Transposition of the great vessels

Transposition of the great vessels (TGV) is a group of congenital heart defects (CHDs) involving an abnormal spatial arrangement of any of the primary blood vessels: superior and/or inferior vena cavae (SVC, IVC), pulmonary artery, pulmonary veins, and aorta. CHDs involving only the primary arteries (pulmonary artery and aorta) belong to a sub-group called transposition of the great arteries (TGA).

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History

TGV was first described in 1797 by Matthew Baillie.^[1]

Description

  In a normal heart, oxygen-depleted blood is pumped from the right side of the 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.

Transposed vessels can present a large variety of atriovenous, ventriculoarterial and/or arteriovenous discordance. The effects 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.

Although "transposed" literally means "swapped", many types of TGV involve vessels that are in abnormal positions, while not actually being swapped with each other. The terms TGV and TGA are most commonly used in reference to dextro-TGA (d-TGA) - in which the arteries are in swapped positions; however, both terms are also commonly used, though to a slightly lesser extent, in reference to levo-TGA (l-TGA) - 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.

Simple and complex TGV

In many cases, TGV is 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, or other defects, of valves and/or vessels may also be present.

When no other heart defects are present it is called 'simple' TGV; when other defects are present it is called 'complex' TGV.

References

1. ^ The Morbid Anatomy of Some of the Most Important Parts of the Human Body (1793)