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
134 Arteriography of the vascular beds
10. Filming error. If opacication of the vascu-
lature is inadequate, there may have been a
poor estimation of timing (ow), inadequate
pressure or volume of contrast injection, or
too much delay in lming. Determine that
contrast was actually administered.
11. Patent “occlusion.” If lling is very slow and
lming is not extended adequately, patent
arterial segments may appear to be occluded.
is occurs commonly in the SFA distal to an
occlusion, especially when using cut lm.
12. Viable foot/no outow. If a foot is viable, but
there is no outow target vessel, pedal arteri-
ography may have been inadequate.
13. Short-necked aneurysm. If the AP aortic
view makes an aneurysm neck appear short
(the aorta oen turns anteriorly distal to the
renal arteries), locate the neck on the video
images as the place where the contrast column
“stops.” e contrast bolus dilutes with swirl-
ing blood in the aneurysmal sac. Obtain a
cranial or caudal view, with some degree of
rotation to “unfold” the tortuous artery and
provide additional detail.
14. Urinary contrast. Excreted contrast mixed
with the uid contents of the ureter are in
motion and can be misinterpreted as arterial
rupture, slow ow, dissection, or other abnor-
malities. Contrast in the bladder obscures the
images of nearby structures, especially with
oblique views of the pelvis.
15. Lesions dicult to characterize. Shelf-like
lesions and those associated with severe
calcication can be dicult to assess. Also, a
lesion in a low-ow distal runo bed can be
dicult to illuminate, especially if there is a
more proximal lesion that is reducing ow to
the area.
LESION INTERROGATION:
SPECIALVIEWS
e aortic arch is demonstrated en face when an
LAO projection is used (see Chapter 9, Figure9.1).
is helps to separate the origins of the arch
branches. If an area of expected critical stenosis
appears only mildly diseased, additional inter-
rogation, such as oblique views, should be con-
sidered. e degree of stenosis at the carotid
bifurcation and proximal internal carotid artery is
best evaluated with lateral or steep oblique views.
During arch aortography, the patient should turn
the head 20–30 degrees to the right. is maneuver
helps to separate the carotid and vertebral arteries.
e innominate artery bifurcation into proximal
right common carotid and right subclavian is best
viewed in an RAO projection. e vertebral artery
usually has its origin from the posterior wall of
the subclavian artery. erefore, to view the proxi-
mal vertebral artery, which oen harbors oricial
stenosis, the image intensier is placed into a
slight craniocaudal position, and may require
some angulation as well.
e celiac artery, superior mesenteric artery,
and paravisceral aorta require lateral views to
evaluate branch artery orice lesions and posterior
wall aortic plaque or aneurysm. e origins of the
renal arteries are best evaluated with a slight ipsi-
lateral anterior oblique (Figure 11.4).
Disease at the iliac and femoral bifurcations
oen requires visualization with oblique views
(Figure 11.8). e common iliac bifurcation and
posterior wall external iliac disease are best delin-
eated using a contralateral anterior oblique pro-
jection. e common femoral bifurcation and
common femoral artery posterior wall are inves-
tigated using an ipsilateral anterior oblique projec-
tion. Occasionally, when there is a high take o of
the profunda femoris artery, with a short common
femoral artery, the profunda femoris artery exits
from the common femoral artery in a straight lat-
eral projection. is occurs more commonly in
women and is best visualized in the AP projec-
tion. Popliteal and tibioperoneal occlusive disease
is oen diuse, and an accurate assessment of
severity sometimes requires oblique views of these
arteries. e distal tibial and pedal arteries are
evaluated with a lateral projection that separates
the tibial and pedal arteries, as mentioned in a pre-
vious section (“Femoral arteriography”).
CARBON DIOXIDE ARTERIOGRAPHY
CO
2
can be administered into the vascular sys-
tem, is absorbed, and is excreted from the body
by exhalation. When renal function is severely
diminished, CO
2
is the only contrast available that
is not nephrotoxic. It has some very specic use
issues that are discussed here. CO
2
may not be used
in the brain or heart and many operators are only
comfortable using it in the infrarenal aorta and
more distally. In the brain and the heart, where
https://t.me/med1917
Carbon dioxide arteriography 135
there is a moment-to-moment dependence on per-
fusion, the passage of gas through the arteriolar
bed will temporarily diminish end organ ow and
cause ischemic events. In the intestinal arteries,
the risk is that an air lock will form that becomes
stationary and prevents forward ow. In the lower
extremities, CO
2
is very well tolerated. Special set-
tings at a high frame rate, usually six frames per
second, are required to image CO
2
. is particu-
lar contrast forms a gas cloud in the vasculature.
