How Do You Know if You Were Injected into an Artery with Radiesse?

It sounds like you are describing a vascular event.  Blanching, throbbing, change in color such as redness, or turning dark or dusky. Usually followed by increasing pain. If the occlusion is severe there can be tissue damage.  To avoid injecting into a vessel, It requires a thorough understanding of the anatomy. There are certain landmarks to avoid, in addition to injection techniques that minimize the risks. Injecting dermal filler should only be done by experienced, well trained medical professionals capable of administering emergency care if required. Complications can be serious but fortunately they are rare.

  Skin death and blindness from filler injection is possible.  Blunt-tipped cannulae can reduce the risk over needle injection.

Thank you for your question. From your description, it sounds like arterial injection was a possibility.  This is a known complication of all injectable fillers.  I would recommend you seek treatment from a surgeon experienced in using blunt tipped micro-cannulas for injection and the aspiration technique. These devices and maneuvers can help to reduce the risk of arterial injection and embolizaiton.