Ventricular Septal Defect (VSD) is a type of congenital heart defect and represents the most common abnormality of the structure of the heart. A VSD is a hole in the wall between two of the heart chambers that normally isn't there. This allows blood to flow from the left ventricle to the right ventricle, which can result in more blood than usual going to the lungs. Unless it is severe, many infants with a VSD can have no symptoms at all. In the more severe forms, it can cause tiredness, poor heart function, high blood pressure in the lungs, poor feeding, and poor weight gain.
By your description, it sounds like your infant son has a very mild form of VSD, which therefore may resolve on its own. If it doesn't, surgery may be required when he is two or three years old where a patch would be placed over the hole to close it. The goals of any treatment are to insure your son grows well, to prevent the development of lung damage, and to prevent infection. A Pediatric Cardiologist will be better able to evaluate your son's VSD further and give you recommendations specific to him.