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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3892_Библиотеки_им_академика_М_И_Перельмана
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60
What are the parts of
a Tuohy-Borst rotating
hemostatic valve?
A rotating Luer-lock male connector
tip, an angled female Luer-lock
connection for continuous flush, and
a valve which allows placement of
additional catheters or wires while
preventing backflow of saline flush or
blood
If an air embolus
is suspected in a
patient with a rotating
hemostatic valve and
saline flush, what can be
done to prevent further
embolization?
Stop the flush immediately to prevent
additional forward flow of fluid and air
emboli. Open the rotating hemostatic
valve and allow backflow of the blood
and air embolus. Immediately place
the patient left side down or head
down. Air emboli will float to the least
dependent position. The Trendelenburg
position keeps a left-ventricular air
embolus away from the coronary
artery ostia to prevent the occlusion
of coronary arteries. Left lateral
decubitus positioning helps to trap air
emboli in the nondependent segment
of the right ventricle to prevent
flowing into the pulmonary arteries.
The left lateral decubitus position may
also prevent air emboli from passing
through a patent foramen ovale
into the left ventricle where it could
embolize to distal arteries, including
intracranial arteries.
When utilizing a coaxial
catheter combination
with an outer guiding
catheter and smaller
inner catheter/
microcatheter, why
is it recommended to
connect an extra flush
system to the outer
guiding catheter?
Avoid thrombus from forming between
the outer catheter and inner catheter
M. C. Taon
https://t.me/med1917
61
When deploying a
detachable coil, why
is it important to
advance the long plastic
introducer completely
into the catheter hub
before advancing the
coil?
To prevent the coil from deploying
within the hub of the catheter
What is a problem
that oil-based contrast
agents such as Ethiodol
(Lipiodol) can cause
when using connectors,
catheter hubs, syringes,
or three-way stopcocks
made of soft plastics?
Oil-based contrast agents such as
Ethiodol (Lipiodol) can dissolve or
crack certain types of plastics and
rubber stoppers. Materials made of
polycarbonate are more susceptible
to damage by Ethiodol. Metal, glass,
polypropylene, polyamide, and
polysulfone materials provide more
durable connections when using oil-
based contrast agents.
When preparing a
heparinized saline
flush bag and tubing,
what is one of the most
important steps?
Clear air from the bag and tubing prior
to procedure to prevent air embolus.
What kind of tubing
should be used with
power injection pumps?
Noncompliant pressure tubing. These
are designed for high pressures
and high flow rates. Low-pressure
connection tubing is more compliant
and may burst if used with a power
injector.
13 Connectors
https://t.me/med1917
63© Springer Nature Switzerland AG 2022
R. Chand et al. (eds.), Essential Interventional Radiology
Review, https://doi.org/10.1007/978-3-030-84172-0_14
How is an
angioplasty
balloon
prepped?
Method 1: Attach a 50-mL syringe filled with
one-half (or one-third dilute contrast to the
angioplasty balloon hub). Aspirate the syringe
to create a vacuum. Upon release of the syringe
plunger, contrast will replace the air within the
balloon lumen. Repeat several times to maximize
air reduction. Lastly, replace the syringe with an
inflation device containing the same contrast
dilution, via a wet-to-wet connection.
Method 2: A balloon can also be prepped using
a three-way stopcock. Attach an inflation device
containing dilute contrast to a three-way stopcock,
and open the stopcock to aspirate the balloon
lumen. The resulting vacuum draws contrast
from the inflation device into the balloon lumen,
replacing the air within the balloon lumen. Rotate
the stopcock to the open port and expel excess
air from the inflation device. Repeat this process
several times to maximize air reduction. Air within
the balloon lumen must be completely replaced
with contrast to ensure that the entire balloon
lumen can be visualized. Air bubbles can obscure
the image and hide a stenosis.
