All of the following are true regarding tetralogy of fallot except: March 2008

Ans. D: Left ventricular hyperophyTetralogy of Fallot constitutes about 10 percent of all congenital hea disease.It iS the most common cyanotic hea defect.It is a congenital cardiac anomaly that consists of four defects: pulmonic stenosis, ventricular septal defect, malposition of the aoa so that it arises from the septal defect or the right ventricle, and right ventricular hyperophy. Radiographic findings-hea is roughly normal size. The curve of the right hea margin is tall. The cardiac apex is elevated above tile diaphragm. There is a visible aoic knuckle. The curve of the left ventricular margin begins immediately below this and also looks longer than usual. The pulmonary vessels are undersized.The hea is often enlarged and may be "boot shaped" as a result of marked right ventricular hyperophy, paicularly of the apical region.The clinical consequences depends primarily on the severity of subpulmonic stenosis, as this determines the direction of blood flow. If the subpulmonary stenosis is mild, the abnormality resembles an isolated VSD, and the shunt may be leftto-right, without cyanosis (pink tetralogy)