Interventional Joseph Kevin

Bonn, MD L. Sullivan,

Palmaz

#{149} Geoffrey A. Gardiner, MD #{149} David C. Levin,

Vascular

Jr, MD MD

#{149}

Stent:

J.

Marcelle

Shapiro,

Initial

Radiology

MD

Clinical

Experience

The safety and efficacy of the Palmaz balloon-expandable vascular stent and its effect on the results of percutaneous transluminal angioplasty (PTA) were assessed in a prospective study. Technical success was achieved in the placement of 34 of 35 stents (97%) in 27 common and external iliac artery lesions in 19 patients (23 limbs) who presented with disabling claudication, rest pain, or gangrene. Stent placement improved the angiographic results achieved by PTA alone in all 19 patients. Seventeen of 23 limbs (74%) had significant (greater than 20%) elevation of the ankle-arm index after combined angioplasty and stent placement, including nine limbs with occlusive outflow lesions. All 10 patients with continuous runoff distal to the stent and one patient with discontinuous runoff had resolution of their symptoms, remaining unchanged at a mean follow-up time of 6 months. There were three complications: One significantly altered the patient’s hospital course, but none detracted from the achieved stent result. Stent placement is effective and does not significantly increase the complication rate of conventional iliac PTA. The current delivery system, however, may limit its utility. Index terms: Arteries, extremities, 98.721 . Arteries, grafts and prostheses, 98.456 #{149} Afteries, iliac, 98.721 #{149} Arteries, transluminal angioplasty. 98.1299

recent chanical,

thermal,

methods

to improve

and clinical translu.minal While PTA

1990;

and

I

From Medical

University

the

Hospital,

technical (1-7).

percutaneous devices and the goal of

many

was

of these

studies

to control

three unfavorable processes ed with PTA: (a) acute vessel caused

by

section; caused eration;

(b) late closure by fibrocellular and (c) delayed

spasm,

sulting

from

the

associatclosure

thrombosis,

or dis-

(restenosis) intimal proliffailure re-

unimpeded

progres-

sion of atherosclerosis. Intraluminal vascular stents have been tested at several centers in an attempt to overcome the limitations of conventional PTA, and early research in animals and humans has been promising (8-22). The balloonexpandable stent developed by Palmaz has undergone extensive laboratory and clinical testing, culminating in a recent

multicenter

study

of stent

placement in human iliac arteries (23). An expanded report of the initial clinical experience at one of the participating

institutions

here. We review of stent placement, and hemodynamic early

clinical

indications its role

is presented

the

technical aspects the angiographic effects, and the

response.

for stent in relation

are also

The

potential

placement

of Radiology, and Suite

Thomas 5609,

Jeffer-

Jefferson New

111 S 11th St. Philadelphia, PA 19107. 1988 RSNA annual meeting. Received 1989; revision requested September 6; received October 26; accepted October dress reprint requests to J.B. ( RSNA, 1990

Hospital,

From the July 27, revision 31 . Ad-

Thirty-five

and

to conventional

AND

vascular

of seven

were

and 95% smoked

risk factors

disease

were

en-

The

phase

METHODS

balloon-expandable intraluminal stents (Johnson & Johnson Interventional Systems, Warren, NJ) were percutaneously placed in 23 limbs in 19 patients (15 men, four women; mean age, 61 years [range, 42-81 years]). Sixteen patients had presented with disabling claudication (mean onset, 50 m), two patients with rest pain, and one patient with a

insulin

63%

dependent),

cigarettes.

II clinical

proved

by the Food

tration

called

trial

protocol

and Drug

ap-

Adminis-

for conventional

PTA

to be

performed on all symptomatic common and external iliac artery lesions considered

significant

graphic the

on the basis

appearance

of angio-

(a stenosis

cross-sectional

diameter

50%) and hemodynamic

reducing by at least

measurements

(a

resting peak-systolic pressure gradient greater than 10 mm Hg). Stents were then to be placed at the newly dilated sites during the same procedure, regardless of

the PTA results. All patients considered conventional

iliac

candidates

PTA

were

for

informed

about the research protocol after they underwent diagnostic arteriography, except those patients with external iliac or cornmon femoral arteries 5 mm or less in diameter, because of concerns that the introducer sheath for the stent would occlusive.

