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255
20
Other devices and how to use them
MICROCATHETERS
Microcatheters are small caliber, lengthy, exible
catheters that are compatible with small caliber
guidewires. ey may be used for strategic angi-
ography, to exchange guidewires, and to provide
support for a guidewire system in challenging
situations. Microcatheters may be used to support
crossing of chronic total occlusions (CTOs).
Microcatheters may also be used to provide ther-
apy, such as when small caliber coils are deliv-
ered or therapeutic medication is administered.
rombolytic agents may be delivered through
microcatheters, for example. Microcatheters are
generally 2.3–3.8-Fr in caliber, in comparison to
the standard 5-Fr catheter used with a 0.035-inch
system (Figure 20.1). e tip of the catheter may
be oppy or sti and may be either straight or have
angles at the tip. ese catheters may be designed
to accept a 0.10-inch, a 0.014-inch, or a 0.018-inch
diameter guidewire. ey come in lengths of 60 to
150 cm. e longer and smaller caliber the catheter
becomes, the more the guidewire–microcatheter
friction increases during wire passage through the
catheter and also during catheter passage over the
wire. Some microcatheters have radiopaque tips,
which make them more readily visible, and some
microcatheters have sti tips. Microcatheters with
sti tips may be used for crossing occlusions. e
catheter and the guidewire can be used in a hop-
scotch manner to get across an occlusion, each
providing support to the other. Microcatheters
may be used to provide support to a guidewire sys-
tem where support is inadequate due to the lack
of strength of the guidewire sha itself. e rela-
tionships of the guidewire to the surrounding
tissues may be changed signicantly by adding a
microcatheter.
Microcatheters have signicantly changed the
practice of caring for vascular patients in several
areas, including neurovascular applications and
delivery of thrombolytic medication for stroke,
and also in terms of tibial artery interventions and
crossing tibial occlusions with a microcatheter
with a sti tip. Microcatheters have also provided
a whole new dimension in terms of opportunities
A B C D
5-Fr 3-Fr
quick cross
catheter
2.3-Fr
prowler
2.5-Fr
renegade
Fig. 20.1 Microcatheters are used regularly
as an adjunct in small vessel intervention.
(A)Astandard 5-Fr angiographic catheter.
(B)A Quick-Cross™ (Support) catheter has a
stiff tip and markers and is used to push across
occlusions. (C) A Prowler
®
Select
®
microcatheter
is a soft, floppy neurovascular catheter with
an angled tip. (D) A Renegade
™
(Hi-Flo
™
)
microcatheter is a low-profile neurovascular
catheter with a straight tip and a marker.
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256 Other devices and how to use them
for wire exchange, visualization, passage of
guidewire–catheter apparatus into tortuous and
extremely remote locations, and also in terms of
options for getting out of trouble. Several of the
major companies make an array of microcatheters
and these are mostly geared toward neurovascular
applications, but their applications may be possible
throughout all of the vascular systems.
RE-ENTRY CATHETERS
Subintimal recanalization has been a true advance
in the endovascular management of occlusions.
is requires several steps including passage of
the guidewire into the subintimal space, advance-
ment along the subintimal plane, and re-entry
into the true lumen of the artery that feeds the
distal runo bed. Among these steps, re-entry
into the true lumen is the rate-limiting factor.
Re-entry catheters are used specically to assist
in re-entry into the true lumen aer a subintimal
recanalization has been performed. When per-
forming a subintimal recanalization, sometimes
the looped hydrophilic wire supported by a cath-
eter will pass spontaneously from the subintimal
space to the true lumen. ere is a tissue barrier
between the false lumen and the true lumen, and
the loop of hydrophilic wire sometimes interrupts
it. Oen, however, the looped hydrophilic wire
stays in the subintimal space. is is especially
true if the re-entry site is also diseased, calcied,
or has a measureable thickness of plaque present.
A re-entry catheter is designed to help the opera-
tor re-enter the true lumen at the desired loca-
tion by means of a hypotube style needle thrust
through the tissues, which permits passage of a
guidewire through it.
