Translational Research in Anatomy 22 (2021) 100083
Contents lists available at ScienceDirect
Translational Research in Anatomy
journal homepage: www.elsevier.com/locate/tria
Cardiac ultrasound: An Anatomical and Clinical Review
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a
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Islam Aly , Asad Rizvi , Wallisa Roberts , Shehzad Khalid , Mohammad W. Kassem ,
Sonja Salandya, Maira du Plessisa, R. Shane Tubbsa,c,d,e, Marios Loukasa,f,∗
T
a
Department of Anatomical Sciences, School of Medicine, St George's University, West Indies, Grenada
Mercy Health Neuroscience Institute, Mercy St. Vincent Medical Center, Toledo, OH, USA
Department of Neurosurgery, Tulane University School of Medicine, New Orleans, LA, USA
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Department of Structural and Cellular Biology, Tulane University School of Medicine, New Orleans, LA, USA
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Department of Neurosurgery and Ochsner Neuroscience Institute, Ochsner Health System, New Orleans, LA, USA
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Department of Anatomy, University of Warmia and Mazury, Olsztyn, Poland
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ARTICLE INFO
ABSTRACT
Keywords:
Echocardiography
Ultrasonography
Heart diseases
Heart
Transesophageal echocardiography
Cardiac imaging techniques
Background: The importance of cardiac examination is supported by the ever-increasing incidence of heart
disease. Traditional examination and auscultation techniques may not provide the level of sensitivity required
for identifying certain conditions. Development of cardiac ultrasound (echocardiography) techniques has added
greatly to the discipline. Ultrasound images do not only provide a means of diagnosis but allow for the devel­
opment of treatment modalities and easy monitoring of disease progression.
Results: Cardiac images may be obtained via several techniques; some are invasive while most are not.
Transthoracic ultrasound may be achieved via several windows in different planes of view and is non-invasive.
While it allows for better imaging of all cardiac structures, some parts such as the mitral and aortic valve
function can be viewed best by transesophageal echocardiography, a more invasive technique. Each modality
and window tend to be more sensitive to certain cardiac structures than others.
Conclusions: This review discusses the different modalities and their advantages and provides a comparison to
other imaging modalities.
Dear Dr. Mario Loukas,
1. Introduction
Cardiac ultrasound, often referred to as echocardiography, has been
integrated into the functional cardiac evaluation of cardiovascular
disease. Although a very basic imaging modality, it provides vast
amounts of information about cardiac structures and function. In fact,
its simplicity is the very reason it is used. Echocardiography is one of
the first line imaging modalities for cardiac assessment. It works by
utilizing sound waves that are described regarding frequency, to view
images.
Echocardiography has become the modality of choice in the initial
assessment of cardiac disease because it is non-invasive, easy to use,
and provides high-resolution imaging and real-time feedback [1]. The
two most common types of cardiac ultrasound are transthoracic echo­
cardiography (TTE) and transesophageal echocardiography (TEE). Each
of these provides an assessment of cardiac structures from some various
views, each with its advantages and disadvantages. Placement of the
∗
transducer is key, and manipulation of it provides for proper imaging
technique. The area in which a transducer is placed is referred to as a
cardiac window [2].
2. Imaging modes
Three different basic modes are often referred to in echocardio­
graphy and are employed for a better understanding of the different
structural and functional elements of the heart.
2.1. Two-dimensional or B-mode
The most basic and standard form of echocardiography that allows
for assessment of the cardiac structures in a real-time cross-sectional
view is the two-dimensional echocardiography. The image generated by
2-D echocardiography is composed of reflections that are made off of
interfaces. The transducer sends out sound waves, which then echoes
off of the structure [3]. Two-dimensional echocardiography (2DE) is
particularly useful for the adequate assessment of the morphological
Corresponding author. Department of Anatomical Sciences, St. George's University, School of Medicine, West Indies, Grenada.
E-mail address: mloukas@sgu.edu (M. Loukas).
https://doi.org/10.1016/j.tria.2020.100083
Received 15 July 2019; Received in revised form 25 July 2020; Accepted 27 July 2020
Available online 31 July 2020
2214-854X/ © 2020 Published by Elsevier GmbH. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/).
Translational Research in Anatomy 22 (2021) 100083
I. Aly, et al.
and functional properties of the left ventricle. This method facilitates
the visual approximation of the ejection fraction (EF) using the mea­
sured left ventricular (LV) volume. The recommended method is the
“Simpson biplane method,” in the apical 4- chamber and apical 2chamber views. This information provided by this scan allows for the
prediction of cardiovascular disease likelihood [4].
