Congenitally uncorrected transposition of the great arteries

Congenitally corrected transposition of the great arteries (ccTGA), also known as levo-transposition of the great arteries (L-TGA) or ventricular inversion, is a rare congenital heart defect in which the heart's two lower chambers (ventricles) are reversed. Despite the somewhat confusing name containing 'corrected,' the condition is not truly corrected — the aorta arises from the morphologic right ventricle and the pulmonary artery arises from the morphologic left ventricle. Because both the atrioventricular and ventriculoarterial connections are discordant (a 'double discordance'), blood flow follows a physiologically appropriate circuit: deoxygenated blood still reaches the lungs and oxygenated blood still reaches the body. However, the morphologic right ventricle must function as the systemic ventricle, a role for which it is not ideally designed. Many patients with ccTGA also have associated cardiac anomalies, which are present in the majority of cases. These commonly include ventricular septal defects (VSD), pulmonary or subpulmonary stenosis, abnormalities of the systemic (tricuspid) atrioventricular valve including Ebstein-like malformation, and conduction system abnormalities leading to heart block. Patients without associated defects may remain asymptomatic for decades, but progressive systemic right ventricular dysfunction and systemic atrioventricular valve regurgitation often develop over time, leading to heart failure symptoms such as exercise intolerance, fatigue, dyspnea, and arrhythmias. Treatment depends on the presence and severity of associated defects and the function of the systemic right ventricle. Surgical options include conventional repair of associated lesions (VSD closure, relief of pulmonary stenosis) or anatomic repair strategies such as the double switch operation (combining an atrial switch with an arterial switch), which restores the morphologic left ventricle to the systemic circulation. Medical management of heart failure and arrhythmias, pacemaker implantation for complete heart block, and ultimately cardiac transplantation may be necessary in advanced cases. Lifelong cardiology follow-up is essential for all patients with ccTGA.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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