Final answer:
Cyanosis is the symptom described by the infant's skin turning blue, which indicates a lack of oxygenated blood, often caused by congenital heart defects such as tetralogy of Fallot and patent foramen ovale.
Step-by-step explanation:
The infant's skin turning blue during temporary deprivation of oxygen is a symptom known as cyanosis.
This condition arises when there is an insufficient supply of oxygenated blood flowing through the body.
In the context of congenital heart defects, such as severe septal defects including tetralogy of Fallot and patent foramen ovale, a child can present with this symptom, often referred to as a "blue baby."
Cyanosis can be seen in individuals when they are active, highlighting the body's increased demand for oxygen that is not being met due to the heart's improper development.