Very oen there are large collaterals near the
re-entry site, because this is also usually the site of
reconstitution of the vessel. Large collaterals that
occur at the desired location of recanalization are
useful to preserve. In addition, very oen the re-
entry site has some disease and some thickness of
the tissue between the subintimal space and the
true lumen that prevents a natural re-entry of the
wire and catheter. ere are two useful re-entry
catheters available: (1) the Outback
®
catheter
where the crossing needle is uoroscopically-
guided; and (2) the Pioneer Plus catheter, which
relies on guidance of the needle by IVUS. Both
catheters use a needle that is well secured to the
tip of the catheter, is carefully oriented toward
the true lumen using imaging, and is manually
advanced using the sharp tip of the needle to
pierce the obstructing tissue. e needle is hollow
and allows passage of a wire through the needle
and into the true lumen. is becomes the access
for the intervention and the eventual repair of the
occluded vessel.
e Outback
®
Catheter has a n “L”-shapedma rker
at the tip, which is viewed in multiple oblique
directions under uoroscopy. is helps the opera-
tor know which way the needle is pointed. e base
A
B C D
Fig. 20.2 Re-entry catheters. (A) A long SFA
occlusion is crossed in the subintimal space.
Because the wire loop was not successful at
re-entry into the true lumen, a re-entry catheter
is selected. (B) The re-entry catheter, either an
Outback
®
catheter or a Pioneer Plus catheter,
is placed in the subintimal space. (C) After
the catheter is carefully oriented so that the
re-entry needle is directed toward the true
lumen, the needle is passed. The Outback
®
catheter is fluoroscopically-guided and the
Pioneer Plus catheter is guided by IVUS. (D) After
advancement of the needle into the true lumen,
a 0.014-inch wire is advanced. The behavior of
the wire as observed under fluoroscopy usually
indicates whether the wire is in the correct
lumen. This is confirmed angiographically. The
needle is retracted and the catheter withdrawn
over the wire.
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Chronic total occlusion catheters and crossing catheters 257
of the “L” points toward the direction of the needle
throw. is is typically done under a road map-
ping view so that the contrast within the reconsti-
tuted true lumen can be visualized. e catheter
hub also allows the operator to turn or rotate the
direction of the device in increments. is turn-
ing ability is essential to get the needle point in
the correct direction toward the true lumen. Very
oen, the re-entry catheter has been passed up-
and-over the aortic bifurcation and through a long
supercial femoral artery (SFA) occlusion, which
adds friction. ese anatomic factors contribute to
a reduction in the maneuverability of the re-entry
catheter. e subintimal space at the location of
the catheter head should not be dilated, because a
small subintimal space in this location helps secure
the catheter tip so that the needle has support.
Sometimes, numerous throws of the needle are
required to reach the true lumen and permit the
wire to be passed. e operator has the ability to
adjust the throws of the needle so that they are only
as deep as appears to be necessary based on the
thickness of the tissue and the distance required.
is is done primarily by the feel of the device and
the experience of the operator.
ere are several similarities with the mech-
anism of the Pioneer Plus catheter. It is about
the same size and relies on the orientation and
manual advancement of a hypotube needle under
visualization. Advantages of the Pioneer Plus
catheter include: the distance of the throw of the
needle is adjusted through a mechanism on the
handle of the catheter; the turning of the cath-
eter with the needle toward the true lumen is per-
formed with guidance by IVUS. is makes the
two-dimensional uoroscopic image much less
important for orientation and also helps decrease
the number of throws of the needle that are typi-
cally required. Although the Pioneer Plus cath-
eter is more expensive and requires availability of
IVUS, the ability to place the needle accurately at
the selected re-entry site and with fewer attempts
is an advantage.
For both devices, once the internal 0.014-inch
diameter guidewire has been advanced into the
true lumen, its location in the lumen is conrmed
by the fact that it passes easily into the existing arte-
rial anatomy. Usually, it is best to advance the wire
as far into the true lumen as it will easily go. At that
point the needle is withdrawn so that it is no longer
protruding from the catheter head. ecatheter is
then carefully removed, with attention paid to the
integrity of the wire to avoid kinking or bending or
partial withdrawal of the wire. Once this is done, it
is usually best to advance a balloon that is compat-
ible with a 0.014-inch diameter guidewire to cre-
ate more space along the occlusion and also at the
junction where the passage has been made from
false lumen to true lumen. Aer this, the recon-
struction can be done over the 0.014-inch diam-
eter guidewire or the wire can be exchanged for a
larger caliber wire before proceeding to denitive
therapy.
