Transposition of the great vessels overview
Transposition of the great vessels Microchapters
Transposition of the great vessels overview On the Web
American Roentgen Ray Society Images of Transposition of the great vessels overview
Editor-In-Chief: C. Michael Gibson, M.S., M.D. ; Associate Editor(s)-In-Chief: Priyamvada Singh, M.B.B.S. ; Cafer Zorkun, M.D., Ph.D. ; Keri Shafer, M.D. ; Assistant Editor(s)-In-Chief: Kristin Feeney, B.S. 
It refers to a group of congenital heart defects involving an abnormal spatial arrangement of any of the primary blood vessel:superior vena cava and/or inferior vena cava, pulmonary artery, pulmonary veins, and aorta.
Transposition of the great vessels (TGV)
- It refers to a group of congenital heart defects involving an abnormal spatial arrangement of any of the primary blood vessel:superior vena cava and/or inferior vena cava,pulmonary artery, pulmonary veins, and aorta.
- The clinical signs and symptoms associated with TGV may range from a change in blood pressure to an interruption in circulation, depending on the nature and degree of the misplacement and which vessels are involved.
- The term "TGV" is often used as a more specific reference to transposition of the great arteries TGA; however, TGA only relates to the aorta and the pulmonary artery, whereas TGV is a broader term which can relate to these vessels as well as the SVC, IVC, and pulmonary veins.
- In its strictest sense, transposition of vessels relates only to defects in which two or more vessels have "swapped" positions; in a broader sense, it may be taken to relate to any defect in which a vessel is in an abnormal position.
- The terms TGV and TGA are most commonly used in reference to dextro-TGA- in which the arteries are in swapped positions.
- Both terms are also commonly used, though to a slightly lesser extent, in reference to Levo-Transposition of the great arteries- in which both the arteries and the ventricles are swapped; while other defects in this category are almost never referred to by either of these terms.
- CHDs involving only the primary arteries (pulmonary artery and aorta) belong to a sub-group called transposition of the great arteries.
- Most patients have an interatrial communication. Two-thirds have a patent ductus arteriosus, and about one-third have a ventricular septal defect.
The TGA was first described in 1797 by Matthew Baillie as a "singular malformation". The word transposition was coined by Farre in 1814.
Right atrium (RA) is connected to a morphologic right ventricle (RV). The morphologic left atrium (LA) is connected to the morphologic left ventricle (LV). This is called atrio-ventricular concordance. In a normal heart, the great arteries (aorta and pulmonary arteries) are concordant with the morphologic LV and RV. This is termed ventriculo-arterial concordance. In addition, the aorta and pulmonary trunk ascend in a spiral relationship. In the TGA the aorta arises from the morphologic right ventricle via a subaortic infundibulum and the pulmonary artery arises from the morphologic left ventricle, without a subpulmonary infundibulum. These ventriculoarterial connection is known as ventriculoarterial discordance. The abnormal origin of the great arteries results in an altered spiral relationship resulting in parallel circulation.
Differentiating Transposition of Great Vessels from Other Diseases
Epidemiology and Demographics
The prevalence of TPA is approximately 47 per 100,000 individuals worldwide. TGA accounts for 5-7 percent of all congenital heart disease and 20 percent of cyanotic heart disease. There is no racial predilection to transposition of great vessels. Transposition of the great arteries has a 60-70% male predominance.
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. Other risk factors in the mother that may increase the risk of this condition include age over 40, alcoholism, diabetes, prenatal malnutrition and rubella or other viral illness during pregnancy.
Natural History, Complications, and Prognosis
If left untreated, over 50 percent of infants with transposition of the great arteries will die in the first month of life. 90 percent will die in the first year. Common complications of TGA include congestive heart failure, arrhythmia, pulmonary artery stenosis and aortic regurgitation. The prognosis for patients with TGA is generally excellent following surgical correction with survival rates greater than 90%. 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.
Diagnostic Study of Choice
History and Symptoms
The clinical features of D-TGA are solely dependent on the degree of mixing between the parallel circuits. Most patients present with signs and symptoms during the neonatal period. Symptoms of D-TGA present with cyanosis, tachypnea and murmurs. Patients with L-TGA present with symptoms of heart failure until later in life when the right ventricle can no longer compensate increased after load.
Echocardiography and Ultrasound
Other Imaging Findings
Other Diagnostic Studies