Itrises against gravity and therefore the patientis
placed in the Trendelenburg position when it is
administered to decrease the likelihood that it
could pass into the cerebral arteries. CO
2
must
be medical grade, the tank must be appropriately
maintained, and the CO
2
reservoir used during
the endovascular procedure must not be contami-
nated with air. CO
2
is used to ll a sterile, airtight
bag; the bag has a one-way valve so that air cannot
be entrained. e tubing is purged several times
before use and is connected to the angiographic
catheter. A small amount of CO
2
is drawn into
the syringe (about 5 cc) and slowly administered
into the catheter. is clears the catheter of uid
to avoid a sudden jet of gas-propelled saline that
could cause injury to the artery during injection.
An aortoiliac arteriogram can be acquired with
20cc of CO
2
. When the CO
2
passes through nor-
mal arteries, the ow pattern of the gas is unpre-
dictable. erefore, in postprocessing, some type
of longitudinal image stacking is usually required
to form a reasonable arteriographic representa-
tion of the system being interrogated. When the
CO
2
encounters signicant disease, the gas begins
to fragment into bubbles and this makes it very
challenging to properly evaluate severely diseased
segments. CO
2
is usually used in combination
with dilute iodinated contrast in order to make
a complete study. Between CO
2
administrations,
wait about 2 minutes for the contrast to pass. Each
time the angiographic catheter is connected to the
CO
2
reservoir, the lines must be carefully purged
of air and the catheter emptied of uid prior to a
CO
2
angiographic run.
A B
C D
Fig. 11.8 Oblique projections of the iliac and femoral bifurcations. (A) Occlusive disease at the
common iliac artery bifurcation is not clearly delineated with the standard AP projection used for
aortoiliac arteriography. The internal iliac artery usually projects posteriorly and overlaps the origin
of the external iliac artery in the AP view. (B) A contralateral anterior oblique projection permits the
iliac bifurcation to be viewed en face. (C) Occlusive disease at the femoral bifurcation is sometimes
difficult to visualize because of overlap between the proximal SFA and the deep femoral artery. The
deep femoral artery usually courses posteriorly and its origin overlaps with the origin of the SFA in the
AP view. (D) An ipsilateral anterior oblique projection allows the femoral bifurcation to “open up” so
that the proximal portions of the branches do not overlap.
https://t.me/med1917
136 Arteriography of the vascular beds
PRESSURE MEASUREMENT
Pressure measurement is time-consuming and is
usually performed selectively. However, it is the
only quantitative physiologic data that may be
yielded by the arteriographic study. Pressure mea-
surements are required only when the results will
inuence the treatment plan. is situation arises
most commonly with moderate degrees of stenosis
where the decision about whether to treat depends
on the hemodynamic signicance of the lesion.
Decisions concerning the treatment of either criti-
cal or mild degrees of stenosis can usually be made
on the basis of the images alone.
Pressure may be measured through a selective
catheter, a diagnostic catheter, or a sheath. e
transducer is placed at the level of the right atrium.
e shortest adequate extension tubing is ushed
with heparin–saline solution, zeroed, and con-
nected to the catheter hub. Blood does not come
into contact with the pressure transducer.
Pressure measurements vary from one cardiac
cycle to the next. e systolic or mean values are
observed until stable and then averaged over ve
readings. e catheter head is moved to the other
end of the lesion and the process is repeated. If the
catheter has been placed through a sheath at least
one French size larger than the catheter, the distal
pressure can be measured through the side arm of
the sheath. During measurement, pressure may
continue to uctuate. If a small gradient is pres-
ent (less than 10 mmHg systolic) or if the lesion in
question is potentially physiologically important,
papaverine (1 ampule, 30 mg) or nitroglycerine
(100 mcg) is administered through the catheter and
into the limb or end organ. Diminished periph-
eral resistance exacerbates any gradient across
the lesion and is revealed by immediately repeat-
ing the measurements. e converse is also true.
Ifthereisincreased resistance in the outow bed,
for example very poor runo, the pressure will
tend to equalize in all the artery segments proxi-
mal to that and will underestimate the true gradi-
ent across a lesion. Pitfalls associated with pressure
measurement across lesions are listed in Table11.1.
