American Journal of Neuroradiology 27:1505-1507, August 2006
© 2006 American Society of Neuroradiology
INTERVENTIONAL
The Significance of Incomplete Stent Apposition in Patients Undergoing Stenting of Internal Carotid Artery Stenosis
M. Onizukaa,
K. Kazekawaa,
S. Nagataa,
M. Tsutsumia,
H. Aikawaa,
M. Tomokiyoa,
M. Ikoa,
T. Kodamaa,
K. Niia,
S. Matsubaraa and
A. Tanakaa
a From the Department of Neurosurgery, Fukuoka University Chikushi Hospital, Chikushino, Japan
Address correspondence Kiyoshi Kazekawa, MD, Department of Neurosurgery, Fukuoka University Chikushi Hospital, 277-one Zokumyoin, Chikushino, Fukuoka 8188502, Japan; e-mail: kazekawa{at}xb3.so-net.ne.jp
 |
Abstract
|
|---|
BACKGROUND AND PURPOSE: Incomplete stent apposition after carotid
angioplasty and stent placement (CAS) is often seen but little
is known about how the incomplete attachment goes after stent
placement. For example, some may change into restenosis around
the stent edge and some may remain unchanged. The purpose of
this study is to clarify the morphologic prognosis of an incomplete
stent apposition at the stent edge.
METHODS: CAS was attempted on 135 consecutive stenotic lesions (124 patients). Angiograms were then evaluated immediately after the procedure. An incomplete stent apposition at stent edge was found in 15 patients, and all of them were followed up by angiography and MR imaging with antiplatelet therapy.
RESULTS: No ischemic event caused by the lesions occurred during the mean follow-up period of 11 months (from 4 to 32 months). The angiography findings of 15 lesions at a mean of 8.8 months (from 2 to 28 months) after CAS showed that all remained unchanged. No patients required any additional intervention. No new ischemic lesions were detected in any of the 15 patients who underwent follow-up MR imaging at a mean of 10 months (from 2 to 32 months) after CAS.
CONCLUSION: In this study, the existence of a segment of incomplete stent apposition had no adverse morphologic or clinical effect.
|
Introduction
|
|---|
Carotid angioplasty and stent placement (CAS) has been shown
to be an effective treatment for patients with carotid artery
stenosis.
1,2 However, the occurrence of an incomplete attachment
between the stent and vessel wall after CAS has not been well
discussed or documented to date. An incomplete apposition between
the stent filaments and the arterial wall can increase the risk
of an embolic source as a result of the stagnation of the blood
flow in the dead space.
3 A strong compression of the vessel
wall on the opposite side of the unattachment at the stent edge
because of the straightening effect on tortuous vascular curves
may induce a kink in the artery that thus could possibly cause
edge restenosis. In our previous study, we showed that a residual
carotid plaque ulceration directly around a stent improved spontaneously.
4 The purpose of our study was to assess the morphologic and clinical
changes of an incomplete attachment at the stent edge after
CAS.
|
Methods
|
|---|
We retrospectively analyzed 135 CAS procedures performed in
124 patients with carotid stenosis at our institute between
February 2001 and December 2004. These 135 procedures represented
all CAS done at our institution during the interval of this
study. All patients received aspirin (81 mg/day) and ticlopidine
(200 mg/day) for at least 3 days before CAS. Under general anesthesia,
CAS was performed with a cerebral protection device (Naviballoon,
Silascon, Kaneka Medix, Tokyo, Japan; PeucuSurge, Medtronic,
Minneapolis, Minn), after a bolus injection of heparin (80 IU/kg).
5 A self-expandable stent, either the Wallstent (Boston Scientific,
Natick, Mass) or SMART stent (Cordis, Miami Lakes, Fla) was
applied after adequate predilation using an angioplasty balloon.
5 The Wallstent was used for 107 cases and the SMART stent was
used for 28 cases. Atropine sulfate (0.5 mg) was given intravenously
just before balloon inflation. The selected stent was 1 to 1.2
times the diameter of the proximal reference vessel. Postdilation
was performed only to dilate any residual stenosis of more than
20%. The lesions were evaluated with angiography in anteroposterior
and lateral directions immediately after CAS. An incomplete
stent apposition at the stent edge was defined in this report
as an open space around a stent in the vessel. An incomplete
stent apposition at the stent edge was detected in 15 patients
(13 men and 2 women) by angiography immediately after CAS. As
a result, 15 patients were followed up with antiplatelet therapy
(81 mg/day of aspirin and 200 mg/day of ticlopidine). Follow-up
neurologic examinations were performed at our clinic. Angiography
and MR imaging were scheduled during the follow-up period. All
images were evaluated by 2 neurosurgeons (M.O. and K.K.). The
degree of stenosis was presented as mean ± SD. The difference
between 2 groups was examined by means of
2 test. A value of
P < .05 was chosen to indicate statistical significance.
|
Results
|
|---|
The clinical characteristics and follow-up findings in these
15 patients are summarized in
Table 1. The mean age of the 15
patients was 72 years, and 88% were men. The mean degree of
stenosis was 76.4 ± 11.2%. Sixty percent of the patients
were symptomatic; 80% had hypertension, and the mean ejection
fraction was 73.1%. Balloon dilation and stent placement were
successful in all patients. Stenosis decreased from a median
of 72.7% before to a median 4.7% after CAS. All 15 patients
were followed for a mean of 11 months (range, 4 to 32 months).
