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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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D. Lehmkuhl et al.
approach are required [8]. In order to begin the
process, a collaborative multidisciplinary team
consisting of cardiologists, emergency physicians, hospitalists, nursing staff, and radiologists
trained in cardiovascular CT must be available.
The next step involves careful selection of ideal
candidates for the study. Candidates best suited
for CCTA are those presenting with negative initial cardiac enzymes, a normal or nondiagnostic
ECG, and are without contraindications or relative contraindications for a coronary CTA. In
addition, candidates should be screened using a
standardized risk stratification tool in order to
prevent exposure to additional radiation in
patients with very low risk or delay patients that
require a more invasive test. Lastly, a standardized report should be generated for the providing
physician and specific treatment plan should be
advised based on the study to create a uniform
communication.
Through a joint effort from multiple disciplines at Baptist Hospital of Miami and Miami
Cardiac and Vascular Institute (MCVI), a protocol to utilize CCTA was developed and implemented into practice [2, 9]. Upon presentation to
the ED, cardiac enzymes are measured, an ECG
is performed and a thrombolysis in myocardial
infarction (TIMI) score is calculated on all
patients who present with chest pain with a possible cardiac etiology. The patient is deemed
moderate to high risk of ACS if they possess any
of the following criteria: TIMI score > 2, a diagnostic ECG, or positive cardiac enzymes. In this
situation, the patient is referred to catheterization
lab or single-photon emission computed tomography myocardial perfusion imaging (SPECT
MPI) based on the clinical scenario and the ACC/
AHA guidelines [10]. If the patient does not meet
the moderate- to high-risk category, the patient is
deemed low risk and is eligible to receive a CCTA
with the primary goal of detection of coronary
stenosis.
Prior to the study, patients at MCVI are
prepped according to a protocol in order to
streamline the procedure and develop the best
possible results in the least amount of time. First,
patients are screened for contraindications or
relative contraindications for the procedure. If a
patient has severe renal insufficiency or iodine
allergy, they are excluded from CCTA completely. If there is a relative contraindication
(pregnancy, inability to perform a breath hold,
inability to lay flat, obese, contraindication to
beta-blockers, nitrates, recent use of phosphodiesterase-5 inhibitors, previous coronary calcium
score > 1000, mild renal insufficiency or arrhythmia that cannot be controlled with beta-blockade), the risks and benefits from the procedure
should be examined. If a patient has a relative
contraindication, an initial evaluation with stress
MPI is a preferred alternative. IV access for contrast injection is established and the heart rate is
measured. If the heart rate is regular and >65
beats/min or >60 beats/min and irregular, the
patient is given a single dose of oral metoprolol
100 mg 1 h prior to the scan. Last, the patient is
given 400 μg of sublingual nitroglycerin a few
minutes prior to being injected for the procedure.
Prospective ECG-triggered technique is the preferred method if the patient has a stable rhythm
and a heart rate < 65 beats/min. Retrospective
EGC-triggered techniques may be used if ECGbased tube current modulation is available to
reduce radiation dose.
In addition to developing a well-defined algorithm for selecting patients who would benefit
from a CCTA, it is also important to stratify
patients who have received a CCTA and determine a treatment algorithm based on the results.
At MCVI, patients who have less than 40% coronary stenosis are deemed to have mild stenosis.
These patients can be safely discharged from the
ED and are instructed to have follow-up outpatient management with a cardiologist. Patients
8 Cardiac CTA in the Emergency Department
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who are found to have between 40 and 70% coronary stenosis are considered to have moderate
stenosis and additional tests with stress MPI or
catheterization with fractional flow reserve are
recommended prior to discharge. If patients are
found to have >70% coronary stenosis, they are
believed to have severe stenosis and catheterization should be performed for further diagnosis
and possible intervention prior to discharging the
patients.
In order to ensure proper treatment following
CCTA, structured reporting between providers
is critical for the implementation of
CCTA. Standardized site-dependent templates
are recommended in order to reduce the likelihood of neglecting important elements in the
report. In addition, a standard template allows
the reporter to convey information clearly to the
interpreter regardless of training background
and improves reliability of the report between
different institutions. Furthermore, reports
should be completed within 1 h and directly
communicated to the ordering physician if there
are any positive findings [11].