No one really knows how much of a gradient is
signicant. e catheter must be placed across
the lesion in order to do the measurement. At that
point, the added morbidity of proceeding with
treatment is minimal.
ARTERIOGRAPHY OF ANEURYSMS
Arteriography has some distinct advantages and
disadvantages with respect to the assessment
of aneurysms. Arteriography is not useful in
determining the size of an aneurysm or the con-
guration of an aneurysmal segment. However,
arteriography is a good option for evaluating
inow and outow arteries, ow surface contour,
and associated aneurysmal or occlusive disease
in juxtaposed arteries. ere is usually slow ow
and substantial mixing of the contrast bolus
withnonopacied blood. Larger contrast volumes
Table 11.1 Pitfalls associated with pressure measurements across occlusive lesions
Systemic pressure
fluctuation
Variations in systemic blood pressure during the few minutes it takes to
measure pressure influence the results of pressure measurements
proximal and distal to a lesion
Pressure in end organ
arteries
Measuring pressure in an end organ artery, such as the renal artery,
presupposes that the lesion must be crossed. The catheter used to
measure pressure must occupy a portion of the residual lumen. In a tight
stenosis, this may falsely lower the distal pressure
Poor outflow If outflow distal to a lesion is poor, pressure tends to equalize proximal and
distal to the lesion
Pressure does not equal
flow
Although pressure measurement provides hemodynamic quantitation, it
does not provide what is really required, which is a quantitative
assessment of flow across a lesion
Pressure is not
measured under
physiologic conditions
Occlusive lesions often become hemodynamically significant only with
exercise. Although vasodilators may mimic this, it is usually not an
accurate representation of physiologic conditions
https://t.me/med1917
Intravascular ultrasound 137
administered over a longer period of time are
oen used. High-pressure injection within the
aneurysm should be avoided because of the pos-
sibility of disrupting thrombus within the aneu-
rysm. e proximal neck is the location where
the contrast bolus seems to stop on the cine loop
during digital subtraction arteriography. Where
the vessel widens substantially is also where the
contrast mixing takes place and the apparent
slow ow. Contrast is administered proximal to
an aneurysm, since injecting within an aneu-
rysm may cause thrombus disruption and embo-
lization. Oblique views or special angles may be
required to fully evaluate the proximal and dis-
tal necks of the aneurysm. Evaluation of runo
distal to an aneurysm may be dicult since the
contrast bolus becomes so diluted. Additional
contrast injections may be required distal to the
aneurysm. e usual way to evaluate aneurysmal
disease involving the aorta is with CTA. is pro-
vides the ability to reconstruct the anatomy of the
vessel and surrounding tissues.
Strategy: How can duplex scanning
be used to limit the amount of
arteriography required?
1. Unilateral lower extremity ischemia and a
normal femoral pulse. Obtain femoral wave-
form and acceleration time and evaluate aor-
toiliac segments directly with duplex scanning.
If these are normal, consider unilateral femoral
arteriography without aortography.
2. Diabetic with gangrene and normal femoral
artery and popliteal artery pulses. Evaluate
aortoiliac and femoral segments with duplex
scanning. If these are normal, consider an
antegrade femoral artery approach and
infrainguinal arteriography only.
3. Diminished femoral artery pulse and no tissue
loss. Evaluate aortoiliac and femoropopliteal
segments with duplex scanning. Ifafocal iliac
artery lesion is identied and the femoropop-
liteal segment is without signicant disease,
consider proceeding to aortography and
balloon angioplasty without performing arte-
riographic runo.
4. Patient with an abdominal aortic aneurysm,
indications for arteriography, and palpable
pedal pulses. Evaluate popliteal arteries
with duplex scanning if any enlargement is
suggested on physical examination. If these are
normal, consider aortoiliac arteriography only
without runo.
5. Recurrent lower extremity symptoms aer
a previous reconstruction. Identify the ow-
limiting lesion with duplex scanning. If a focal
lesion is identied, consider either very limited
arteriography for lesion anatomy or no arteri-
ography at all.
6. SFA occlusion that requires therapy. Identify
the length of the occlusion and the location
where ow reconstitutes with duplex scanning.
