side branches,
such as the subclavian, carotid, and renal arter-
ies, guiding sheaths have advanced signicantly
https://t.me/med1917
156 Access for endovascular therapy
and have become an important adjunct in treat-
ment. A guiding sheath is designed for placement
in a major branch vessel origin (Figure 14.4). Like
other sheaths, there is a dilator for use during
placement, a side arm port, and a hemostatic valve.
e shape of the tip reects its intended function.
In Figure14.4, the long (90-cm), straight sheath
with a exible tip may be used for brachiocephalic
arteries. e 40-cm up-and-over sheath with
the nearly semicircular curve of the tip is used to
go up the iliac artery, over the aortic bifurcation,
and down the contralateral iliac artery. e 45-cm
sheath with various curved tip congurations is
used for renal artery balloon angioplasty and stent
placement. e tip of the sheath has a radiopaque
marker. e length of dilator that extends beyond
the sheath is usually short to reect its intended
passage into a side branch that may contain a lesion.
e guiding catheter has a specially designed tip
shape so that it can be used to enter a renal artery,
a carotid artery, or a visceral artery and func-
tion as a guiding sheath. Guiding catheters oer
many more shapes and sizes than are available
with guiding sheaths, but there are some signi-
cant disadvantages. Guiding catheters do not have
a dilator or obturator to facilitate smooth passage.
To compensate for this, they are usually introduced
through the so tissue and into the artery through
a standard hemostatic access sheath. is gener-
ally means that the arteriotomy is slightly larger
than would otherwise be necessary. Aer passage
into the artery, they oen require another device,
such as a selective catheter, to act as an obturator
for passage into the desired side branch location.
ere is no end valve for hemostasis. A Tuohy-
Borst adaptor or other hemostatic valve must be
used to make a guiding catheter hemostatic and
allow it to be ushed. It is likely that when a broad
array of guiding sheaths become available, guid-
ing catheters will be used only rarely for noncoro-
nary indications. Nevertheless, if a certain shape
is required to guide passage and it is not available
with a guiding sheath, a guiding catheter should
be used.
In later chapters on balloon angioplast y and stent
placement in various vascular beds, the placement
of guiding sheaths is described when indicated.
Ingeneral, placement of guiding sheaths is carried
out as follows. Flush aortography is performed.
A selective catheter and steerable guidewire are
used to cannulate the side branch of interest. e
catheter is advanced as far into the branch as is
deemed safe. e selective guidewire is removed
and exchanged for an exchange guidewire. e
exchange guidewire becomes the rail over which
the treatment is delivered. e arterial entry site is
dilated, usually to the same size arteriotomy as will
be required by the sheath, and the selective sheath
is advanced over the exchange guidewire. Aer the
tip of the sheath is in the side branch, the dilator is
removed, arter iography is performed, and therapy is
initiated. Care must be taken to avoid inadvertently
A B C
Fig. 14.4 Guiding sheaths. Special shapes and sizes have simplified access and provide more
reliability. (A) A long straight sheath with a flexible shaft and a radiopaque tip can be used for
brachiocephalic balloon angioplasty and stenting. (B) The up-and-over guiding sheath has a curve
for passage over the aortic bifurcation. (C)An angled guiding sheath may be used for renal artery
interventions or interventions in a variety of branches.
https://t.me/med1917
When do you use a guiding sheath versus a guiding catheter? 157
advancing the dilator across the lesion. Because of
this, it is occasionally useful in the nal stages of
guiding sheath placement to hold the dilator steady
and advance the sheath over the dilator for its last
few centimeters. An up-and-over sheath and a
Flexor
®
Raabe Guiding Sheath are good examples
of frequently used guiding sheaths. ese are useful
for contralateral iliac or infrainguinal intervention.
ey maintain hemostatic access at the femoral
artery, promote and maintain guidewire access
across the lesion, permit interval arteriography, and
enhance the ability to evaluate the runo bed. e
technique of placement of the sheath over the aor-
tic bifurcation is described in Figure 14.5. Tips for
managing the very dicult aortic bifurcation are
presented in Chapter 24.