Three-dimensional echocardiography (3DE) is quickly becoming the
modality of choice over 2DE. Currently, since the technology is still
being refined, it is used to complement 2DE [4]. Three-dimensional
echocardiography (3DE) is superior to the two-dimensional echo­
cardiography (2DE) because of its realistic imaging of native valves and
their anatomic relationships; improved geometric quantification of the
valve, and improved reproducibility of disease severity results [3]. It
supplements 2DE's prosthetic valve evaluation, allowing visualization
of the valve from any orientation. 3DE offers narrow-angle, zoom or
magnified, and wide-angle acquisition modes, resulting in varying
pyramidal scan volumes and degrees of spatial resolution, which allows
for characterization of specific components of the valvular apparatus
[3]. Moreover, 3DE allows for a more accurate evaluation of left ven­
tricular volume and mass and the left atrium. This improved imaging
results from the fact that 3DE does not rely on geometric approximation
as does 2DE [4]. The result is more accurate results which correlate
more precisely with patient outcome statistics [5]. Development is still
underway with regards to 3DE assessment of right ventricular volumes
and function. Some notable shortcomings of the 3DE are the poor
temporal resolution, and a deficiency with regards to the information
color Doppler offers [4]. A comparison of the advantages and dis­
advantages of 2D and 3D echocardiography is given in Table 1.
3. Transthoracic echocardiography
Transthoracic echocardiography (TTE) has become the modality of
choice within the emergency setting due to the speed with which it's
done, as well as its noninvasive nature. The ease with which the clin­
ician uses TTE is dependent on his/her knowledge of the windows and
views that the device can produce, especially since each window allows
for the identification and assessment of a different cardiac structure.
The proper technique of transducer placement when performing a TTE
is directly on the patient's chest in one of the four windows: parasternal,
apical, subcostal, and suprasternal [8]. The transducer used has a fre­
quency that ranges from 3 to 5 MHz, which is slightly lower than that
for TEE. It is key to have a thorough understanding of transducer pla­
cement and manipulation to visualize the structures adequately.
4. Parasternal view
Two views are possible based on the direction of the probe resulting
in either a long or short axis view.
5. Parasternal long axis
To perform one of the parasternal views, the transducer is placed on
the left of the sternum, between the 3rd and 4th intercostal space with
the probe marker pointing towards the patient's right shoulder [8]
(Fig. 1). This is known as the long axis view and allows for the as­
sessment of the heart in slices [2]. Long axis parasternal views may be
obtained from both left and right. The left parasternal long-axis view
(as described above) is used for the identification of mitral valve pro­
lapse. Structures that are typically seen with this view include the
coronary sinus (within the atrioventricular groove), left ventricle in
sagittal view, right ventricular inflow tract, the left ventricular outflow
tract, and the descending aorta (posterior to the left atrium) [3]. When
the transducer is properly aligned one can assess and measure the left
ventricular outflow tract (LVOT), aorta left atrium and ventricle. This
view is one of few that allows for adequate Doppler evaluation of tri­
cuspid regurgitation and proper appraisal of right ventricular systolic
pressure [3].
The right parasternal long-axis view requires movement on the
patient's part. The patient must be in the right lateral decubitus position
with the transducer placed near the costochondral junction between the
3rd and 5th intercostal space [3]. To get an optimal image, the trans­
ducer must be angled towards the midline. This particular view allows
for the observance of the proximal ascending aorta. This window is of
great value in the assessment of aortic stenosis aiding in the estimation
of the degree of stenosis.
2.2. The M-mode
The M-mode, specifically used in the assessment of moving struc­
tures, produces a one-dimensional image based on the motion of the
sound waves away from the transducer and towards the structure being
detected. The lack of “spatial reference” makes the yield of useful
clinical information minuscule [6]. Thus, M-mode echocardiography is
rarely used, so much so that it is rarely included by guideline com­
mittees such as the American Society of Echocardiography [7].
2.3. The Doppler mode
This mode is used in the assessment of blood flow through the
cardiac vessels and chambers. Using this mode can help determine the
velocity as well as the direction in which blood flow travels. Thus, this
mode facilitates a hemodynamic assessment as the velocities are eval­
uated against time [4].
Clinically, this mode is utilized to assess the cardiac functional
capability, specifically as it relates to diastolic function; pressures in the
pulmonary artery, left and right atria; left ventricular stroke volume;
and quantification of a regurgitant valve, if present [4]. Assessment of
the filling patterns of the left ventricle, in addition to the diastolic
function of the heart, has been shown to have clinical implications as it
relates to morbidity and prognostic evaluations [4].
5.1. Parasternal short axis
To obtain the short-axis view, the transducer probe is rotated 90°
from the left parasternal long-axis view with the marker pointed to­
wards the patient's left shoulder (Fig. 2). This view helps with the
evaluation of the majority of valves (tricuspid, pulmonic, aortic), as
well as, the right ventricle. The aortic valve can be identified as the
“Mercedes Benz” sign. The short axis is also said to provide a better
Table 1
Comparison of 2-D and 3-D echocardiography.
Imaging modality
Advantages
Disadvantages
2-D echocardiography
-Better temporal and spatial resolution
-Easier probe to maneuver
-No geometric assumptions required when assessing volumes or areas
-Only slices of structures can be seen (the rest has to be based on memory)
3-D echocardiography
-Limited temporal and spatial resolution
-Software for 3D is rarely available
Adapted from Monaghan M and Adhya S; Three dimensional echocardiography (Chapter 3 in The EAE Textbook of Echocardiography). Oxford University press,
2011; pp. 36.