CHRONIC TOTAL OCCLUSION
CATHETERS AND CROSSING
CATHETERS
CTO catheters are catheters that are specially
designed to support a guidewire in the traversal
of a CTO. Typically, the wire is a CTO wire or a
wire specically designed for crossing occlusions.
is is either a 0.014-inch or a 0.018-inch diam-
eter guidewire. CTO wires typically have fairly
sti wire tip. Some have a hydrophilic coating.
Atypical CTO wire tip will support a weight of
10–15 grams without bending to the point of a
180-degree turn. e CTO catheter is meant to
be supportive. erefore, the catheter itself may
be somewhat sti. It may have an angled tip or a
straight tip, and a tapered tip that allows the cath-
eter to be advanced to follow the wire with the
least amount of friction. Examples of CTO cath-
eters include the CXI
®
Support catheter and the
Quick-Cross
™
catheter. Both of these have radi-
opaque markers at the tip and along the sha so
that they can be identied under uoroscopy and
advanced as necessary. In general, when recana-
lizing a CTO, it is best to lead with the wire and
then advance the catheter at intervals in order to
support the wire.
Crossing catheters have been developed to add
mechanization to the crossing of a CTO. ese are
typically rotating units that help bore through an
occlusion in the hope of keeping the guidewire
in the true lumen while crossing the lesion. e
Crosser
®
CTO Recanalizationcatheter provides a
hydraulic force to assist the operator in crossing
heavily calcied occlusions (Figure 20.3). Several
other crossing catheters are available with the
concept of manual rotation of the catheter, which
permits the tip to function like a drill.
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258 Other devices and how to use them
ATHERECTOMY
Atherectomy is performed by a device that removes
a portion of the atheroma from the luminal sur-
face using a cutting sanding or grinding mecha-
nism. ere are dierent types of atherectomy
devices, such as directional shaving devices and
rotational devices (Figure 20.4). In each, a cath-
eter is passed to the site of the target lesion and
the plaque is modied according to the selected
method. e advantage of these devices is the
potential to remove some of the plaque and gain
more space in the lumen, rather than just push-
ing the plaque aside as all the other methods do.
In the noncoronary arteries, atherectomy is used
primarily in the common femoral artery, the SFA,
the popliteal artery, and the tibial arteries. When
the common femoral artery is treated with ather-
ectomy, directional atherectomy is the best tool.
In other arterial segments of the lower extremity,
either atherectomy mechanism may be used. Laser
may also be used to perform atherectomy and is the
subject of the next section. Depending on the arte-
rial segment treated, atherectomy may be used as
a stand-alone treatment, but it is frequently com-
bined with balloon angioplasty. One advantage of
atherectomy is that there is a lower incidence of
dissection than with a balloon-based revascular-
ization mechanism and there is less need for stent
placement aerward. ere is a growing eort to
understand the potential results of atherectomy
followed by drug-coated balloon angioplasty in
the supercial femoral and popliteal arteries. In
general, atherectomy is another method of revas-
cularization with conceptual advantages, but it
has been challenging to prove its real advantage
compared with other methods of lower extrem-
ity revascularization. e conceptual appeal has
to do with the potential to restore the artery back
to its native condition, restore signicant lumen,
A
B
C
Fig. 20.4 Directional atherectomy.
(A)Thecatheter handle contains the
motor controls. The tip is tapered. The
nose cone contains the cutting device
and space to collect plaque specimen.
(B)Close-up of the nose cone showing
the cutting chamber in the open position.
(C)When engaged for cutting plaque, the
tip of the catheter becomes angulated.
This allows eccentric positioning of the
cutting chamber against the wall of
theartery.
BA
Fig. 20.3 Crossing catheters. (A) Crossing
catheters add mechanization to the
process of traversal of an occlusion. The
crossing catheter is advanced to the
leading edge or top cap (hard portion at
the proximal end) of the occlusion. (B)This
may be a rotating or hydraulic force. In
this example, gentle forward pressure
and a forward hydraulic force combine
to advance the catheter through the
occlusion while staying in the true lumen.
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Atherectomy 259
modify the compliance of the vessel, and avoid at
least some stents. e challenges with these devices
include: the risk of distal embolization during the
procedure; increased time and radiation associated
with multiple device passes; and the incidence of
recurrent stenosis on later follow-up. Atherectomy
may also be employed in dierent ways, given the
disease morphology and the vessel segment being
treated. Atherectomy may be used to debulk eccen-
tric calcium, debulk undilatable calcium, bore a
hole large enough to pass a stent delivery catheter,
as a vessel prep tool, or as stand-alone therapy.
e operator must decide how the atherectomy
device will be incorporated into an individual
treatment plan.
