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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3676_Библиотеки_им_академика_М_И_Перельмана
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9 Cardiac CTA in the Evaluation of Stents
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and edge). DES markedly reduce the incidence
of in-stent restenosis but are unlikely to affect
stenosis outside of the stent. The etiology of
restenosis occurring at the edge of a stent is
likely multifactorial. Diffuse proliferative
restenosis is an aggressive restenotic response
primarily within the stent, with extension to
the stent edge and beyond. Other causes would
include brachytherapy and barotrauma from
catheter balloon injury. Additionally, Attila
et al. hypothesized that edge restenosis may be
related to low-oscillating shear stress, causing
a
b
expression of several growth factors, which leads
to intimal proliferation and restenosis [1, 2].
9.8.5 Pearls and Pitfalls
On CTA, it may be difficult to differentiate an
edge stenosis, also referred to as a “napkin ring
stenosis,” from common CTA artifact that causes
decreased, drop out, density in the edge of a stent.
The artifact usually does not extend beyond
1–2 mm beyond the edge of the stent.
cd
Fig. 9.8 (a, b) cMPR and stretched, LCX: Proximal and distal stent edge stenosis (arrow). Low density in the stent
from restenosis (short arrows). (c, d) cMPR and stretched, RCA: Proximal stent edge stenosis (arrow)
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9.9 Case 9.9
9.9.1 History
A 67-year-old female presented with a history of
shortness of breath. The status was post midLAD PCI.
9.9.2 Findings
The mid-LAD has an intramyocardial course
(appearance of a myocardial bridge) with a stent.
The proximal segment of the stent is fractured
with a gap in the coronary artery (Fig. 9.9a, b).
9.9.3 Diagnosis
The diagnosis is fractured stent.
9.9.4 Discussion
Stent fracture is an uncommon complication, leading to unstented gaps between two completely
opposed segments of a stent. Subsequent restenosis may occur. A more disastrous consequence of a
stent fracture would include late distal embolization or migration of the fractured portion of the
stent. Multiple mechanisms of stent fracture have
been proposed including overexpansion of the
stent with a high-pressure inflation, shear stress
from vessel tortuosity, or overlapping of stents.
9.9.5 Pearls and Pitfalls
Without detailed knowledge of the procedure, the
clue that the stent is fractured instead of there being
a second stent is that the stent fragment (<5 mm) is
shorter than the manufactured stents (>6 mm).
Fig. 9.9 (a, b) cMPR and stretched, LAD: The proximal segment of the stent is fractured (arrows)
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9.10 Case 9.10
9.10.1 History
A 74-year-old male, asymptomatic with a history
of abnormal stress test, presented with status post
left circumflex coronary artery PCI in 1996.
9.10.2 Findings
There is a long bare metal stent in the proximal to
mid-left circumflex coronary artery with metallic
markers in the proximal and distal ends of the
stent, which obscure partially the lumen of the
artery; otherwise, the stent appears patent
(Fig. 9.10a–c).
9.10.3 Diagnosis
There is a bare metal stent with proximal and distal metallic markers (unknown brand).
deployed the first coronary stent to act as a scaffold, thus preventing vessel closure during percutaneous transluminal coronary angioplasty
and reducing the incidence of angiographic
restenosis, which had an occurrence rate of
30–40% [3, 4]. By 1999, stenting composed
84.2% of all PCIs. Despite the widespread use of
these devices, bare metal stents have been associated with a 20–30% restenosis rate requiring
reintervention. Restenosis occurs as a result of
neointimal hyperplasia—growth of scar tissue
within the stent—due to the proliferation and
migration of vascular smooth muscle cells. This
phenomenon is clinically evident within the first
6–9 months after stent placement and occurs in
response to strut-associated injury and inflammation. Various stent designs were initially created, including the one seen in this case, with
metallic markers that were commonly made with
gold. The markers allowed the angiographer to
identify under fluoroscopy the position of the
stent.