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Fig. 1. Parasternal long-axis view (Illustration by Angélica Ortiz ©2019, provided under CC-BY–NC–ND).
7. Subxiphoid view
view of the coronary arteries (left anterior descending, circumflex and
right coronary) [8].
The best way to access imaging in this window is by having the
patient hold their breath upon inhalation. Another way to do this is by
having them bend their knees while in the supine position, which is also
commonly referred to as the xiphoid or sub-xiphoid view. The concept
behind these positions, irrespective of the technique used, is to allow
the patient's abdominal muscles to relax as images may otherwise be
skewed. The transducer is placed in the xiphoid or epigastric position,
with the probe towards the sternum and the notch at the three o'clock
position (Fig. 4). This view yields optimal images of the four chambers
of the heart with the aortic valve at the center of the image, just
anterior to the left atrium and posterior to the right ventricular outflow
tract. The right ventricle situated at the top of the image and the atria
towards the left side [3]. This view is of extreme importance in an
emergency setting because it allows for easy assessment of pericardial
effusion.
Various authors have emphasized the use of this view during peri­
cardiocentesis procedures. Using the sub-xiphoid view for needle gui­
dance can help decrease the risk of iatrogenic cardiac tamponade [9].
Maizel et al. [10] assessed whether the use of the sub-xiphoid window
could be used as an accurate alternative in the absence of the apical
view in the management of hemodynamic parameters since both views
are highly regarded in the emergency setting. They concluded that in
the absence of an apical view, the sub-xiphoid view could only provide
partial information. Therefore adequate assessment of hemodynamic
6. Apical view
This is used synonymously with the phrase: “four-chamber view,”
although it is not the only window in which all four chambers are
visible. The apical view ultrasound is also performed in the supine
position; however, it may be difficult to perform in certain patients. If
optimal images are not obtained in this way, the patient is turned to­
wards their left, the so-called left decubitus position, while the probe is
maintained in position. This is the same technique employed in similar
patients to locate the apical pulse. The four-chamber view allows for the
assessment of some cardiac structures. In an ideal four-chamber view,
the annuli of both atrioventricular valves are visible; this allows for
accurate calculation of their dimensions [3] (Fig. 3). This window can
aid in the evaluation of end-diastolic and end-systolic volumes of the
left ventricle. Thus, it allows the clinician to estimate the ejection
fraction. The use of the Doppler in this manner becomes quite bene­
ficial, as not only does the apical 4-chamber view allow visualization of
the right ventricular free wall, but it also aids in the clinical assessment
of the functioning of the structures during systole [2]. According to
Lang et al. [3], the apical view is also valuable in the assessment of
atrioventricular valve function and bi-atrial size.
3
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Fig. 2. Parasternal short-axis view (Illustration by Angélica Ortiz ©2019, provided under CC-BY–NC–ND).
essential imaging modality for interventional cardiologists and cardiac
surgeons. Various authors consider TEE as the “gold standard” imaging
modality for the posterior cardiac structures, such as the left atrium,
mitral valve, and sub-valvular apparatus, interatrial septum and left
atrial appendage [8]. TEE is typically used when images produced by
TTE are found to be suboptimal. TEE is of particular importance in the
evaluation of valvular disease because of its accuracy in acquiring
valvular measurements [3]. Unlike TTE, TEE has quite some views; the
following are the commonly used midesophageal views.
parameters would not be attained [10]. The sub-xiphoid view was
found to be reliable in the evaluation of both ventricular morphology
and function [10]. Haemodynamically, the sub-xiphoid view has
proven to be successful in assessing mitral flow, aortic flow, as well as,
left ventricular ejection fraction.
8. Suprasternal view
The suprasternal view is not typically used because it can be quite
uncomfortable for the patient. Typically to attain proper images in this
view, the patient must be in the supine position with their neck ex­
tended and head slightly turned. The transducer is placed in the su­
prasternal notch, parallel to the trachea with the probe marker pointing
towards the right supraclavicular area [3] (Fig. 5). Placement of the
transducer is crucial for obtaining adequate images. This placement
allows for the imaging of the proximal portion of the aortic arch and a
portion of the ascending aorta.
9. Five chamber view
This is the first view that is encountered as the probe is advanced
down the esophagus. Several structures can be appreciated including
the aortic valve, left ventricular outflow tract, both atria and ventricles.
To get an optimal apical five-chamber view, a good apical four chamber
view. The objective of this view, as the name suggests is to visualize the
“5th chamber: the aorta. Since the aorta is the anterior most structure,
the probe needs to be angled superiorly: “this will cause the tricuspid
valve and RA to go out of the imaging plane, while the aorta will appear
in the middle of the screen.” In some cases, the previous intercostal
space should be used, with a more lateral placement of the probe to
allow for a better alignment with the LV outflow tract. This view has
proven to be quite useful in the diagnosis of valvular regurgitation,
8.1. Transesophageal echocardiography
Transesophageal echocardiography (TEE) utilizes a gastroprobe that
is advanced into the stomach through the esophagus (Fig. 6). TEE uses
less depth and higher frequency than TTE, allowing for greater re­
solution of the posterior cardiac structures [8]. TEE has become an
4
Translational Research in Anatomy 22 (2021) 100083
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Fig. 3. Apical view (Illustration by Angélica Ortiz ©2019, provided under CC-BY–NC–ND).
which can be analyzed by the use of color flow Doppler [3].
