A sliver of anything ( metal, glass) can travel through your body and end up anywhere. But usually before this happens, the site around the foreign object becomes infected and works its way out or is surgically removed.
But, there have been cases of what you just said.
False. I just dont see how that could happen. A needle is long and sharp. It would have to get stuck somewhere along the way. Venous walls are not solid structures like PVC pipe. They are elastic and actually contract to help propel blood back to the heart. Try to imagine a needle traveling from the foot, going through all the bends and contractions of the veins and making it all the way to the heart without getting stuck.
the answer to your question is no
you can have intracardiac injections by a Dr for certain medical problems