Scout is correct. Contact MullenLE, be prepared to attach your med records. There are a lot of different types of heart murmurs. A flow murmur can be different than the traditional murmur. You can't just take the assumption that they all are all equal.
Make sure you know the exact murmur and the diagnosis before you contact him. The more info you give the more concise of an answer he can give regarding the DodMerb process.
That being said, you are in front of the 8 ball, because you will need to get a DodMerb exam. If you know the exact reg, which MullenLE will help you with, than if you need a waiver you will be able to fight it from a stronger stance because you understand the requirements for the waiver.
Good luck.