12. Two chamber view
To obtain this image, one must rotate the gastroprobe 80–100° from
the previous mitral commissural view. This view is used to appreciate
the left atria and its appendages, the left ventricle, and the mitral valve.
One can visualize both the anterior and inferior walls of the left ven­
tricle, as well as, the coronary sinus.
10. Four chamber view
This view is used for comprehensive assessment of cardiac anatomy
and function. This view specifically focuses on the evaluation of mitral
and tricuspid valve function and ventricular systole [3]. This view is
obtained by advancing the gastroprobe approximately 30–35 cm down
the esophagus. Other structures that can be appreciated in this view
include the left and right atria, interatrial septum, left and right ven­
tricles, and the inter-ventricular septum.
13. Long-axis view
This view is believed to reproduce the same image as the TTE threechamber view, yet obtaining this view is more complex than the TTE.
The transducer must be rotated 120–140° from the two-chamber view.
This view allows for the assessment of a number of structures including
the mitral valve, aortic valve, left atria and ventricle, left ventricular
outflow tract, and the proximal ascending aorta.
11. Mitral commissural view
Obtaining the mitral commissural view can be quite complex; it
requires proper angulation and manipulation of the probe. The gas­
troprobe must be rotated 50–70° from the four-chamber view to obtain
an ideal mitral commissural view. Therefore, without attaining an
adequate four-chamber view, a mitral commissural view may be
skewed. Diagnostically this view evaluates the left ventricular function
and mitral valve function. The anterolateral and posteromedial papil­
lary muscles (with attitudinally correct nomenclature will be super­
oposterior and inferior papillary muscles respectively) can be demar­
cated in this view along with their chordae tendineae [3].
14. Aortic valve views
Two views can be used to assess the aortic valve. The first, Aortic
valve long-axis view, is obtained by withdrawing the gastroprobe back
while still maintaining it at the rotated angle of 120–140° (which is
used for the basic long-axis view). This view is particularly used to
obtain the measurements of the sinotubular junction and the annulus of
the aortic valve. Although rare, one can utilize this view in the as­
sessment of the right coronary ostium. This view has become essential
in transcatheter aortic valve procedures [3]. The second, ascending
5
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Fig. 4. Sub-xiphoid view (Illustration by Angélica Ortiz ©2019, provided under CC-BY–NC–ND).
aorta long-axis view, allows for the assessment of the proximal as­
cending aorta. Obtaining this view is rather challenging: it requires
withdrawing the gastroprobe from the aortic long-axis view while ro­
tating it 90°.
cardiac source for their stroke or transient ischemic attack (TIA), only
18% were identified using TTE, the remainders were diagnosed on TEE.
In 2015, Biswas and Yassin [14] contended that TEE was a superior
initial diagnostic evaluation for endocarditis as TTE had a low sensi­
tivity of 29.6% for vegetation detection, especially with regards to the
mitral and tricuspid valves. They further asserted that while TTE was
cheaper, due to its low diagnostic yield, often prompting a TEE any­
ways, it would be more cost effective to adhere to the American Heart
Association guidelines and use TEE as the initial test in high-risk in­
dividuals.
Although TEE has proven to be extremely beneficial and precise in
the assessment of valves, it is more often utilized to assess for post­
operative complications [3]. As with any procedure, there are compli­
cations with the use of TEE imaging. First and foremost, one must take
into consideration that although minimally invasive, it is still invasive.
The most common complications while using TEE imaging include lip
injury and hoarseness. Some of the more serious complications can be
an esophageal perforation, major bleeding, heart failure and even death
in some cases. All the complications experienced with TEE are listed in
Table 2.
15. Comparison between TEE and TTE
Many studies have explored the difference in diagnostic yield be­
tween TTE or TEE. For the evaluation of valvular disease, TEE is fa­
vored over TTE, as previously mentioned. Grayburn et al. [11] com­
pared the results of baseline TEE and TTE imaging of the mechanism
and severity of functional mitral regurgitation in patients with ischemic
cardiomyopathy. The authors found that there was only a moderate
correlation between TTE and TEE measurements; the discrepancy was
believed to be a result of varying imaging planes. They also concluded
that TTE overestimates mitral regurgitation severity, in comparison
with TEE. Therefore, this study emphasized that TEE is the gold stan­
dard when it comes to the assessment of valve malfunction and dis­
eases.
