I'm sorry to read that he has a heart murmur. I hope it does go away with age.
 
Miko had a heart murmur when we got him...He was around 13 weeks old, I think, and his heart murmur went away!! Thank goodness...Two different vets heard the heart murmur and were somewhat concerned, but it went away. Miko is almost 4 yrs old now, and I still have them check for that heart murmur when we goto the vet, but it's gone!! 