Chapter 14
Balloons
MatthewCzarTaon
M. C. Taon (*)
Kaiser Permanente Los Angeles Medical Center,
Los Angeles, CA, USA
(continued)
https://t.me/med1917
64
What is the
nominal
pressure?
Nominal pressure is the amount of pressure,
in atmospheres (atms), required to inflate the
balloon to its labeled diameter.
What is the
rated burst
pressure?
The pressure level, in atmospheres (atms), a
balloon can expand to without rupture. The rated
burst pressure is based invitro testing. Generally,
at least 99.9% of the balloons (with 95%
confidence) will not burst at or below their rated
burst pressure.
What is the
working range
of a balloon
catheter?
Working range is the inflation range between
nominal and rated burst pressure.
What is the
working length
of a balloon
catheter?
The surface of the balloon that contacts the vessel
wall when inflated
What is the
mechanism
of plain
old balloon
angioplasty
(POBA) to
treat an arterial
atherosclerotic
stenosis?
Plaque fracture, vessel stretching, and lumen
expansion. Essentially, plain balloon angioplasty
creates controlled vessel wall ripping of the intima
and some of media.
What are the
types of wall
stresses
involved
with balloon
angioplasty?
Torsional stress, radial stress, and longitudinal
stress. Torsional stress is imparted on the vessel
wall through a twisting motion when a balloon
unfolds during inflation. Radial stress is imparted
outwardly on the vessel wall as a balloon unfolds.
Longitudinal stress elongates the vessel wall
during balloon inflation.
M. C. Taon
https://t.me/med1917
65
What is the
relationship
between vessel
injury and the
rate of vessel
wall stretching?
There is a direct relationship between vessel injury
and the rate at which the vessel wall is stretched.
Slow, low- pressure inflations tend to minimize
trauma.
What are the
two
components
of a drug-
coated
balloon
matrix
coating?
Antiproliferative drug and drug-
transferring
excipient. Antiproliferative drugs include
paclitaxel and sirolimus which reduce in-stent
restenosis. Excipients, such as urea and shellac,
are polymers that create a matrix which functions
to both retain the drug on the balloon surface
and transfer it to the vascular endothelium. The
molecular characteristics of the excipient influence
the adhesion and diffusion of drugs into the
vascular endothelium.
What are the
complications
associated
with balloon
angioplasty?
Flow-limiting dissection, vessel rupture, elastic
recoil, and restenosis
14 Balloons
https://t.me/med1917
67© Springer Nature Switzerland AG 2022
R. Chand et al. (eds.), Essential Interventional Radiology
Review, https://doi.org/10.1007/978-3-030-84172-0_15
What
characteristics
differentiate a
balloon-expandable
stent from a self-
expanding stent?
Balloon-expandable stents demonstrate
increased radial strength and more
predictable placement but are generally
less flexible compared to self-expanding
stents. Balloon-expandable stents are not
recommended at flexion points due to risk
of stent collapse. Self-expanding stents are
highly flexible, can be placed at flexion
points due to their ability to re-expand,
but have a less predictable deployment
compared to balloon-expandable stents.
Additional balloon angioplasty may be
performed after a self-expandable stent
is deployed to obtain better vessel wall
apposition.
Chapter 15
Stents
MatthewCzarTaon
M. C. Taon (*)
Kaiser Permanente Los Angeles Medical Center,
Los Angeles, CA, USA
(continued)
https://t.me/med1917
68
What
characteristics
differentiate a
covered stent from
a non-covered
stent?
A covered stent (stent graft) is a metal stent
lined with polytetrafluoroethylene (PTFE)
or Dacron. They can be available in self-
expanding or balloon-expandable platforms.
Generally, covered stents require a larger
sheath size compared to non-covered stents.
Covered stents can completely exclude
plaque and thrombus.
How does
intravascular
ultrasound
(IVUS) compare
to contrast
angiography in
terms of sizing
vessel diameters?
