Syncope hyper-cyanotic spell true true https://www.ncbi.nlm.nih.gov/pubmed/16302879 Hyper-cyanotic spells are most frequently seen in infants with Tetralogy of Fallot (known as 'tet spells'), however can be seen in other congenital cardiac defects with pulmonary or subpulmonary stenosis and a ventriculoseptal defect and in pulmonary hypertension. Spells may be precipitated by tachypnea or tachycardia and by dehydration. Spells may be characterized by crying, panic, rapid deep breathing, deepening cyanosis, limpness and subsequently a tonic-clonic episode. It is important that hyper-cyanotic spells are recognized as failure to manage these events correctly can lead to prolonged hypoxia and death.