8th March 2024

Tetralogy of Fallot

Tetralogy of Fallot (TOF) is one of the commonest congenital heart diseases requiring intervention in the first year of life. Its prevalence in the UK is approximately 1 in 3600 live births with equal occurrence in males and females. It is characterised by four cardiac defects, which can be remembered by the mnemonic “International House Of Pancakes:”

• I – Interventricular septal defect
• H – Hypertrophic RV 
• O – Overriding aorta 
• P – Pulmonary stenosis (RVOT obstruction)
  

TOF may occur in isolation or with genetic conditions, including DiGeorge syndrome (22q11 deletion) and Down syndrome (trisomy 21). It is associated with cardiac features including right aortic arch; persistent left SVC and anomalous origin of the left anterior descending artery (LAD) from the right coronary artery. Pentalogy of Fallot describes TOF with associated (secundum) ASD. 

Image Source: Wikimedia Commons (2006). Tetralogy of Fallot, Licensed under a creative commons licence. Available for free at: https://en.wikipedia.org/wiki/Tetralogy_of_Fallot (Accessed: 26 January 2024).