what does this chest xray show? what is the diagnosis?

"coeur en sabot" or "boot shaped heart"
it characteristic for:
tetralogy of fallot (TOF)

TOF is a congenital cyanotic heart disease formed of four components:
Pulmonary artery stenosis
VSD
over-riding of the aorta
mild right ventricular hypertrophy

read more at this link ..