This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pediatrics
In which of the following conditions left atrium is not enlarged 
Select and explain. 
A. Ventricular septal defect, B. Atrial septal defect, C. Aoopulmonary window, D. Patent ductus aeriosus
B: Atrial septal defect
Answer: B: Atrial septal defect 
Explanation: In ASD left atrium does not enlarge unless associated with other anomalies like mitral regurgitation . Ref : Ghai essential of pediatrics,eighth edition P.no: 413