What is the most likely diagnosis? 
              
- 49 year-old female undergoing cardiac CT for suspected coronary artery disease

  
  Contrast-enhanced axial CT through heart
            
              
              
                - Bicuspid aortic valve
- Left ventricular thrombus
- Left atrial myxoma
- Ostium primum atrial septal defect
- Sinus venosus atrial septal defect
Additional Images - Additional contrast-enhanced axial CT
            
             
            
               
              Additional Images
               
              
              Additional contrast-enhanced axial CT
              
             
            
              
                  Answer:
               
              
                5. Sinus Venosus Atrial Septal Defect
                 
              
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              Sinus Venosus Atrial Septal Defect
                
              
              General Considerations
              
                - Atrial septal defects       (ASD) represent 10-15% of congenital cardiac abnormalities
                    
                      - Sinus venosus  type of ASD accounts for 10% of ASDs and only 1% of  all congenital heart lesions