Similarly, TEE was recognized as the gold standard for cardiovas­
cular source evaluation in patients with acute ischemic stroke patients,
who were deemed to have a low risk for cardiogenic emboli. In ap­
proximately half of the 68 patients assessed, TEE revealed an abnormal
lesion which demanded amendments to clinical treatment to reduce the
risk of further ischemic strokes. None of these lesions were apparent on
TTE [12]. de Bruijn and colleagues [13] came to a similar conclusion as
from the 59% (114/192) of patients identified as having a potential
16. Clinical significance
Echocardiography, as previously established, has been evolutionary
in the generation of non-invasive clinically useful cardiac images (see
Table 3). This has allowed for greater diagnostic yield and thus, more
precise clinical management. Some of the more common cardiac
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Fig. 5. Suprasternal view (Illustration by Angélica Ortiz ©2019, provided under CC-BY–NC–ND).
pathologies are discussed below, with regards to their echocardio­
graphic findings/relevance.
Thus, an accurate functional assessment of the valves is paramount to
the field of cardiology. Doppler echocardiography has emerged as the
imaging modality of choice for the detection and assessment of this
condition. Additionally, it also allows for the identification of the un­
derlying pathology. The severity of the valvular regurgitation can be
accurately assessed by an evaluation of the following three parameters
of the regurgitant jet: origin, as well as the width (vena contracta), flow
convergence, and spatial orientation in the recipient chamber. Being
able to accurately assess the severity directly impacts clinical decision
making as mild regurgitation is considered a benign condition versus
the more pathological severe regurgitation [15].
17. Dilated cardiomyopathy
Dilated cardiomyopathy is readily assessed with the use of echo­
cardiography. Notable changes on cardiac ultrasound include LV dila­
tation with normal thickness of the wall and increased mass.
Functionally, there is a reduction in the systolic function which is seen
as a reduction in the ejection fraction, and consequently the cardiac
output. Criteria dictate that an “LV internal diastolic dimension of
greater than 2.7cm/m2 of body surface area” is considered dilated [4].
20. Aortic stenosis
18. Hypertrophic cardiomyopathy
In developed countries, aortic stenosis represents the most common
valvular heart disease. While it has already been established that the
heart valves can be accurately assessed using echocardiography, in
patients with aortic stenosis, ultrasound goes beyond diagnosis and
clinical evaluation of severity. Recent advances have seen the in­
troduction of trans-catheter aortic valve replacement (TAVR) to replace
the more invasive surgical aortic valve replacement (SAVR) in patients
who are not surgically fit [16]. Echocardiography plays an integral role
in the TAVR procedure as it is used for a baseline assessment, in­
traoperatively, and postoperatively [17]. Baseline assessment requires
the use of TTE to first confirm the diagnosis of severe aortic stenosis in
the surgically unfit patient. Once this diagnosis is made, the dimension
of the aortic ring needs to be evaluated to determine the prosthesis size.
2DE is the gold standard for the assessment of hypertrophic cardi­
omyopathy. This diagnosis requires both imaging results, in combina­
tion with the clinical presentation. On echocardiography, a localized or
global thickening of the ventricle, without clinical comorbidities,
causing pressure overload raises the suspicion for this diagnosis.
Generally, a ventricular measurement of > 15 mm in the correct clin­
ical background is considered hypertrophic. 2DE also allows for the
assessment of the point of obstruction [4].
19. Valvular regurgitation
Valvular regurgitation is implicated in a number of pathologies.
7
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Fig. 6. Transesophageal echocardiography (Illustration by Angélica Ortiz ©2019, provided under CC-BY–NC–ND).
procedural complications such as mitral valve obstruction or paraprosthetic leaks. Moreover, it provides information with regards to the
procedure itself: balloon valvuloplasty, deployment of the prosthesis,
and functionality. Post-procedural TEE is done before discharge and
one month after as follow-up [17].
Table 2
Complications of TEE 1.
Complications
Incidence for diagnostic TEE
Lip injury
Hoarseness
Dysphagia
Major morbidity
Laryngospasm
Dental injury
Heart failure
Esophageal perforation
Mortality
Major bleeding
Bronchospasm
Minor pharyngeal bleeding
Arrhythmia
13%
12%
1.8%
0.2%
0.14%
0.1%
0.05%
< 0.01%
< 0.01%–0.02%
< 0.01%–0.02%
0.06%–0.07%%
0.01%–0.2%
0.06%–0.3%
21. Constrictive pericarditis
Constrictive Pericarditis is diagnostically challenging due to the
difficulty in differentiating between it and other etiologies of right heart
failure. In a recent systematic review, Ardhanari and colleagues [18]
suggested that echocardiography should be used as the initial non-in­
vasive modality of choice. They recognized that due to the high sensi­
tivities (> 90%); the absence of respiratory ventricular septal shift or
reduced mitral annular e’ (< 9 cm) on echocardiography can be used to
exclude constrictive pericarditis. Moreover, this imaging modality
provided an effective means of differentiating between other causes of
constrictive pericarditis. Nonetheless, the authors recognized that car­
diac MRI was the preferred choice. Thus, they suggested that cardiac
MRI should be used in cases in which the echocardiography was not
definitive, or cases, where echocardiography was definitive but more
accurate information was needed for surgical planning [18].
Adapted from Hahn RT, Abraham T, Adams MS et al. Guidelines for performing
a comprehensive transesophageal echocardiographic examination: re­
commendations from the American Society of Echocardiography and the
Society of Cardiovascular Anesthesiologists, J Am Soc Echocardiogr
26:921–964, 2013.