A
B C
D
G
E F
Fig. 14.5 Placement of an up-and-over sheath. (A) A guidewire and catheter are passed over the aor-
tic bifurcation (see Chapter 6, F i gur e 6 .10). (B) The catheter is advanced into the contralateral femoral
level. (C) An exchange guidewire is placed and the catheter removed. (D) The arteriotomy is dilated,
if this has not already been done. The up-and-over sheath is oriented with the tip directed toward the
contralateral side and the side arm of the sheath is directed toward the ipsilateral side. (E) The sheath
is advanced over the guidewire. The dilator and the tip of the sheath are observed as they pass over
the aortic bifurcation. A slight back-and-forth rotating motion along the shaft of the sheath is some-
times helpful during passage. (F) The sheath is advanced to its hub. If resistance is met, check to see
that the guidewire is advanced far enough so that there is plenty of stiff guidewire to support the
advancing sheath. The tip of the sheath may be placed anywhere from the mid-iliac to the proximal
femoral level to be functional. The more complex the lesion, the more useful it is to have the tip of the
sheath close to the lesion. If the sheath is not advanced to its hub and some length of it is left outside
the access site, the extra length must be taken into account when guidewire and catheter length are
considered. (G) The dilator is removed and the sheath is ready for use.
https://t.me/med1917
158 Access for endovascular therapy
HOW DO YOU KNOW IF THE
SHEATH IS FOLLOWING THE
EXCHANGE WIRE?
e typical sheath placement for endovascular
therapy is by placing a sti exchange guidewire
and the sheath being advanced over this wire,
using it as a rail. If the sheath is not following
the exchange wire, the operator needs to detect
that right away before damage is done. If there
is a high degree of concern, the sheath can be
observed with continuous uoroscopy during
advancement. If the sheath is not following the
wire, the patient may have pain in the groin or the
ank. If there is signicant resistance to the pas-
sage of the sheath and then it suddenly gives way,
one has to be concerned about the potential for
arterial rupture. Most of the time it is impossible
to know if the sheath is following the exchange
guidewire unless uoroscopy is used to observe
the advancement of the sheath. If the sheath goes
into the subcutaneous tissue, it can form a loop in
the tissue if the patient has a large enough pan-
nus. erefore, use a wire that is sti enough that
the sheath will follow through the subcutaneous
tissue. Guide the sheath into the artery by manip-
ulating the access site by hand. If you observe the
tip of the wire uoroscopically and see that the
wire starts to move back in the artery, it means
that the sheath is taking a dierent path. If you
observe the sheath tip and advance the sheath
but do not see a commensurate advancement of
the tip, it means that the sheath is bowing in one
place or another along the path.
Technique: How to place an up-and-
over sheath
1. A starting guidewire is placed in the aorta
through a retrograde femoral puncture. Ahook-
shaped catheter, such as an Omni
®
Flush, is
placed just above the aortic bifurcation and a
Glidewire
®
advanced antegrade into the con-
tralateral iliac system. Selective catheterization
of the aortic bifurcation is described in detail in
Chapter 9.
2. Aer the guidewire is advanced into the
femoral artery, the hook-shaped catheter is
advanced to the distal external iliac or proxi-
mal femoral artery.
3. A stier guidewire for exchange is placed,
such as an Amplatz Super Sti
®
guidewire or a
Supra Core guidewire.
4. e catheter is removed and the entry site
enlarged with arterial dilators. e up-and-
over sheath is advanced over the exchange
guidewire. e radiopaque tip of the sheath
can be followed with uoroscopy to evaluate
progress over the bifurcation. e side arm of
the sheath is oriented opposite the curvature
inthe sheath tip.
5. e sheath is advanced to its hub if it will go,
but if signicant resistance occurs, the sheath
tip can be parked anywhere in the contralat-
eral iliac system.
6. e dilator is removed and the sheath aspi-
rated and ushed.
