Thank you all for your answers and suggestions. Blue was his favorite color, which is why they were using the blue hearts. I know his family is still using blue hearts as Facebook icons but I'm still not sure ... it would probably be OK to use them but I am thinking I could come up with something more representative of his life instead of the end of his life. I think I agree that I'll just have to spend some time thinking about it, I feel sure something will come to me.
Thanks again.