Comprehensive and Detailed Explanation From Exact Extract:
Tetralogy of Fallot (TOF) is a congenital heart defect characterized by four key anatomical abnormalities: an outlet (malalignment) ventricular septal defect (VSD), an overriding aorta that receives blood from both ventricles, right ventricular outflow tract (RVOT) obstruction (commonly infundibular stenosis), and resultant right ventricular hypertrophy. These defects cause cyanosis due to right-to-left shunting and impaired pulmonary blood flow.
Option A describes Ebstein anomaly, characterized by a displaced tricuspid valve and atrialization of the right ventricle.
Option B describes features more consistent with Shone complex or other left heart obstructive lesions.
Option C describes atrioventricular septal defect (AVSD), seen in conditions like Down syndrome.
In unrepaired TOF, echocardiography demonstrates the large malalignment VSD, overriding aorta, RVOT obstruction, and hypertrophied right ventricle. These are classic textbook findings described in adult and pediatric echocardiography literature, including “Textbook of Clinical Echocardiography” (Chapter on Congenital Heart Disease) and ASE guidelines【16:Textbook of Clinical Echocardiography, 6e†p.560-565】【12:ASE Adult Congenital Guidelines†p.400-410】.