Magnetic resonance imaging of cardiac function and morphology in patients with transposition of the great arteries following Mustard procedure.

In order to assess the diagnostic possibilities of magnetic resonance imaging (MRI), 30 children (mean age 11.5 years) with d-transposition of the great arteries (TGA) corrected by the Mustard procedure were studied. Patient values were compared to those of 10 healthy volunteers. The most important postoperative abnormalities such as baffle leaks, systemic or pulmonary venous obstructions, left ventricular outflow tract (LVOT) stenosis and tricuspid regurgitation were assessed. Cardiac volumes and muscle mass were measured. Baffle leaks were found in 5 and obstruction of the baffle limbs in 6 patients. On gradient echo images 13 patients showed signs of LVOT stenosis and 12 tricuspid incompetence. Right ventricular end diastolic volumes in patients were significantly higher than the left ventricular volumes, but slightly lower than right ventricular volumes in the normals. In patients with TGA and ventricular septal defect (VSD) (n = 7) right ventricular (RV) volumes were found to be higher than in patients with intact ventricular septum (n = 23) and in normals. In contrast to the normal RV function of patients after Mustard surgery only patients with previous VSD showed a diminished RV ejection fraction. The muscular mass in TGA patients showed a ratio of 1.9:1 between right and left ventricles. In normals the ratio was 1:1.5. Magnetic resonance imaging allows a quantitative insight into the ventricular function and the morphology of the heart after inflow correction. Thus, it supplements the noninvasive evaluation of TGA patients.