The convexity of the great vessel arising from the anterior ventricle- an aide in the fetal diagnosis of transposition of the great arteries (TGA)

  • Doctor Amichay Rotstein, Department of cardiology and cardiac surgery,The Royal children's hospital Melbourne, Australia
  • Prof Samuel Menahem, Fetal diagnostic unit, Monahs Medical center, Melbourne Australia, Australia
  • Doctor Simon Meagher, Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia, Australia

    • OBJECTIVE: The fetal diagnosis of conotruncal abnormalities including TGA remains problematic. The diagnosis of TGA is commonly based on demonstrating the bifurcation of the great vessel arising from the posterior left ventricle and by the parallel course of the great arteries.
    METHODS: We retrospectively reviewed fetal studies where a postnatal diagnosis of TGA was confirmed, specifically images of the great vessel arising from the anterior chamber as it courses cranially to the three vessel tracheal view (3VTV). We compared these images to those in the fetus with a structurally normal heart (SNH).
    RESULTS: In all 9 recent TGA cases, scanning the great vessel (aorta) cranially following it from the anterior ventricle to the 3VTV demonstrated a convexity to the right, as opposed to a convexity to the left of the great vessel (pulmonary artery), in all the cases with SNH. We note that only 2 vessels were demonstrated in the 3VTV in patients with TGA, (SVC and transverse aorta), as opposed to 3 vessels, in the fetus with a SNH (SVC, transverse aorta and pulmonary artery). Figures 1 illustrates these findings.
    DISCUSSION: The 3VTV as a routine part of fetal cardiac scanning has been well described. Determining the direction of the convexity of the great vessel arising from the anterior right ventricle may aid in the fetal diagnosis of TGA. The relative ease, in which this view may be obtained, may prove to be the view of choice in the fetal diagnosis and screening of TGA.