Nuclear Cardiology: A 53 year old woman being evaluated for dyspnea

Nuclear Cardiology case image

The above images represent the exercise dual isotope study (stress sestamibi/rest thallium) of a 53-year old woman being evaluated for dyspnea. In 1991 transthoracic echocardiogram had suggested an ASD, which was not confirmed by transesophageal echo. What is the abnormality?
Click the button below to view answer:

Comments