Directional atherectomy
A common directional atherectomy tool avail-
able is the SilverHawk (Peripheral Plaque Excision
System) atherectomy device. is comes in dier-
ent sizes depending on the lumen of the artery that
is going to be treated. e larger devices, used for
treatment of arteries proximal to the tibial vessels,
are passed over a 0.014-inch diameter guidewire.
e size of sheath required is either 6-Fr or 7-Fr,
again depending on the size of the lumen. e
atherectomy device is passed through the sheath
to a point where the cutting chamber is visible
uoroscopically just proximal to the location of
the lesion to be treated. When the catheter is prop-
erly positioned, the motor handle is engaged and
the motor is turned on, which can be heard turn-
ing the cutting device, and the catheter is slowly
advanced over the guidewire with the cutting
chamber up against the plaque. When the motor
is engaged, the catheter itself is designed to assume
an angulated conguration at its tip, which helps
direct the cutting chamber up against the wall of
the artery at the site intended for plaque removal.
e pass of the atherectomy catheter is performed
under uoroscopy. e guidewire is carefully held
in place while the atherectomy cutting chamber is
advanced. e atherectomy catheter is advanced
at a fairly slow rate of approximately 1 cm every
5–10 seconds along the same plane so that it cuts
a trough through one quadrant of the lesion. e
atherectomy cutting chamber eventually passes
the lesion and the motor is disengaged. is
straightens the catheter tip. With disengagement
of the motor, the cutting chamber is closed and
tamps down the atherectomy specimens that have
accumulated in the chamber of the nose cone of
the catheter. e wire is held steady as the ather-
ectomy catheter is withdrawn until it is proximal
to the lesion. e atherectomy catheter has on its
sha a steering device that helps assist in rotation
of the catheter head to another quadrant within the
lesion. By holding the sha or handle of the cath-
eter steady, the catheter may be rotated or pivoted
and approximately six to nine clicks of the rotation
will allow the cutting device to turn approximately
90degrees. If it is not possible to see if the catheter is
rotating with the clicks, the catheter may have to be
withdrawn and readvanced slightly to remove any
gathered tension. Sometimes, the potential energy
of twisting is built up within the catheter and not
expressed by movement at the level of the cath-
eter tip and cutting chamber where the action is.
Aer the catheter has been rotated approximately
90 degrees, the motor is re-engaged, opening the
cutting chamber, and this allows the chamber to
be advanced again across the lesion and another
quadrant of cutting is performed. Aer each cut,
the catheter is rotated approximately 90 degrees.
When the cutting chamber becomes full or nearly
full, the tamping device will only reach across the
opening to the cutting chamber and will not reach
all the way into the nose of the cutting chamber.
is can be visualized uoroscopically. When this
is the case, the entire catheter is withdrawn over
the wire. e cutting chamber is opened and the
chamber ushed so that the atherectomy speci-
mens can be removed. Once all the specimens have
been removed, the atherectomy catheter is then
passed again along the guidewire to the location
of the lesion and additional atherectomy may be
performed.
Clinically signicant embolization is uncom-
mon, although it is common to produce emboli
with atherectomy devices. It is quite common to
have the impression that the lesion removed in
terms of the actual specimens is much less than the
amount of the lumen that has been created. ere
are some possible explanations for this. One is that
the atherectomy specimens as they are removed are
compressed into the cutting chamber, thus mak-
ing them look smaller than they might otherwise
have been while in situ. ere may also be some
rigid catheter dilation eect from the atherectomy
device itself. Another concern is that the atherec-
tomy cutting device works at a fairly constant rate
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260 Other devices and how to use them
of speed, while the plaque being cut is heteroge-
neous. Some plaque is more solid and calcic and
some is soer and more malleable. erefore, as
the atherectomy device is being pushed across the
lesion, no matter how steady and gradually this is
performed, there is the sense of skipping or hop-
ping of the catheter head as the cutting chamber
moves across the more calcied or dicult areas
to cut. Atherectomy in the lower extremity is par-
ticularly useful at locations where stents are unde-
sirable, such as where the artery will bend with
exing of the knee or the hip. In addition, the
origin of the SFA, the origin of the tibial arteries,
and possibly the common femoral artery are other
locations undesirable for stenting that may possi-
bly be well treated with atherectomy.
