According to my knowledge, blood arrow does not cancel itself when u dont have enough hp, but rather kills u instead. Except if its something they have modified.
Do u use some macro/comboengine maybe to cancel the buff when ur hp is < 20% for example? If yes, the problem should be there instead.
As far back as I can remember, they have NEVER killed you unless you have a pheonix on. This goes for any of the skills that consume hp. They shut off automatically. And no, I don't use anything to shut it off.