Strategy: Managing a brachial
access site
1. Consider using ultrasound guidance and a
micropuncture needle for entry.
2. Because the brachial artery tends to spasm,
consider placing the full-size sheath needed for
treatment early in the course of the procedure.
3. Administer systemic heparin early in the case.
4. Monitor the pulse at the wrist and the appear-
ance of the hand to have ongoing assessment
of upper extremity perfusion distal to the
puncture site.
5. Keep the hand wrapped or covered to prevent
distal vasospasm.
6. Use small doses of nitroglycerine (50–100 μg)
into the brachial artery prior to sheath place-
ment for distal vasodilation.
7. Flush with heparinized saline in between all
catheter exchanges.
8. Use dilators when establishing access.
9. A 7-Fr sheath can usually be accommodated
with a percutaneous approach. e brachial
artery size can be assessed with ultrasound at
the beginning of the procedure.
10. e distance to the arch is 40–55 cm and cath-
eter lengths must take that into account.
11. If the subclavian and axillary arteries are
redundant, these can be stretched out a bit and
the path made smoother by bringing the hand
closer to the patient’s side, instead of having it
fully abducted.
https://t.me/med1917
Sheath placement in remote branch arteries 159
USES FOR UPPER EXTREMITY
ACCESS
Upper extremity access, including through the
radial, brachial, or axillary artery, may be useful for
cannulating an aortic branch a rtery with downgoing
projection, such as a superior mesenteric artery or
a downgoing renal artery. Arteriography or ther-
apy of the branches of the aorta through the upper
extremity may be performed if the femoral arteries
are hostile to puncture. Upper extremity access pro-
vides an alternative when trying to cross an occlu-
sion from the proximal direction in the aorta or iliac
arteries. Upper extremity access may be preferred in
some subclavian artery treatments. Axillary artery
access is also very helpful in situations of gra
placement when there is a complex aortic aneurysm
treatment with multiple branch gras.
SHEATH PLACEMENT IN REMOTE
BRANCH ARTERIES
Sheath access is possible and can be done safely
in any vascular bed in the body. However, for
remote branch arteries such as the carotid or tibial
arteries, multiple well-planned steps are required
to avoid injury. Some of these steps are reviewed
in the example in Figure 14.6 of a carotid access
sheath placement. Many of the fundamentals
reviewed in earlier chapters come in handy in
such an endeavor. Skill at handling guidewires
and catheters and an ability to perform complex
selective catheterization is required to get into the
carotid artery. Emboli and microbubbles must be
avoided with meticulous technique. Knowledge of
carotid anatomy and imaging permits the bifurca-
tion to be opened up so that the external carotid
artery can be safely accessed. A sti exchange
guidewire is placed in a safe location, based on the
operator’s clinical sense of what the anatomy can
handle, depending on conguration, tortuosity,
calcication, and ectopic atherosclerotic disease
present along the pathway. e sheath is selected
with the reconstruction in mind and placed at
the appropriate location to create a platform for a
smooth procedure.
When a sheath is being placed for therapy,
the operator’s challenge is to achieve a stable
sheath position so that the platform is sturdy
enough from which to work. One way to do this
in challenging situations is to use a buddy wire to
stabilize the sheath. Examples of this are shown in
Figure14.7. In these examples the sheath can be
placed, but once it is in place it is too unstable to
use as a platform from which to perform therapy.
Ifthesheath is upsized by one or two French sizes,
the buddy wire may be placed so that the wire
is in an alternative vessel and helps to hold the
sheath steady during treatment of the target lesion.
A
B C
D
E
Fig. 14.6 Placement of a carotid sheath.
(A)Astandard femoral access sheath is placed.
