Coronary sinus ASD. (A) 2D mid-oesophageal commissural view showing an unroofed CS. (B) 2D mid-oesophageal modified bicaval view showing an unroofed CS with a shunt from the LA to the CS and then into the RA. (C) 3D-TOE live narrow-sector view of the mid-oesophageal four-chamber view showing the unroofing of the coronary sinus with direct communication between the LA and the CS. CS, coronary sinus; LA, left atrium; RA, right atrium.