Stab wound to the heart

[eiluned]

I'm writing an X-Men story where a character needs to die quickly. If someone is stabbed directly in the heart, how long would it take for them to die? The best I've found on Google is that it usually takes less than five minutes depending on where the wound is and how big it is, but I can't seem to pin down anything more precise than that. Wikipedia was spectacularly unhelpful.

Let's say someone was stabbed directly in the heart with Wolverine's claws. He knows how to kill quickly, so he would maybe twist or move the claws a certain way to do more damage. If his claws damaged the aorta (at least, I'd imagine that all three claws going in would damage pretty much the entire heart), how quickly would that person bleed out? Would two and a half to three minutes be believable?

Thanks in advance. :)