Sequencial segmental approach to chd

© 2020 Journal of the Indian Academy of Echocardiography & Cardiovascular Imaging | Published by Wolters Kluwer - Medknow244
Focus Issue - Congenital Heart Disease
Introduction
A systematic segmental analysis of cardiovascular anatomy is
essential for optimal management of patients with congenital
heart disease (CHD). Understanding cardiac anatomy is integral
to the pediatric cardiology training, while it is much less
discussed among adult cardiologists and echocardiographers.
Nonetheless, it is not uncommon for an adult cardiologist and
echocardiographers to encounter a patient with unrepaired or
repaired CHD. Therefore, it is important to understand the
basics of sequential segmental approach. Besides, the uniform
use of such an approach helps in easy communication among
team members managing a patient with suspected CHD.
For obvious reasons, while most anatomic details are well
delineated on echocardiography, it is not always possible to
demonstrate all aspects of cardiac anatomy and necessitate the
use of other imaging modalities. In this article, we provide a
brief description of the sequential segmental approach to cardiac
anatomy with an emphasis on echocardiographic evaluation.
Sequential Segmental Analysis
Van Praagh first conceptualized the segmental classification
of cardiac anatomy.[1]
Their description was limited to
relationships of three main cardiac segments, namely, the
atrial chambers, the ventricles, and the arterial trunks. Later
in the 1970s, Anderson et al. highlighted the importance of
morphology of the connecting segments, atrioventricular (AV)
and ventriculoarterial (VA) junctions, in defining cardiac
malformations.[2]
It is also well known that the assessment
of each cardiac segment should be strictly based on its
morphologic characteristics and not on its location, orientation,
and connection with other segments.[3]
This assumes greater
significance in the setting of CHD, where the variation in
the orientation and connection of various cardiac segments
is common. The sequential segmental analysis is a 10‑step
approach for a detailed assessment of “main segments” and
“connecting segments” of the heart.
Thoraco‑abdominal situs
The situs refers to the spatial orientation and sidedness of organs.
Normally, visceral organs are lateralized. The arrangement of
thoraco‑abdominalorgansisimportantasitprovidesinformation
about the atrial arrangement, thus laying the foundation for
further analysis of cardiac morphology (see later).
Sequential Segmental Approach to Congenital Heart Disease
Samir Shakya1
, Palleti Rajashekar2
, Saurabh Kumar Gupta1
1
Department of Cardiology, All India Institute of Medical Sciences, New Delhi, India, 2
Department of Cardiothoracic and Vascular Surgery, All India Institute of Medical
Sciences, New Delhi, India
The sequential segmental approach is essential for better understanding of cardiac anatomy in normal and malformed hearts. It is based on
a detailed analysis of the three main cardiac segments, namely atria, ventricles, and great vessels, and the two connecting segments, namely
atrioventricular and ventriculoarterial connections. Each segment is systematically defined based purely on its morphological characteristics.
In most cases, echocardiography is sufficient, but some cases necessitate the use of other imaging modalities. Systematic identification of
different segments, connections, and their abnormalities helps in making an accurate diagnosis of congenital heart disease (CHD). This review
provides a brief description of the sequential segmental approach for detecting CHD on echocardiography.
Keywords: Congenital heart disease, echocardiography, sequential segmental approach
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Abstract
Address for correspondence: Dr. Saurabh Kumar Gupta,
Department of Cardiology, Room No. 9, 8th
Floor, Cardio‑Thoracic Sciences
Centre, All India Institute of Medical Sciences, New Delhi ‑ 110 029, India.
E‑mail: drsaurabhmd@gmail.com
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How to cite this article: Shakya S, Rajashekar P, Gupta SK. Sequential
segmental approach to congenital heart disease. J IndianAcad Echocardiogr
Cardiovasc Imaging 2020;4:244-52.
