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244 Stents, covered stents, stent–grafts

A B C

D E F

Fig. 19.7 Tapering a balloon-expandable stent. (A) The guidewire is passed through an iliac artery

stenosis. (B) The sheath and dilator are advanced through the lesion. (C) The balloon and mounted

stent are advanced through the lesion and the sheath is withdrawn. (D) The balloon-expandable stent

is deployed to a size appropriate to the diameter of the external iliac artery. (E) A larger diameter

angioplasty balloon is used to enlarge the proximal end of the stent. (F) A slight taper of the stent is

created across the iliac bifurcation. Balloon-expandable stents can only be made to taper in a minimal

way, but by ﬂaring the end of the stent, it can often be molded to the appropriate shape.

B C D

Fig. 19.8 Moving a self-expanding stent.

(A)The guidewire is placed across the lesion.

(B)Stent deployment is initiated more proxi-

mally than its ﬁnal intended location. (C) The

entire delivery apparatus is withdrawn to

move the proximal partially expanded end

of the stent into the intended location. Stent

systems vary in terms of how much leeway

the operator has to do this. (D) After correct

positioning, deployment continues.

https://t.me/med1917

Tricks of the trade 245

released from the catheter and it is strongly in con-

tact with the arterial wall, do not adjust its posi-

tion at this point. Dragging the stent aer it has

fully engaged the vessel may cause the structure

at the end of the stent to be mangled. If the stent

has not been deployed in the correct location, the

best solution is to place another stent at the desired

location.

Crossing a stent

Once a stent has been deployed, the guidewire

position across the stent is not relinquished until

the procedure is completed. If the guidewire posi-

tion is lost, or if a repeat study is necessary in a

patient who has a stent, it is best to cross the stent

using a J-tip or oppy tip guidewire (Figure 19.9).

e elbow of the J-tip guidewire is less likely to

pass through the struts of the stent. If there is

any doubt about the position of the guidewire, it

should be withdrawn and a repeat crossing per-

formed. e J-tip guidewire should be able to

twirl and bob freely within the lumen of the stent.

Aerthe guidewire is across the stent, the intralu-

minal position can be checked using a 5-Fr straight

angiographic catheter passed over the wire. Any

resistance as the catheter passes through the stent

indicates a false passage, probably between the

struts of the stent. Use a small eld view for mag-

nication and oblique views if needed. Passing the

guidewire through the interstices of the stent will

lead to complications if it is not recognized that

this has occurred.

Placement of a balloon-expandable

stent without a crossing sheath

Placement of balloon-expandable stents was

designed to be performed with a sheath across

the target site. is permits protection of the

stent from migrating on the delivery catheter in

response to friction. Premounted stents are reliable

and have largely changed this approach to one in

which the stent delivery catheter is passed without

sheath coverage. In certain situations, placement

of the sheath into the desired location across the

lesion is challenging, especially with highly tortu-

ous approach arteries or when the sizable sheath

hangs up on the lesion itself (Figure 19.10). One

option is to advance the premounted stent over the

guidewire and through the lesion without a sheath

for protection. Use a premounted stent that comes

in a package with the stent already sealed onto the

balloon. If treating a critical stenosis, predilate the

lesion so that the stent will pass through without

being dislodged from the balloon.

Technique: Bailout maneuvers for

balloon-expandable stents

1. Sheath will not advance across the lesion.

Dilate the lesion and then advance again.

Consider using a stier guidewire.

2. Balloon with stent will not pass through

the sheath. e sheath may have kinked

(Figure19.11). Visualize under uoroscopy.

Consider pulling the kinked part of the sheath

back into a straighter segment of the artery

and try again to pass the balloon and stent.

If unsuccessful, pull out the balloon and

stent with the sheath but leave the guidewire

in place. Change the sheath and start again.

Consider using a self-expanding stent for tor-

tuous arteries. (Predilate the lesion; use a larger

sheath and stier wire.)

A B

Fig. 19.9 Crossing a stent. (A) After deployment,

there are many potential routes of false passage

through the struts of the stent. (B) Passage

through the struts is usually avoided with a J-tip

guidewire or an atraumatic guidewire with the tip

looped on itself.

https://t.me/med1917

246 Stents, covered stents, stent–grafts

Fig. 19.10 Placement of a balloon-expandable stent without crossing the lesion with a sheath.

(A)The guidewire is placed across a lesion at the origin of the subclavian artery. (B) A transbrachial

sheath is placed but the artery is too tortuous to permit safe passage of the sheath through the

lesion. (C)Theangioplasty balloon with premounted stent is passed beyond the sheath and through

the lesion. (D) The stent is deployed. Because the process of premounting of balloon-expandable

stents has improved, the concern about the stent coming off the balloon before full deployment is

decreased, but the operator should be aware that this could still occur.

