Cyanotic spells are episodes of bluish discoloration of the skin and mucous membranes, which is caused by low blood oxygen levels in infants with congenital heart defects.
It's possible you're referring to a different term that sounds similar to "tet," such as:
* "Tet" for "Tetralogy of Fallot": This is a common heart defect that can cause cyanotic spells. It's a combination of four heart defects: ventricular septal defect (VSD), pulmonary stenosis, overriding aorta, and right ventricular hypertrophy.
* "Tet spell": This is a more common term referring to the episodes of cyanosis (bluish discoloration) caused by low oxygen levels in infants with Tetralogy of Fallot. These spells are triggered by crying, feeding, or exertion.
Please clarify your question, and I will be happy to give you a more specific answer.