<prompt> Essential criteria for TOF includes all except,Valvular stenosisInfundibular stenosisOverriding of aortaRVH  <response>: Ans. is a i.e. Valvular stenosis Right ventricular outflow obstruction is one of the characteristic of tetralogy of fallot.This right ventricular outflow obstruction is mainly caused due to infundibular stenosis.Pulmonary valve stenosis alone rarely contributes to the right ventricular outflow obstruction in tetralogy of fallot..Hurst cardiology says The pulmonary valve is often malformed, usually being either bicuspid or unicuspid. The valve may contribute to pulmonary stenosis, but, only uncommonly, it is the only site of significant obstruction to the pulmonary flow.Causes of right ventricular outflow tract obstruction.Infundibular stenosis 45.Obstruction at the pulmonary level 10.Combination of infundibular and valvular obstruction 30.Pulmonary atresia 15. 