It is a poetic or figurative phrase that emphasizes the intense emotion or passion associated with something.
Here are some possible interpretations:
* Deep love: The blood of the heart could symbolize the intense love and passion someone feels.
* Sacrifice: It could also refer to the ultimate sacrifice one would make for someone they love deeply.
* Pain and sorrow: In some contexts, it might represent the intense pain and sorrow associated with heartbreak or loss.
The specific meaning will depend on the context in which the phrase is used.