Christoph L. Zollikofer, Erich Salomonowitz,

MD MD

a Francesco Antonucci, Gerd Stuckmann, MD

a

MD #{149} Ion

#{149} Markus Pfyffer, MD Largiad#{232}r, MD #{149} Anton

Arterial Stent Placement with Use of the Wallstent: Midterm of Clinical Experience’ Self-expandable stents of the Wallstent type were used in 26 iliac and 15 femoropopliteal artery lesions of 31 patients to treat stenoses or occlusions. The indications were confined to complex lesions, including residual stenoses and dissections after percutaneous procedures or previous surgery in the iliac artery lesions, and long-segment (mean, 13.5 cm) occlusions with inadequate response to percutaneous recanalization in the femoropopliteal artery lesions. In the iliac artery group, after stent placement, 96% of the lesions were patent at a mean followup of 16 months (range, 6-30 months). In the femoropopliteal artery group, of 11 patients available for follow-up, only six had patent stents at 7-26 months (mean, 20 months). Four of these six patients required one to three secondary interventions. Self-expanding endoprostheses are of great value in complex iliac artery lesions where simpie balloon dilation is insufficient. Stent placement for long femoral artery lesions should be performed with utmost reserve, and the extent of stent placement should be as short as possible. Index

terms:

grafts

and

stenosis ies,

Arteries, prostheses

femoral a

iliac

92.458,

984.458

angioplasty.

Arteriosclerosis,

92.721

Radiology

1991;

92.128,

#{149} Arteries,

984.128

or mecanabized

From

the

ES.,

Surgery

Departments

multifactomial and includes elastic vessel recoil, flow obstruction due to intimal flaps or residual wall imregulamities, intimal hyperplasia, and fibrous scar formation. Therefore, an

expandable endovascualr stent deemed useful for eliminating ondamy shown

recurrences previously

tonsspital

Medicine

Kantonsspital 15,

8401

Winterthur,

(C.L.Z.,

(M.P.),

Frauenfeld,

and

Winterthur, Switzerland;

of Surgery, University Hospital, and Department of Surgery,

Frauenfeld,

quests

accepted

January

to C.L.Z. RSNA,

1991

Figure 1. lam braided bility

is sec-

(Wallstent;

Medinvent,

Switzerland)

4. Address

reprint

re-

tubuflexi-

demonstrated.

AND

membrane

with

stent

and

membrane

2).

While

steel

rolled,

occlu-

diameter)

woven

form a tubular the filaments

nal

filaments

endoprosthesis

and axis

the stent, reduced,

highly (Fig

flexible

1). By

its diameter which allows

by

means

to

ph-

in the

moderately

longitudielongating

can be substantially mounting of the

stent on a special catheter for tion into the vascular system. The stent is constrained on catheter

pattern

The cmosspoints of soldered, rendering self-expandable,

of a doubled-over

un-

radially

because

for

12-

and

guide

14-mm

stent

wire and/or

low the

was

than

after PTA

mechanical of the dis-

of the stent, the ends of the stent in

enough vessel

were

or

mecanalization

evidence quate sure than

of the

placed

lumen, gradients 20 mm

the 20%-40%

(dediameter

to be

10%-18%

native

artery

after

of extensive

lead

length The

pressure by wall to prevent

Stents ses

chosen

that

stents,

The introducing a conventional

constrained state are marked by markers (Fig 2). During deployment, stent shortens by approximately

(0.10-mm

(Fig

is being

sizes up to 10 mm, the introducis placed with use of a 7-F hesheath;

greater

op-

matericatheter

of the filavessel curvature.

of its original constrained pending on stent diameter).

in a crisscross

braid. are not

expands

eased artery. For exact placement proximal and distal

METHODS

the

friction

membrane

the stent

stent system

by

of contrast between

spring characteristics and adapts to the

0.035-inch recanalization

iliac

of surgical-grade

alloy

is retracted

to eliminate

the

mostatic

and

consists

that

a 9-F sheath is required. catheter is placed over

Lausanne, artery

ing

For ing

been

in 31 patients

and/or femoropopliteal sive disease.

able,

Switzerland

expanded stent. The with its longitudinal

erator during injection a! into the virtual space

of the ments

We report our midterm results with a self-expandable metallic stent

the Kan-

Fully mesh

is well

of the

(IL.). From the 1990 RSNA scientific assembly. Received September 24, 1990; revision requested November 12; revision received January 2, 1991;

as has (7-12).

