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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3752_Библиотеки_им_академика_М_И_Перельмана
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© Springer International Publishing 2016
M.J. Budoff, J.S. Shinbane (eds.), Cardiac CT Imaging: Diagnosis of Cardiovascular Disease,
DOI 10.1007/978-3-319-28219-0_25
Cardiovascular CT: Interventional
Cardiology Applications
Jeffrey M. Schussler
Abstract
Interventional cardiologists should embrace cardiac CT as a helpful addition al to their
armamentarium in the treatment of cardiovascular disease. CCTA can improve the discrimination of patients for whom invasive evaluation and treatment will be most helpful. It can
be used in lieu of invasive evaluation after coronary and cardiac intervention, and is now
mandatory in the evaluation of the structural heart disease patient.
Keywords
CCTA • Coronary CTA • CTCA • Coronary angiography • Percutaneous coronary
intervention • PCI • Non-invasive Angiography
Introduction
With its high specifi city, coronary computed tomographic
angiography (CCTA) can be an extremely helpful test in
determining which patients do not require cardiac catheterization. Given this fact, it seems somewhat counterintuitive
that this technology would be embraced by interventional
cardiologists. One would theorize that a strong non-invasive
angiography program would reduce volume and divert
patients away from the catheterization lab. In fact, centers
where CCTA is available do not appear to have led to a
reduction in invasive volumes [ 1 ].
Prior to invasive catheterization, CCTA can also help
interventionalists plan percutaneous coronary intervention
(PCI) strategies by alerting them to the presence of left main,
ostial, or multivessel disease, length and severity of lesions,
presence and amount of calcifi cation, tortuosity, coronary
variants, and anomalies. It can also be used to guide strategies for approaching chronic total occlusions. After percutaneous revascularization, CCTA has utility in evaluation of
stent patency, and after coronary artery bypass grafting
(CABG) to evaluate graft patency. In the arena of structural
heart disease, it can be used for planning for transcatheter
aortic valve replacement, atrial septal defect closure, as well
as planning of other cardiac interventional procedures. In
addition, given the climate of scrutiny regarding appropriateness of interventions, CCTA can be used to reduce unnecessary diagnostic cardiac catheterization volume.
Invasive Cardiac Catheterization
Invasive cardiac catheterization, the “gold standard”
diagnostic technique for the evaluation of coronary artery
disease (CAD), has been used for clinical evaluation of
coronary stenosis since the 1960s [ 2 – 4 ]. However, it has
several well-known drawbacks. There is a certain degree of
inter-observer variation when describing degree of stenosis
[ 5 ]. Quantitative coronary angiography, which is not used
routinely in clinical practice, is helpful but does not
eliminate this error [ 6 , 7 ].
J. M. Schussler , MD, FACC, FSCAI, FSCCT, FACP
Division of Cardiology, Department of Internal Medicine ,
Baylor University Medical Center, Dallas, TX/Jack and Jane
Hamilton Heart and Vascular Hospital , 621 N. Hall St. Suite 400 ,
Dallas , TX 75226 , USA
Division of Cardiology, Department of Medicine ,
Texas A&M College of Medicine , Dallas , TX , USA
e-mail: Jeffrey.Schussler@Baylorhealth.edu
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Invasive coronary angiography allows only for the defi nition of the lumen of the coronary. The plaque protruding into
the lumen of the coronary artery remains non-visualized
unless intravascular ultrasound is used [ 8 , 9 ]. This may lead
to under-identifi cation of the presence of disease in patients
with minimal angiographic disease, and can contribute to
underestimation of plaque burden due to compensatory
expansion of the coronary arteries [ 10 – 13 ]. These non-fl ow-
limiting stenoses can be the cause of future acute coronary
syndromes and myocardial infarction [ 14 ].
