ABSTRACT
Introduction Transposition of the great arteries (TGA) describes cardiac pathology in which the aorta arises from the morphological right ventricle and the main pulmonary artery (MPA) from the morphological left ventricle, also known as ventriculoarterial (VA) discordance. This pathology was first described in 1797 by Matthew Baillie; however, the term TGA was coined by John Farre in 1814.1,2 TGA is most frequently associated with normal atrioventricular (AV) connections (or D-ventricular looping with a morphological right ventricle rightward and anterior and morphological left ventricle leftward and posterior) or AV concordance, a lesion also referred to as D-TGA or complete TGA (Figure 29.1). Far less commonly, there may be concomitant AV and VA discordance, in which the ventricles are inverted (or L-looped) and the great arteries again arise from the incorrect ventricle: aorta from the left-sided morphological right ventricle and MPA from the right-sided morphological left ventricle (Figure 29.1). The latter, first described by Karl von Ritansky in 1875,3 is also referred to as L-TGA or physiologically and congenitally corrected TGA: as the pulmonary venous flow is ejected through the aorta to the body and the systemic venous flow through the pulmonary artery to the lungs. Defining the AV connection and the VA connection is crucial to determine the pathophysiology and clinical manifestations of the patient postnatally. These two entities have entirely different pathophysiology; therefore, they are approached separately in this chapter.