Stent Characteristics Placement

of Radiology

Internal

(AM.),

Department Zurich (FR.);

me-

179:449-456

CS.),

Brauerstrasse

however,

cm in length, however, have a limited success rate of 50%-60% (3-6). The cause for long-term failure of PTA is

stainless I

amtemies,

main a bothersome problem. Short segmental stenoses of iliac and femoropopliteal arteries have a high patency rate after PTA. Long irregular stenoses or occlusions of more than 3

The

F.A.,

a

transluminal angioplasty (PTA), local thrombolysis, and aspiration thromboembolectomy have replaced surgical interventions in many instances, with significant savings in cost and loss of productivity, and with lower morbidity and mortality rates (1,2). Restenosis and occlusion of dilated

a

, 984.721

VMD

ERCUTANEOUS

MATERIALS

#{149} Arter-

Redha, MD

Marty,

Results

Arteries,

Arteries,

or obstruction,

transluminal

a

P

#{149} Falah

the stent migration. PTA

to a!-

against

of steno-

of occlusions

with

dissection

or made-

or

in cases of residual presacross the lesions of more Hg. The different indications

introducthe

delivery roll-

Abbreviation: minal

PTA

=

percutaneous

translu-

angioplasty.

449

a.

b.

C.

Figure

2. Release mechanism of the Wallstent. (a) The stent is mounted eate the proximal and distal ends of the constrained stent. Straight arrow holds the constrained stent on the catheter. Note the sliding side-arm port and sliding membrane. (b) By sliding back the side arm to which one end progressively unfolded, thereby releasing the stent. Note foreshortening rolled membrane. (C) The stent is fully released by complete retraction of The membrane is now completely rolled back (short arrow).

for stent placement Table 1 . Whenever

a stenosis

fully

stent

relieved

are

after

was performed in the the stent to accelerate sion

of the

summarized

on the introducing catheter. Two lead markers (arrowheads) delinindicates the distal end of the doubled-over rolling membrane that (curved arrow) for injection of contrast material between catheter of the rolling membrane is attached (long arrow), the membrane is of the stent. Short arrow indicates the distal end of the partly Unthe rolling membrane with the sliding side-arm port (long arrow).

in

was

not

placement,

segment maximum

PTA

containing expan-

stent.

Patients Thirty-one men)

patients

aged

50-83

(10

years

women,

21

(mean,

64 years)

received treatment for 41 arterial lesions (26 iliac, 15 femoropophiteal) with a total of 74 Wallstent endoprostheses measuring

5-12

mm

in

had previously In 80% of our vasive

studies

such

and

oscillometry

fore

stent

arteries

placement.

values rivatives, months agulation

performed

Most

patients

procedure,

infusion of per 24 hours,

the

patients

noninvasive

ed otherwise.

a

with

patients

15,000-20,000 IU until therapeutic

of

(Quick) test. anticoagulaof the pen-

and angiographic the clinical evaluation followed

means

up

62.5 stents

Radiology

patients

aged

years)

received

6-12

mm

lesions

in

and

of 18 patients a claudication

with

stage

hA,

two

50-77 diameter

for

24

occlusions.

stage

first stage

IIB),

Fifseen II (four

two

had

1st

3 6-12 was perindicat-

total

7.7

cm).

ac arteries, rent stenosis

and

patients had these patients lateral disease. femoropopliteal

Femoropopliteal

two or more lesions; three of received treatment for biIn one patient, bilateral stent placement had

performed stenotic

previously. segments

measured

1-20

the

two

occlusions

measured

2.5

en to cover

the

entire

lesion.

In one

pa-

tient, stents were placed in the entire iliac artery on one side (Fig 3). The lengths of the implanted stents varied from 30 to 70

all

but

arterial

seg-

3.5-20.0

two

radiation

cm

patients,

the

Arteries

(average, (76%)

claudication stage IlA, tients Only

had two

less. Seven superficial 3-17

four sions

cm had of

ili-

therapy.

