I played for like an hour I think I already found a glitch ("already achieved player level : butcher") . I figure that there is the heart hit box on the left chest and maybe the neck artery on the left neck, I can cut from the right armpit to the left shoulder to completely severe the heart from the head while keeping it alive. and even cutting off the heart on the left chest piece. so then I can just damage the rest all I want without dealing further damage.
I just like making clean cuts sometimes