A B C

Fig. 19.11 Kinked sheath preventing passage of a stent. (A) The guidewire is passed through a lesion

in a tortuous iliac artery. (B) The sheath and dilator are advanced through the lesion in preparation for

stent placement. (C) After the dilator is removed, the sheath becomes kinked. (D) The balloon with

mounted stent cannot pass because the sheath is kinked. If there is too much friction or a hard stop

while passing a stent delivery catheter, use ﬂuoroscopy to evaluate the sheath.

https://t.me/med1917

Tricks of the trade 247

3. Loose stent inside the sheath. Pull out the

sheath, balloon catheter, and stent. Leave

the guidewire, if possible. Use uoroscopy

to ensure that the stent comes out with the

sheath. If the stent is on the sha of the cath-

eter, the balloon can be inated just slightly in

order to keep the stent on the catheter while

the catheter is being removed.

4. Loose stent on the catheter sha beyond the

end of the sheath. Pull the balloon back into

the stent using the tip of the sheath to pin the

stent. Pull the stent back into the sheath, if

possible. Use a partially inated balloon to

pull the stent and remove the sheath. If the

stent cannot be pulled back into the sheath,

pin the back end of the stent with the tip of

the sheath and deploy in a neutral location

(Figure 19.12).

5. Loose stent on the guidewire. Advance a

small balloon into the stent to are the end

and stabilize it. Deploy in a neutral location

(Figure19.13).

6. Stent embolizes. Use a long sheath and cardiac

biopsy forceps or a loop snare to pull or push

the stent into a favorable location where it can

be abandoned (internal iliac, deep femoral, or

tibial arteries) or retrieved surgically (common

femoral artery).

7. Balloon ruptures during deployment of bal-

loon-expandable stent. Perform high-pressure,

hand-powered balloon ination with saline

solution in an attempt to overwhelm the hole

in the leaky balloon (Figure 19.14). Advance

the sheath to pin the stent so that it is not with-

drawn with the balloon. Rotate and remove the

ruptured balloon, cross the stent with another

balloon, and inate.

8. Dissection at the end of the stent. Place a new

overlapping stent (Figure 19.15).

9. Stent tilts. Some balloon-expandable stents are

too rigid for tortuous arteries. Self-expanding

stents are oen a better choice (Fig ure 19.16).

Place another stent to straighten the curve and

create a smooth surface at the end of the stent.

Fig. 19.12 Balloon-

expandable stent loose on

the catheter shaft. (A) A stent

becomes dislodged from its

position on the balloon cath-

eter during passage through

the sheath. (B)An attempt is

made to pull the stent back

into the sheath. (C) The entire

sheath is removed with the

stent inside. (D) If the stent

cannot be dragged back into

the sheath, the end of the

stent is pinned with the tip of

the sheath. (E)The balloon

is pulled back into the stent

to reload. (F)The sheath is

withdrawn and the newly

remounted stent deployed in

a neutral location.

https://t.me/med1917

248 Stents, covered stents, stent– grafts

Fig. 19.13 Balloon-expandable

stent loose on the guidewire.

This is a more severe problem

than having a stent loose on the

catheter shaft. In this situation, the

delivery balloon usually cannot be

used as a tool to help solve the

problem. If the stent is not securely

mounted on the balloon, the stent

may shoot forward off the bal-

loon during inﬂation. The end of

the stent may be partially ﬂared

and dangling on the guidewire.

(A)Theguidewire is advanced

to allow room to maneuver.

(B)

Asmaller, lower proﬁle balloon

is exchanged. (C) One end of the

stent is ﬂared further. This pro-

vides space to permit an attempt

to place the appropriately sized

balloon for deployment of the

stent. (D) The appropriately sized

balloon is substituted. (E) The stent

is deployed in a neutral position.

Stents deployed in a neutral posi-

tion in this manner are usually well

tolerated by the patient and do not

cause subsequent problems.

Fig. 19.14 Balloon rupturing during deployment of a balloon-expandable stent. (A) The angioplasty

balloon ruptures on the sharp edge of the stent during deployment. (B) High-pressure, hand-powered

inﬂation attempts to overwhelm the leak in the balloon. Often, but not always, the ends of the stent

ﬂare enough to prevent immediate migration using this maneuver. (C) A new balloon is placed to

complete the deployment.

https://t.me/med1917

Tricks of the trade 249

10. Balloon sticks in the expanded stent. Material

is caught in the struts. Do not yank because

the material may fragment. Rotate the cath-

eter, reinate, push gently to advance, and

then withdraw. If that does not work, advance

the sheath so that its tip can at the same time

hold the stent in place and act as a funneling

device to accept the torn balloon.

11. Stent requires surgical removal. If the stent is

expanded but not deployed, retrieving the stent

may be a challenge that requires open surgery.

