I studied/researched wound ballistics for about 20 years...I try to avoid hitting the heart at all cost.
Studies in humans showed if the heart was destroyed with a high power rifle your brain will still function for 19 seconds. That gets you most of the way there.
Next when the heart is destroyed the artery leading to the brain can become plugged maintaining the blood pressure. When this happens you can "live" almost a full 60 seconds.
Next...research shows in some 4 legged animals (dogs, maybe deer too) 80% of the running and walking functions are controlled in the spine rather than in the brain like humans.
Shall I continue?
We also have a pretty good clue what causes the death run in heart shots.
We also know what angle is likely to cause a deer to drop the fasted when shot with an arrow. We know the effects of the diaphragm being punctured vs not, etc.
We also know cause and effect of animals dropping on the spot.
My research started out to answer questions I had about hunting and crossed over to LEO for a few years. Some stuff published in a Gun Magazine and LEO book. Some of the stuff was pretty new and people had no clue how worked was done by some projectiles.
Anyhow, it gets to be a dark subject at times and people believe what they want to believe regardless of what is proven. Bottom-line is today I could pretty much care less.