Submitted: 10‑Sep‑2020 Accepted in Revised Form: 02‑Oct‑2020
Published: 18-Dec-2020
Videos Available on: www.jiaecho.org
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Shakya, et al.: Sequential segmental approach to CHD
Journal of the Indian Academy of Echocardiography & Cardiovascular Imaging ¦ Volume 4 ¦ Issue 3 ¦ September-December 2020 245
In situs solitus or usual arrangement, the spleen, pancreas,
stomach, and sigmoid colon are located on the left, while the
liver, cecum, and appendix are on the right side.The left lung has
two lobes with a relatively longer bronchus that lies below the
left pulmonary artery (hyparterial). The right lung, in contrast,
has three lobes and a wider, shorter bronchus that lies above the
right pulmonary artery (eparterial) [Figure 1]. In some cases, the
arrangement is a mirror image of the normal. This arrangement
istermedassitusinversusalthoughthereisnoup‑downinversion
oforgans.However,foreaseofcommunication,wewillcontinue
to use the terms “situs solitus” and “situs inversus” in this article.
Sometimes, thoraco‑abdominal organs lack asymmetry, and the
arrangement is inconsistent. This arrangement, also known as
situs ambiguous or visceral heterotaxy, is commonly associated
with the isomerism of atrial appendages (see later) and has high
chances of CHD.[4]
Cardiac position
The position of the heart in the chest cavity provides important
clues about cardiac anatomy and underlying CHD. Most often,
the heart is left‑sided in the setting of situs solitus, whereas
it lies on the right side if there is situs inversus. The cardiac
position other than expected for the thoraco‑abdominal situs
is associated with a high likelihood of CHD.
The description of the cardiac position includes:
1. The position of the cardiac mass relative to the midline.
The heart can be left‑sided (levocardia), right‑sided
(dextrocardia), or lie in the midline (mesocardia)
2. The orientation of the long axis (base to apex) of the
heart.[5]
In most instances, the cardiac position and base‑to‑apex
orientation are concordant, and it is sufficient to describe
the cardiac position. The discrepancy on rare occasion
necessitates a description of both features separately.
Cardiac segments
Atrial situs
The identification of cardiac morphology starts from the
determination of which atrium is the right atrium (RA) and
which is the left atrium (LA). The atria are defined neither
by their venous connections nor by the side of the body on
which the atrium lies. Instead, it is the morphological features,
particularly of the atrial appendage, that defines a chamber as
morphologically RA or LA. Based on the morphology of the
atrial appendage, the atrial arrangement is classified as:
i. Usual arrangement or situs solitus: morphological RA
located to the right of the morphological LA
ii. Mirror image arrangement or situs inversus:
morphological RAlocated to the left of the morphological
LA. This is a left–right inverted arrangement compared
to situs solitus
iii. Atrial isomerism or situs ambiguous: both the atriums have
morphologically similar appendage. The arrangement
can be either right isomerism or left isomerism. This
arrangement is commonly associated with disorganized
left–right symmetry of abdominal organs and is also known
as heterotaxy syndrome.
In clinical practice, it is common to encounter difficulties in the
exact localization of atriums. In such a scenario, since a high
Figure 1: The arrangement of thoraco-abdominal organs in situs solitus, situs inversus, and situs ambiguous. Situs solitus has trilobed right lung
with eparterial bronchus, bilobed left lung with hyparterial, right-sided liver, and left-sided spleen and stomach. The arrangement in situs inversus is
a mirror image of situs solitus. In situs ambiguous or visceral heterotaxy, the liver is in the midline and splenic abnormalities are common. Both the
lungs are bilobed or trilobed in the setting of left or right isomerism, respectively

Journal of the Indian Academy of Echocardiography & Cardiovascular Imaging ¦ Volume 4 ¦ Issue 3 ¦ September-December 2020246
concordance exists between thoraco‑abdominal, bronchial, and
atrial situs, the atrial situs is adjudged based on the relative
position of the inferior vena cava (IVC) and the aorta.[6]
In situs
solitus, the aorta is to the left of the spine, and the IVC lies
anterior and to the right of the aorta [Figures 2 and 3 and Video
1]. In cases with situs inversus, the aorta is to the right with the
IVC lying to its left and anterior. On most occasions, drainage
of a patent IVC identifies the RA, although rarely it can drain
anomalously to the LA.[7]
In the setting of left isomerism,
sometimes, the infrahepatic portion of the IVC is interrupted,
and instead, the blood from the lower body drains via azygos
vein, which runs posterior to aorta. The identification of the
arrangement of the abdominal situs is readily possible on
echocardiography. The assessment of bronchial situs, however,
mandates chest X‑ray or computed tomography.
