<prompt> A 21-year old male presents with exeional dyspnea, raised JVP and loud P2. ECG shows right axis detion. All of the following conditions are possible exceptAtrial septal defectMitral stenosisOstium primumPulmonary thromboembolism  <response>: An ostium primum atrial septal defect ASD occurs when then atrial septum near the atrioventricular valves has a communication between the two atrium causing a left to right shunt. This rarely develops into Eisenmengers syndrome if pulmonary hypeension develops reversing the direction of the shunt to right to left. Ref Davidson 23rd edition pg 453 