IVUS is superior to angiography for sizing
vessel diameters since it provides a two-
dimensional axial view of the vessel lumen
and vessel wall. In addition to sizing, IVUS
can offer much valuable information,
including plaque characterization, whether
or not atherectomy should be performed
prior to balloon angioplasty or stent
placement, and after stent deployment to
assess for appropriate wall apposition and
plaque coverage.
In failing dialysis-
access grafts, how
does the use of
covered stent grafts
compare to balloon
angioplasty in
terms of patency?
Use of a stent graft is associated with
longer patency and freedom from repeat
interventions compared to standard balloon
angioplasty.
What is the
mechanism of
action of drug-
eluting stents to
treat peripheral
arterial disease?
Drug-eluting stents work mechanically
to treat elastic recoil and dissection and
molecularly via the antiproliferative drug,
paclitaxel, to mitigate peripheral arterial
disease progression, injury response, foreign
body reaction, and in-stent restenosis.
M. C. Taon
https://t.me/med1917
69
What are the
factors that can
make venous
stenting more
challenging?
Venous vessel walls are very thin.
Veins are inherently compressible.
Venous flow is much slower than arterial
flow.
Veins contain valves.
No accurate noninvasive or invasive test
is available to evaluate the hemodynamic
significance of venous outflow obstruction.
The degree of venous stenosis that is
hemodynamically critical is unknown.
15 Stents
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71© Springer Nature Switzerland AG 2022
R. Chand et al. (eds.), Essential Interventional Radiology
Review, https://doi.org/10.1007/978-3-030-84172-0_16
What are the two general
classifications of embolic
agents?
Temporary agents which include
autologous blood clot and
Gelfoam. Permanent agents
which include coils and vascular
plugs, particulates, and liquid
(alcohol, sodium tetradecyl sulfate
(Sotradecol), cyanoacrylate, and
ethylene vinyl alcohol (Onyx)).
What are the three important
aspects to evaluate when
choosing an appropriate
embolic agent?
Assess the size of the vessel/
vascular bed to be embolized.
Determine whether the goal
is temporary or permanent
occlusion. Determine whether the
embolized tissue should remain
viable after embolization.
Chapter 16
Embolization
MatthewCzarTaon
M. C. Taon (*)
Kaiser Permanente Los Angeles Medical Center,
Los Angeles, CA, USA
(continued)
https://t.me/med1917
72
Prior to administering NBCA
(n-butyl-2-cyanoacrylate)
glue for embolization, what
solution should be flushed
through the microcatheter
to prevent the glue from
prematurely solidifying
upon contact with an ionic
solution?
5% dextrose solution. This
nonionic solution is used instead
of an ionic saline flush to prevent
polymerization of the NBCA
mixture on contact with residual
blood or saline in the catheter
tip. Furthermore, injecting
dextrose creates a local nonionic
environment at the catheter tip
which enables more distal NBCA
progression.
Prior to administering
ethylene vinyl alcohol
(Onyx) for embolization,
what solvent should be
flushed through the catheter
to prevent precipitation
within the lumen of the
microcatheter?
Dimethyl sulfoxide (DMSO).
Onyx is an ethylene vinyl alcohol
copolymer dissolved in the
organic solvent dimethyl sulfoxide
(DMSO) opacified with tantalum
powder. Once it comes into
contact with an ionic solution,
such as blood, the DMSO
dissipates and the Onyx solidifies
into a spongy, cohesive embolic
material.
Prior to preparing a catheter
with DMSO, what aspect
of the catheter should be
verified?
The microcatheter must be
DMSO compatible. DMSO
can break down many plastic
materials.
What is the relationship
between embolic agent size
and likelihood of organ
ischemia?
In general, the smaller the embolic
agent, the greater the likelihood
of organ ischemia. Smaller
embolic agents are able to flow
more distally into arterioles and
capillary beds, thereby increasing
risk of necrosis. The larger the
particle size, the less likely the risk
of ischemia given the presence of
collateral arterial flow.
M. C. Taon
https://t.me/med1917
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