Hypercyanotic episodes in tetralogy of fallot

Hypercyanotic episodes or as they are also referred to ‘cyanotic spells’ most frequently occur in young children with Tetralogy of Fallot, but may occur in children with other forms of pulmonary stenosis with ventricular septal defect. Precipitating factors include crying, defecation, feeding, wakening from sleep, dehydration, fever, tachycardia, tachypneoa and events provoking agitation.

They are characterised by:

• Period of uncontrolled crying/panic/irritability
• Rapid and deep breathing
• Increased cyanosis
• Limpness and lethargy
• Reduced murmur intensity
  (signifying substantial blood flow reduction across right ventricular outflow tract)
• The older child squatting

Hypercyanotic spells require early recognition and management to prevent the development of complications from prolonged hypoxia. Whilst medical intervention may be required, many episodes are self-terminating.