I have witnessed a deer run a hundred yards after being shot through the heart and lungs before collapsing.
Shot one running one time, he flipped, jumped up and ran about 70 yards, then crumpled.
As you have stated, this one was heart shot. Seems that lung shots drop
them quicker, but the heart must cause something to happen in their
system that they have that sudden burst of energy.
I have also seen a man shot in the heart and drop like a sack of potatoes. In a calm state the adrenalin isn’t pumping, down you go. When the adrenalin is pumping, that is a different story.
My ex-SIL shot herself in the heart (suicide attempt). She was in ICU for months, in hospital for many more months and never fully recovered from all the damage; however, she lived for another 15-20 years at least.