Thirteen patients aged (mean, 74 years) received lesions consisting of three 12 occlusions, measuring tients

in length. For lesions more than 5 cm in length, up to three stents were placed in a tandem fashion and overlapped each oth-

of

was

another patient had recurof the external iliac artery

undergoing

length

cm

In

length

stents

stenoses were of an atherosclerotic natune. In one patient, stents were placed for tumorous compression from metastatic disease of the common and external

after

stent;

(ie, Doppler

the

containing

stage III, and one had stage IV. Twelve patients showed one stenotic lesion (eight common iliac and four external iliac). Six

The

again

and

(mean,

treatment

(83%) were Fontaine

1 1 with

years

cm, with an average length of 4.6 cm. Twenty-one of 26 lesions (80%) measured 5 cm or less and were treated with one

studies in

the

mm,

teen with

been

disease. were

pressures and oscillometry) within week after stent placement, every months for the 1st year, and every months thereafter. Angiography formed after 6-12 months unless

450

Arteries

ments

(mean,

obtained, with coumarin dewhich were continued for 6-12 unless contraindicated. Anticowas regularly monitored with a

of concomitant

with

Iliac

Eighteen

un-

were

odic angiologic as well as on The

be-

5,000 IU of hepamin; afterreceived an intravenous hepa-

partial thromboplastin time The decision to discontinue tion was based on the results

case

pressures

been

dilation of the diseased stent placement was per-

the

given they

rin drip heparin

patients

stenotic

formed. During

were ward,

All

as Doppler

had

balloon before

derwent

diameter.

undergone angiography. patients, additional nonin-

13.5 were

cm).

first

stage

patients femoral

III,

Ten

seen

Fontaine seven with occlusions

62-83 years treatment for stenoses and 3-23 cm in

stage stage and

one

measured

had artery

in length (mean, femoropopliteal 12-28 cm in length

of

15

13 pa-

a clinical II (three with JIB), two pawith

had

stage 3 cm

IV. or

occlusions of the that measured 8.7 cm), and artery occlu(mean, 18.2

May

1991

a.

b.

Figure PTA

on

3. Stage the left

by

previous

nal

iliac

iliac into sal

III claudication and had been performed

PTA

of

the

left

external

shows

decreased

artery. (c) After the external and

implantation common

of

arteries

claudication

a. Figure

to

bilateral previously.

stage

iliac flow

occlusion of the superficial (a) Pelvic arteriogram

(b) Control

artery. from

C.

extensive

pophiteal

junction

viously

and

unknown

after

placement

mm,

overlapping

ening

of

fect

adaptation

the

in

the

of

distal

and were

popliteal

an

left

artery of the

and

unrelieved

and three iliac artery

stenosis

overlapping lumen

in

the

stents bilaterally

proximal

right

external

6, 7, and 8 mm in diameter with rapid flow and never-

while

the

as well

aneurysm

Wallstent

compared

stent

artery

implanted

into with

knee

d.

man with recanahization

artery

8-mm

also

surface the

the

c. in a 67-year-old axis. (b) After pophiteal

of a 6-mm luminal

on

iliac

hA.

recanalized stents

dissections

of an 8-mm stent in the right external iliac arteries on the left, there is reconstitution

Radiographs obtained of the femoropopliteal

occlusion

angiogram

intimal

b. 4.

femoral arteries in a 67-year-old man. Surgical endarterectomy and shows severe diffuse bilateral disease with a dissected lumen caused obtained after PTA of the right external and left common and exter-

that

into in

the and the

occlusion

the

in d)

and

popliteal

the

Control

popliteal

femoral lateral

e.

history of claudication local thrombolysis and (c,

distal

distal b,

in

as an is shown.

the

is bent

1-month with

tibiofibular

trunk

angiograms

in

artery the

just

proximal

artery

projection.

(e)

stage IIB. PTA, there

proximal to

and

aneurysm

is partly

Overlapping

of

the

expanded

Note

the

25-cm femoro-

Also,

a pre-

projections

5 days

tnifurcation. There

stents

shows at the artery.

lateral

recanalized arteries.

thrombosed. fully

tibial and

now

popliteal

angiogram stenosis

anterior

anteropostenior

to the

middle

(a) Femoral is a persistent

Three

is marked

smooth-

flexibility

and

is shown

1 week

10per-

after

placement.

cm). Stent placement one patient for bilateral ral artery occlusions, current stenosis after

was

performed superficial in one patient PTA, and in

ditional patient for obstructing after thromboendanterectomy. tient, stents were viously undetected well as a residual

Volume

179

a

in femofor reone ad-

plaques In one

pa-

placed because of a prepopliteal aneurysm as superficial femoral an-

Number

2

teny

stenosis after a long-segment femoropopliteal artery recanalization (Fig 4). The segments containing stents measured 3-8 cm (mean, 5.5 cm) for the three stenoses, 23-32 cm (mean, 28 cm) for the eight superficial femoral artery occlusions, and 7-38 cm (mean, 25 cm) for the four

(three

femoropophiteal

measured

artery

more

than

occlusions

25 cm).

