tetralogy of Fallot

Last edited 02/2023

Tetralogy of fallot is probably best thought of as having two essential features:

  • a large ventricular septal defect, usually sited high up in the membranous part of the septum beneath the aortic valve, such that the right ventricle ejects directly into the aorta; not via the left ventricle
  • right ventricular outflow tract obstruction. It is this element that determines much of the severity of the condition

In addition to, and at least in part as a consequence of this, there are the other two features of the tetrad:

  • overriding aorta, as a result of the malformation from the ventricular septal defect, which may be dextropositioned
  • right ventricular hypertrophy - as a result of, but not totally caused by the outflow obstruction

TOF represents 7% to 10% of congenital defects, affecting males and females equally and occurring in 3 to 5 of every 10,000 live births (1)