LOL, the antidote for nerve agent (Atropine and 2-Pam Chloride) are auto (spring loaded) self-injectors that one is supposed to use in their thigh. So, yeah...probably not a good thing to put a hole in your heart. Besides, the needles in those kits probably aren't long enough (maybe just over an inch long) to reach the heart on most people, but it sure looked painful when a fella I knew triggered one into his thumb. The needles are kind of soft as well and it hooked nicely when it hit his thumbnail before it filled his thumb with the stuff.
Note, when I was in the Corps, we would occasionally trigger one off to later use it as a training aid. Most of us were smart enough to not try and trigger one with our thumb. My buddy got a trip to the hospital for that one. I can only imagine the look on the medical staff's face when he told them how he filled his thumb with nerve agent antidote.