In patients with a good acoustic window, it is possible to define
the morphology of the atrial appendage. Broadly speaking, an
atrium with a triangular appendage with a broad base and a
wide mouth is a morphological RA [Figure 4 and Videos 2 and
3]. The LA, on the other hand, has a long, tubular, finger‑like
appendage with a narrow orifice [Figure 5a and Video 4].
The parasternal short‑axis view is often sufficient to define
the LA appendage. The subcostal long‑axis view enables
visualization of the RA appendage. Some cases with complex
cardiac malformation or poor acoustic window mandate
transesophageal echocardiography or other cross‑sectional
cardiac imaging such as computed tomography or magnetic
resonance imaging.
Venoatrial connection
Apart from atrial situs, it is important to delineate the
venous connection to the atrial chambers. A combination
of subcostal, thoracic, and suprasternal views is generally
sufficient [Figure 4 and Video 2]. In some cases with difficulty
and suspicion of anomalous systemic venous connection,
a carefully performed and interpreted saline‑contrast
echocardiography is extremely useful.[7]
Compared to systemic
veins, the delineation of pulmonary veins is more challenging.
In children and adolescents with normal connections, a
modified high parasternal view, also known as crab view, is
most useful for defining the connection of all four pulmonary
veins. A similar modified parasternal short‑axis view also
provides details of the common chamber and pulmonary
veins in patients with supracardiac and cardiac forms of total
anomalous pulmonary venous connection. Obtaining these
views in adults is challenging, where the apical four‑chamber
view and subcostal view are used to delineate the connection
of pulmonary veins to LA.
Atrioventricular valve
Morphologically, the AV valve represents the ventricular
chamber and it is one of the features used to identify a ventricle
as right or left. In hearts with concordant AV connections, the
tricuspid valve guarding the rightAV junction has three leaflets
and is positioned distally (apical offsetting) compared to the
left‑sided bi‑leaflet mitral valve [Figure 6 and Videos 5 and 6].
Unlike the mitral valve, the tensor apparatus of the tricuspid
valve connects to the ventricular septum. These findings
are useful in echocardiographic identification of tricuspid
and mitral valves. In the setting of atrioventricular septal
defect (AVSD), the AV valve is common with no apical
offsetting of the left and the right components of the valve.[8]
Since the valve is common and does not possess characteristics
of a normal mitral or tricuspid valve, it is better to use the term
left and rightAV valves, instead of tricuspid and mitral valves.
The apical offsetting is also absent in cases with inlet type of
ventricular septal defect (VSD) and both AV valves are at the
same level [Figure 6c].
En face view of the AV valves in the subcostal short‑axis
and the left anterior oblique views helps in identifying the
morphology [Figure 7a andVideo 7].The parasternal short‑axis
view at the level of the mitral valve can also be used to study
the morphology of mitral valve leaflets [Figure 7b].A detailed
assessment of the AV valves and their tensor apparatus
necessitates imaging in multiple echocardiographic views.
