Essential criteria for TOF includes all except ?

Ans. is 'a' i.e., Valvular stenosis o Right ventricular outflow obstruction is one of the characteristic of tetrology 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 biscuspid or unicuspid. The valve may contribute to pulmonary stenosis, but, only uncommonly, it is the only site of significant obstruction to the pulmonaryflow". Causes of right ventricular outflow tract obstruction. i) Infundibular stenosis (45%) ii) Obstruction at the pulmonary level (10%). iii) Combination of infundibular and valvular obstruction (30%). iv)Pulmonary atresia (15%).