No new neurologic symptoms caused by the lesion appeared in
any of the patients during the follow-up period. Follow-up angiography,
which was performed on 15 patients at a mean of 8.8 months (2
to 28 months) after CAS, showed that the 15 lesions remained
unchanged (100%). However, in-stent restenosis was observed
in 1 lesion; as a result, angioplasty was required. Stent-induced
kinking was observed in 8 patients, and it continues to demonstrate
the same shape at follow-up angiograms. No new ischemic lesions
were detected in any of the 15 patients who underwent MR imaging
at a mean of 10 months (range, 2 to 32 months). The number of
patients with the incomplete stent apposition tended to be lower
with the SMART stent than with the Wallstent (approximately
10.3 [3/28] and 11.2% [12/107] respectively), but this difference
is not significant (
P = .79).
View this table:
[in this window]
[in a new window]
|
TABLE 1 Clinical characteristics and follow-up results of 15 patients with an incomplete stent apposition at the stent edge
|
|
|
Discussion
|
|---|
In our series, an incomplete stent apposition at the stent edge
showed no change in shape in any of the lesions that underwent
angiography within a mean time of 8.8 months after CAS. In addition,
no ischemic events occurred as a result of the lesions in any
of the 15 patients for a mean follow-up time of 11 months. We
considered that clot formation outside the proximal edge of
the stent might possibly occur after CAS because of the stasis
of the blood flow in the space between the stent and the vessel
wall. The stent struts might entrap emboli coming into the cerebral
blood flow from outside the stent.
3,6 Ischemic stroke might
also be expected because of the clots in the space. As a result,
we prescribed antiplatelet drugs after CAS to prevent clot formation
outside the stent. Clot formation outside a stent is accelerated
by the decreasing of turbulent flow caused by the decreased
blood flow velocity at the stenotic lesion by stent placement.
7,8 According to the results of the follow-up digital subtraction
arteriography, as long as the stent showed no change or migration,
no significant clot formation or neointimal hyperplasia was
seen. Combination therapy with aspirin and a thienopyridine
drugs (ticlopidine or clopidogrel) has come to be used for patients
undergoing vascular stent placement because their additive effects
through different pathways provide more substantial benefit
than any single drug therapy.
9,10 Therefore, a low-dose combination
of aspirin (81 mg) and ticlopidine (200 mg) is usually used
at our institute for patients at high risk for ischemic stroke
and patients after CAS.
11,12 In this study, our choice of antiplatelet
therapy is therefore considered to be effective for preventing
thromboembolic strokes and restenosis.
|
Conclusion
|
|---|
The existence of a segment of incomplete stent apposition had
no adverse morphologic or clinical effect.
View larger version (131K):
[in this window]
[in a new window]
|
Fig. 1. Patient 5. An asymptomatic 77-year-old man. A left carotid angiogram (lateral view) showing an incomplete stent apposition at the proximal stent edge (arrow).
| |
View larger version (131K):
[in this window]
[in a new window]
|
Fig. 2. Patient 9. A 60-year-old man with transient ischemic attacks. A left carotid angiogram revealing an incomplete stent apposition at the distal stent edge (small arrow) and stent-induced kinking (large arrowhead).
| |
|
References
|
|---|
- Fox DJ Jr, Moran CJ, Cross DT 3rd, et al. Long-term outcome after angioplasty for symptomatic extracranial carotid stenosis in poor surgical candidates. Stroke 2002;33:2877–80[Abstract/Free Full Text]
- Shawl F, Kadro W, Domanski MJ, et al. Safety and efficacy of elective carotid artery stenting in high-risk patients. J Am Coll Cardiol 2000;35:1721–28[Abstract/Free Full Text]
- Tanaka N, Martin JB, Tokunaga K, et al. Conformity of carotid stents with vascular anatomy: evaluation in carotid models. AJNR Am J Neuroradiol 2004;25:604–07[Abstract/Free Full Text]
- Kohyama S, Kazekawa K, Iko M, et al. Spontaneous improvement of peristent ulceration after carotid artery stenting. AJNR Am J Neuroradiol 2006;27:151–56[Abstract/Free Full Text]
- Nagata S, Kazekawa K, Aikawa H, et al. Hemodynamic stability under general anesthesia in carotid artery stenting. Radiat Med 2005;23:427–31[Medline]
- Berkfeld J, Martin JB, Theron JG. Complications of carotid angioplasty and stenting. Neurosurg Focus 1998;5:1–19[Medline]
- Ohyama M, Mizushige K, Ohyama H, et al. Carotid turbulent flow observed convergent color Doppler flowmetry in silent cerebral infarction. Int J Cardiovasc Imaging 2002;18:119–24[Medline]
- Orlandi G, Fanucchi S, Fioretti C, et al. Characteristics of cerebral microembolism during carotid stenting and angioplasty alone. Arch Neurol 2001;58:1410–13[Abstract/Free Full Text]
- Herbert JM, Bernat A, Samama M, et al. The antiaggregating and antithrombotic activity of ticlopidine is potentiated by aspirin in the rat. Thromb Haemost 1996;76:94–98[Medline]
- Mueller C, Roskamm H, Neumann FJ. A randomized comparison of clopidogrel and aspirin versus ticlopidine and aspirin after the placement of coronary artery stents. J Am Coll Cardiol 2003;41:969–73[Abstract/Free Full Text]
- Bhatt DL, Bertrand ME, Berger PB, et al. Meta-analysis of randomized and registry comparisons of ticlopidine with clopidogrel after stenting. J Am Coll Cardiol 2002;39:9–14[Abstract/Free Full Text]
- Collaborative meta-analysis of randomised trials of antiplatelet therapy for prevention of death, myocardial infarction, and stroke in high risk patients. BMJ 2002;324:71–86[Abstract/Free Full Text]
Received June 16, 2005;
accepted after revision November 19, 2005.
TOP
Abstract
Introduction