Equal oxygen saturation in all four cardiac chambers

In which condition can there be equal oxygen saturation in all four cardiac chambers?

Conventionally, it is taught that oxygen saturation in all four cardiac chambers will be almost equal in total anomalous pulmonary venous connection.

But due to streaming of blood from superior vena cava to right ventricle and from inferior vena cava to left atrium across an atrial septal defect, left ventricular saturation will be less than that of right ventricle, in supracardiac form of TAPVC.