While multi-slice CT remains the gold standard, 2D or 3D echocardio­
graphy may be used. Intra-operatively, current procedural standards
dictate that TEE is used to determine LV function and immediate post8
Translational Research in Anatomy 22 (2021) 100083
I. Aly, et al.
Table 3
Comparison of Echocardiography to other imaging modalities.
Echocardiography
Advantages
Modalities
Limitations
1
2
3.
4.
5.
1.
2.
3.
4.
5.
6.
7.
8.
1.
2.
3.
4.
First line diagnosis and follow up
Easily accessible
Low cost
Safe
Bedside
M-mode
2D echo
Doppler
Tissue Doppler velocities
Deformation imaging
3D echo
Contrast echo
Twist and rotation
Limited windows
Poor quality images
Operator dependent
Limited tissue characterization
Cardiac CT
CMR
1.
2.
3.
4.
Better anatomic description
Evaluates associated/extracardiac disease
Pre-op planning
Detects pericardial calcification
1.
2.
3.
4.
Better anatomic description
Evaluates associated/extracardiac disease
Pre-op planning
Repeatable
1.
2.
3.
4.
Axial imaging
Multiplanar reconstruction
Volume rendered imaging
Cine-imaging
1.
2.
3.
4.
5.
6.
Bright blood-single-shot SSFP
Black blood images (+STIR)
Tagged cine-images
Bright blood cine-images
Late gadolinium enhancement images
Real-time gradient-echo cine-images
1. Ionizing radiation
2. Iodinated contrast
3. Functional evaluation only possible with retrospectivegrated studies
4. Difficult in case of arrhythmias
5. Need for breath-hold
6. Haemodynamically stable patients only
1.
2.
3.
4.
5.
6.
Time consuming
High cost
Difficult in case of arrhythmias
Contraindicated with some devices (pacemakers)
Calcifications not well visualized
Gadolinium not recommended if glomerular filtration rate
< 30 mL/min
7. Need for breath-hold
8. haemodynamically stable patients only
Adapted from Verhaert D,Gabriel RS,Johnston D,Lytle BW,Desai MY,Klein AL.Theroleofmulti-modality imaging in the management of pericardial disease. Circ
Cardiovasc Imaging 2010; 3:333–43.
22. Circulatory shock
echogenicity of the blood, especially when comes to the examination of
the heart, vessels and vascularization in general. Studies have shown
that CEUS has high diagnostic accuracy especially differentiation be­
nign from malignant tumors, thrombus from tumors, degree of neo­
vascularization etc [22–24].
Approximately one-third of all critically ill patients go into circu­
latory shock. Circulatory shock is a medical emergency due to its in­
creased risk for multiorgan failure, and eventually death. A combina­
tion of “best practice” parameters is used to assess for shock: vitals, skin
perfusion, urine output, and mental status. However, in case scenarios
where the inciting cause remains elusive, critical care ultrasound
(CCUS) is recommended to assess the cardiac function, in an effort to
reveal the type of shock. However, further research is needed to eval­
uate the diagnostic and prognostic value of CCUS in circulatory shock
[19].
24. Nomenclature
This paper is using the attitudinal correct nomenclature as described
by Loukas et al. [25],
25. Conclusion
Echocardiography has revolutionized cardiac assessment. It allows
for evaluation of cardiac disease in a cost-efficient, and minimally in­
vasive manner making it appealing to both patient and clinician. Threedimensional imaging has allowed for a more definitive image replica of
cardiac anatomy. Transthoracic echocardiography has become the
preferred modality for cardiac chamber quantification, whereas trans­
esophageal echocardiography is used in the assessment of valvular
diseases and posterior cardiac structures. Echocardiography, unlike
other imaging modalities, does not require a patient to maintain re­
stricted positions. MRI and CT require patients to be immobile, to hold
their breath (which may be troublesome for those with orthopnea
secondary to cardiomyopathy or mitral regurgitation), exposes them to
radiation (in the case of CT), and are time consuming (in the case of
MRI) [26]. Due to the ease of assessment and diagnosis with ideal
images echocardiography will continue to be the imaging modality of
choice.
23. Echocardiography vs. other imaging modalities
Most clinicians have turned to the use of echocardiography and
Doppler as first-line imaging modalities when there is suspicion of
cardiac disease. It is favorable due to the low cost and less invasiveness
in comparison with other imaging modalities [20]. Other imaging
modalities that have been used particularly in individuals with con­
genital heart disease include CT and MRI.
Although both CT and MRI may be costly, at times, they are ex­
tremely beneficial, especially for elderly patients with poor acoustic
windows, in whom echocardiography may not be the best modality [1].
Before aortic valve replacement, images are taken to get the proper
measurements in order to size the valve. Transthoracic echocardio­
graphy has provided optimal images in the assessment of aortic valves.
