Thank you for your query.
I can understand your concern. However hoarseness
of voice can be due to other reasons like upper respiratory tract
infection for which your son will be prone to. I suggest that you get him examined by the doctors who shall evaluate the cause of the hoarseness and even look for early signs of CHF. Without a clinical examination CHF cannot be ruled out.
I hope I have answered your query to your satisfaction.
Wishing your son an early recovery.
Rajiv K Khandelwal