<prompt> In which of the following conditions left atrium is not enlarged:Ventricular septal defectAtrial septal defectAoopulmonary windowPatent ductus aeriosus  <response>: Answer is B ASD ASD is associated with an enlarged right atrium right ventricle to accommodate large volume of bloilL The left atrium is not enlarged because it decompresses itself by shunting blood to the right atrium at a minor difference in pressure. The left atrium may enlarge once Eisen mengers syndrome develops and a reversal of shunt is seen across the defect. 