An artery cannot be occluded with a clamp at the

location of a stent. e ends of the stent are sharp!

12. Avoid deployment of stent in the sheath. Be

sure that the tip of the sheath has been with-

drawn adequately to avoid capturing the end

of the stent.

Technique: Bailout maneuvers for

self-expanding stents

1. End of the stent is not fully expanded. e

hoop strength of the self-expanding stent may

not be adequate to compress the lesion. Dilate

the body of the stent to make sure it is properly

seeded, and then dilate the ends (Figure 19.17).

A B C D

Fig. 19.15 Dissection at the end

of the stent. (A) A guidewire is

placed across the lesion. (B)Astent

is placed but a dissection ﬂap

develops at the interface between

the lesion and the adjacent nondis-

eased segment. This may occur in

situations in which the stent does

not quite cover the entire diseased

segment or in which aggressive

postdilation was performed at

the edge of the stent and extend-

ing into the adjoining segment

of artery. (C) Another stent is

advanced into position with a slight

overlap of the previously placed

stent. (D) Stent placement repairs

the dissection.

Fig. 19.16 Tilted balloon-expandable stent.

Balloon-expandable stent placement usually

reﬂects the presence of any signiﬁcant wire bias.

If there is a tortuous path for the wire, when the

stent is placed, there is a slight tilt reﬂecting

this dynamic. Occasionally, this is a problem;

one end of the stent may not be opposed to the

artery wall in its intended manner. (A) A guide-

wire is passed through a stenosis along a curve

in the artery. (B) A stent is placed across the

lesion. The combination of the curvature of the

artery and the location of the lesion prevents

the edge of the stent from being well opposed

to the arterial wall. (C) Balloon angioplasty of

the protruding end of the stent is performed.

(D) If angioplasty is not successful, another stent

is placed to force the edge of the stent against

the wall.

https://t.me/med1917

250 Stents, covered stents, stent–grafts

2. Stent is undersized for the given artery.

echosen stent is too small. ere is no

goodsolution.

3. Stent extends into an undesired location. It is

worth trying to dilate the opposite end of the

stent; this sometimes leads to foreshortening

of the stent so that it encroaches a little less on

the segment of concern (Figure 19.18). is

works well with a Wallstent

. Other types of

self-expanding stents can sometimes be moved

a very short distance by inating a balloon and

pulling gently on the catheter.

4. Stent location is inaccurate. The only way

to avoid this is to deploy the leading end of

the stent at the location of highest interest.

This portion of the deployment process has

the greatest precision (Figure 19.19). The

finished location of the trailing end of the

stent is much less accurate in self-expanding

systems.

5. The end of the stent extends into the hemo-

static introducer sheath. The stent will not

deploy. Sheaths with radiopaque markers

are used fairly routinely. If the tip of the

sheath does not have a radiopaque marker,

it may be difficult to visualize. Puff contrast

through the sheath. Pull the sheath back

slightly while holding the stent delivery

catheter in place to release the crimped stent

(Figure19.20).

6. Stent collapses in its mid-section. Repeat

the angioplasty. If that is unsuccessful, place

a balloon-expandable stent inside the self-

expanding stent (Figure 19.21). is most oen

occurs in the setting of severe calcication and

inadequate vessel preparation.

7. Balloon breaks on the end of the stent. Balloon

the end of the stent last or use a thicker poly-

mer balloon.

8. Artery with stent in it requires clamping. Use

shodded arterial clamp. e artery can be

clamped enough to occlude inow but may

damage the stent. Balloon occlusion can also

be obtained using a standard angioplasty

balloon of 4 cm in length and the appropriate

diameter.

9. Stent requires surgical removal. It is rare

for a stent to require removal. When a self-

expanding stent is removed, it usually comes

out in pieces as the structural integrity of the

stent cannot stand up to the process.

Fig. 19.17 End of the self-expanding stent is not

expanded. (A) A self-expanding stent is placed

but there is signiﬁcant residual stenosis and it

is also causing one end of the stent to not fully

expand to meet the vessel wall. (B) A balloon

catheter is passed into the segment of residual

stenosis. (C) Angioplasty is performed aggres-

sively along the stent, ﬁrst in the area of residual

stenosis and then at the end of the stent.

