Serce - Serce

I know this is kind of gross, but I am curious as to the physical and psychological affects of taking a bullet directly in the heart. What happens in the brain (emotionally, psychologically)? What happens to the organ itself? What kind of physical reactions occur? Any release of neurological chemicals? Can you live after such an injury? What are the chances of being killed instantly versus living for a few moments? I guess watch too many crime TV shows…
Thanks for answering!