Atrioventricular connection
The next step is to define the AV connection. In normal hearts
and most of the malformed hearts, each atrium connects to a
morphologically appropriate ventricle, an arrangement known
as concordant AV connection. Less commonly, the atrium
connects to morphologically inappropriate ventricle which
is called discordant AV connection. In the setting of atrial
isomerism with both atriums being either left or right, the
AV connection is anatomically mixed as one of the atriums
will mandatorily connect to morphologically inappropriate
ventricle. The connection, nevertheless, is not always
physiologically abnormal. For example, it is physiologically
normal in case morphologic right ventricle (RV) receives
Figure 2: The arrangement of abdominal viscera and vessels in situs solitus (a), inversus (b), and ambiguous (c)
a b c

systemic venous blood and morphologic left ventricle (LV)
receives blood from the pulmonary veins, irrespective of
whether both the atriums are morphologically right or left.
Connection‑wise, as highlighted earlier, the AV valves are
usually committed fully to one of the ventricles, although, in
the setting of single‑ventricle physiology, one of the valves
may be atresia, e.g., tricuspid atresia and mitral atresia. In
some cases, mostly in the presence of a VSD, the AV valve
can be connected to both the ventricles. In this regard, the
term overriding is used if the valvular annulus overrides the
ventricular septum. The degree of override greater than 50%
assigns the valve to the ventricle, receiving a greater share
of the annulus. The AV valve is termed as straddling when
the tensor apparatus is supported by the other ventricle, in
addition to the ventricle with the dominant connection.[9,10]
The identification of straddling and overriding of AV valve
is important as it is often associated with hypoplasia of the
ipsilateral ventricle precluding biventricular surgical repair.
Rarely, theAV connection can have both atriums connected to
one ventricle (double‑inlet ventricle) or one atrium connecting
to both the ventricles (double‑outlet atrium) creating
single‑ventricle physiology. Figure 8 summarizes possible
variations in the AV connection.
Ventricles and ventricular looping
After the determination of the atrial situs, this is the most
important step of the segmental analysis. RV has more complex
geometry with an apically displaced tri‑leaflet tricuspid
valve having an attachment to the ventricular septum, coarse
trabeculations, and a distinctly trabeculated septal surface,
which includes septal and moderator bands [Figure 9 and
Videos 8 and 9]. A normal RV has an inlet, apical, and outlet
portions with the infundibulum separating the pulmonary
valve from the tricuspid valve. The LV is more elliptical and
has a smooth septal surface, fine trabeculations, two distinct
papillary muscles, and no attachment of bi‑leaflet mitral
valve to the ventricular septum. The LV has a more acute
angle between the mitral and aortic valves bringing both the
valves in continuity [Figure 10a]. Among all morphological
features, the morphology of the AV valve is most reliable in
identifying a ventricle as RV or LV.[11]
For obvious reasons,
as highlighted earlier, this cannot be used in cases with AVSD
and double‑inlet ventricle.
Once the ventricles are identified, the focus is shifted to
the ventricular topology or loop, which defines the spatial
relationship of the ventricles.[12,13]
The understanding of the
ventricular loop is clinically relevant as it determines the
pattern of coronary arteries and the conduction system. The
ventricular topology is a morphological concept based on
chirality. In d‑loop or right‑handed topology, the RV permits
the placement of the right hand so that the thumb is in the inflow
and fingers are in the outflow, while the palmar surface of the
hand faces the ventricular septum. This is expected in cases
with situs solitus and concordant AV connection. In contrast,
in the setting of l‑loop or left‑handed ventricular topology,
the morphological RV can accommodate only the left hand
in this fashion. This left‑handed topology is expected in the
setting of situs inversus and concordantAVconnection. Cardiac
Figure 3: Trans-thoracic echocardiogram in subcostal short-axis view
from a neonate with situs solitus. The IVC is to the right and Ao is to the
left of the vertebral body in situs solitus, while the reverse arrangement
is seen in patients with situs inversus [see Figure 2]. IVC: Inferior vena
cava, Ao: Aorta
Figure 4: Trans-thoracic echocardiogram in subcostal bicaval view
(a) showing the usual location of broad triangular RAA in a child with
an atrial septal defect (arrow). (b) Juxtaposed RAA in a neonate with
transposition of great arteries in which the RAA is abnormally located on
the left side. IVC: Inferior vena cava, LA: Left atrium. RA: Right atrium,
SVC: Superior vena cava, RAA: Right atrial appendage
a b
Figure 5: Trans-thoracic echocardiogram in parasternal short-axis
view (a) showing normal relation of great arteries with pulmonary valve
lying anterior and to the left of the Ao. A tubular, finger-like LAA (broken
lines) and origin of the right coronary artery (arrow) are also well seen.
