Well, you can't aim at what you can't see. But visualizing how the vitals lie within the chest cavity at the angle you're shooting at and running that thru the hair covered computer, I chose the exact hair I aim at on the entrance side in order to get the arrow to arrive at the spot I intend for the exit hole to be. I like to go to the zoo and practice that visulization technique on living animals.

The zoo staff gets kinda flustered when they see me draw my imaginary bow to anchor and execute a flawless release though.