Aselective catheter is used to catheterize the left
common carotid artery. (B) The image intensifier
is rotated to provide the best view that shows the
bifurcation and the external carotid artery is road
mapped. (C) The steerable guidewire is advanced
into the external carotid artery and the selective
catheter is advanced over it. The exchange
guidewire is placed. (D) The catheter is removed,
leaving the exchange guidewire. (E) The sheath is
advanced over the exchange guidewire.
https://t.me/med1917
160 Access for endovascular therapy
is isusually thecasewhen the lesion for treat-
ment is near the origin of a branch artery with a
signicant angle. Another possibility is when the
operator is attempting to recanalize an occlusion,
such as an external iliac artery occlusion, from the
proximal end and the common iliac artery is too
short for stable positioning and pushability. It may
take signicant force to get through an occlusion.
Technique: Tips for difficult sheath
placement
1. Use dilators at the access site to remove as
much friction as possible from the actual site
of arterial entry. If it is a hostile entry site
(e.g.,calcied, scarred, redo), use one size
larger dilator than usual.
2. Use a stier wire: Supra Core, Amplatz Super
Sti
®
, or even Lunderquist
®
Extra Sti.
3. Use the telescoping technique with gradual sti-
ening of the treatment platform (Figure 14.8).
4. Advance a long but small caliber balloon ahead
of the sheath (e.g., 3 mm × 80 mm) and use it
as a dilator. In this scenario, the balloon is in
the tip of the sheath but is placed mostly ahead
of the sheath. e balloon is inated to low
pressure. As the balloon is being deated, the
sheath is advanced over the deating balloon
(Figure 14.9).
5. Inow disease, even moderate stenosis, may be
treated to help decrease points of friction on
the access.
6. Do not advance the sheath as far as originally
planned. If it is extremely dicult to advance,
it may also be dicult to remove. When the
A B
C
D
Fig. 14.8 Using the telescope technique fordiffi-
cult up-and-over sheath placement. (A) Theusual
scenario is that a stiff exchange wire is placed
over the bifurcation and the sheath is placed over
it. Occasionally, when the bifurcation is quite
high and/or narrow, the sheath will not follow the
stiff wire. (B) Advance the stiff wire more distally
in the contralateral lower extremity. (C) Advance
the sheath as far as the system will allow.
Advance a long dilator through the sheath and
over the wire. Use a dilator that is longer than
the one that comes with the sheath intended
for placement. For example, when placing a
45-cm length sheath, use a 65–70-cm length
dilator. (D) Advance the sheath over the dilator
while holding the dilator in the wire steady.
Arotating motion back-and-forth helps during
advancement. Caution: sheaths that are difficult
to insert may also be difficult to remove.
A B
Fig. 14.7 Use of a buddy wire to stabilize a
sheath. (A) An external iliac artery occlusion
requires treatment. The common iliac artery
is too short, so that when forward pressure is
exerted to cross the occlusion, the sheath tends
to back up. In this case a buddy wire has been
placed in the internal iliac artery to stabilize
the sheath. (B) An internal iliac artery aneurysm
requires embolization. The sheath is unstable in
the common iliac artery. A buddy wire is placed
in the external iliac artery to stabilize the sheath.
https://t.me/med1917
Sheath placement in remote branch arteries 161
sheath tip is farther from the target than desired,
it means more contrast will be required and
the platform may not be as secure as desired.
However, treatment can usually proceed.
7. When removing the sheath, if it really
stretches, it may break. Advance a balloon,
3or 4 mm in diameter, to the tip of the sheath.
Inate the balloon with the tip of the balloon
sticking out the end of the sheath to create a
bulge beyond the sheath prole. Withdraw the
balloon with the sheath.
8. Do not enlarge the skin access site with a
#11blade aer the sheath is in place because
the sheath itself is delicate and thin-walled and
may be cut by the blade tip. If this happens, the
sheath will need to be replaced.
Strategy: Sheath-related trouble
shooting
1. If the wire or catheter will not pass through
the sheath aer it is in place, it means that the
sheath itself has kinked. is may occur at the
aortic bifurcation or other tight turn.
2. If there is no backbleeding from the sheath,
it could mean that the tip of the sheath is up
against the wall. However, it usually means
that thrombus has accumulated within the
sheath. Pull the sheath back and aspirate.
Ifthere is no aspiration, do not ush the sheath
as it may have lled with thrombus. Evaluate
the anticoagulation status. Replace the sheath.