In

two

patients the stents crossed and in another two patients

the the

knee joint, stents

ended just proximal to the level of the joint space. The lengths of the implanted stents measured 30-80 mm, and the stent diameters varied from 5 to 12 mm. Apart from three patients with one stent each (23%), all other patients had two to six stents

placed

in

tandem

fashion

Radiology

and

over-

a

451

lapping

each

eased tients,

the

sclerotic

to cover

segments treated

origin,

to be or

other

arterial

performed

the

(Fig

lesions

were

and

stent

for

poor

entire

dis-

4). In all paof atheno-

placement result

Table 2 Clinical Results

after

Iliac

RESULTS

rized

in Tables

all but artery follow-up

After

two

and

stent stent

At latest

Stage

Time

I

hA

IIB

III

IV

0

4

11

2

1

15

3

0

0

0

15

2

0

0

0

Ankle/Arm Indexes

placement placement

follow-up

0.63

± 0.25 (15) 0.85 0.22 (15) 0.88 ± 0.22

Femoropophiteal Before

placement

stent

stent

At latest

All tame stage

patients with claudication stage II had improvement I; the three patients with

conversion ranged

with a mean from one acute

Fonto stage

to stage 6 to 30

from

NA 26 of 26 (100) 25 of 26

of 16 months. occlusion, 25 of

(96)

arteries1 0

3

7

2

1

8

0

3

1

0

5

1

0

0

0

0.61

± 0.15 (10) 0.89 ± 0.23 (10) 0.90 ± 0.10 (16)

2-4.

Arteries

Patency*

(15)

The patency rates groups are summa-

Iliac

months Apart

Stents

arteriest

Before

After

III and IV had IIA. Follow-up

Patent

Fontaine Site

after 6-30 months. of the two patient

with

PTA

recanalization.

Among the 31 patients, patients from the femoral group were available for

in Patients

had

placement follow-up

NA 15 of 15 (100) 7 of 13 (54)

Note.-Values for Fontaine stage are numbers of patients. Values for ankle/arm indexes are means 1 standard deviation (numbers of patients are in parentheses). Values for patency are numbers lesions (percentages are in parentheses). * NA = not applicable. t Number of patients, 18; number of lesions, 26; follow-up ranged from 6 to 30 months (mean, months). I Number of patients, 13; number of lesions, 15; follow-up ranged from 7 to 26 months (mean, months). One patient was lost to follow-up. One patient died after 3 months, with a patent stent.

±

of

16 20

26 arteries (96%) containing stents were patent without significant signs of mestenosis. our results

A detailed overview of is given in Tables 2 and 3.

Follow-up five patients

angiograms after 1 year

obtained showed

in

intimal

hyperplasia

main-

left

side after 4 months. Atherectomy and PTA were performed. The patient was free of symptoms 1 year later, and the foblow-up angiogram showed only

moderate intimal reaction. In another patient who bilateral

stent

calcified

iliac

had

ed PTA

not

was

fully

for

stenoses,

452

of a femoropophiteal as well as a stenosis

a

Radiology

Cause

19

Stent

Placement

Management

NA

NA

1

Decreased outflow

Surgical

2

Intimal

Outcome Patent at 6-30 mo (mean, 16 mo), no secondary

Thrombotic clusion wk

ocafter 2 steno=

4)

Note-Definite

hy-

occlusion

Intimal hyperplasia occurred

in one

ath-

erectomy PTA PTA

of 24 lesions

inter-

vention Stent occluded

bypass

Percutaneous

perplasia 2

8-

Repeat-

with

no resid-

ual pressure gradient after angioplasty and with clinical reversal to stage hA. No clinical on angiographic recurrence of stenosis was so far observed in any of the other patients with stents placed in iliac arteries (Tables 2, 3). However, one patient who underwent stent placement for postsurgical dissection of the external iliac artery and ipsilateral subtotal occlusion graft,

None

after

Lesions

Patent

at 28 mo

Patent

at 6 mo

and

(4%). NA

not applicable.

partly

the

expanded.

