This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pediatrics
Most impoant determinant in Fallot&;s tetralogy is 
Select and explain. 
A. RVH, B. Sub-pulmonic stenosis, C. Pan systolic murmur, D. Enlargement of hea
B: Sub-pulmonic stenosis
Answer: B: Sub-pulmonic stenosis 
Explanation: The more severe pulmonary stenosis the shoer the ejection systolic murmur and more the stenosis.Thus the severity of stenosis is directly propoional to severity of pulmonary stenosis ,but the intensity of the systolic murmur is inversely related to the severity of the pulmonary stenosis. Ref : page 420 Ghai pediatrics eighth edition