Obviously this problem is related to a complication of surgery and is unfortunate. We really do not know the cause of Double aortic arch. During development of the arch in the foetus, the arch is always duplicate and one of them regresses. This has failed to occur. I am not aware of any relation to smoking or positive toxoplasma results and these are so difficult to prove. There is association between Double aortic arch and 22q 11 deletion in chromosome but we are far from understanding why these deletions occur. It is suggested that both parents should have tests for asymptomatic chromosome deletion and this is something that Dr. I. C. Verma may be able to guide. If any of the parents are positive for deletion, then there is 50% chance that the next sibling may have cardiac problems related to q11 deletion. If the parents are negative then we would consider this as a mutation and then the chances are less (although not zero) for the next sibling to have a congenital heart disease. Many of these can however be detected by expert fetal echocardiographer early in pregnancy and appropriate counselling be performed.