Approximately

invited

to participate

cluded only.

and

underwent

The protocol tutional review sent

was

10%

refused

10-F be

of patients

to be in-

conventional

PTA

was approved by the instiboard, and informed con-

obtained

from

each

patient

after

the nature of the investigational procedune was fully explained. All patients were premedicated with 325 mg of aspirin the

night

a baseline

before

the procedure.

ankle-arm

index

After

was obtained,

diagnostic pelvic arteniography was performed with a 5-F pigtail catheter intro-

duced oral

from artery

the uninvolved or the

common

left brachial

ter the arteriogram

discussed.

Palmaz

toe. Significant

for peripheral

(three

174:741-745

Department College

the

gangrenous

countered in this patient population: had hypertension, 37% had diabetes

pharmacologic

results of percutaneous angioplasty (PTA) remains the standard

MATERIALS

son

in me-

against which all new vascular interventional techniques are judged,

PTA Radiology

has been conducted years on numerous

ESEARCH

artery.

was obtained,

fernAf-

the

pigtail catheter was left in the distal abdominal aorta for opacification and localization of the iliac lesion and for simultaneous intraluminal pressure measurements before and after the intervention.

A 5- or 6-F vascular retrograde oral artery,

sheath

in the involved and the patient

Abbreviation: minal angioplasty.

PTA

=

was placed common received

percutaneous

ferna

translu-

741

.;

-

..s

1,.

1

.,.ss,

c. Figure 1. (a) Pelvic arteriogram depicts an eccentric, high-grade common-to-external iliac stenosis with an associated dissection created du ni rig provivuslv performed, more distal external iliac artery PTA. (b) After conventional PTA (performed between the arrows), there is littie’ improvement in lumen diameter and no change in the dissection. (c) After PTA and stent placement (between the arrows), there is m,irked improve.rnont in lumen size and wall contours, with elimination of the dissection and maintenance of patency at the internal iliac artt’rv origin.

7r ,.

..,

a.

b.

Figure

2.

between tht’re’

(a)

ante’niognarn

Polvic

there

the’ .trrows), is

of the

resolution

dOse’s prce’du

were res.

pe’.tk-svstolic en t’. we’re’

measured

artery vi’.odilator

se’gme’nt chai1t.nge

ion

Ic contra.t

to!

1Ze)l

fe’moral

across

material,

both

with

and

after

ac

742

t’ss

.

through was then

Radiology

the femoral used to pass

lumen

catheter,

and

formed.

The the

moved, The

patency

and

conventional

guide

artery

after

the

post-PTA via

the

ipsilateral

was

balloon

pigtail

over

was

sheath

the guide

was

wire

with

use

was

across

sheath; a balloon

this

proximal Palmaz onto

iliac

lesion

lenica,

until

its

tip

the

deflated

8-mm

Mass).

advanced

PTA The

over

X 3-cm

catheter

balloon-stent

the guide

the

PTA

(between

(performed

the arrows),

balloon

(USCI, assembly

through the hemostatic valve of the introducer sheath, and into position under fluoroscopy. To protect the stent from damage as it passed through the valve, a 5-cm-

passed further landmarks, material

from

was

wire,

conventional

placement

long metal sleeve was first passed over the guide wire and into the valve, opening the leaflets as the stent and balloon

then

to the lesion. The 3-cm-long stent was crimped mechanically

a 7-F PE-Plus-II was

re-

was

ipsilateral

the

per-

catheter.

femoral

After

stent

contours.

was

arteriography

(b)

PTA and

maintained

the

not

stenosis.

smooth

PTA

wire

lesion

and

performed

iliac

at the PTA site. (c) After

30-cm 10-F Teflon stent-introducer sheath, which was advanced retrograde

or

cv:isidi’re’d routine but offered more cornp1 ete’ he’ITtOd y naniic information in the clinical re’se’srch setting. The lesion was crossed retrograde by guide wire and cithe’te’r

full

exchanged

intraarterial

nitroglycerin,

i Ii

a

common

stenosis

with

across

pressure gradithe diseased il-

eccentric

a residual

deformities,

heparin.

at rest

jecte’d through she’ith. Vasodilator

1 ne’

a moderate,

and

given during Preintervention

intraluminal

i1(

clefts

angiographic

of intravenous

holus

501)0-lU

Additional ic n gthv

demonstnates

are deep

..

c.

of

Bil-

were

through. the

valve

The once

sleeve the

was stent

removed had

passed

into

used

the introducer sheath. Bone metallic markers, or contrast injected via the pigtail catheter

for precise

balloon-stent assembly proper position, the sheath was withdrawn

guidance.