performed

of 24 Iliac Artery No. of Lesions

Complications

Recurrent sis (ii

mm stent had expanded to only 5 mm at the site of a localized stenosis on the might after 4 months. Because the patient was symptomatic again (stage IIB), angiography was performed and showed significant intimal hypemplasia at the area where the stent

of Follow-up

underwent

placement

artery

3

Results

a

thin layer of intimal proliferation covering the filaments in three patients. One patient with bilateral subtotal stenoses of the proximal common iliac artery had a recurrence due

to marked by on the

Table

bypass of the

deep

femoral

flow,

artery

suffered

causing

reduced

an acute

occlusion

out-

of

the segment containing the stent after one month. This occlusion occurmed before meoperation on the severely diseased femoral axis could be performed.

stage III and IV had conversion to stage I and IIB, respectively. In an other patient, recurrent early thrombotic occlusion after stent placement in a recanalized 17-cm-long superfiwith

cial femoral worsening

JIB. The Femoropopliteal Of the

12 patients

Arteries with

femorab

and femoropopliteal lesions available for follow-up immediately after stent placement, three did not have improvement. In one patient, stent placement could not completely eliminate poor runoff from a single stenotic vessel to the calf after dissection during recanalization. In two patients, the segments containing stents thrombosed in the 1st week. Seven patients had improvement from stage II to stage I; two patients

artery occlusion caused from clinical stage hA to

underlying

bly elevated never dropped range during

cause

was

proba-

fibrinogen levels, which to the therapeutic percutaneous throm-

bobysis. A detailed overview of the results are shown in Tables 2 and 4. There were another five thrombotic occlusions (Tables 2, 4). One early occlusion was successfully recanalized with percutaneous aspiration thrombectomy and PTA 2 weeks after stent placement returned after rent symptoms. showed severe (Fig 6a), which

(Fig 5). The patient 12 months with recurAngiography intimal hyperplasia again was treated

May

1991

a.

b.

Figure

5.

artery. partially

There is only the anterior patent lumen. (c) After

tery

Claudication

placed

proximally,

which

Table 4 Results of Follow-up

in

an

resulted

diabetic

in complete

of 14 Femoral No.

Thrombotic

occlusion (n = 4)

2 wk

Thrombotic

in

occlusion

woman.

after

(b)

(a)

Arteniogram

e.

shows

13-cm

occlusion

in

the

distal

superficial

femoral

recanalization with 200,000 IU of urokinase and PTA, there is only a of 6 and 7 mm in diameter, full patency of the superficial femoral anocclusion occurred. The stents are further expanded compared with those in c. clot aspiration was performed. and an additional overlapping 7-mm stent (arrows) restoration of the entire lumen. Patient’s claudication was relieved.

and Femoropoliteal

After stents

Artery

after

Lesions

Stent

Placement

of

Lesions

None

first

82-year-old

tibial artery as distal runoff. placement of three overlapping

Complication

d.

C.

IIB

(d) Two weeks later, acute thrombotic recanahization by means of percutaneous

is restored.

(e) Successful was

stage

Cause

Outcome

Management

4

NA

NA

1 1

Possible level Decreased

1 1t

Decreased Decreased

outflow inflow

I

Decreased

outflow

1

Anticoagulation stopped at 4 mo, cerebral hemorrhage, hemiparesis lntimal hyperplasia Progressive atherosclerosis, moderate intimal hyperplasia Intimal hyperplasia leading to occlusion

No

21

Intimal

hyperplasia

bilaterally

Bilateral

1

Intimal sive

hyperplasia, atherosclerosis

progres-

increased

fibninogen

outflow

at 2 mo

3 patent at 4 and 25 mo, no secondary intervention, I patent at 3 mo (patient died) Stent occluded

Percutaneous and surgical thrombectomy Percutaneous lysis and aspiration Surgical bypass Iliac stent placement and surgical thrombectomy

Stent occluded Patent after one repeated PTA for intimal hyperplasia at 18 mo

Surgical

Stent

occluded

Stent

occluded

bypass

Patent

after

second

repeated

PTA

2wk(n2)

Recurrent

(n

stenosis

6)

1 1 1

Note-Definite S

I

occlusion

occurred

in five

Two

complications

in the

same

patient.

Two

complications

in the

same

patient.

of 14 lesions

with PTA. After 9 months without symptoms, the patient again had to undergo treatment with PTA for mecurrent intimal hypemplasia (Fig 6b, 6c).