3. When using a monorail device, the wire and
the catheter are both traversing the hemostatic
valve. If you aspirate too aggressively, this will
entrain air through the valve. Be careful when
doing this and be sure to purge the air from the
valve. is is especially important for carotid
cases.
4. If bleeding occurs from around the sheath,
you have to think about whether the artery is
injured. You can hold pressure at the site of
the access or you can put a purse-string suture
around it or, if none of these work, upsize the
sheath.
5. If you have a situation where the tip of the
sheath keeps popping out of its intended loca-
tion, use a buddy wire (see Figure 14.7).
6. If the patient has unexpected pain dur-
ing sheath placement, an injury may have
occurred.
7. When advancing the sheath, watch the guide-
wire tip. If the wire starts to back up, it means
that the sheath is going in the wrong direction.
A
C
B
D
Fig. 14.9 Option for difficult sheath place-
ment: advancing the sheath incrementally over
small caliber balloon. (A) Sheath advancement
stalls despite best efforts. (B) Remove dila-
tor. Advance a 3- or 4-mm diameter × 80-mm
length 0.035-inch compatible balloon with a
5-Fr catheter shaft. Advance the balloon so that
most of it is beyond the tip of the sheath but
the back end is within the sheath. (C) Inflate the
balloon gently and to a low pressure. (D) As the
balloon is deflated the sheath is advanced over
the balloon. If necessary, the balloon catheter
can also be withdrawn a bit as the sheath is
advanced. The process is repeated. This usually
permits a few centimeters of advancement with
each balloon deflation, but can be used to get
past a fixed point of friction.
https://t.me/med1917
https://t.me/med1917
163
15
Setting up the therapeutic maneuver:
Crossing lesions
INTRODUCTION
ere are only two reasons to cross an occlusive arte-
rial lesion. e rst is to set up a therapeutic interven-
tion. e second reason to cross a lesion is because
this may be the best option for evaluating that lesion
(i.e., by measuring pressure) and the surrounding
vasculature (e.g., no other reasonable route to per-
form arteriography). Guidewire advancement is per-
formed deliberately but gently. In this chapter, these
principles are applied in concept and practice to the
management of arterial occlusive disease. e ide-
ally placed guidewire will “dance” across the lesion.
Negotiating guidewire passage across a reluctant
arterial segment oers a sense of accomplishment.
In general, a comprehensive approach with a
multistep plan has the highest chance of success. If
treatment of the lesion is intended, place the guid-
ing sheath early and use it as a platform to launch
the chosen catheter and guidewire. Waiting until
the lesion is crossed before placing the sheath is the
hard way to do it. Access for intervention is cov-
ered in detail in Chapter 14. Assess ow conditions
proximal and distal to the lesion to avoid stagnant
ow and the risk of thrombus formation. Choose
the puncture site with the likely treatment in mind
and estimate the distance between the access site
and the target lesion to give yourself every advan-
tage possible before attempting to cross the lesion.
THREE TYPES OF LESIONS
e challenge to any endovascular operator is posed
by the lesions that are encountered. ere are three
general types of lesions facing every endovascular
specialist: (1) lesions that the guidewire sails across
easily; (2) lesions that require multiple tricks to get
across; and (3) lesions that seem impossible, almost
no matter what is done (Figure 15.1). Although
this is an oversimplication, categorizing lesions as
such may help shorten the learning curve by focus-
ing attention on the dicult ones and what needs
to be done to get across them. Lesions included in
each of these categories may vary depending on the
A B C
Fig. 15.1 The three types of lesions.
(A)A guidewire may pass easily across a lesion,
sometimes even one that looks quite complicated.
(B)Alesion may require multiple guidewire–
catheter maneuvers to traverse it. (C) Some lesions
appear to be impossible. The more experience one
has gathered with a variety of crossing techniques,
the smaller this third category becomes.
https://t.me/med1917
Соседние файлы в папке Библиотека им академика М.И. Перельмана