(b) The circle and sausage appearance, with the Ao in the center and
PA with branching seen to the left of Ao. N: Noncoronary cusp, L: Left
coronary cusp, LPA: Left pulmonary artery, R: Right coronary cusp, RA:
Right atrium, RPA: Right pulmonary artery, Ao: Aorta, LAA: Left atrial
appendage, PA: Pulmonary artery
a b

malformations related to faulty looping such as congenitally
corrected transposition of great arteries are common in
cases with discordance between the atrial arrangement and
ventricular looping. The concept of chirality is difficult to
demonstrate on echocardiography. Therefore, despite being
inaccurate in a minority of cases, the ventricular topology is
defined on the basis of the spatial orientation of the inlet of
the ventricles. Thus, for practical considerations, the tricuspid
valve lying to the right of the mitral valve is labeled as d‑loop
or right‑hand topology [Figure 9]. The left–right inversion
of this arrangement, with the tricuspid valve lying to the left
of the mitral valve, is termed as l‑loop or left‑hand topology.
Infundibulum
The infundibulum is the connecting segment between the
ventricles and the arterial trunks. In normal hearts, there is
a complete subpulmonary conus with muscular separation
between the pulmonary and the right‑sided tricuspid valves,
whereas the subaortic conus is absent, allowing fibrous
continuity between the left and noncoronary cusps of the aortic
valve and the base of the anterior mitral leaflet [Figure 10a]. In
some hearts, the aortic valve is separated from the mitral valve
when it is labeled as aorta–mitral discontinuity [Figure 10b and
Video 10]. In morphological terms, this indicates subaortic
conus. Any arrangement other than isolated subpulmonary
conus, i.e., bilateral conus, subaortic conus with absent
subpulmonary conus, and bilaterally absent conus, is
abnormal.[14]
A subpulmonary conus is typically absent in the
setting of transposition of great arteries (TGA), which in turn
results in continuity between the pulmonary valve and the
mitral valve, although this is not an essential morphological
feature to define TGA [Figure 11a and Video 11]. Similarly,
bilateral conus is commonly associated with a double‑outlet
RV but is not necessary for the diagnosis.
Thus, although the infundibulum provides an important clue
about cardiac anatomy, it is not the defining feature of either
ventricle or VA connection, and therefore, the morphology of
the infundibulum should not be used to define the ventricle
or VA connection.
Ventriculoarterial connection
Next, the outflow of the ventricles is examined to determine
from which cardiac chamber the great arteries originate. VA
connection also determines how the semilunar valves and their
respective great vessels align with the underlying ventricles.
Assessment of VA connection is easy in most hearts with
normal connections. The assessment may be is challenging in
the setting of CHDs, especially conotruncal malformations. In
cases with coexisting interventricular communication in the
outflow region, one of the semilunar valves can override the
ventricular septum. Again, in malformations with a possible
double outlet of a ventricle, the application of the so‑called
“50% rule” helps in assigning a valve to one of the ventricles.[15]
Like many other morphological principles, this “50% rule”
is not easily demonstrable on echocardiography due to the
complex three‑dimensional (3D) relationship of the ventricles
and the great arteries, curved sigmoid shape of the ventricular
septum, and rotational and translational cardiac motion.
Advanced 3D imaging techniques are superior, but the exact
delineation may still be challenging in some complex cases.