Six lesions oped

Volume

containing

recurrent

179

stenoses

a

Number

2

stents

devel-

in five

pa-

(36%).

therapy

PTA X 2 Percutaneous PTA No further

PTA

atherectomy

and

therapy

and

Fontaine

stage

I at 26

Patent,

Fontaine

stage

I at 26 mo

Stent

PTA

X 2, PTA

Patent,

atherectomy

occluded

mo

at 6 mo

Bilateral intimal

stents patent, hyperplasia,

stage Patent,

hA at 18 mo Fontaine stage

recurrent Fontaine

I at 15 mo

X 1 NA

not

applicable.

tients secondary to intimal hyperplasia or progression of atherosclerotic disease after 5-12 months. Two of these lesions were outside the area containing the stent. Five lesions in four patients underwent successful treatment with atherectomy and/or

repeated PTA. In the fifth patient, clusion developed after 6 months control, and any further intervention was denied (Table 4). Currently, six of the 1 1 patients available for long-term follow-up have patent stents at 7-26 months

Radiology

ocof

a

453

(mean, 20 months) the six underwent

(Table 4). Four of secondary inter-

ventions. Five patients have a claudication Fontaine stage I, and one has stage hA. Another patient died without symptoms 3 months after stent placement for a superficial femomab

artery occlusion. Follow-up angiography of nonmeoccluded femoropopliteal artery stents was performed in six patients more than 3 months after placement. Two had a recurrent stenosis outside the area containing the stent, with only (less

moderate than 40%

intimal of the

hyperplasia stent diameter)

within the stent. Two examined for recurrent ten

9 months

and

Angiography

patients were symptoms af-

1 year,

showed

respectively.

extensive

inti-

mal proliferation within the stents leading to mestenosis. Both under-

went

treatment

with

PTA

(Fig

6). The

second patient had to undergo treatment twice at intervals of 3 and 5 months; at the last treatment, pencutaneous athemectomy was performed in addition to PTA. In a patient with

a dilative form who underwent

of atherosclerosis, stent placement

obstructing surgical follow-up

stenoses and thromboendarterectomy, angiogmam at

showed

smoothening

a 1 year

previ-

Complications only

one

case

of

stent dislocation at the time of placement. In a short subtotal stenosis of the proximal common iliac artery, a stent of 3-cm length was squeezed

backward out of the stenosis and migrated 3 cm downstream. A second, 6-cm-long stent was then placed coaxially eming stent.

through the stenosis

In one

the

first, as well

instance,

problems releasing the rolling membrane completely retracted. released stent was

with

the

through

the

thereby as the

coyfirst

we experienced the

stent because could not be The partially retrieved together

introducing

instrument

check-flow

one patient, a groin oped that required

patient

as in Figure

5 shows

within

the

containing

(a) Follow-up segment

sheath.

In

hematoma devebsurgical evacua-

The main reasons for ten necanalization and/or mural thrombus formation

gressive

organization

454

a

Radiology

stent.

Patient

Two (Tables

were 3, 4).

mestenoses afPTA are with pro-

and

perplasia by myofibroblasts Both factors are related injury may flaps,

wall

irregularities

causing

tion

or turbulence

of flow.

(6) and

Kaufman

intimal

hy-

(13-18). to the con-

trolled vessel wall angioplasty, which clefts, obstructing

induced at produce and marked

et al (19)

obstrucCobapinto

have

dem-

onstrated that the rate of restenosis is significantly higher with a residual pressure gradient of 15 mm Hg on more. A higher patency rate with a smooth luminal surface after PTA

was

shown

by Van

Intraluminal should compensate

stent

Andel

et al (20).

placement the mechanical

wall damage induced at PTA. a! stenosis may be eliminated

wall,

placement.

the

1 year after with multiple

hyperplasia

DISCUSSION

al) after

necanalized

intimal

One patient had an acute cerebral hemorrhage with hemiparesis after 4 months. Anticoagubation had to be discontinued, and occlusion of the previously open femoropopliteal axis (Fig 4) occurred 2 weeks later.

expansile force of the regularities, particularly flaps, eccentric plaques, thrombus, are pushed

stent

severe

C.

obtained was

mildly

stent placement in same localized stenoses

symptomatic

(stage

IIA).

