Dear Laura Lee,
Respiratory syncytial virus (RSV) is a virus that can cause significant pulmonary as well as cardiac damage. Without having further information about your son, I can't say exactly what happened with him. I can say that myocarditis, which in children is typically due to a viral infection, causes damage to the heart most likely from both the virus itself as well as the body's immune response. Some children tolerate myocarditis and recover; others can have irreparable damage. To be fair, myocarditis is not preventable, as far as we know. RSV infection, while preventable with giving a therapy called Synagis, is not indicated for patients with previous myocarditis. And, once contracted, is very difficult to treat.
By the tone of your second question, I would recommend that, if you have questions about performance of a medical team, this is not the venue to discuss it.