An atrial septal defect (ASD) is a hole in the heart that can lead to heart failure. Depending on the size and severity of the ASD, They can be treated during a heart catheterization with a special device that can permanently seal the ASD, but knowing the exact size and severity of the ASD is crucial. Newer MRI techniques may provide a better way at diagnosing the size and severity of an ASD. We compared MRI to other standard clinical ways for evaluating an ASD.