If a clinician has a high suspicion for a pulmonary embolism (PE) or aortic dissection in
addition to ACS and the patient is classified
low risk as previously established, the patient
can be considered for a “triple-rule-out”
(TRO) protocol with extended thoracic coverage. A recent study showed that a TRO protocol had a NPV of 99.4% in 201 patients with
low-to-moderate risk ACS patients for adverse
outcomes at 30 days [12]. The efficacy of this
demonstrates the usefulness for this protocol
in situations where the differential diagnosis is
broad.
The TRO protocol requires simultaneous
attenuation of both the pulmonary arterial vasculature and systemic circulation in order to properly visualize the necessary structures. Since
peak enhancement of contrast in the pulmonary
arteries occur 10–12 s prior to systemic arterial
circulation (bolus transit time), the contrast must
be introduced at a high contrast bolus volume of
a minimum 130 cm3 of non-ionic iodine contrast
at a slow flow rate of 4 cm3/s. Both of these modifications allow for an increase in the bolus transit
time in order to extend the timeframe for the CT
image acquisition. With this altered protocol, the
TRO protocol has an advantage to view extracardiac structures but has the drawback of additional
radiation dosage and less sensitivity when compared to CCTA [13].
In conclusion, CCTA has been shown to be a
highly effective tool in multiple single-center
and multicenter trials. CCTA has been shown to
lower costs, reduce hospital length of stay, and
decrease time to diagnosis. For proper implementation of CCTA to rule out ACS, a hospital
system must be equipped with the proper personnel and an algorithm detailing the patients
who would benefit. Patients should be streamlined with proper management prior to imitation
of the study. In addition, patients undergoing
CCTA should also have a comprehensive algorithm for management after results are obtained.
Moreover, the physicians involved with the
patient’s care should have a standardized report
within a timely fashion. If the ordering clinician
is uncertain of the etiology of chest pain and the
possibility of aortic dissection or pulmonary
embolism is entertained, a TRO study can be
performed due to its high NPV.
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D. Lehmkuhl et al.
8.1 Case 1
A 61-year-old male presented with increasing
frequency of chest pain over the last 2 weeks.
Fig. 8.1 (a) Axial and (b) curved multiplanar reforma-
tion (MPR) views show focal high-grade stenotic lesion in
the proximal left anterior descending artery estimated to
narrow the lumen by greater than 70% by a noncalcified
“soft” plaque. Patient had an Agatston-Janowitz Calcium
Score of 4 units all within left circumflex artery. (c)
Upon presentation to the ED, he was found to
have one set of negative troponins and ECGs.
The patient had hypertension and a family history
of heart disease. TIMI risk score: 0.
c
Angiography showed mild hypokinesis in the anterior
wall of the left ventricle and 95% stenosis in the left anterior descending artery. The stenosis was treated with a
drug-eluting stent that resulted in TIMI 3 flow with 0%
stenosis
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8.2 Case 2
ing performed a year prior to presentation that
was negative for any cardiac abnormalities. The
A 53-year-old male presented with intermittent
central chest pressure over the past month. The
chest pain was unrelated to activity and would
patient’s risk factors were hypertension, former
smoker, and family history of heart disease. TIMI
risk score: 1.
last up to 2 h. He had previous noninvasive test-
c
Fig. 8.2 (a) Axial and (b) curved MPR views show a
focal noncalcified plaque in the middle of the right coronary artery creating a greater than 70% stenosis was confirmed on all phases of the cardiac cycle. Patient had an
Agatston-Janowitz Calcium Score of 0. (c) Angiography
showed single vessel coronary disease with a 95% stenotic lesion in the middle of the right coronary artery. The
remainder of the coronary tree was normal. A drug-eluting stent provided TIMI 3 flow with 0% stenosis
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D. Lehmkuhl et al.
8.3 Case 3
on arrival to the ED. The patient had hypertension, diabetes mellitus, hyperlipidemia, a family
A 50-year-old male presented with progressive
angina over the past month with severe chest pain
c
history of heart disease. He had taken aspirin in
the past week. TIMI risk score: 2.