If it is a short occlusion and not at the SFA
origin, consider an antegrade approach
and recanalization. If it is a long occlusion
withreconstitution above the knee, consider
SFA recanalization and stenting using CO
2
arteriography versus an above the knee femo-
ropopliteal bypass without arteriography.
7. Use noninvasive methods to evaluate the lower
extremity contralateral to the symptomatic
limb to avoid performing bilateral runo
studies.
INTRAVASCULAR ULTRASOUND
Intravascular ultrasound (IVUS) is a tool that
has been available for a long time but for which
clear indications are now being developed. An
ultrasound crystal is mounted in the tip of a
catheter and this provides information about
real-time cross-sectional anatomy (Figure 11.9).
IVUS is absolutely essential for aortic dissection
evaluation and for guiding therapy in that setting.
A B C
Fig. 11.9 Intravascular ultrasound.
(A)Postangioplasty angiographic image. (B)An
IVUS probe is advanced through a treated lesion.
(C) IVUS detects a significant dissection with
interruption of the internal elastic lamina and a
large amount of mobile tissue in the lumen of the
target site segment.
https://t.me/med1917
138 Arteriography of the vascular beds
Other situations in which arteriography is not
optimal or where IVUS can add important infor-
mation include the following: assessment of post-
angioplasty dissection and in-stent restenosis. In
these situations, IVUS information can help deter-
mine the results of treatment and assist the opera-
tor in deciding whether more therapy is required.
In smaller caliber, mobile arteries, such as the
coronary arteries, IVUS has become important in
helping decide which lesions need stent placement.
Various sized probes are available that permit
insonation of a range of diameters from the IVUS
catheter, from a few millimeters to several centi-
meters in diameter.
https://t.me/med1917
PART II
Endovascular therapy
12 Endovascular workshop 141
13 Medications for endovascular therapy 145
14 Access for endovascular therapy 149
15 Setting up the therapeutic maneuver: Crossing lesions 163
16 Crossing challenging lesions 171
17 Balloon angioplasty: Minimally invasive autologous revascularization 191
18 More about balloon angioplasty: Keeping out of trouble 205
19 Stents, covered stents, stent–grafts 223
20 Other devices and how to use them 255
https://t.me/med1917
https://t.me/med1917
141
12
Endovascular workshop
WHERE WE WORK DETERMINES
WHAT WE CAN DO
Dramatic developments in endovascular interven-
tion have prompted the common dilemma about
where the modern vascular specialist should be
working to get the best results: the operating room,
the interventional suite, or the catheterization lab-
oratory. In many institutions, endovascular oper-
ating rooms have been constructed to solve this
problem and provide superior imaging in an oper-
ating room (OR) setting. oughtful and deliber-
ate requests for expensive equipment and space are
usually required to pave the way for this change in
practice. e facility where the work is done can
either promote or hamper success. Vascular spe-
cialists must be clear about what is required to pro-
vide high-quality care. Fixing vascular problems is
already complicated without the case being placed
at a disadvantage before the procedure starts.
High-resolution imaging, endovascular inventory,
and uniquely trained personnel are all required to
deliver modern vascular care.
OPERATING ROOM VERSUS
SPECIAL PROCEDURES SUITE
VERSUS CATHETERIZATION
LABORATORY
ORs are well suited to the sterile technique of open
surgery, handling blood vessels, and implanting
prosthetic material. Hybrid procedures are facili-
tated. e protocol for sterile technique is typically
at a high level. Special procedures suites, such as
angiographic suites and cardiac catheterization
laboratories, are designed to support percutane-
ous interventions and generally have excellent
uoroscopic imaging available. Many catheter-
ization laboratories have small image intensiers
since they were usually originally designed to treat
coronary arteries. Table 12.1 compares these envi-
ronments. Special procedures suites were designed
for the purpose they are each named to undertake:
angiography in angio suites; cardiac catheteriza-
tion in cath labs. ese facilities usually have a
high volume of foot trac and oen have poor
lighting, since they are not usually designed with
Table 12.1 The operating room or the special procedures suite
Operating room Special procedures suite
Advantages Best sterile technique Best imaging quality
Handle blood vessels Broader inventory of devices
Manage bleeding Personnel trained in interventions
Implant prosthetic material Personnel trained in imaging technique
Better anesthetic capability
Disadvantages Lower imaging quality Poor sterile technique
Smaller endovascular inventory Poor environment for open surgery
Poor staff support for interventions Inadequate equipment, lighting, and staff
support
Poor anesthetic capability
https://t.me/med1917
142 Endovascular workshop
the sterility and visualization in mind required for
open surgery or hybrid procedures. ese facilities
typically have excellent imaging capability.
