I have heard of this on and off. I even read a Radiesse disclaimer from a dr. office that says something like "Radiesse may be accidentely injected into a blood vessel causing pain and pressure, may result in a heart attack, stroke, skin necrosis or an infraction". I heard it was easy to break a blood vessel, etc. I can see them all in my face and I need injections right where the larger veins are. I am VERY scared and paranoid and it is keeping me from going in and doing this.