Fig. 8.3 (a) Axial and (b) curved MPR views show a
mixed plaque which was predominantly noncalcified in
the mid left anterior descending artery causing a greater
than 90% stenosis. Patient had an Agatston-Janowitz
Calcium Score of 472; (Percentile: 98). (c) Angiography
demonstrated single vessel disease with a 99% stenosis of
the mid left anterior descending artery with TIMI 2 flow
ab
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8.4 Case 4
infarction 4 years prior to the event that resulted
in placement of two stents placed in the right
A 56-year-old male developed chest pain on postoperative day #1 after a laparoscopic cholecystectomy. The patient had a previous myocardial
coronary artery. He had a history of diabetes mellitus, hypertension, and hyperlipidemia. TIMI
score: 2.
c
d
Fig. 8.4 (a) A curved MPR view of the right coronary
artery demonstrated patent stents with nonobstructive
(less than 30% stenosis) disease. (b) A curved MPR view
of the left anterior descending artery and left main demon-
strated nonobstructive disease. (c) Axial and (d) coronal
show pulmonary emboli in the distal right main pulmonary artery that extended into the subsegmental arteries of
the right upper lobe and right middle lobe
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D. Lehmkuhl et al.
8.5 Case 5
A 55-year-old male presented with intermittent chest pain unrelated to physical activity.
ab
c
The patient had a history of hypertension,
hyperlipidemia, and diabetes mellitus. TIMI
risk score: 1.
d
e
Fig. 8.5 (a) Axial view showing a focal greater than 50%
obstructing noncalcified plaque within the proximal right
coronary artery and (b) an axial view of a tandem greater
than 70% obstructing noncalcified plaque seen in the mid
right coronary artery. (c) A curved MPR view shows both
lesions in the right coronary artery. (d) Axial view showing
a nonobstructive (less than 30%) lesion in the left circumflex
and a greater than 50% mixed plaque within the first obtuse
f
marginal artery. Patient had an Agatston-Janowitz Calcium
Score of 489; Percentile: 96%. (e) Angiography demonstrated a greater than 90% eccentric stenosis of the mid right
coronary artery and (f) a 50–60% narrowing in the left circumflex and 80% narrowing of a mid-obtuse marginal
branch. A drug-eluting stent was utilized to treat the right
coronary artery. A fractional flow reserve was measured and
the left circumflex was not treated
ab
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8.6 Case 6
A 53-year-old male presented with chest pain
radiating to the upper back for 2 days. Upon
arrival to the ED, he had a TIMI risk score of 2.
His risk factors were diabetes mellitus, hypertension, hyperlipidemia, smoking history, and family
Fig. 8.6 (a) A curved MPR showed greater than 70%
stenosis secondary to a noncalcified plaque was seen in
the mid left circumflex artery. Additionally, nonobstructive disease (less than 30% stenosis) was seen in the left
anterior descending artery and right coronary artery
history of heart disease. TIMI score at time of
CCTA: 2. After CCTA was performed, he developed positive troponins with a peak of 3.2 and
new T wave inversions in leads II, III, aVF, and
V5-V6. A 2D-echocardiogram showed no segmental abnormalities.
(not shown). Patient had an Agatston-Janowitz Calcium
Score of 197; Percentile: 93. (b) Between 90% stenosis
of the mid segment of the circumflex artery was seen on
angiography. A drug-eluting stent was deployed
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8.7 Case 7
lupus erythematosus, hyperlipidemia, and a family history of heart disease. She had used aspirin
A 48-year-old female presented with acute chest
in the preceding week. TIMI risk score: 2.
pain. She had a history of peripheral vascular disease, atrial fibrillation, hypertension, systemic
d
c
e
Fig. 8.7 (a) Axial view shows a mixed plaque within the
left anterior descending artery that was nonobstructive (less
than 30%). (b) An additional axial view shows a greater than
70% stenosis in the mid left circumflex artery due to a noncalcified plaque. (c) Curved MPR of the left circumflex is
shown. The patient had an Agatston-Janowitz Calcium
Score of 239; Percentile: 99%. (d) The left circumflex demonstrated a 90% stenosis that was treated with angioplasty
and stent placement. (e) There was nonobstructive plaque in
the left anterior descending artery
ab
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8.8 Case 8
disease, diabetes mellitus, hypertension, hyperlipidemia, and kidney disease. He had used aspi-
A 66-year-old male presented with worsening
rin in the preceding week. TIMI risk score: 3.
chest pain that was consistent with unstable
angina. He had a history of peripheral artery
dc
Fig. 8.8 (a) Axial view shows focal significant stenosis
of 70% was found in the proximal left anterior descending artery due to a noncalcified soft plaque. (b, c) Two
curved MPR views further illustrate the soft plaque. The
patient had an Agatston-Janowitz Calcium Score of 54;
Percentile: 58. (d) The left anterior descending artery
showed 80% proximal stenosis that was reduced to 0%
via a drug-eluting stent with post-dilatation balloon.
TIMI 3 flow was seen after deployment
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