of four anatomic features: Anterior malalignment of the infundibular septum leading to RV outflow obstruction (pulmonic stenosis), VSD, overriding aorta and RV hypertrophy. Echocardiography is the primary imaging method to examine a child with suspected TOF. Important views are: Subcostal coronal and subcostal sagittal, subcostal paracoronal, apical four-chamber, suprasternal long- and short-axis.

2D echo identifies Intracardiac anomalies, including pulmonary stenosis (infundibular, valvular, supravalvular), VSD location and size, position of the aortic root over-riding the VSD, ASD, pulmonary annulus size, branch pulmonary arteries confluence and size, coronary artery origin, systemic venous anomaly as bilateral SVC and side of arch.

Color Doppler mapping is used to look for direction of shunt across VSD/ASD, additional VSD (need to reduce color scale), RVOT flow turbulence, PDA/collateral flow and any associated valve regurgitation (AV valve, aortic valve, pulmonary valve in case of TOF absent pulmonary valve), systemic and pulmonary venous connection.

Doppler interrogation of the pulmonary outflow tract is used to measure the velocity gradient in the RVOT and to differentiate severe stenosis from atresia. In small children, echo provides complete information and decision about surgical intervention (single stage or two stage) can be taken on the basis of echo alone.

In small number of children (suspicion of additional VSD, collaterals) and grown up children where acoustic windows are not good, cardiac catheterization or CT pulmonary angiography will be required before surgical intervention.