Dextro-transposition of the great arteries/complete transposition of the great arteries

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. [2]; Cafer Zorkun, M.D., Ph.D. [3]; Keri Shafer, M.D. [4]; Assistant Editor(s)-In-Chief: Kristin Feeney, B.S. [5]

dextro-Transposition of the great arteries is a cyanotic congenital heart defect (CHD) in which the primary arteries (the aorta and the pulmonary artery) are transposed with the aorta anterior and to the right of the pulmonary artery. In segmental analysis, this condition is described as ventriculoarterial discordance with atrioventricular concordance, or just ventriculoarterial discordance. dextro-TGA is often referred to simply as transposition of the great arteries (TGA); however, TGA is a more general term which may also refer to levo-transposition of the great arteries (l-TGA). Another term commonly used to refer to both d-TGA and l-TGA is transposition of the great vessels (TGV), although this term might have an even broader meaning than TGA.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. [2]; Cafer Zorkun, M.D., Ph.D. [3]; Keri Shafer, M.D. [4]; Assistant Editor(s)-In-Chief: Kristin Feeney, B.S. [5]

d-TGA is often accompanied by other heart defects, the most common type being intracardiac shunts such as atrial septal defect (ASD) including patent foramen ovale (PFO), ventricular septal defect (VSD), and patent ductus arteriosus (PDA). Stenosis of valves or vessels may also be present.

d-TGA which is not associated with additional cardiac defects.

d-TGA which is associated with other defects.

One of the most common cardiac defects associated with d-TGA is a VSD, which is present in 40% of d-TGA patients. Pulmonary stenosis and a VSD are present in 31% of patients. Although it may seem illogical, complex d-TGA presents better chance of survival and less developmental risks than simple d-TGA, as well as usually requiring fewer invasivepalliative procedures. This is because the left-to-right and bidirectional shunting caused by the defects common to complex d-TGA allow a higher amount of oxygen-rich blood to enter the systemic circulation. However, complex d-TGA may cause a very slight increase to length and risk of the corrective surgery, as most or all other heart defects will normally be repaired at the same time, and the heart becomes “irritated” the more it is manipulated.

Leida Perez, M.D. nl:Transpositie van de grote vaten Template:WH Template:WS

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. [2]; Cafer Zorkun, M.D., Ph.D. [3]; Keri Shafer, M.D. [4]; Assistant Editor(s)-In-Chief: Kristin Feeney, B.S. [5]

• In dextro-transposition of the great arteries there exist an arterial-ventricular discordance with atrial-ventricular concordance.
• The position of the aorta and the pulmonary artery is switched relative to the ventricular septum.
• The atrio-ventricular connections are normal.
• Differences in the shape of the atrial septum and/or ventricular outflow tracts affect the anatomical positions of the aorta and pulmonary artery.
• In the majority of d-TGA cases, the aorta is anterior and to the right of the pulmonary artery, but it can also be directly anterior or anterior and to the left.
• The aorta and pulmonary artery can also be side by side, with the aorta located on either side. This is a less common variant, and with this arrangement, an unusual coronary artery pattern is common.
• There are also some cases in which the aorta to the right and posterior to the pulmonary artery.^[1]
• The left coronary artery arises from the left aortic sinus and the right coronary artery from the posterior aortic sinus. In 31 of 149 cases, the circumflex originates from the posterior aortic sinus. ^[2]

• In a normal heart, oxygen-depleted (blue) blood is pumped from the right heart, through the pulmonary artery, to the lungs where it is oxygenated. The oxygen-rich red blood then returns to the left heart, via the pulmonary veins, and is pumped through the aorta to the rest of the body, including the heart muscle itself.
• With d-TGA, blue blood from the right heart is pumped immediately through the aorta and circulated to the body and the heart itself, bypassing the lungs altogether, while the left heart pumps red blood continuously back into the lungs through the pulmonary artery.
• In effect, two separate “circular” (parallel) circulatory systems are created, rather than the “figure 8” (in series) circulation of a normal cardio-pulmonary system.
• In d-TGA, the pulmonary and the systemic circuits are in parallel circulation, rather than in series, which is incompatible with life if there is no mixing of the two systems. Therefore, in most cases, a complex d-TGA is the one that allows survival due to the presence of other heart defects like patent foramen ovale (PFO) for mixing blood between the two systems. Other possible mixing sites include a PDA or a VSD.
• The course of TGA is determined by the degree of hypoxia, and the ability of each ventricle to sustain an increased work load in the presence of reduced coronary arterial oxygenation. It is also important the nature of associate heart defects, and the status of the pulmonary vascular circulation.
• The pulmonic flow is increased in those cases with transposition and large VSD or large PDA without obstruction to left ventricular outflow. In these cases, pulmonary vascular obstruction develops by 1 to 2 years of age.

Leida Perez, M.D. nl:Transpositie van de grote vaten Template:WH Template:WS

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. [2]; Cafer Zorkun, M.D., Ph.D. [3]; Keri Shafer, M.D. [4]; Assistant Editor(s)-In-Chief: Kristin Feeney, B.S. [5]

The causes of most congenital heart defects are unknown.

The cause of most congenital heart defects is unknown. Factors in the mother that may increase the risk of this condition include:

• Age over 40
• Alcoholism
• Diabetes
• Prenatal nutrition
• Rubella or other viral illness during pregnancy
• Generally, TGA is not known to be associated with any specific single gene defect, but some studies have shown possible genetic association in some cases of TGA, involving deletions of chromosome 22q11.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. [2]; Cafer Zorkun, M.D., Ph.D. [3]; Keri Shafer, M.D. [4]; Assistant Editor(s)-In-Chief: Kristin Feeney, B.S. [5]

Patients with dextro-transposition of the great arteries should be differentiated from other cardiac and non-cardiac causes of cyanosis-

Cardiac causes (starts with ‘t’)-

• Tetralogy of Fallot
• Truncus arteriosus
• Total anomalous pulmonary venous connection
• Other tricuspid valve abnormalities like tricuspid regurgitaton, tricuspid stenosis

Other less common causes are- pulmonary atresia, hypoplastic left heart syndrome, anomalous systemic venous connection. Non-cardiac causes

• Pulmonary diseases – Structural abnormalities of the lung, V/P (ventilation-perfusion mismatch), airway obstruction, pneumothorax, and hypoventilation.
• Abnormal hemoglobin like methemoglobin, polycythemia
• Peripheral cyanosis for e.g. sepsis, hypoglycemia, dehydration, and hypoadrenalism.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. [2]; Cafer Zorkun, M.D., Ph.D. [3]; Keri Shafer, M.D. [4]; Assistant Editor(s)-In-Chief: Kristin Feeney, B.S. [5]

Transposition of the great arteries (TGA) is one of the most common cyanotic congenital heart defects present in the first 24 hours of life.

• Heart defects are the most common birth defect, occurring in approximately 1% of live births.
• Transposition of the great arteries TGA is one of the most common cyanotic congenital heart defects present in the first 24 hours of life.
• Approximately one million people worldwide are currently living with a CHD.
• TGA represents 5-7% of all CHD with an incidence at birth of 20-30 in 100000 live births and almost 20 percent of all cyanotic CHD defects.
• TGA is more common in infants of diabetic mothers.
• Boys outnumber girls with an approximate ratio of 2:1.
• Without treatment, 30% of infants die within the first week of life, 50% will die in the first month, 70% will die in the first 6 months and 90% of infants will die before the end of the first year.
• Having a child with a CHD increases an individual’s chances of having another child with a CHD from 1% to 3%. Subsequent children born with a CHD increase that individual’s chances further.

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