Like the analysis of other areas of the heart, the VA alignment
should also be solely assessed based on the connection and
spatial relationship between the semilunar valves and the
underlying ventricles and not on the variable characteristics
of ventricular outflow and infundibulum.
JustlikeAVconnection,theVAconnectioncanalsobeconcordant,
discordant, or absent. Unlike theAVconnection,VAconnection
cannot be mixed as isomerism of the ventricular chamber is
unknown. The connection can also be double outlet when
Figure 6: Trans-thoracic echocardiogram in apical four-chamber view (a) showing the normal apical displacement of the tricuspid valve compared to
the mitral valve. An excessive apical displacement (>8 mm/m2
in children and >15 mm in adults) of the tricuspid valve indicates Ebstein anomaly (b).
Panel c shows lack of apical offsetting of the tricuspid valve in the setting of an inlet ventricular septal defect (star). LA: Left atrium, LV: Left ventricle,
RA: Right atrium, RV: Right ventricle
a b c
Figure 7: Trans-thoracic echocardiogram in subcostal left anterior
oblique view (a) showing atrioventricular valves en face with anterior (A),
posterior (P), and septal (S) leaflets of the tricuspid valve and anterior
(A) and posterior (P) leaflets of the mitral valve. The septal attachment
of the tricuspid valve is also well seen. Parasternal short-axis view at
the level of the mitral valve (b) showing the anterior and posterior mitral
leaflets. AML: Anterior mitral leaflet, LV: Left ventricle, PML: Posterior
mitral leaflet, RV: Right ventricle
a b

both arterial trunks arise from only one ventricle [Figure 12].
In most conditions, it is the RV that has a double outlet with
a minority having double outlet of the LV. There may also be
a single outlet from the heart. This group includes a common
arterial trunk and a single outlet with atresia of one semilunar
valve. In the common trunk, both ventricles are connected via
a common arterial valve to this trunk that directly provides
systemic, pulmonary, and coronary circulation [Figure 11b and
Video 12]. A single outlet with atresia of one semilunar valve
includes a single pulmonary trunk with aortic atresia or a single
aortic trunk with pulmonary atresia.
Semilunar valves and arterial trunks
In normal hearts, the pulmonary trunk is connected to the
RV, whereas the aorta arises from the LV and gives rise to the
coronary arteries and brachiocephalic vessels.
Although commonly thought to represent the spatial
relationship of the aorta and the pulmonary trunk, in reality,
the analysis is to clarify spatial relationships between the
aortic and pulmonary valves [Figures 13 and 14 and Video 4].
However, since the relationship of the proximal‑most part of
the arterial trunk is the same as the relationship of the valves,
these are commonly used interchangeably. The relationship
of semilunar valves is generally a reflection of VA connection
although there are many exceptions to this rule.
In the earlier version of the sequential analysis, the relationship
of the arterial trunks was depicted as “D” or “L” to indicate
the right or left position of the aorta relative to the pulmonary
Figure 8: The variations in atrioventricular connection. AV: Atrio-ventricular
Figure 10: Trans-thoracic echocardiogram in the parasternal long-axis view
showsaorto-mitralcontinuityinachildwithanormalheart(a)andaorto-mitral
discontinuity (b) with a wedge of tissue (broken line) between the base of the
AML and the annulus of the aortic valve in a child with double-outlet RV with
subaorticventricularseptaldefect(star).AML:Anteriormitralleaflet,Ao:Aorta,
LA:Leftatrium,LV:Leftventricle,PML:Posteriormitralleaflet,RV:Rightventricle
a b
Figure 9: Trans-thoracic echocardiogram in apical four-chamber view
(a) showing the MB, a characteristic morphologic feature of the RV.
(b) Subcostal short-axis view below the level of atrioventricular valves
showing a trabeculated RV side of the ventricular septum (arrows)
compared to a smooth surface on the LV side. Note right-hand topology
with the inlet of RV lying to the right of LV inflow. LA: Left atrium, RA:
Right atrium, MB: Moderator band, RV: Right ventricle, LV: Left ventricle
a b

trunk.[16]
This notation, however, lacks crucial information
about relationships in the anteroposterior direction. Therefore,
it is better to provide a detailed description.