PTA

was repeated, and patient was again asymptomatic. (b) Arteniogram obtained another year later (2 years after stent placement) again shows intimal reaction but of a much lesser degree compared with that in a. Patient again had claudication stage IIA. (C) After repeated PTA, the lumen was much improved, and the patient became asymptomatic. Note that the collaterals are still patent within the segment containing the stent.

tion. There was acute thrombotic occlusion in the first 2 weeks in five besions (one iliac, four femoropoplitesuccessfully

b. arteriograms

femoral

after

ously irregular arterial wall with moderate intimal hyperplasia in the two segments of the superficial femonab artery and popliteal artery contaming stents (Fig 7).

We experienced

6.

for

flaps

of the

a. Figure

The

resulting favorable

hemodynamic

develop,

lumen. and

causing

nestenosis.

In spite

of concomitant femoral and/or liteal artery stenosis or occlusion the ipsibatemal side in six patients, which was subsequently treated

popon in

three, theme was substantial improvement in clinical stages and ankbe/ arm pressure indexes (Table 2). The indications for iliac artery stent placement can therefore be handled more liberally compared with those for femomopoliteal artery stent placement. Even in cases of long segmental lesions and extensive dissections, stents can be implanted successfully before surgical intervention . Procedure-related complications

are Residuby the

stent. Wall inobstructing or organized against the

in a smooth

clinical results in the iliac artery group with a patency rate of 96% aften 6 months to 21/2 years demonstrate the value of placing vascular stents in complex iliac artery lesions. Most of our patients would otherwise have been candidates for surgery. In contrast to the femorab artery group, only one thrombotic occlusion was observed and in only two patients did significant intimal hyperplasia

not

higher

when

compared

conventional PTA. The limited stent migration sequela and was treated ment of a second stent.

with

one case of had no direct with place-

Stent placement may also serve as a means for prevention of embolization during PTA in heavily ulcerated lesions. In two such cases, stents

May

1991

in most promised

of these outflow

patients, due

with to only

cornone or

two patent runoff arteries in the calf. In our patient population, however, we could not establish a definite relationship between tent runoff arteries

the

occlusion

that

smaller diameter of the arteries, compared

of the

consequential

iliac

factor.

coagulopathies

one

levels,

of our

patients,

b.

patient

Figure

7. IIA,

stage

In an surgical

5 months

previously.

stenosing

intimal

There

is occlusion

placement intimal the

flap, ends

stents tion

of of with

of

the

81-year-old man thromboendarterectomy (a) flaps of

an there

the

the

8-mm

only

is smoothening (c)

moderate

segments

in

of

intimal artery

shows at

trunk. the

(b)

popliteal relief

of

follow-up

Guenther et al (9), and Vorwerk and Guenther (10) with use of balloon-expandable Palmaz stents or the selfexpandable Wallstent. Nonetheless, until more and long-term results become available in sufficiently large series, we recommend stent placement in iliac arteries only for complicated lesions that do not respond well to PTA, in cases of iliac artery occlusion, or for obstructing lesions caused by prior surgery or PTA. The results of our femoropopliteal artery group are not as favorable as reported elsewhere (11,18). Also, the patient populations can hardly be compared, since we treated 13 occlusions, of which seven measured 10 cm on more, and only three stenoses. Such patients generally have not

179

a

Number

2

After the

of

PTA and

but stent

no

of

has

the the

previously

stent

tibial

to

stenotic shows

of

claudication been performed artery

anterior anterior

a 12-mm

signs

and had

axis

femoropopliteal

origin

arteniogram

reaction without

dilated the

artery

were inserted before balloon dilation. The stents were then balloon dibated secondarily for immediate full expansion. For the same reason, we underdilated considerably (with use of 4-5-mm-diameter balloons) after recanalization of an iliac artery occlusion with the guide wire. Only after stent placement (8-10-mm diameter) was the previous occlusion completely dilated to its full appropriate diameter. Similar results for iliac artery lesions were recently reported by Palmaz et al (8,21), Rees et al (7),

Volume

form of arteriosclerosis of the femoropophiteal

a stenosis

and

One-year

the

dilative

arteriogram and

tibiofibular stent

stents).

with

Femoral (arrows)

al patient

c.

tibial

artery

bridge

the

lesions

complete

recurrent

with artery.

stenosis.

and femoral

(arrows expansion Further

mark of

the

dila-

occurred.

