I am also sorry to hear the kitties are unwell, i just wanted to tell you my Ash was recently diagnosed also with a heart murmur, he is an older cat and it is not very bad, the vet just wants to check him in a while but other than that has given me no instructions, it depends it if gets worse, he may require medication, sorry i cannot be of much help , but know i also worry about my ole boy too, HUGS .