There is a small but inherent risk of complication associated with invasive evaluation of the coronary arteries. This is
due to the need to directly instrument the coronary arteries, as
well as the obligate arterial access. The risk of major complications such as death are approximately 0.1 % [ 15 , 16 ], with
a combined risk of all major complications, such as stroke,
renal failure, or major bleeding, of ≤2 % [ 17 , 18 ]. Minor
complications, such as local pain, ecchymosis, or hematoma
at the access site, can be higher, and are frequently a source of
delayed discharge and patient dissatisfaction [ 19 ].
Invasive coronary angiography is considered the “gold
standard” for defi nitive cardiac evaluation in patients with
chest pain [ 20 ]. As it is such a powerful tool, invasive
angiography has even been suggested as the test of choice in
inpatients with chest pain [ 21 ]. Angiography has been shown
to be better able to detect the presence of atherosclerotic
coronary disease than functional tests, reduces early returns
to the emergency department, and has an overall higher level
of patient satisfaction [ 22 ]. Invasive angiography has even
been suggested as the screening test of choice in the primary
prevention of CAD [ 23 ]. However, due to the aforemen-
tioned risks, it often is used as a second line study in patients
who have low-to-moderate presumed risk or after performing functional testing [ 24 ].
CT Coronary Evaluation Prior to Invasive
Coronary Evaluation
Determination of Coronary Atherosclerosis
Prior to Invasive Evaluation or Intervention
While traditional invasive angiography may be highly
accurate, less than 40 % of those patients who have invasive
angiography ultimately are found to have signifi cant coronary
disease [ 25 ]. With its high specifi city and negative predictive
value, CCTA has the ability to accurately evaluate those
patients who have no signifi cant coronary disease, obviating
the need for further evaluation [ 26 ].
In patients with chest pain who have no observable
coronary disease by CCTA, there is a nearly 100 % chance
that they will not require further cardiac evaluation, and will
have no cardiac events for several years (Fig. 25.1 ) [ 27 ].
Accuracy is high enough to determine whether coronary
arteries have high-grade lesions, and which have minimal
disease (Fig. 25.2 ), and can accurately exclude left main or
multi-vessel coronary disease prior to catheterization [ 28 –
32 ]. This can mean the difference between planning an inter-
vention on a single proximal vessel or on the expectation of
a diffi cult multiple vessel intervention [ 33 , 34 ].
CCTA may also allow for improved planning of
antiplatelet loading prior to catheterization. If suspected
surgical disease is discovered on CCTA, a “loading dose” of
clopidogrel may be withheld, reducing a delay in surgical
revascularization (Fig. 25.3 ). While still not standard of care,
newer studies suggest that it may be feasible in the future to
send patients directly to coronary artery bypass graft surgery
without invasive angiography, relying on CCTA alone to
guide surgical decision-making [ 35 ]. Once lesions are found,
CCTA can also act as a “preview” of the coronary anatomy
for planning of stent placement, including stent sizing prior
to invasive coronary angiography (Fig. 25.4 ) [ 36 ].
Visualization of Coronary Ostia
Visualization of the ostia of the coronaries may help an
interventionalist in several ways. Anomalous coronary
arteries are better seen with CT, and can be helpful in
planning catheter selection prior to invasive angiography
[ 37 ]. Even in cases where true anomalies are not present, it
can be helpful to know that a patient has an “anterior takeoff”
of a right coronary or a “posterior takeoff” of a left main, as
this may lead to use of specifi c types of catheters for the
engagement of that artery (Fig. 25.5 ). Coronary CT is
superior to invasive angiography in evaluating location and
severity of ostial stenosis (Fig. 25.6 ), and does not induce
coronary spasm, which can mimic ostial disease [ 38 ].
Chronic Total Occlusions
Since the bolus of contrast reaches the arteries simultaneously,
it is diffi cult to distinguish high-grade lesions from totally
occluded coronaries. Newer data suggest that when
occlusions are found, CCTA may be helpful in defi ning the
length of stenosis, complexity of the plaque, and therefore
give insight into the potential ease or diffi culty in undertaking
complex percutaneous revascularization of these lesions
(Fig. 25.7 ) [ 39 – 42 ].