Rotational or orbital atherectomy
Rotational atherectomy involves a rotating head
that is power driven and rotates at thousands of
revolutions per minute. e speed with which the
mechanical tip rotates will determine the heat that it
generates and the eciency with which it turns the
atherosclerotic plaque into particulate. e faster
the rotation, the smaller the particulate. Rotational
atherectomy requires several passes of the rotating
head along the length of the lesion being treated.
e highest rotation speed utilizes a sanding burr
and results in orbital atherectomy. As the rotation
speed increases, the orbit made by the tip typically
increases in size. erefore, passes may be done with
increasing rates of speed to obtain a larger luminal
gain. is may be helpful in heavily calcied lesions
of the SFA to modify the plaque enough so that it
can be manipulated more easily with subsequent
balloon angioplasty. In some of the heavily calcied
tibial vessels, there will be lesions that are immune
to angioplasty but could be pumped opened with
rotational atherectomy. ere are several companies
that make rotational or orbital atherectomy devices
with a variety of features. ey are all passed over a
guidewire for extra control. As the tip is advanced
through the lesion, it is advanced slowly so that it is
permitted to do a complete job of plaque modica-
tion. ere are auditory cues that reect the interac-
tion between the rotating tip and the lesion. Some
devices may be advanced or retracted while the burr
is spinning. Some devices feature a continuous ush
to cool the device tip while others feature continu-
ous aspiration to remove particulate matter.
LASER
Lasers are being used both in the coronary and
noncoronary arteries and in the venous system.
e peripheral laser may be used as a crossing
device, to perform atherectomy, or as a thrombec-
tomy device. Reconstruction of the artery is usu-
ally accomplished with some other modality, such
as a drug-coated balloon or stent.
When laser is used as a crossing device, it is usu-
ally in the management of a SFA or tibial artery
occlusion. ese are typically fairly straight arter-
ies that follow a mostly predictable course. If there
is a highly calcied cap on a lesion that prevents
entry to the occlusion to be recanalized, the 1-mm
laser tip can be parked with the guidewire at the
cap (hard portion) at the end of the occlusion and
the laser energy used to create an entry point for
the wire (step-by-step approach). Aer the laser
A
B C
Fig. 20.5 Rotational or orbital atherectomy.
There are a variety of devicesavailable. Each
one is passed over a guidewire and has some
variation in the concept of a cutting head
or sanding burr. (A)Aposterior tibial artery
occlusion is identified by arteriography.
(B)Anantegrade sheath is placed and
a guidewire advanced across the lesion.
(C)Arotational atherectomy device is advanced
to the proximal end of the occlusion. The burr
is motorized and the lesion engaged. The
atherectomy burr is advanced slowly through
thelesion to create a lumen.
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Drug-coated balloons and drug-eluting stents 261
is used against the cap, the wire is advanced a few
millimeters, then the laser is advanced and the
process repeated. Laser also has the capability of
vaporizing thrombus and can be used to chase
peripheral embolus that occurs during complex
lower extremity revascularization. A wire is passed
beyond the embolized material. e laser must be
advanced over the wire directly into the thrombo-
embolus before being activated. e laser may be
used to recanalize by treating chronic compacted
thrombus, acute thrombus, or plaque.
Laser may also be used to perform debulking of
plaque by means of laser atherectomy. Quite oen,
laser is used as an adjunct along with some other
method. Aer debulking, it is common to use a
balloon to gain additional lumen. Laser catheters
come in dierent sizes and each size has a range
of diameters for arteries for which it can be used
(Figure 20.6). e laser is passed over a guidewire.
e tip of the laser catheter is advanced to within
less than a centimeter of the lesion for crossing and
the laser is activated. e laser is advanced very
slowly to perform even treatment of the plaque.
Inaddition, there is a sled or booster that can be
used to carry t he laser catheter. is permits a slight
angulation of the laser tip and this device may be
rotated within the artery to bore a larger space
and create a larger passageway. Laser debulking
has been successful in recanalizing occluded SFA
stents. Removal of the tissue and chronic throm-
bus helps create a lumen that cannot be achieved
with the angioplasty mechanism alone. e key is
to advance the catheter very slowly so that the tis-
sue in-growth can be treated.
