thanks for your quiry
you are rightly concerned, but have not mentioned the details of what congenital defect he has?
and at what age he started having these symptoms of heart faliure
for some cardiac surgeries time is given till the symptoms of heart faliure regress, and child gains weight to bear the stress
of surgery and anesthesia
kindly continue with the medication, and send me your details to be better answered
get wwell soon