However, these images are not always adequate for transcatheter aortic
valve replacement. In a comparative study, Vaquerizo and colleagues
[21] evaluated the difference between 3D-TEE and multi-slice CT when
measuring the aortic annulus. They assessed the aortic annulus of 53
individuals, with both multi-slice CT and 3D-TEE imaging. The authors
found a 9% difference in measurements between the two imaging
modalities. 3D-TEE provided smaller measurements than those ob­
tained by multi-slice CT. It was suggested that although 3D-TEE may be
beneficial in the assessment of the non-circular area of the valve, it is
not the only modality that should be used when assessing the mea­
surements needed for the replacement valve [21].
Lastly, contrast-enhanced ultrasound (CEUS) is the newest imaging
modality that utilizes microbubble-based contrast media to enhance the
Ethical considerations
Ultrasound images used in this paper were taken with permission
from healthy volunteers.
Ethical statement
I testify on behalf of all co-authors that our article submitted to
Translational Research in Anatomy that;
1) this material has not been published in whole or in part
9
Translational Research in Anatomy 22 (2021) 100083
I. Aly, et al.
elsewhere;
2) the manuscript is not currently being considered for publication
in another journal;
3) all authors have been personally and actively involved in sub­
stantive work leading to the manuscript and will hold themselves
jointly and individually responsible for its content.
In regard to our manuscript, “Cardiac Ultrasound: An Anatomical
and Clinical Review.“, the authors wish to report no conflicts of interest
associated with this publication. We confirm that the manuscript has
been read and approved by all named authors and that there are no
other persons who satisfied the criteria for authorship but are not listed.
We further confirm that the order of authors listed in the manuscript
has been approved by all of us.
We confirm that we have given due consideration to the protection
of intellectual property associated with this work and that there are no
impediments to publication, including the timing of publication, with
respect to intellectual property. In so doing we confirm that we have
followed the regulations of our institutions concerning intellectual
property.
Any correspondence should be directed to me at the following ad­
dress:
Marios Loukas (Corresponding author).
Anatomy Department.
St. George's University, School of Medicine.
St. George's, Grenada.
[9] F. Vayre, H. Lardoux, M. Pezzano, J. Bourdarias, O. Dubourg, Subxiphoid peri­
cardiocentesis guided by contrast two-dimensional echocardiography in cardiac
tamponade: experience of 110 consecutive patients, Eur. J. Echocardiogr. 1 (2000)
66–71.
[10] J. Maizel, A. Salhi, C. Tribouilloy, Z. Massy, G. Choukroun, M. Slama, The sub­
xiphoid view cannot replace the apical view for transthoracic echocardiographic
assessment of hemodynamic status, Crit. Care 17 (2013) R186.
[11] P. Grayburn, L. She, B. Roberts, K. Golba, K. Mokrzycki, J. Drozdz, A. Cherniavsky,
R. Przybylski, K. Wrobel, F.M. Asch, T.A. Holly, H. Haddad, M. Yii, G. Mauer,
I. Kron, H. Schaff, E.J. Velazquez, J.K. Oh, Comparison of Transesophageal and
Transthoracic Echocardiographic measurements of mechanism and severity of mi­
tral regurgitation in ischemic cardiomyopathy (from the surgical treatment of is­
chemic heart failure trial), Am. J. Cardiol. 116 (2015) 913–918.
[12] A. Blum, S. Reisner, Y. Farbstein, Transesophageal echocardiography (TEE) vs.
transthoracic echocardiography (TTE) in assessing cardiovascular sources of emboli
in patients with acute ischemic stroke, Med. Sci. Mon. Int. Med. J. Exp. Clin. Res. 10
(2004) CR521–523.
[13] S.F.T.M. de Bruijn, W.R.P. Agema, G.J. Lammers, E.E. van der Wall, R. Wolterbeek,
E.R. Holman, E.L.E.M. Bollen, J.J. Bax, Transesophageal echocardiography is su­
perior to transthoracic echocardiography in management of patients of any age
with transient ischemic attack or stroke, Stroke 37 (2006) 2531–2534.
[14] A. Biswas, A.M.H. Yassin, Comparison between transthoracic and transesophageal
echocardiogram in the diagnosis of endocarditis: a retrospective analysis, Int. J.
Crit. Illn. Inj. Sci. 5 (2015) 130–131.
[15] W.A. Zoghbi, M. Enriques-Sarano, E. Foster, P.A. Grayburn, C.D. Kraft, R.A. Levine,
P. Nihoyannopoulos, C.M. Otto, M.A. Quinonones, H. Rakowski, W.J. Stewart,
A. Waggoner, N.J. Weissman, American society of echocardiography: re­
commendations for evaluation of the severity of native valvular regurgitation with
two-dimensional and Doppler echocardiography: a report from the American so­
ciety of echocardiography's nomenclature and standards committee and the task
force on valvular regurgitation, developed in conjunction with the American college
of cardiology echocardiography committee, the cardiac imaging committee, council
on clinical cardiology, the American heart association, and the European society of
cardiology working group on echocardiography, Eur. J. Echocardiogr. 4 (2003)
237–261.
