Stopping the Pulse
As hard as it seems, this is nothing but a magic trick. His heart didn't really stop beating, it only wasn't detectable in his wrist.
So, how do you stop your pulse like Derren Brown?
It is in fact very easy and not dangerous at all. You will need something like a smaller ball or a crumpled piece of paper. It should be just big enough to fit under your armpit. Once you have it there, all you need to do is press your arm against your body. The object under your armpit will press on a major artery in your arm, making it hard for the blood to come through. Your pulse should gradually slow down and then completly disappear.
Again, this is not dangerous and can be performed by anyone.