[TISSUE_TEMPLATE:HEART_TEMPLATE]
[TISSUE_NAME:heart tissue:NP]
[FUNCTIONAL]
[STRUCTURAL]
[SCARS]
[TISSUE_MATERIAL:LOCAL_CREATURE_MAT:HEART]
[RELATIVE_THICKNESS:1]
[HEALING_RATE:100]
[VASCULAR:10]
[PAIN_RECEPTORS:5]
[CONNECTS]
[TISSUE_SHAPE:LAYER]
I can see the problem. It only bleeds about twice as much as muscle. I have no idea on the science behind major arteries bleeding, but taking 100 tiles until he bled out seems a bit much.
Another oddity I've seen is when you destroy someone's upper spine they will still crawl around on the ground trying to attack you for quite some time before they finally suffocate.
I just imagine they're using their face to move and try to kill you by head butting you in the shin.