With

stabilized 10-F introducer until the

in stent

March

the

the was

1990

b. Figure

3.

(a) Initial

arteriogram

reveals

a chronic

C.

left common

iliac artery

artery stenosis (between the long arrows). (b) Subsequent arteriogram tandem in the left common iliac artery (between the short arrows) rows). (c) Arteriogram 1 year after the initial procedure demonstrates the short arrows and between the long arrows), with only minimal tery.

exposed

in

the

vessel.

panded

to a diameter

balloon deflated,

inflation. gently

portion

adhering

the expanded through the Intraluminal

The

The rotated

and

after

the was

stent was performed

then

inner

Thirty-four

any

expanded

surface

of

removed measurements

vasodilation

were

at

repeated

deployed. Arteriognato document the re-

suit. The procedure was repeated for each stent placement, with tandem stents positioned to overlap approximately onethird

of the

than

one

stent

stent

length. was

When

indicated,

more the

pre-

ferred placement sequence was from most cephalic to most caudal. In several cases this sequence was reversed when a residuai

pressure

gradient

proximal

lesion

placement. Twenty-seven were

noses,

and

occlusion.

across

caudal

artery, artery.

with

the

18 were

and nine Twenty-six

one

was

a common

The

mean

length

in

bai-

in the were in the were ste-

iliac of the

artery lesions

was 2.4 cm (±1.9), and the mean reduction of the vessel diameter was 76% (±14%). Nine patients received a single stent, six patients two stents, two patients three

stents,

and

two

patients

four

stents

each.

Patients were maintained on 325 mg of aspirin for 3 months for its anti-plateletaggregation

thrombosis endothelial Clinical examination

properties,

12-month

Volume

the

risk

of

while the stent acquires a new coating is not yet known. follow-up consisted of pulses, and

of ankle-arm indexes 6, 9, and 12 months repeat

since

arteriogram

174

was

Number

#{149}

of a history, measurement

at 2 weeks and 1, 3, after the procedure. A obtained

visit.

3

at the

of 35 stents successfully,

(97%)

were

including

stents placed in tandem in each of six patients and stents placed bilaterally during the same procedure in each of four patients. One stent became dislodged from its balloon during expansion, most likely because the stent had been inadequately crimped onto the balloon. This partially expanded stent was repositioned and fully expanded slightly proximal to the targeted common iliac artery lesion; a second overlapping stent was subsequently placed in the proper position.

a

stent lesions

treated

stent:

iliac iliac

external

noted

more

atherosclerotic

the 23 limbs loon-expandable common

was

after

In the 34 arterial segments in which the stent was successfully ployed, the angiogram obtained

deafter

conventional balloon PTA and before stent placement had demonstrated various degrees (usually mild) of nesidual narrowing, intimal-medial flap formation, or luminal irregularity. Angiograms obtained after stent placement in these 34 segments showed complete resolution of these defects, such that in all instances placement of the stent resulted in improvement in both the degree of pa-

tency

and

lumen

arrow)

and

a long-segment

shows the result after recanalization and a single stent in the right common the durability of the original result formation of neointima in the distal

RESULTS

ex-

was

to detach

to the

rest

was

(short

by a single

balloon

stent, and sheath. pressure

after phy

stent

of 8 mm

occlusion

appearance

that

was

noted after conventional PTA (Figs 1, 2). The 35th stent was unsuccessfully deployed proximal to the targeted lesion in an arterial segment without significant disease and was therefore not included in the analysis of the effect of the stent on the results of PTA. It was previously demonstrated

right

common

iliac

and placement of two stents in iliac artery (between the long ar(PTA and stent placement between aspect of the left common iliac ar-

that eccentric atherosclerotic stenoses will frequently resist balloon dilation, since the force of the balloon is dissipated in stretching the relatively uninvolved portion of the vessel

wall,

reducing

the

stenosing plaque cases demonstrated

the

ability

eccentric mon iliac maintaining ly around

impact

on the

(24-26). that

Several the stent

to concentrically

has

dilate

an

lesion in a tortuous comartery by distributing and the dilating force equalthe entire circumference.

Compared

with

stenoses,

total

oc-

clusions of the iliac arteries have had less favorable technical and longterm clinical PTA results (27-30). Figure 3 illustrates the use of stents to treat a 6-cm-long total occlusion of the left common iliac artery and a stenosis of the right common iliac anteny. It also shows the minimal reduction in lumen diameter within the left iliac stent typically seen on a

1-year

follow-up

angiogram,

likely tion,

the result as previously

of neointima reported

maz

most by

formaPal-

et al (23).

