Oh yeah, I totally misread that. Through the wall?
Yeah, through the wall.
When standing at a bit of a distance from the circular wall and firing the (normal) shotgun, not the sawed off, you see the explosion on the wall, so the wall is actually detected and bullets are hitting it, but I think code-wise the bullets are deleted a few milliseconds too late so they actually hit those blood vessels before disappearing. This worked with all vessels surrounding the heart.
Haven't tested this thoroughly with other weapons, only once with the three ninja knives, but I think they are moving too slow to have this effect.
I'll try to make a movie, but am not really good at that and also do not really have a place to put them, so I might not feel like doing that, sorry ;)