9.10.5 Pearls and Pitfalls
9.10.4 Discussion
The markers at the ends of the stent cause bloom-
Since the introduction of percutaneous transluminal coronary angioplasty by Gruntzig in 1977,
major advancements have been made in the clinical practice of PCI. Puel and Sigwart, in 1986,
Fig. 9.10 (a–c) cMPR, stretched, volume rendering. LCX: Long bare metal stent with metal markers in the proximal
and distal ends (arrows)
ing artifact, which obscures the adjacent arterial
lumen and consequently the inability to assess
stenosis. Fortunately, these are no longer
implanted in the United States.
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9.11 Case 9.11
9.11.1 History
A 76-year-old male presented with atypical chest
pain and a history of an abnormal stress test. He
is status post first obtuse marginal (OM1) coronary artery PCI approximately 5 years prior, with
a bare metal stent.
9.11.2 Findings
There is an advanced diffuse disease in the proximal LAD. There is diffuse low density in a stent in
OM1, with no evidence of distal flow (Fig. 9.11a–c).
9.11.3 Diagnosis
The diagnosis is occluded bare metal stent in OM1.
Fig. 9.11 (a–c) Volume
rendering, cMPR,
stretched, OM1:
Occluded (thrombosed)
stent (arrows)
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9.11.4 Discussion
The images demonstrate diffuse low density in
the lumen of the stent, with no distal flow,
diagnostic of an occluded stent. Stents are the
most widely used devices for coronary intervention despite two problems: subacute stent
thrombosis (1–2%) and high restenosis rate
(5–40%). Subacute stent thrombosis occurs
within the first month after stent placement
and can be prevented using the double antiplatelet regimen with aspirin and clopidogrel.
Some risk of subacute thrombosis remains
beyond the first month when DESs are used.
DESs require prolonged antiplatelet therapy.
DESs are the most significant innovation in
interventional cardiology. They can reduce the
incidence of restenosis in native stable coronary arteries to 3–5%. However, the long-term
studies comparing bare metal stents and DESs
do not show significant differences in the rate
of major adverse cardiac events (death, myocardial infarction), especially in patients with
diabetes after the treatment of bifurcating
lesions.
9.12 Case 9.12
9.12.1 History
A 78-year-old female presented with new onset
of atypical chest pain. She had had CABG
approximately 10 years prior, with interval occlusion of the vein graft to the distal RCA, with subsequent multiple PCIs with bare metal stents and
also DESs in the previous 5 years.
9.12.2 Findings
There is high-grade stenosis in the ostium of the
RCA, in the proximal edge of the first stent, and
suspected in the mid-RCA (Fig. 9.12a, b). There
are multiple sequential and overlapping stents
throughout the RCA (full metal jacket), with additional patchy areas of low density in the lumen of
the distal stents that were considered indeterminate
for a high-grade restenosis. There is adjacent metal
artifact from median sternotomy wire sutures.
9.12.3 Diagnosis
9.11.5 Pearls and Pitfalls
Severe in-stent restenosis may mimic an occluded
stent. The lack of opacification of the artery
beyond the stent indicates stent thrombosis and
total occlusion.
The diagnosis is high-grade stent restenosis.
9.12.4 Discussion
The CTA demonstrates definite high-grade stenosis in the proximal edge of the first stent and
questionable in the mid- and distal RCA.
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The patient underwent coronary angiography that
confirmed high-grade ostial and mid-RCA stenosis (Fig. 9.12c). Angioplasty and an additional
two stents were deployed in the proximal and
mid-RCA, with satisfactory results (Fig. 9.12d).
9.12.5 Pearls and Pitfalls
When clinically indicated, CTA is an excellent
noninvasive study in the evaluation of coronary
stents.
Fig. 9.12 (a, b) RCA cMPR, stretched: High-grade ostial
stenosis in the proximal edge of the first stent and suspected mid-segment high-grade stent restenosis (arrows).
(c) Coronary angiogram confirming high-grade stenosis at
the ostium of the RCA and mid-segment (arrows). (d)
Coronary angiogram following angioplasty and deployment of an additional two stents in the RCA, with satisfactory results
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9.13 Case 9.13
9.13.1 History
A 47-year-old male presented with a history of
PCI in the previous 2 months, with placement of
DESs in the mid-LAD and RCA. The patient presented with new onset of chest pain. (Case courtesy of Dr. William Bugni, Tampa, FL.)
