Congenitally Corrected Transposition of the Great Arteries
Classically, identifying a chamber with a right ventricular (RV) morphology on two-dimensional echocardiography relies on: (1) a coarse and irregular endocardial surface, (2) chordae tendineae attaching directly to the ventricular septum, (3) the presence of an infundibulum, (4) a triangular-shaped ventricular cavity, (5) the presence of a prominent moderator band, and (6) recognition of the atrioventricular (A-V) valve as tricuspid.
The features associated with left ventricular (LV) morphology include: (1) a smooth and uniform endocardial surface, (2) two distinct groups of papillary muscles, (3) an ellipsoid-shaped ventricular cavity, and (4) identification of the A-V valve as mitral.
In Van Praagh's classification, congenitally corrected transposition of the great arteries (CCTGA) is referred to as ventricular inversion or L-transposition and is described as follows:
Key Features in Van Praagh's Classification:
Atrioventricular (AV) Discordance
The morphologic right atrium (RA) is connected to the morphologic left ventricle (LV), and the morphologic left atrium (LA) is connected to the morphologic right ventricle (RV).
This is termed AV discordance because the atria and ventricles are mismatched in morphology.
Ventriculoarterial (VA) Discordance
The morphologic LV ejects blood into the pulmonary artery (PA), while the morphologic RV ejects blood into the aorta - (depends on if there is valvular patency)
This is termed VA discordance because the ventricles are mismatched with the great arteries they supply.
Physiological Correction
Despite the discordant connections, the circulation is "physiologically corrected" because deoxygenated blood flows to the lungs, and oxygenated blood flows to the systemic circulation. However, the RV, not the LV, functions as the systemic ventricle, which poses long-term challenges.
Anatomical Description
Situs solitus: The normal positioning of the atria.
L-looping of the ventricles: The morphologic LV is positioned on the right, and the morphologic RV is on the left (hence the "L" in L-transposition).
The full description would be S,L,L (situs solitus, L-looped ventricles, L-transposition).
Associated Lesions
CCTGA is often accompanied by other congenital abnormalities, such as:
Ventricular septal defect (VSD)
Pulmonary stenosis (PS) or atresia.
Tricuspid valve anomalies (e.g., Ebstein-like malformation or regurgitation)
Conduction system abnormalities, including heart block.
Echocardiography example
Case of cc-TGA (L-TGA) with pulmonary atresia. Here there is no heart block during the echocardiography.
Case of atrial situs solitus; laevocardia (heart predominantly in the left hemithorax) and congenitally corrected transposition of great arteries (discordant atrioventricular & ventriculo-arterial connections, ventricular septal defect and pulmonary atresia, Ebstein's malformation of tricuspid valve. Tortuous patent arterial duct (pulmonary atresia type - aortic arch to pulmonary artery) shunting left to right. Large nonrestrictive perimembranous central ventricular septal defect (VSD) and Left aortic arch.
In this apical view, one may appreciate the coarse trabeculation of the morphological right ventricles on the left side of the patient, with a inferiorly displaced atrio-ventricular valve with attachments to the septum. This tricuspid valve is Ebstanoid.
The morphological left ventricle which has a smooth surface is on the right side of the patient. There is a large inlet ventricular septal defect. The right sided atrio-ventricular valve is superiorly placed compared to the left sided atrio-ventricular valve.
Focus on the morphological left ventricle on the right side of the chest. It is connected to the atrium receiving the SVC and IVC (unseen in this image).
Focus on the left-sided morphological right ventricle which receives the blood flow from the atrium that received the pulmonary venous return (not show here).
Sweep outlining that the left-sided morphological right ventricle leads to an anteriorly placed vessel that does not bifurcate, which is the aorta.
Colour flow from the morphological RV to the aorta.
Subcostal sweep with the morphological RV and its outflow tract leading to the ascending aorta.
In this particular patient, there is a IVC and SVC (no interruption) that are connected to the atrium that feeds the morphological left ventricle.
The branch pulmonary arteries are being fed by the patent ductus arteriosus (pulmonary atresia type configuration). The morphological left ventricle on the right side of the patient does not have a patent connection towards the pulmonary artery ("pulmonary atresia" setup).
Aortic arch and ductus arteriosus seen.
It is important to outline the coronary branching in cases of ccTGA.
Presentation by Dr Sariya Sahussarungsi and Dr Abdullah Alghamdi - January 2025
Great presentation prepared by Dr Sariya Sahussarungsi and Dr Abdullah Alghamdi for the NICU Cardio Rounds at McGill University of January 2025. Reviewed in collaboration with Dr Tiscar Cavallé Garrido (pediatric and fetal cardiologist).

Important Articles
