Subcostal view showing a 15 mm secundum atrial septal defect
RA: Right atrium; LA: Left atrium; ASD: Atrial septal defect; ?SVC flow: Flow from superior vena cava into the right atrium. ASD flow: Left to right shunt from left atrium to right atrium (Red colour of the flow is because flow is towards the transducer; right to left shunt will be blue in colour in the subcostal view as the flow would be away from the transducer). Slight mosaic colour of the ASD flow jet is seen, indicating mild turbulence of the stream. In this view the ASD is seen to have good rims on either side, suggesting that it may be an ideal case for device closure. Good rims all around the ASD is considered as a favourable sign when device closure is being considered as the device is likely to be well seated and held in place during movements of the heart. This minimizes the chance of device migration, as may occur in cases where one or more rims are defective.