What is Atrial Switches Operations (Senning or Mustard Operation) ?

In transposition of the great arteries there is ventriculo arterial discordance whereby aorta arises from right ventricle and pulmonary arterial from left ventricle. In atrial switch operation a baffle is placed in the arterial in such a way that blood from SVC and IVC flows under the baffle to mitral valve and left vent icle and to the pulmonary artery. Pulmonary venous return flows over the patch to tricuspid valve and RV and then to aorta.