Contrary to what FA says, TAPVR IS NOT a right-to-left shunt. Oxygenated blood from the lungs(now left side) is returning back to the right atrium(right side). This means blood never enters the left heart. This can't be a right-to-left shunt. Additionally, the creation of a large foramen ovale to allow flow to the right side of the heart will prevent further cyanosis.
It is a right-left shunt as for someone to survive you need a PFO or ASD which is why this says R-L shunt. Source: https://radiopaedia.org/articles/total-anomalous-pulmonary-venous-return?lang=us#:~:text=In%20TAPVR%2C%20all%20systemic%20and,atrial%20septal%20defect%20(ASD). I think you have a misunderstanding of blood flow in this context




Watch Right to Left Shunts