The term “normally related great arteries” is used when the
aortic valve is located to the right and posteriorly relative to
a b
Figure 11: Abnormal ventriculoarterial connections. (a) Parasternal long-
axis view from an infant with discordant ventriculoarterial connections
(transposition of great arteries) with a large subpulmonic ventricular
septal defect (star) with pulmonary stenosis. Note the presence of
continuity between the mitral valve and pulmonary valve (arrow). (b)
Subcostal short axis view in diastole from a child with a common arterial
trunk with sinusal origin of main pulmonary artery segment and a large
subtruncal ventricular septal defect (star). Ao: Aorta, LA: Left atrium, LV:
Left ventricle, PA: Pulmonary artery, RV: Right ventricle
Figure 12: Abnormalities of ventriculoarterial connection. CAT: Common arterial trunk; ccTGA: congenitally corrected transposition of great arteries;
DORV: Double outlet right ventricle; HRHS: Hypoplastic right heart syndrome; HLHS: Hypoplastic left heart syndrome, LV: Left ventricle, RV: Right
ventricle, TGA: Transposition of great arteries
the pulmonary valve. Any other relationship of the semilunar
valves is malposition of great arteries [Figure 13]. The
malposition is not the same as TGA. While malposition only
depicts an abnormal spatial relationship of semilunar valves
and arterial trunk, TGA is a type of discordant VA connection
in which the aorta arises from the RV and pulmonary trunk
arises from the LV [Figure 11a and Video 11].
The attention is then shifted to the aortic arch, its sidedness, and
its branching pattern.[17]
The aortic arch is left sided if it courses
over the left bronchus. In children, this assessment can be made
by sweeping the probe in the left‑to‑right direction to assess
the relationship with the trachea. This, however, is difficult to
visualize in older children and adults. In such cases, the arch
sidedness is assessed by analyzing the probe orientation that
permits the best visualization of the arch. A well‑visualized
aortic arch when the probe marker is pointed toward the left
shoulder indicates the left arch [Figure 14 and Video 13]. In
contrast, the right arch is better visualized when the probe
marker points toward the right shoulder.The pattern of the neck
vessels also provides important clues. Except in the presence
of isolated carotid or brachiocephalic artery, the first branch
contains a carotid artery opposite to the side of the aortic arch.

Table 1: Summary of steps for sequential segmental analysis of cardiac anatomy
Steps Cardiac segments Assessment required
1 Thoraco-abdominal situs Are liver and spleen lateralized?
If yes, is it usual or mirror image arrangement?
If no, midline liver suggests visceral heterotaxy.
Is IVC patent or it continues as azygos vein behind aorta?
If IVC is patent, IVC to the right of the aorta - usual arrangement
IVC to the left of the aorta - mirror image arrangement
2 Cardiac position Is the heart left-sided, right-sided, or midline?
3 Atrial situs Is the atrial arrangement usual, mirror image, or isomeric?
If exact definition not possible then follow the abdominal situs
4 Venoatrial connection Do the inferior and superior vena cava drain to the right atrium?
Is there a left-sided SVC - if yes, where does it drain?
Are pulmonary veins draining normally to the left atrium?
Is there an anomaly of pulmonary venous drainage?
Presence, location, and size of the atrial septal defect
5 Atrioventricular valve Are there two patent valves?
If yes, identify and localize tricuspid and mitral valves
If no, is it a common valve or single valve with atresia of one valve?
6 Atrioventricular connection Is each atrium connecting to only one ventricle?
If yes, is AV connection concordant, discordant, or mixed?
If no, is there double inlet ventricle or double outlet atrium?