[16] G. Tarantini, P.A.M. Purita, A. D'Onofrio, C. Fraccaro, A.C. Frigo, G. D'Amico,
L.N. Fovino, M. Martin, F. Cardaioli, M.R.A. Badway, M. Napodano, G. Gerosa,
S. Iliceto, Long-term outcomes and prosthesis performance after transcatheter aortic
valve replacement: results of self-expandable and balloon-expandable transcatheter
heart valves, Ann. Cardiothorac. Surg. 6 (2017) 473–483.
[17] C. Caldararu, S. Balanescu, Modern use of echocardiography in transcatheter aortic
valve replacement: an Up-Date, Mædica 11 (2016) 299–307.
[18] S. Ardhanari, B. Yarlagadda, V. Parikh, K.C. Dellsperger, A. Chockalingam, S. Balla,
S. Kumar, Systematic review of non-invasive cardiovascular imaging in the diag­
nosis of constrictive pericarditis, Indian Heart J. 69 (2017) 57–67.
[19] B. Hiemstra, R.J. Eck, G. Koster, J. Wetterslev, A. Perner, V. Pettila, H. Snieder,
Y.M. Hummel, R. Wiersema, A.M.F. A de Smet, F. Keus, I.C. C van der Horst,
Clinical examination, critical care ultrasonography and outcomes in critically ill:
cohort profile of the Simple Intensive Care Studies-I, BMJ. Open. 7 (2017) e017170.
[20] J. Roelandt, The 50th anniversary of echocardiography: are we at the dawn of a
new era? Eur. J. Echocardiogr. 4 (2003) 233–236.
[21] B. Vaquerizo, M. Spaziano, J. Alali, D. Mylote, P. Theriault-Lauzier, R. Alfagih,
R.G. Martucci, J. Buithieu, N. Piazza, Three-dimensional echocardiography vs.
computed tomography for transcatheter aortic valve replacement sizing, Eur. Heart.
J. Cardiovasc. Imaging 17 (2016) 15–23.
[22] X. Wang, Y. Li, W. Ren, X. Yu, X. Tan, Clinical diagnostic value of contrast-enhanced
ultrasonography in the diagnosis of cardia masses: a pilot study, Echocardiography
37 (2020) 231–238.
[23] L.E. Mantella, K.N. Colledanchise, M.F. Hétu, S.B. Feinstein, J. Abunassar,
A.M. Johri, Carotid intraplaque neovascularization predicts coronary artery disease
and cardiovascular events, Eur. Heart. J. Cardiovasc. Imaging. 20 (2019)
1239–1247.
[24] R. Motoyama, K. Saito, S. Tonomura, H. Ishibashi-Ueda, H. Yamagami, H. Kataoka,
Y. Morita, Y. Uchihara, K. Iihara, J.C. Takahashi, K. Sugie, K. Toyoda, K. Nagatsuka,
Utility of Complementary Magnetic Resonance plaque imaging and contrast-en­
hanced ultrasound to detect carotid vulnerable plaques, J. Am. Heart. Assoc. 8
(2019) e011302.
[25] M. Loukas, I. Aly, R.S. Tubbs, R.H. Anderson, The naming game: a discrepancy
among the medical community, Clin. Anat. 29 (2016) 285–289.
[26] D. Dudzinski, J. Hung, Echocardiographic assessment of ischemic mitral regur­
gitation, Cardiovasc. Ultrasound 12 (2014) 1–16.
Declaration of competing interest
The authors declare that there are no conflicts of interest.
Acknowledgments
The authors wish to thank Angélica Ortiz, MS, CMI, Medical
Illustrator for the illustrations used in this publication. We also wish to
acknowledge the individuals who donated their bodies without whom
this project would not have been possible.
References
[1] R. Pignatelli, C. McMahon, T. Chung, G. Vick, Role of echocardiography versus MRI
for the diagnosis of congenital heart disease, Curr. Opin. Cardiol. 18 (2003)
357–365.
[2] K. Horton, Case Based Echocardiography, first ed., Springer-Verlag London Ltd,
London, 2011, pp. 13–21.
[3] R.M. Lang, W. Tsang, L. Weinert, V. Mor-Avi, S. Chandra, Valvular heart disease, J.
Am. Coll. Cardiol. 58 (2011) 1933–1944.
[4] M.F. Jan, J. Tajik, Modern imaging techniques in cardiomyopathies, Circ. Res. 121
(2017) 874–891.
[5] T. Stanton, C. Jenkins, B.A. Haluska, T.H. Marwick, Association of outcome with left
ventricular parameters measured by two-dimensional and three-dimensional
echocardiography in patients at high cardiovascular risk, J. Am. Soc. Echocardiogr.
27 (2014) 65–73.
[6] J. Roelandt, The Practice of M-Mode and Two-Dimensional Echocardiography,
Martinus Nijhoff Publishers, Massachusetts, MA, 1983.
[7] H. Frigenbaum, Role of M-mode technique in today's echocardiography, J. Am. Soc.
Echocardiogr. 23 (2010) 240–257.
[8] S. Shillcutt, J.A. Bick, Comparison of basic transthoracic and transesophageal
echocardiography views in the perioperative setting, Anesth. Analg. 116 (2013)
1231–1236.
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