Raw heart is rich in taurine which is good for some heart issues. Cooking destroys the taurine. I buy whole beef hearts from my local supermarket (do need to order them as they are not a stock item) they are very inexpensive. I freeze them and when ready to use I let them partially thaw as they are much easier to cut up when firm. Taurine is important for issues like dialated myocardiopathy, not sure about heart murmur, but raw heart is a great cheap protein source and dogs love it. Hope this helps.