Laser has been used with success in SFAs to
reopen occlusions and is frequently used in combi-
nation with angioplasty and/or stenting. e laser
is another device that is in the midst of a resur-
gence aer previous eorts have not been found
to be substantially valuable. e utility of this tool
will be determined sometime in the coming years
as additional data is accumulated.
DRUG-COATED BALLOONS AND
DRUG-ELUTING STENTS
e concept of drug delivery to help reduce
restenosis has arrived in the peripheral vascu-
lature. A key feature of the drug delivery para-
digm is that each segment that is treated should
also have a drug applied to enhance long-term
results. Drugs may be delivered by drug-coated
balloons or drug-eluting stents (DESs). e drug
must be attached to the balloon or the stent by
some mechanism. Drug-coated balloons have an
excipient and DESs use a polymer. e crystal-
line formulation of paclitaxel is readily transfer-
able to the wall of the artery on balloon ination.
Each drug-coated balloon has an excipient, which
binds the paclitaxel to the balloon surface tightly
enough to be delivered but loosely enough so that
it can be transferred to the artery wall on balloon
ination. Paclitaxel is a common antineoplastic
medication and is the primary medication cur-
rently used for drug-coated balloons. ey are
applied to lower extremity revascularization and
dialysis access treatment. Paclitaxel is cytotoxic
and there is evidence that it can lead to positive
remodeling with decreased late lumen loss. As
already mentioned, the more crystalline the prep-
aration, the more readily transferable it is to the
artery wall. e more amorphous the preparation,
the more challenging it is to transfer to the wall.
One negative aspect of the crystalline preparation
A
B
C
D
Fig. 20.6 Laser for peripheral artery use (CVX-
300
®
Excimer Laser System). (A) The tip of the
laser catheter. (B) The laser booster is a cradle
that allows a broader sweep of the arterial lumen
for the tip of the catheter. (C) Laser atherectomy
is being performed over a guidewire. (D) Laser
atherectomy is being performed to a wider
diameter using a laser booster.
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262 Other devices and how to use them
is the potential for particulate paclitaxel crystals
to be washed into the distal runo.
ere are some technical aspects to drug-
coated balloon angioplasty that must be followed
in order to obtain better results. Do not wipe the
balloon; this will prevent medication washing o
the balloon surface. In placing the balloon into the
sheath, plan to have the balloon inated at the site
of treatment within 30 seconds, so that it is not sit-
ting for a prolonged period in the blood stream.
e balloon should be inated for a minimum of
2minutes, and 3 minutes may be better. e bal-
loon should be inated to at least 7 or 8 atm of pres-
sure and should be sized to the artery at a 1.1 to
1.0 ratio. Predilation should be performed with a
balloon that is the same size as the reference vessel
diameter or 1 mm smaller. If a single balloon is not
adequate to cover the whole length of the lesion,
make sure that there is a slight overlap between the
two balloons to avoid a geographic miss. e medi-
cated portion of the balloon should extend beyond
the lesion for a few millimeters to a centimeter.
Aer drug-coated balloon angioplasty, when dis-
section results, spot treatment is recommended to
minimize the amount of metal being implanted.
DESs have had a signicant impact in the care
of coronary artery disease but a less signicant
impact in the treatment of noncoronary artery
disease. ere is one FDA-approved stent in the
US for the treatment of SFA occlusive disease
(Zilver
®
PTX
®
Drug-Eluting Peripheral Stent). is
device is a self-expanding nitonol stent, uses pacli-
taxel, and is supported by 5-year data from a pro-
spective randomized trial. ere are no approved
DESs for the tibial arteries, although there have
been trials using a coronary DES o-label in the
tibial arteries. Several trials are currently evalu-
ating DESs in the supercial femoral and tibial
arteries. e concept of the DES is to coat the stent
with a drug that is gradually delivered to the artery
wall in a sustained manner. e drug is intended
to cause a diminishment, if not inhibition, of cell
division at this location so that intimal hyperpla-
sia may be prevented. One issue central to the DES
mode of action is the method by which the drug
adheres to the stent. In the coronary arteries, this
typically involves adherence to a polymer that is
coated onto the surface of the stent. is is also
being developed for the lower extremity arteries.
Studies in the coronary arteries using DESs have
shown just such an eect. e drug delivery, how-
ever, is for a nite period of time. e coronary
arteries are, of course, much smaller than the
supercial femoral and popliteal arteries and the
same mechanisms of action may not take place in
these locations.