Left Main Disease
The presence of severe left main disease is potentially dangerous if not known prior to diagnostic angiography. Placement
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ab
cd
e
Fig. 25.1 Normal CCTA in a patient with risk factors for coronary
disease and chest pain. A 3-D view ( a ) and maximum intensity
projection ( b ) of the coronary anatomy demonstrates a right dominant
system without coronary anomalies. Individual curved reformatted
images of the left anterior descending ( c ), left circumfl ex ( d ), and right
coronary artery ( e ) demonstrate no plaque in any of the arterial tree. Ao
aorta, LAA left atrial appendage, LAD left anterior descending, Dx
diagonal, LCx left circumfl ex, RCA right coronary artery, PA pulmonary
artery, LV left ventricle, OM obtuse marginal, PDA posterior descend-
ing artery
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of a catheter into a diseased left main coronary artery can
cause dramatic reduction of coronary blood fl ow, and can even
result in death during diagnostic angiography [ 43 , 44 ]. In a
situation where left main disease is discovered on the CCTA,
plans can be made to use smaller diagnostic catheters, or even
have an intra-aortic balloon pump stationed close at hand.
Left main disease identifi ed on the CCTA allows
preparation for the potential hemodynamic compromise of
ab
Fig. 25.2 Patient with chest pain referred for CCTA. On CT images, a high-grade lesion is seen in the mid left anterior descending ( a , arrow ).
More moderate plaque is noted proximal to the lesion ( a , arrowhead ). The same lesions are seen on the follow-up invasive angiogram ( b )
a b
Fig. 25.3 A CCTA demonstrating a high-grade non-calcifi ed plaque
involving the ostium of the left anterior descending (LAD) and distal
left main ( a , arrow ). The invasive angiogram ( b ) is shown for
comparison. Based on the fi ndings of the CCTA scan, it was felt that the
location of the plaque was unfavorable for PCI as there would be a high
risk for compromise of the left circumfl ex, ramus intermedius (RI), and
fi rst diagonal branches. This was less apparent on invasive angiography.
A surgical consultation was obtained, and the patient went on to
successful bypass of the LAD, diagonal, and RI
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engaging a catheter in a severely diseased left main coronary artery. It is important to remember that CCTA cannot
provide hemodynamic information. It is prudent to proceed
to invasive evaluation if non-invasive angiography suggests
signifi cant left main stenosis (Fig. 25.8 ). Now that left main
coronary intervention has become more commonplace,
CTCA is a useful tool in pre-PCI planning for left main
coronary intervention. It allows for accurate sizing of vessels, and gives additional insight into plaque burden, calcifi cation and geometry of the major epicardial branches
[ 46 – 48 ].
Fractional Flow Reserve and Myocardial
Perfusion Using Computed Tomography
As with invasive angiography, CT coronary angiography
provides an anatomic assessment of coronary artery stenoses. It is clear that CCTA is at least as good, if not better,
than perfusion assessment in evaluating for the presence and
signifi cance of coronary disease [ 49 , 50 ]. Functional assess-
ment of coronary lesions, especially when combined with
anatomic assessment, allows for improved discrimination of
fl ow limiting versus non-fl ow limiting stenosis [ 51 ]. Proving
functional signifi cance prior to PCI leads to enduring clinical benefi t [ 52 , 53 ]. Newer techniques combining non-
invasive coronary angiography with either myocardial
perfusion (CT-MPI) or fractional fl ow reserve (FFRCT)
may allow for both anatomic as well as functional evaluation using CT [ 54 , 55 ].
Plaque Evaluation
Comparison of CTCA with Intravascular
Ultrasound
CCTA, like intravascular ultrasound (IVUS), has the ability
to visualize plaque and to roughly quantify its amount [ 56 – 58 ].
It is well known that patients with minimal CAD may still
ab c
d e f
Fig. 25.4 CCTA of a patient with cardiac risk factors and chest pain.
