a child dying of heart murmur suggests that he had a congenital heart disease and he must have gone into Congestive heart failure and succumbed(commonly seen in these conditions). If ECHO was done, that could have explained the type of heart defect in the child. If the child has Cynotic CHD, in that condition a Hypoxic event can lead to seizures. Children with CHD are prone to sever pneumonias which are difficult to treat and can lead to septicemia and Meningitis, which is another cause of seizures. Apart from these conditons, brain abscess in CCHD or any structural malformation in the brain(Syndromic baby) can also cause seizures.