In the same vein as the no head question, how long could you live without a pulse??

 

in the fighting game mortal kombat one of the characters has a move where he reaches into his opponents chest, pulls out their heart and shows it to them before they die. this, however, is not what i mean. because of massive wounding etc. you would die or pass out pretty quickly.

 

but lets suppose that we had some kind of electronic gizmo that could send a shock of e.m. radiation or something into the heart, disrupt the elecrical activity and bring it to a dead stop without any wounding.

 

how long, then, before you keel over??

A few seconds. As soon as the circulation had stopped, neurones would begin to starve of oxygen. You would pass out in a few seconds. Cell death would occur after a few minutes.