7 Ventricles and ventricular looping Morphology of ventricular chambers and looping - d-loop or l-loop?
Presence, location, size, and relationship of the ventricular septal defect
8 Infundibulum Is the pulmonary valve separated from the tricuspid valve (subpulmonary conus)?
Is aorta- mitral discontinuity (subaortic conus) present?
9 Ventriculoarterial connection Is each ventricle connected to one arterial trunk?
If yes, is the connection concordant or discordant?
If no, is there a double outlet, common outlet, single outlet with atresia of one valve?
The appearance of outflow tracts, presence, location, and severity of obstruction
10 Semilunar valves and arterial trunks Are there two semilunar valves?
If yes, are the valves normally related or malposed?
If no, is it a common valve or single valve with atresia of the other valve?
Appearance, orientation, and function of semilunar valves
Origins of coronary arteries
Size, position, and branching pattern of arterial trunks including sidedness of aortic arch
Presence and severity of obstruction - branch pulmonary stenosis, coarctation of the aorta
IVC: Inferior vena cava, AV: Atrioventricular, SVC: Superior vena cava
In the setting of the left aortic arch, the first vessel is the right
brachiocephalic artery, whereas in cases with the right aortic
arch, the first branch is the left brachiocephalic artery.
Defects and anomalies
Once the three main cardiac segments and the two connecting
segments have been evaluated and categorized, all associated
cardiac malformations are systematically examined and
described. The description can be either in the order of
hemodynamic significance or an anatomic order related to the
location of the abnormality within the heart.
Tips for Echocardiography in a Patient
Suspected to Have Congenital Heart Disease
Most of the cardiologists and echocardiographers dealing
with children are familiar with this step‑by‑step sequential
approach to cardiac morphology. Typically, unlike adult
echocardiography, which starts with a parasternal long‑axis
view, the echocardiography for suspected CHD starts with a
subcostal view for determination of the thoraco‑abdominal
and atrial situs.
Some modifications in the echocardiographic approach are
extremely useful while evaluating suspected CHD. The
assessment of all cardiac segments is greatly enhanced using
the “sweep” technique in which, depending upon views, the
echo probe is moved slowly from right to left or anterior to
posterior to create a series of images in a particular view.
Fundamentally, the technique is the same as that used in
assessing LV in the parasternal short‑axis view but is much
more detailed in the setting of CHD. This sweeping of echo
probe permits a detailed assessment of cardiac chambers and
their connections.

Once the cardiac segments have been identified and the
connections have been described, then associated anomalies
are assessed and described using the same systematic approach.
The sequential segmental approach can be further condensed
to a 10‑step analysis [Table 1].
Conclusion
The sequential segmental approach includes the use of multiple
echocardiographic views and other imaging modalities for
systematic evaluation of cardiac anatomy. This stepwise
approach permits accurate detection of all morphologic aspects
relevant for managing a patient with suspected CHD.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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Figure 13: Possible variations in the relationship of the great arteries.
The Ao to the right and posterior to the MPA is the only arrangement
labeled as normally great vessel relationship (circles with solid outline).
All other arrangements indicate the malposition of great arteries. MPA:
Main pulmonary artery, Ao: Aorta
Figure 14: Trans-thoracic echocardiogram in suprasternal long-axis
view with the marker of the echo probe pointing toward the left shoulder
showing left aortic arch and its branches. Note the reducing caliber of neck
vessels with the first branch, the RBCA containing right subclavian and
right carotid artery, being the widest, and the LSCA being the narrowest.
The arch sidedness is assessed by the branching pattern of neck vessels.
Other than a few exceptions, the first branch from the aortic arch contains
contralateral carotid artery. A well-visualized aortic arch with the probe
marker pointing toward the left and right shoulders identifies the left and
right-sided aortic arch, respectively. DTA: Descending thoracic aorta,
LCCA: Left common carotid artery, RPA: Right pulmonary artery, RBCA:
Right brachiocephalic artery, LSCA: Left subclavian artery

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