been candidates for percutaneous necanalization. In addition, stent placement was performed only in cases in which conventional recanalization

by means

of guide

wines

aided

by

thrombolysis and subsequent balloon dilation did not produce satisfactory results and immediate or early reocclusion without stent placement would certainly have occurred. The relatively high rate of thrombotic occlusion and/or recurrent stenosis secondary to intimal hyperplasia (77%) remains a difficult problem to solve. Although 11 of 13 patients with femoropopliteal stents initially had improved hemodynamic and clinical stages, four patients had subsequent permanent occlusion, and four of six patients with currently patent stents needed one or more secondary interventions, either pencutaneous or surgical. The reasons can only be speculated. First, there was a high proportion of long segments with stents implanted compared with the results of other authors (11,18). In 10 patients, overlapping stents were placed tandemly for 20-38 cm to smoothe the entire diseased lumen. Thus, a significant amount of the arterial surface was exposed to foreign thrombogenic material. Second, there was diffuse disease

and

flow

its

seem

Furthermore, as elevated

as was

the

can

fi-

case

be the

in

cause

occlusion. Although our so far is limited to only

with

than 2 years cumrence (at a.

on

such

of an acute experience

one

arteries,

effects

an important bninogen

of paand

rate.

Third, the femoropopliteal

with

the number in the calf

a follow-up

of more

without significant methis writing an addition-

is at 5 months

after

stent

placement), patients with a dilative form of atherosclerosis, and therefore large-caliber peripheral arteries, may have better results than those with obliterating atherosclerosis. Finally, the significance of reduced inflow was clearly shown in a patient with acute occlusion after stent placement oven a 35-cm segment of superficial fernonal artery because of an additional iliac artery stenosis. The importance of the latter was underestimated at initial angiography. After relief of this inflow obstruction by means of PTA and stent placement, the superficial femoral artery memained open after surgical thrombectorny. The contralateral side with a 25-cm stented occlusion of the superficial fernoral artery produced no earby problems. Stent size is another factor that may influence intimab reaction. A mismatch of artery and stent diarneten by more than 20%, resulting in ovenexpansion of the arterial wall, may induce increased intirnal prolifenation (18,22,23). Furthermore, a mismatch between the transition of the artery containing the stent and the native artery may cause turbulence of flow and shearing forces that may again induce thrombosis or intimal hyperplasia. Therefore, correct sizing of the stent is essential and should be performed in analogy to PTA measurements of the diameter of the stenotic segment as well as of the diameter of the more or less normal adjacent artery. Because of the considerable rate of acute occlusions or restenoses associated with fernoropopliteal artery stent placement, patients must be fobbowed up closely to implement secondary interventions in due time.

Radiology

a

455

We have lysis tomy,

used

percutaneous

4.

fibmino-

and clot aspiration, and repeated PTA

atherecsuccessfully

in these patients. But again, recurrence of intimal thickening after mepeated PTA seems more likely in femomopopbiteab

pared

with

artery

lesions

lesions

com-

5.

iliac

amter-

be

more

suc-

Johnston study plasty.

ies. cessful intimal

might

than simple proliferation

because

of the

PTA for treating (24). However,

diffuse

disease

7.

and

possible compromise of blood flow by prolonged procedure time, we tend to treat long-segment restenoses

secondary only with Because

must

be

anticipated,

sions tion,

8.

only if mechanical including atherectomy

bogenic

9.

stent occlu10.

recanalizadevices

2.

stent placement in the shortpossible to reduce thromforeign-body surface. U

11.

12.

13.

Doubilet

14.

P. Abrams

angioplasty Zeitler Results

HL.

percutaneous for

N EngI

peripheral

I Med

E, Richter

Roth

of percutaneous

gioplasty.

JC,

Zeitler

Garcia

OJ,

Schatz

RA,

E,

stents

in

iliac

first

ology Vorwerk

1989;

172:725-730. D, Guenther

use

RW.

Radiology

cost

transluminal 1983;

of undis-

15.

310:95-102. FJ, Schoop 146:57-60.

#{149} Radiology

18.

171

iliac

of self-expandable

19.

W. an-

Sanborn

following

TA,

Weber

transluminal

proliferation stenosis

20.

of smooth for after

recurrent

Reste-

angioplasty

percutaneous

cells

coronary

5. Berlin:

of

perIn:

Heuck radiolo-

Springer-Verlag,

J, Mahler

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F, Do D, et al.

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SL, Barth

KH,

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