Intraluminal pressure measurements during each procedure underscored the hemodynamic significance of the combination of PTA and stent placement. Peak-systolic resting pressure gradients across the iliac le-

sions

in 22 of the

procedure

one

limb

(the

was

23 limbs

pressure

inadvertently

before gradient

not

the in

ob-

tamed) measured a mean of 52 mm (±28) Hg, rising to a mean of 66 mm (±30) Hg after vasodilation with intraartenial contrast material, nitroglycerin, or tolazoline. After PTA

Radiology

743

#{149}

and stent placement, the mean resting pressure gradient fell to 2 mm (±2) Hg. The hemodynamic contnibution of the stent independent of the effect achieved by means of PTA alone is under further investigation. Noninvasive monitoring at the time of the procedure and at followup also illustrated the quality of the hemodynamic result achieved with PTA and stent placement. The mean ankle-arm

index

for

all

23 limbs

at

initial presentation was 0.51 (±0.28), which rose to a mean of 0.76 (±0.28) after stent placement, and at a mean 6-month follow-up examination remained at 0.73 (±0.23). A subset of 10 of the 23 limbs had continuous distal runoff at presentation; this group initially had a mean ankle-arm index of 0.71 (±0.17), which rose to a mean of 1.00 (±0.06) after stent placement. At a mean follow-up time of 7 months, the index for this subset of 10 limbs was 0.92 (±0.12), which was not a statistically significant decline (P .06). Eleven of the 19 patients (58%) experienced complete resolution of their symptoms and at a mean follow-up time of 6 months remained asymptomatic. Seven patients had improvement in their symptoms without complete resolution, and one patient noted no significant change; each of the latter eight patients had occlusive

lesions

distal

to their

iliac

stents and may require additional revasculanization procedures. Three complications occurred, two of which did not alter the patient’s hospital course. The latter two were marked focal narrowing of the middie segment of the external iliac antery, seen after the 10-F introducer sheath was retracted after more proximal stent placement. Although at first this was considered to be spasm, the focal narrowing did not immediately respond to oral nifedipine or intraarterial nitroglycerin, and so thrombolysis was begun. Both patients underwent local infusion of high-dose urokinase (120,000 IU and 750,000 IU, respectively). There was complete resolution in both cases and no residual intraluminal pressure gradient across the affected areas. One major complication occurred in a patient who at presentation had a common iliac artery stenosis and complete occlusion of the ipsilateral superficial femoral artery with distal perfusion through profunda femoral artery collaterals. Arteriography with the introducer sheath still in place revealed a successful common iliac artery stent placement but occlusion 744

Radiology

#{149}

of flow in the profunda tery. Surgical exploration

femoral under

anesthesia

the

revealed

that

anlocal

intro-

ducer sheath, entering the ipsilateral common femoral artery through a low puncture, had occluded flow to the profunda femoral artery. Flow was restored once the sheath was nemoved; no thrombus was found, and there were no clinical sequelae. The patient’s hospital stay was prolonged several days to allow monitoring of the exploration site. The Palmaz stent effectively dilated and maintained the patency of all 27 lesions

in these

19 patients

during

a mean follow-up period of 6 months. Eleven patients (13 limbs) have passed the 1-year anniversary and have angiographically proved stent patency with a mean ankle-arm index of 0.72.

Several critical aspects of the technique of stent placement should be emphasized. Precise localization of the lesion by means of both anatomic landmarks and angiography is essential, not only to determine how many stents may be needed to cover the area but also to select the best location for each stent. Unlike conventional balloon PTA, in which miscentening of the balloon on a lesion can be remedied by simply repositioning and reinflating at the correct location, malpositioning of a stent nequires the extra time, cost, and risk of placing a second tandem stent in the proper position. Patient selection is important because of the large (10 F) size of the sheath.

