Detection of caval obstruction by MR imaging in postoperative transposition of the great arteries

Vena caval obstruction may cause significant morbidity after atrial repair of transposition of the great arteries (TGA). The authors compared two noninvasive methods of diagnosing vena caval obstruction with cardiac catherization. Gated MR imaging and Doppler echography were performed in 14 patients with TGA (Mustard procedure performed in six patients, Senning procedure in six, imaging performed 0.5-13.5 years after operation). Complete superior (SVC) or inferior (IVC) vena caval occlusion or partial obstruction (≥ 5 mm Hg mean gradient from cava to systemic venous artium) was present at catheterization in seven of 14 patients. MR imaging directly displayed complete SVC obstruction in both patients with this catheterization-proved diagnosis. A dilated azygous-hemiazygous complex (≥ 5 mm in diameter) was seen on MR imaging in five of seven patients with complete or partial vena caval obstruction and in none of seven patients without obstruction. SVC dilation (ratio of SVC to aortic diameter, ≥ 1.45) was seen in three of five patients with and in none of seven patients without vena caval obstruction. Saline contrast echography, performed in 11 of 14 patients was positive in only two patients with complete SVC obstruction. Turbulent nonphasic flow in the systemic venous atrium was seen on Doppler echography in five of seven patients with and three of seven patients without vena caval obstruction. Thus, MR imaging and Doppler echography are fairly sensitive detectors of vena caval obstruction in postoperative TGA, but MR imaging has greater specificity