ORs were designed to meet the standards
required to provide therapy in terms of sterility,
quality control, planning for contingencies, man-
aging sick patients, and performing procedures
eciently. e primary advantage of special pro-
cedures suites over ORs, as they exist in most insti-
tutions, is radiographic imaging. ere is a major
trend toward recognition of high-resolution digital
arteriography as an essential component of vascu-
lar procedures of all types, including open vascular
operations. ere is some validity to the concept
that quality imaging is required in the OR, regard-
less of whether the majority of endovascular inter-
ventions are performed there. e unsatisfactory
choice of multiple suboptimal facility options is
being resolved in each institution. Eventually, most
institutions that can support modern vascular care
will develop a specic endovascular room where
this work can be carried out.
STATIONARY VERSUS PORTABLE
IMAGING SYSTEMS
Table 12.2 compares stationary and portable uo-
roscopic imaging equipment. Angiographic suites
are constructed with stationary imaging equip-
ment, including a ceiling- or oor-mounted C-arm
conguration (Figure 12.1). Endovascular suites
also typically have installed stationary equipment.
In most surgical ORs that have not been con-
verted to endovascular suites, portable C-arm
digital arteriographic imaging can be obtained
when necessary (Figure 12.2). Many oce-based
laboratories also use portable imaging equipment
since its portability makes it quite versatile.
Stationary equipment oers high resolution
and maximal C-arm mobility for multiple views.
is tends to make a given case go smoother and
faster, especially if it is a complex case. Portable,
Table 12.2 Stationary versus portable fluoroscopic imaging equipment
Stationary Portable
Advantages Better resolution Less expensive
Easy to use Can be used in different locations
Versatile positioning
Bolus chase
Best units available simulate quality of
stationary equipment resolution, road
mapping, postimage processing, and
storage
Disadvantages More expensive
Usage restricted to single location
Some units difficult to adapt to use
with open surgery
Requires room renovation
Inconvenient and cumbersome to move and
position
Resolution inferior to fixed unit
Impractical for survey arteriography
Often no dedicated personnel
Fig. 12.1 Stationary imaging system. The C-arm
may be either ceiling mounted, as in this example,
or floor mounted. Monitors are usually ceiling
mounted on booms. These systems usually have
larger generators for better image quality. A floor
mounted table on a pillar provides imaging access
to the entire body.
https://t.me/med1917
The ideal vascular workshop 143
digital arteriographic units have been developed
that produce adequate images for completing com-
plex endovascular procedures. Available features
include multiple frame rates, digital storage, road
mapping, video playback, last-image hold, postim-
age processing, and variable elds of view. e por-
table uoroscopic unit lacks the convenience of a
specially designed room. It is more cumbersome to
position and use and more setup time is required.
However, portable units are cheaper and can be
used (and therefore justied) by many dierent
services in the same institution. e most complex
procedures in endovascular intervention, such as
endovascular aortic gras, have been performed in
the OR with portable digital imaging systems and
with very acceptable results. Imaging capability
with portable systems has improved dramatically
in the past few years.
THE IDEAL VASCULAR WORKSHOP
Important components that should be included in
a vascular workshop are listed in Table 12.3. ere
are facility, equipment, and personnel require-
ments to consider.
Facility requirements
e facility should have a minimum of 750
2
. is
is a bare minimum for a functional endovascular
suite. e walls must be lead lined. e regulations
Fig. 12.2 A portable imaging system provides more flexibility and can be moved from room to room.
It consists of a portable C-arm (image intensifier and X-ray tube) and a portable monitor. These gener-
ally have a smaller generator and lower heat capacity.
Table 12.3 Components of the ideal vascular
workshop
Facility Space
Lighting
Lead-lined walls
Anesthetic gases
Air flow
Limited foot traffic
Equipment High-resolution imaging
Pressure injector
Radiographic table
Inventory
Other ultrasound (intravascular
ultrasound)
Personnel X-ray technologist
Scrub nurse or assistant (both open
and endovascular technique)
Circulating nurse
Anesthesiologist/anesthetist
https://t.me/med1917
Соседние файлы в папке Библиотека им академика М.И. Перельмана