A five day old, full term male infant was severely cyanotic at bih. Prostaglandin E was administered initially and later ballooned atrial septosomy was done which showed improvement in oxygenation. The most likely diagnosis of this infant is:

Administration of Prostaglandin E and ballooned atrial septosomy which shows improvement in oxygenation in a severely cyanotic five day old male infant suggest this case as transposition of great vessels. Oxygenation is normal before bih but, after bih as ductus aeriosus closes, severe hypoxia occurs and in the absence of V.S.D, or ASD child presents with cyanosis and tachypnea at bih. Ref: O P Ghai Essential Pediatrics, 6th Edition, Pages 406-413