Everything is Backwards

Due to the progressive symptom of shortness of breath, an MR study was requested to help determine the need of potential surgical correction.

Figure 1. PA CXR demonstrating situs inversus totalis with left ventricle apex on right, right sided aortic arch, stomach bubble on right, and liver on left side. Also note enlarged pulmonary arteries at level of hilum.

Figure 2. CT demonstrating situs inversus with liver on left side and spleen and stomach right sided.

Figure 3. CT and bright blood MR (balanced steady-state free precession [SSFP] sequence) demonstrating a trabeculated morphologic right ventricle (systemic ventricle white arrow) communicating with left atrium through tricuspid valve (white arrowhead) and smooth morphologic left ventricle (pulmonary ventricle black arrow) communicating with right atrium through mitral valve (black arrowhead). Membranous VSD demonstrated (curved black arrow) allowing for direct communication of ventricles.

Figure 4. CT and black blood MRI demonstrating enlarged pulmonary artery and right-sided aortic arch.

Figure 5. CT and MRI black blood image demonstrating right sided aortic arch (white arrow) to right of pulmonary artery (black arrow) and dilated left atrium (double white arrow).

Figure 6. Bright blood 3-chamber view demonstrating morphologic trabeculated right ventricle communicating with aorta (ventriculoarterial discordance) with mild aortic regurgitation demonstrated by small dephasing jet (black arrow). There is moderate regurgitation of tricuspid valve into left atrium as demonstrated by a more severe dephasing jet (white arrow). Note the separation of the tricuspid from the aortic valve as would be expected from a morphologic right ventricle.

Figure 7. Bright blood MR image of morphologic left ventricle outflow tract to pulmonary artery (ventriculoarterial discordance) demonstrating turbulent flow (dark jet) from subpulmonic stenosis (white arrow) extending towards pulmonary artery during ventricular systole.

Figure 8. MR pulmonary angiogram performed to evaluate for branch stenosis demonstrates enlarged pulmonary arteries without branch stenosis.

Both CT and MR demonstrate atrioventricular discordance and ventriculoarterial discordance diagnostic of CCTGA.

Congenitally corrected transposition of the great arteries (CCTGA) is a rare form of congenital heart disease occurring in less than 1% of congenital heart disease approximately 1/33,000 live births.

Most patients with CCTGA will have one or more associated cardiac anomalies.

The systemic AV valve and systemic RV function are the most prognostic factors determining survival in patients with CCTGA and according to the study of Prieto,4 there was a strong association with systemic AV valve regurgitation (SAVVR) with systemic RV dysfunction suggesting a causal relationship.

They found that the mean time from onset of SAVVR to systemic RV failure was only five years, suggesting that SAVVR appears to be central to the progression to systemic RV failure and early death in patients with CCTGA.

While chest X-ray and echocardiography should be the initial imaging work-up of patients with complex congenital heart disease, CT and MRI are often useful in further elucidating the complexity of these disorders.