Those

patients

with ipsilateral common femoral or external iliac arteries 5 mm on less in diameter (uncorrected for a 20% magnification factor) were excluded from the study. There was relatively liberal use of antispasmodics (premedication with oral nifedipine and frequent intraarterial boluses of 100 ag of nitroglycerin) and both intravenous and intraarterial heparin (averaging 10,500 IU per patient) to prevent thrombus formation in the area of diminished flow around the large sheath. With future reductions in the size of this introducing system, patient

selection

may

not

or concentric, stenoses,

calcified or or in a long-

segment occlusion. was noted between

No difference

the technical results in the common iliac and external iliac arteries. In addition, the per-

fonmance

of the

dent

of the

PTA

and

many

stent

quality

the

length

as three

was

indepen-

of the

preliminary

of the

tandem

lesion;

stents

ing 6 cm were placed to open a PTA-induced

in one patient dissection

distal to the balloon dilation Balloon PTA with concomitant stent placement demonstrated

ty record

on par

be as critical

and antispasmodics may not be routinely needed. The stent was remarkable for the uniformity of its angiographic outcome. A smooth and fully patent lumen was seen after all stent deployments, whether in focal or diffuse,

as

cover-

with

site. a safe-

conventional

iliac PTA alone: The 4.3% limbs) frequency of major tions (those significantly

(one of 23 complicaaltering the

patient’s

hospital

compares

favorably

with

course) those

of several

published series (27,31-34). minor complications that

large

The required

brief exposure to high-dose bolysis are of concern and

DISCUSSION

introducer

eccentric noncalcified

two

thromappear

to

be related to the large outer diameter of the stent introducer sheath compared with small common femoral and external iliac arteries. Clinical improvement was related to the

quality

of runoff

distal

to the

stents. All 10 patients (12 limbs) with unimpaired runoff and one patient (one limb) with an outflow occlusion had complete resolution of their symptoms and have remained asymptomatic after a mean follow-up time of 6 months. When the seven other patients (nine limbs) with occlusive runoff lesions who had improvement in their symptoms are included, the initial clinical efficacy of the procedure is 96%, a figure companable with or exceeding those of most large iliac PTA series (27,32-36). Despite the well-documented high rate of technical and long-term clinical success of conventional iliac PTA, there

is still

room

for

improvement,

especially in more complex iliac stenosos and occlusions for which, according to Schwarten (37), 5-year patency rates

may

be as low

as 65%.

This

early

clinical experience with the Palmaz stent demonstrates that the stent improves PTA by producing and maintaming better angiognaphic results. It is able to straighten tortuous, calcified vessels and secure large PTA-induced intimal-medial flaps and even more extensive dissections. In view of the improved angiographic appearance of lesions after stent placement compared with

their

appearance

PTA

alone,

further

planned residual

conventional

of the pressure

after

balloon

evaluation

effect the gradients

is

stent has on noted after

PTA. March

1990

At the indication in the

present time, one probable for use of the stent will

treatment

of lesions

that

5.

be

typi-

cally respond poorly to conventional PTA, such as complex, calcified, or eccentric stenoses, long-segment stenoses, and complete occlusions. Another likely indication will be salvage of suboptimal angiographic or hemodynamic PTA results caused by elastic recoil, large intimal-medial flaps, extensive dissections, or residual stenoses. Whether stents should be used for all iliac artery lesions is still open to conjecture, which can be verified only with longer-term follow-up data. One might suspect that since the stent minimizes certain physical

factors

that

promote

fibro-

cellular intimal proliferation (endothelial denudation, exposed media, intimal-medial flaps, elastic recoil, and turbulence), it would reduce the frequency

and

severity

of

after conventional PTA. Fivepatency rates after conventional PTA have ranged from 50% to

87%

(38).

results

can

be

We thank Diane RehEhrlich for their expert asthis manuscript.

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1989; Cragg monowitz

im-

proved while complication rates remain in the acceptable range, it will be advisable to use stents for all iliac artery dilations. Current limitations of the stent introducer system pose a safety concern in some patients. Improvements in the system are expected to reduce procedural morbidity and broaden the indications for stent placement. U Acknowledgments: mann and Saundra sistance in preparing

7.

restenosis

seen year iliac

If these

6.

Becker GJ, Lee BI, Waller BF, et al. Radiofrequency balloon angioplasty: rationale and proof of principle. Invest Radiol 1988; 23:810-817. Schwartz L, Bourassa MG, Lesperance J, et al. Aspirin and dipyridamole in the prevention of restenosis after percutaneous transluminal coronary angioplasty. N EngI J Med 1988; 318:1714-1719. Minar E, Ehringer H, Ahmadi R, et al. Platelet deposition at angioplasty sites and its relation to restenosis in human ili-

stenotic

DT,

Hayashi renal

balloon-expandable Radiology 1987;

H, et al. experiintraluminal 164:705-708. arteries:

Radiology

745

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