Thanks for your query.
I understand your concern
Relax,there is nothing to worry.
Recurrent respiratory infections upto 6 to 8 are common in young children .
Congenital heart disease
precipitates infections but it depends on type of heart disease as well.
Be in regular follow up with your pediatrician
Give him nutritious diet rich in proteins
,minerals and vitamins
as this will help in boosting immunity.
Give plenty of fluids.
Warm fluids will be soothing
Give steam inhalation.
In case symptoms persist get him examined by doctor as physical examination will be needed for further management.
Hope I have answered your query.
Let me know if I can help further.
Wishing your child good health.