A B

Fig. 19.18 Self-expanding stent extends into an

undesired location. (A) A self-expanding nitinol

stent is placed in the external iliac artery but

extends into the common femoral artery. (B)Slight

overdilation of the proximal end and the body of

the stent with angioplasty may cause the stent to

shorten a very small amount. Slight traction on

the balloon placed into the body of the stent may

also help to move the distal end of the stent a

millimeter more proximally.

https://t.me/med1917

Tricks of the trade 251

A B C

Fig. 19.19 Self-expanding stent location is inaccurate. Deployment should be initiated at the end

where the most accuracy is required. Since self-expanding stents deploy in the direction of the tip

end to the hub end, this should be taken into account when choosing a stent or choosing the direc-

tion from which it will be deployed. (A) An external iliac artery lesion can be approached either

antegrade or retrograde. (B) Self-expanding stent placement through a retrograde approach ensures

precise placement of the proximal end of the stent. (C) The ﬁnal length of the stent may be difﬁcult

to predict. The distal end of the stent extends into undiseased common femoral artery. (D) Self-

expanding stent placement through an antegrade approach places the distal end of the stent ﬁrst

because the working room between the inguinal ligament and the lesion is limited. (E) The excess

length of the upper end of the stent extends into the proximal external iliac artery.

Fig. 19.20 Partially deployed self-expanding

stent extends into the delivery sheath. (A) Stent

deployment begins but the second end of the

stent cannot be deployed because the tip of the

access sheath impinges on the stent. This occurs

when the working room between the deploy-

ment site and the arterial entry site is limited.

(B) The hemostatic access sheath is withdrawn

enough to permit the stent to expand. A sheath

with a radiopaque tip may help avoid this prob-

lem. When withdrawing the sheath, hold the

stent delivery catheter ﬁrmly and provide back

pressure. If there is a substantial length of stent

within the sheath, this maneuver can cause unde-

sirable elongation of the stent.

https://t.me/med1917

252 Stents, covered stents, stent– grafts

ACUTE COMPLICATIONS OF STENT

PLACEMENT

Complications that occur during stent placement

or immediately thereaer include arterial dissec-

tion and/or occlusion, arterial rupture, migration

or embolization of the stent, or embolization of

atherosclerotic material.

Arterial dissection

If acute arterial dissection occurs in juxtaposi-

tion to a stent, an additional stent is placed in this

location (Figure 19.15). e lead point for arterial

dissection associated with stent placement is usu-

ally within a centimeter of the end of the stent.

Astent is placed in this segment even if it is not

clear exactly where the lead point of the dissection

is located.

Arterial occlusion

e stented site may occlude as a result of arterial

dissection or placement of a stent that is not fully

expanded. Aer stent placement, additional bal-

loon dilation is usually performed to ensure full

expansion of the stent.

Arterial rupture

If arterial rupture occurs during stent placement

and the stent has been fully deployed, a balloon

catheter is inserted and placed within the stent

along the area where the rupture is thought to have

occurred. e balloon is then inated. A covered

stent can be placed in the same location or emer-

gency operative repair is undertaken.

Migration or embolization of

thestent

Migration of the stent may occur during deploy-

ment, usually because the size of the stent that was

required was underestimated. Another potential

cause is if the delivery platform is not stable and

begins to move as the stent is deployed. If the stent

has migrated enough that the area of interest has

not been adequately stented, another stent should

be placed in this location.

Embolization of atherosclerotic

material

Distal embolization may occur as a result of

instrumentation of a friable atherosclerotic

lesion. It is unusual for further embolization to

occur aer the entire lesion has been covered

with stents. is is more likely to occur when

treating occlusions.

Fig. 19.21 Self-expanding stent collapses in its

mid-section. (A) A guidewire is placed across

the lesion. (B) A stent is placed but remains

partially constrained in its mid-section. This is

most likely to occur in a heavily calciﬁed lesion,

especially when it is eccentric, that has not been

adequately prepared prior to stent placement.

(D)Because self-expanding stent hoop strength

is low, a recalcitrant lesion may impinge on

the stent, which results in incomplete expan-

sion. A central stent narrowing can also occur

if the stent is placed across a segment with too

sharp a turn. (E) If angioplasty is unsuccessful,

a balloon-expandable stent is placed to resolve

the stenosis.

https://t.me/med1917

Chronic complications of stent placement 253

CHRONIC COMPLICATIONS OF

STENT PLACEMENT

Chronic complications from stent placement that

may develop over time include intimal hyperpla-

sia, recurrent stenosis, infection, and damage to

the stent from external forces.

Intimal hyperplasia and recurrent

stenosis

Intimal hyperplasia that causes recurrent stenosis

can be treated with repeat balloon dilation, addi-

tional stents, atherectomy, or drug-coated balloon

angioplasty. Surgery is usually reserved for situa-

tions of multiple endovascular failures. If recurrent

stenosis occurs in juxtaposition to a stent, an over-

lapping stent is placed.

Infection

Infection of a stent is rare and is managed by excis-

ing the stent and the arterial segment.

Stent damage

Stents can be damaged by external forces. Chronic

repetitive shoulder motion with compression of

a stented subclavian artery against the rst rib

leads to stent fracture. Stents can also be crushed,

especially balloon-expandable stents, by arterial

clamps, blood pressure cus, motion at joints, and

external blunt trauma.

https://t.me/med1917

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