A CCTA ( a , b , arrows ) demonstrated a high grade lesion in the proxi-
mal right coronary artery. The severity is suggested by the complex
nature of the plaque, with both soft and calcifi c portions, as well as the
compensatory expansion of the artery within the most severe area ( c ).
The length and the extent of plaque were evident from the CCTA ( d ).
Invasive coronary angiogram confi rmed the high grade lesion in the
right coronary artery. A stent was selected ( e ) to cover not only the high
grade area ( arrow ), but also the more moderate plaque proximal and
distal to the most severe portions of the lesion ( f ) (Reprinted from
Bhella et al. [ 36 ]. With permission from Bhella et al., Baylor University
Medical Center Proceedings)
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have events due to plaque which is not fully defi ned by invasive coronary angiography. These types of non-stenotic
plaques are detectable by CCTA, and there is ongoing
research in the evaluation of plaque-stability using CCTA
(Fig. 25.9 ) [ 59 – 62 ].
Coronary Remodeling
Unless IVUS is used, Glagov remodeling of coronary
atherosclerotic lesions can be appreciated on CCTA better than with invasive angiography (Fig. 25.10 ) [ 63 ]. As
a b
cd
Fig. 25.5 CCTA of a patient with an “anterior” takeoff of the right
coronary artery (RCA). The axial image ( a ) demonstrates the ostium of
the right coronary artery slightly higher and more anterior than normally seen. The location on the axial “clock-face” of the aortic root is
approximately “1 o’clock” rather than the normal “10 to 12 o’clock”
location of a typical RCA ostium. This RCA location is not truly anom-
alous and has no impact on the function of the artery. The ostium, seen
on the 3-D reconstructed image ( b ), has a normal round orifi ce. Three
dimensional views ( c ) show the high-anterior takeoff in relation to the
cusp and the left main. The pulmonary outfl ow ( d ) does not impinge on
the artery. This artery would be best catheterized using a modifi ed
Amplatz-type catheter rather than a typical Judkins-right catheter
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the plaque intrudes on the lumen of the artery, compensatory arterial expansion occurs, which is seen on CCTA,
but not by conventional angiography [ 64 , 65 ]. Outward
coronary remodeling is often a clue that the plaque is
unstable, or that the stenosis seen by CCTA is severe
(Fig. 25.11 ) [ 66 , 67 ].
Post Intervention Evaluation by CTCA
Post-PCI Evaluation
While technically more challenging, CCTA can be used for
coronary evaluation after stent placement. Imaging through
stents, especially in smaller caliber arteries, can be problematic due to a signifi cant amount of beam hardening artifact
due to the scatter of x-rays by the metallic stents. It is important to use appropriate window and threshold levels to obtain
adequate images, and techniques are available to assist in
reducing artifact. In-stent restenosis, a process that occurs
through smooth muscle cell migration and neointimal hyperplasia, has also been successfully evaluated by CCTA
(Fig. 25.12 ) [ 68 , 69 ]. Patients who have had ostial stents
placed can be evaluated for geographic “miss” of stenoses, in
preparation for repeat coronary angiography or intervention
[ 70 , 71 ].
Post-bypass Evaluation
There is excellent data to support the use of CCTA in the
evaluation of CABG patients [ 72 – 74 ]. In some respects, the
imaging of bypass grafts is easier than native arteries, as
there is less movement of the grafts and greater contrast
between the contrast in the grafts and the surrounding tissue.
Visualization of graft patency is often more easily performed
using 3-D views rather than axial or even MPR views. For
many newer post-bypass studies, CCTA has become the test
of choice to evaluate graft patency rather than traditional
invasive evaluation [ 75 – 79 ] (Fig. 25.13 ).
In post CABG patients, it is important to alert the
technologist that the study is to be performed with the
intention of looking at aorta-coronary bypass grafts, so that
more of the ascending aorta is visualized. Slice thickness
may be increased to reduce radiation. Imaging can be
performed on conduits with metallic proximal connectors,
but there may be some hardening artifact when many metallic
clips are present [ 77 , 80 , 81 ].
