Right ventricular failure in TOF is rare because right ventricle is not exposed to more than systemic pressure, neonatal RV can handle systemic pressure as RV is seldom called to do more than this, RV failure is rare in TOF. However in few situations right ventricle fails in TOF, and is frequent asked question by examiners.
Pulmonary atresia with large systemic to pulmonary collaterals, this is a kind of paradox in TOF i.e. extreme degree of pulmonary stenosis is sometimes associated with increased pulmonary blood flow. If blood flow in to pulmonary circulation is more than needed, TOF patents will have volume overload of both ventricle which can lead to biventricular failure.
VSD of TOF is nonrestrictive so pressure across LV and RV aorta are equal, if VSD becomes restrictive, RV pressure can become suprasystemic because of associated PS, than RV may fail. Restrictive VSD of TOF is mostly because of prolapsed septal leaflet of tricuspid valve
Acquired stenosis of aortic valve due to calcification and systemic hypertension lead to increase in after load on both ventricles leading to increase in RV pressure leading to failure
Aortic regurgitation of TOF leads to volume over load of both ventricles, so biventricular failure may occur.
Infective endocardities of aortic valve leading acute biventricular failure which can be catastrophe