Congenitally corrected transposition

Abstract

Congenitally corrected transposition is a rare cardiac malformation characterized by the combination of discordant atrioventricular and ventriculo-arterial connections, usually accompanied by other cardiovascular malformations. Incidence has been reported to be around 1/33,000 live births, accounting for approximately 0.05% of congenital heart malformations. Associated malformations may include interventricular communications, obstructions of the outlet from the morphologically left ventricle, and anomalies of the tricuspid valve. The clinical picture and age of onset depend on the associated malformations, with bradycardia, a single loud second heart sound and a heart murmur being the most common manifestations. In the rare cases where there are no associated malformations, congenitally corrected transposition can lead to progressive atrioventricular valvar regurgitation and failure of the systemic ventricle. The diagnosis can also be made late in life when the patient presents with complete heart block or cardiac failure. The etiology of congenitally corrected transposition is currently unknown, and with an increase in incidence among families with previous cases of congenitally corrected transposition reported. Diagnosis can be made by fetal echocardiography, but is more commonly made postnatally with a combination of clinical signs and echocardiography. The anatomical delineation can be further assessed by magnetic resonance imaging and catheterization. The differential diagnosis is centred on the assessing if the patient is presenting with isolated malformations, or as part of a spectrum. Surgical management consists of repair of the associated malformations, or redirection of the systemic and pulmonary venous return associated with an arterial switch procedure, the so-called double switch approach. Prognosis is defined by the associated malformations, and on the timing and approach to palliative surgical care.

Figure 1

This illustration from the atlas of the Baron von Rokitansky shows the short axis of the ventricular mass viewed from the ventricular aspect in a specimen with congenitally corrected transposition.

Figure 2

The superior caval vein (SCV) and inferior caval vein (ICV) are connected to the morphologically right atrium (mRA), which in turn empties through the mitral valve (MV) to the morphologically left ventricle (mLV) and thence to the pulmonary trunk. There is a ventricular septal defect (VSD) present below the pulmonary valve. The right atrium shows the normal position of the oval fossa (OF) and the coronary sinus (CS).

Figure 3

This dissection is made to replicate the parasternal long echocardiographic projection. It shows the coronary sinus (CS) opening to the right-sided morphologically right atrium, which connects to the morphologically left ventricle (mLV) through the mitral valve (MV). The oval fossa (OF) is clearly seen in the atrial septum

Figure 4

This illustration demonstrates how the morphologically right atrium, with its characteristic appendage (RAA), is connected to a morphologically left ventricle (mLV) across the mitral valve (MV), with the ventricle then connected to the pulmonary trunk (PT). Note the smooth septal surface of the ventricle.

Figure 5

This illustration shows the morphologically left atrium connected to the morphologically right ventricle (mRV) across the tricuspid valve (TV), with the ventricle giving rise to the aortic valve. The ventricle possesses coarse trabeculations, with the leaflets of the tricuspid valve attached directly to the muscular ventricular septum.

Figure 6

Note the reversed off-setting of the attachments of the leaflets of the atrioventricular valves to the septum (Arrow), with the mitral valve (MV) on the right side attached appreciably higher that the tricuspid valve (TV) on the left side.

Figure 7

The image shows the fibrous continuity between the leaflets of the pulmonary trunk (PT) and mitral valves (MV) in the roof of the right-sided morphologically left ventricle (mLV).

Figure 8

Note how the aorta is supported by a complete muscular infundibulum above the coarsely trabeculated morphologically right ventricle (mRV), the infundibulum interposing between the hinges of the aortic and tricuspid (TV) valves.

Figure 9

This illustration demonstrates the apical displacement (lines) of the septal and mural leaflets of the tricuspid valve (TV). The morphologically left atrium (mLA) is connected to the morphologically right ventricle (mRV) through an Ebstinoid-like tricuspid valve. Note the flap valve of the oval fossa on the atrial septal surface.

Figure 10

The upper part of cardiac silhouette as seen in the chest radiograph appears abnormally straight because of the loss of the normal arterial relationships.

Figure 11

The electrocardiogram shows a qR pattern in lead V1, with absence of Q waves in leads V5 and V6, demonstrating abnormal ventricular depolarization.

Figure 12

The four-chamber transthoracic echocardiogram shows reversed off-setting of the leaflets of the mitral and tricuspid valves.

Figure 13

The parasternal long axis transthoracic echocardiogram shows the subaortic infundibulum (arrow), with lack of fibrous continuity between the left-sided tricuspid (TV) and aortic valves (AoV).

Figure 14

The magnetic resonance image shows a right-sided heart with the apex pointing to the right. The pulmonary veins are seen entering the left atrium (PV), with the tricuspid valve [TV] guarding the junction with the coarsely trabeculated systemic morphologically right ventricle.