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“Corrected transposition, when first encountered, resembles an unreal apparition…. All of the important people were there doing their expert job. The operation began well. The individual cardiac chambers and structures were present and accounted for, and the ventricular septal defect was in the perimembranous location. But something else was fundamentally wrong. Almost everything was out of place in a weird mime of normal, clearly an illusion characteristic of another nightmare. There seemed no choice but to press on even in the face of this confusion, hoping as always that by applying basic principles one could win out. The ventricular septal defect was therefore carefully patched so as to avoid the conduction system, and perfusion was discontinued.

Heart block ensued, cardiac output became poor, and tragedy loomed.”

Dwight McGoon, 19831

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Key Concepts

  • Epidemiology

    • Congenitally corrected transposition of the great arteries (CC-TGA) is a rare condition, comprising less than 1 percent of all congenital heart defects.

  • Morphology

    • In the most common variety, there is situs solitus with discordant atrioventricular (AV) and ventriculoarterial connection (double discordance). Associated anomalies include Ebstein malformation of the tricuspid (systemic) valve, ventricular septal defect (VSD), obstruction of the right ventricular outflow tract, situs inversus, and anomalous course of the AV conduction system.

  • Pathophysiology and clinical features

    • These are based on the cumulative effects of the associated lesions and the long-term performance of a morphologic right ventricle (RV) facing systemic afterload. Cyanosis and pulmonary overcirculation can ensue, with great variability in the timing of presentation.

  • Diagnosis

    • Chest x-ray usually discloses mesocardia.

    • Echocardiography and cardiac catheterization are complementary in determining the necessity and timing of intervention. More recently, cardiac magnetic resonance imaging can be very helpful in determining respective right and left ejection fractions, volumes and help with surgical planning.

  • Treatment

    • Some patients may remain asymptomatic, whereas others will only require pacemaker insertion for heart block. Early in infancy, shunting or pulmonary artery (PA) banding (PAB) of symptomatic patients is indicated. Eventually, depending on the timing of presentation and the type of pulmonary outflow, one of three pathways can be chosen: (1) conventional physiologic repair (the RV remains in the systemic circulation); (2) anatomic repair, with recruitment of the morphologic RV and left ventricle (LV) to the pulmonary and systemic circulations; and (3) staged palliation to single-ventricle physiology.

  • Outcomes

    • Anatomic repair is technically more challenging but offers the long-term advantage of biventricular physiology. Fontan palliation can be a valid alternative to repair, with acceptable outcomes. Heart transplantation can be indicated in end-stage scenarios (see Chapter 77).

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Definition and Sequential Analysis

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The classic definition of “congenitally corrected transposition of the great arteries” (CC-TGA) derived from the observation that the effects of such transposition are “corrected” by the congenital inversion of the two ventricles, with the two circulatory pathways “physiologically” in series despite morphologic derangements. Basically the same as “two negative gives a positive,” this condition comprises less than 1 percent of all congenital heart defects.

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