I like Akzidenz's color edit, the pic needed more contrast
The heart looks awesome! ..but I'm not a great fan on health bars, especially if the pointer covers half of it
I would think that at full health, the heart would look as you made it, throbbing relatively slowly. At 2/3 health, blood is spurting out of it at each throb, it's pulsating faster and starting to get a greenish/grayish tinge. At 1/3 health, it's leaking with blood, has taken a strong grayish/greenish tinge, is slightly shrunken, beating at full speed.
My idea