What is the Van Praagh classification for D-Transposition of the Great Arteries (D-TGA) and L-Transposition of the Great Arteries (L-TGA)?

Van Praagh Classification for D-TGA and L-TGA

The Van Praagh classification for D-TGA is characterized by atrioventricular concordance with ventriculoarterial discordance, where the aorta arises rightward and anterior to the pulmonary artery from the systemic right ventricle, while L-TGA involves atrioventricular discordance with ventriculoarterial discordance, resulting in physiologically corrected circulation. 1, 2

D-Transposition of the Great Arteries (D-TGA)

• D-TGA is defined by each great artery arising from the wrong ventricle, with atrioventricular concordance but ventriculoarterial discordance 1
• In D-TGA, the aorta arises rightward and anterior to the pulmonary artery from the systemic right ventricle 1
• This creates parallel circulations rather than the normal series circulation, with the right ventricle connected to the aorta and the left ventricle connected to the pulmonary artery 3
• D-TGA accounts for 5-7% of all congenital heart defects and is the second most common cyanotic heart disease 4

Associated Lesions in D-TGA

• Ventricular septal defect (VSD) occurs in up to 45% of D-TGA cases 1
• Left ventricular outflow tract obstruction is present in approximately 25% of cases 1
• Coarctation of the aorta is found in approximately 5% of cases 1
• Coronary artery anomalies are common and require clear delineation for surgical planning 1

L-Transposition of the Great Arteries (L-TGA)

• L-TGA, also known as congenitally corrected transposition (CCTGA), involves both atrioventricular and ventriculoarterial discordance 3, 2
• In L-TGA, the left atrium connects to the morphological right ventricle, and the right atrium connects to the morphological left ventricle 3
• Despite the anatomical abnormality, blood flows in the correct physiological sequence (hence "corrected"), with systemic and pulmonary circulations functioning in series 5
• The most common anatomic variant is [S,L,L] (solitus atria, L-loop ventricles, L-transposition), occurring in 94% of cases 2

Clinical Implications of L-TGA

• Heart failure develops by age 45 years in 67% of L-TGA patients with associated lesions (VSD, tricuspid insufficiency, pulmonary stenosis) and in 25% of those without associated lesions 1
• The morphological right ventricle functions as the systemic ventricle in L-TGA, which can lead to long-term ventricular dysfunction 1, 5
• Anomalies of the left-sided systemic tricuspid valve are present in 97% of classical L-TGA [S,L,L] cases 2
• Malformations of the left-sided systemic right ventricle occur in 91% of cases 2

Surgical Considerations

• D-TGA is typically repaired in infancy, with the arterial switch operation (ASO) being the current preferred approach 4, 3
• Older adults with D-TGA often have had Mustard or Senning procedures (atrial baffle repairs) that redirect blood flow at the atrial level 1
• Common complications after atrial switch include baffle obstruction, baffle leaks, arrhythmias, and systemic right ventricular dysfunction 1, 3
• For L-TGA, a double-switch operation (combining atrial and arterial switch) may be performed to achieve anatomic correction 3, 2

Imaging and Follow-up

• Annual follow-up with a cardiologist experienced in adult congenital heart disease is recommended for all patients with repaired D-TGA 1
• Comprehensive echocardiographic imaging should be performed at a regional ACHD center to evaluate anatomy and hemodynamics 1
• Additional imaging with TEE, CT, or MRI should be performed to evaluate the great arteries, veins, and ventricular function 1
• Assessment of systemic right ventricular function is challenging and may require specialized techniques 1