CUTTING, SCORING, AND
CRYOPLASTY BALLOONS
e mechanism of balloon angioplasty is discussed
in Chapter 17. Modied angioplasty balloons are
designed to improve the angioplasty mechanism
for a variety of reasons including exerting more
force, modifying the plaque, or causing less injury.
e concept of a cutting balloon is to place a cut-
ting device on the outside of the balloon so that
when the balloon is inated the blade will cut the
lesion (Figure 20.8). is will provide the poten-
tial for a more predictable cleavage plane when
balloon angioplasty is performed. Cutting bal-
loon angioplasty was developed to treat coronary
in-stent restenosis but it has been only moderately
successful in this application. Cutting angio-
plastyballoons are approved for both coronary and
noncoronary usage. e smaller diameter balloons
are in 0.5 mm incremental steps up to 4.0 mm in
diameter. ese are monorail platform, 0.014-inch
compatible. e larger balloons are in 1 mm incre-
mental steps from 5 mm to 8 mm. Because the ath-
erotomes make the balloon relatively rigid, these
A
B
Fig 20.7 Drug-coated balloon. (A) A standard
angioplasty balloon has a smooth, clear surface.
When expanded, it is transparent. (B) Drug-
coated balloons generally consist of the same
type of balloon but covered with a medication
preparation. The medication causes the surface
of the balloon to appear opaque. In its expanded
state, there is typically a coarse appearance to
the surface. The balloon itself should not be
manually manipulated prior to insertion because
this can disrupt the medication.
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Cutting, scoring, and cryoplasty balloons 263
balloons are fairly short. e blades have T-shaped
notches in them to assist with exibility, although
they still remain somewhat rigid. When the bal-
loon is inated, it is usually not possible to see a
waist since the balloon sides are fairly rigid and
expand all at once. e cutting balloon usually
expands at fairly low pressures since the blades
incise the tissue and allow expansion of the bal-
loon. It is rare to proceed to a nominal pressure of
approximately 8 atm without expanding the bal-
loon. ese balloons are semi-compliant. Caution
should be exercised to avoid overination for fear
that a rupture of the balloon may cause loss of
an atherotome. e smaller caliber balloons are
1.8 cm in length and the atherotome is 1.5 cm in
length. Care should be exercised when inserting
the balloon into the sheath. Avoid cutting a nger
by supporting the relatively sti balloon catheter at
the back end of the balloon with a pincer grasp as
it is pushed into the sheath. Aer that, it advances
in a manner much the same as any other monorail
platform balloon.
ere are a variety of concepts around modied
balloons that are dierent from cutting balloons.
Scoring balloons typically have a wire mounted
on the balloon surface but external to the balloon.
When the balloon inates the wire is pushed into
the lesion and into the wall of the arter y. is design
can also be called a focal force balloon because the
force of the angioplasty balloon is focused on the
wire. is dramatically increases the force with
which the wire penetrates the wall of the artery.
e wire may be in a longitudinal orientation or it
may be in a circular or slanted orientation. Scoring
balloons have been used for a variety of purposes,
as detailed below.
Scoring and cutting balloons have applications
in in-stent restenosis, recurrent stenosis due to
intimal hyperplastic tissue, vein gra stenosis, ste-
nosis within dialysis gras, central vein stenoses,
and pulmonary artery stenoses. Heavily calcied
lesions may also be treated with modied balloons.
When infrainguinal vein bypass gras or central
vein stenoses are treated, consider undersizing the
balloon; it should be large enough to incise the
lesion but not large enough to cut the juxtaposed
normal vein tissue. en follow up with a balloon
sized to the desired nal diameter. Scoring and
cutting balloon angioplasty has also been used for
focal infrainguinal artery lesions. Scoring balloon
angioplasty may be used for heavily calcied com-
mon femoral artery lesions in patients who are not
candidates for open surgery to perform femoral
endarterectomy. Cutting or scoring may be use-
ful with focal tibial artery lesions where standard
angioplasty is somewhat limited because of the
A
B
C
D
Fig. 20.8 Cutting and scoring balloons. (A) The cutting balloon has blades or atherotomes onits
side. (B) When the balloon is inflated, the cutting blades dig into the plaque. (C) The blades create
an impression on the luminal surface of the plaque. (D) Scoring balloons have a wire on the outside
surface that can be oriented longitudinally or circumferentially (shown). When the balloon is inflated,
the wire engages the artery wall and the lesion.
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