Patients are sometimes referred for invasive catheterization
with a history of CABG surgery, without information
regarding the types of grafts or which arteries were bypassed.
It can then be a challenging and time-consuming task to fi nd
all of the grafts at cardiac catheterization. CCTA can be
helpful, not only by delineating which grafts are patent, but
by providing a “roadmap” as to the number of grafts, their
a b
Fig. 25.6 Oblique reconstructed views of the right coronary artery
(RCA) demonstrate a focal, high-grade ostial lesion ( a – arrow ).
Corresponding invasive angiogram ( b – arrow ) confi rms location and
severity of this blockage. Given the CCTA, care was taken with the
diagnostic angiogram not to aggressively “seat” the catheter inside the
artery. Foreknowledge of the anatomy allowed for planning of guide
selection, as well as pre-loading with dual antiplatelet therapy, as there
was no suggest of surgical disease
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origins, as well as the location of the anastomoses with native
vessels prior to invasive angiography.
Even though evaluation of bypass grafts is relatively
straightforward with CCTA, it has to be kept in mind that in
most cases the clinical situation will warrant evaluating not
only the status of the patient’s bypass grafts, but also that of
the native coronary arteries either distal to the bypass
insertion site or of those coronary arteries that did not receive
a bypass graft. Frequently, evaluation of native arteries in
patients with bypass grafts tends to be diffi cult or even
impossible with CCTA because of the often pronounced
calcifi cation that exists in the native coronary arteries of
CABG patients [ 82 , 83 ].
Evaluation of the Non-coronary Cardiac
Surgery Patient
There is growing literature to support a strategy of noninvasive coronary angiography in patients with only low or
moderate risk for coronary disease, prior to non-coronary
cardiac surgery [ 84 ]. In patients with valvular disease, such
a b
c d
Fig. 25.7 A patient with multivessel coronary disease: A high-grade
lesion is shown in the left anterior descending, demonstrated by invasive
angiography ( a ) and CCTA ( b ). The lesion has the same CCTA charac-
teristics as a complete occlusion with bridging collaterals
( c , d – arrow ). Severity of stenosis is suggested by the paucity of con-
trast, compensatory expansion, and a large plaque burden in the artery.
Complete occlusions cannot be easily distinguished from very highgrade stenoses based on CCTA characteristics
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as aortic valve stenosis or regurgitation, it is feasible to
exclude concomitant coronary stenosis prior to aortic valve
surgery or even TAVR [ 85 – 87 ]. With congenital heart dis-
ease, coronary anomalies, or cardiac masses, it may actually be more advantageous to perform a CCTA, as it gives
additional structural information which is relevant to the
case [ 37 , 88 – 90 ]. Technology is now at the point where
many decisions to proceed with cardiac surgery can proceed without any invasive tests being performed
(Fig. 25.14 ).
ab
c
Fig. 25.8 A high-grade stenosis of the left main coronary artery seen
by CCTA ( a , b , arrowhead ). The corresponding invasive coronary
angiogram is seen ( c , arrowhead ), demonstrating a severe angiographic
stenosis. There was immediate “damping” of the pressure tracing upon
engagement of a 4-French diagnostic catheter. The noninvasive study
was so dramatically abnormal that it prompted the operator to deliberately choose a smaller French-sized catheter than normal, and have an
intra-aortic balloon pump in the room prior to catheterization (Reprinted
from Schussler et al. [ 45 ]. With permission from Schussler et al.,
Baylor University Medical Center Proceedings)
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ab
Fig. 25.9 Essentially “normal” coronary angiogram in a 33-year-old
woman. A “luminal irregularity” ( a , white arrowhead ) in the left
anterior descending artery corresponds to a non-calcifi ed plaque ( b ,
black arrow ) seen by CCTA. It is possible that by defi ning asymptomatic,
subclinical plaque in younger patients, they may be prescribed statin
therapy long before they would otherwise have been treated, which may
change their long-term clinical course
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