9.13.2 Findings
There is a short segment of endoluminal low density in the distal segment of the stent in the LAD
(Fig. 9.13a, b). There is also localized endoluminal low density in the distal segment of the stent
in the RCA extending just beyond the stent (napkin ring stenosis). There is discontinuity of the
struts in the mid-segment of the same stent suggesting the strut fracture (Fig. 9.13c, d).
9.13.3 Diagnosis
9.13.4 Discussion
In-stent restenosis may involve any part of the stent
and frequently involves the proximal or distal ends
of stents. The patient underwent coronary angiography (Fig. 9.13e, f) with intravascular ultrasound
that confirmed the high-grade stenosis in the distal
segments of the stents and in the mid- segment of
the RCA stent, where disruption of the struts was
previously noted on the CCTA. Due to the early
failure (within 2 months) of the stent placement
and involving two major coronary vessels, surgical
revascularization was recommended.
9.13.5 Pearls and Pitfalls
Localized in-stent restenosis may be difficult to
visualize without proper windowing of the
images. Widened window width well above 1000
with adjusted window level is commonly required
to identify the abnormality.
The diagnosis is early onset of high-grade instent restenosis in the LAD and RCA.
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a
b
d
c
Fig. 9.13 (a, b) LAD cMPR, stretched: Localized distal
stent endoluminal low density indicating high-grade instent restenosis (arrows). (c, d) RCA cMPR, stretched.
Localized distal stent endoluminal low-density napkin ring
appearing high-grade in-stent restenosis. Discontinuity of
e
f
the struts in the mid-segment of the stent suggesting a strut
fracture (arrows). (e) Left coronary angiogram confirming
the stenosis in the distal segment of the stent in the LAD
(arrow). (f) Right coronary angiogram confirming the stenosis in the stent in the RCA (arrows)
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9.14 Case 9.14
9.14.1 History
A 62-year-old female with atypical chest pain
status post PCI to the RCA.
9.14.2 Findings
There is a dissection in the RCA distal to the edge
of the patent stent.
9.14.3 Diagnosis
Dissection of the RCA distal to the stent
(Fig. 9.14a, b).
a
9.14.4 Discussion
The case demonstrates one of the complications following a PCI, which is a dissection of
the non- stented segment of the artery. This
may result from a wire injury perforating the
intimal layer of the vessel or barotrauma to the
intima during the stent deployment and/or
ballooning.
9.14.5 Pearls and Pitfalls
Complications from PCI can occur within the
stented segment, at the edge of the stent, and
beyond the area of intended intervention.
b
Fig. 9.14 (a) cMPR of RCA (b) Stretched cMPR of RCA
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9.15 Case 9.15
9.15.1 History
A 71-year-old female with acute onset of chest
pain. Status post RCA-PCI.
9.15.2 Findings
The patient had a CCTA in the previous 8 months
that demonstrated a mid-strut stent fracture
located in the proximal RCA, but is otherwise
patent (Fig. 9.15a). The new CCTA study demonstrates an acute thrombosis of the stent at the site
of the fracture with subtotal occlusion (Fig. 9.15b:
arrow indicating the fracture site). A coronary
angiogram was performed the following day
showing complete thrombosis of the stent
(Fig. 9.15c).
ab c
9.15.3 Diagnosis
Fractured stent developing an acute thrombosis.
9.15.4 Discussion
Stent fracture is a known complication from a
PCI. Fracture of the stent struts cause altered
laminar flow through the segment, which results
in decreased patency rates and complications
such as thrombosis as demonstrated in this case.
9.15.5 Pearls and Pitfalls
In the evaluation of stents, it is important to look
carefully to identify the discontinuity of the struts
(Fig. 9.15a) in order to diagnose a non-displaced
strut fracture.
Fig. 9.15 (a) cMPR of RCA (b) cMPR of RCA with the arrow indicating the fractured strut site. (c) Right coronary
angiogram
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