Successful balloon atrial septostomy in TGA (transposition of great arteries) with intact IVS (interventricular septum) reduces trans septal gradient by:
a) < 2 mm Hg
b) < 3 mm Hg
c) < 4 mm Hg
d) < 5 mm Hg
Answer: a) < 2 mm Hg
A very low gradient indicates an unrestrictive atrial septal defect which would allow good mixing at the atrial level which would improve systemic oxygen saturation by allowing desaturated systemic venous return to reach the lungs for oxygenation.