I have been using Botox for well over 10 years and I have NEVER seen or heard of such potential complication. Botox does NOT cause Heart palpitations. Either you did not understand your physician or you went to a really misinformed professional who spent the last 10 plus years in a cave cut off from the medical world.
Barring a VERY unlikely injection into a large vein or the heart (I cannot even imagine how that could happen), when Botox is injected properly it STAYS locally and superficially under the skin or in the facial muscles into which it was injected. It then causes weakness of the very muscles it was placed in.
The work up of palpitations is a COMMON problem which every internist or Cardiologist should be able to do in their sleep if they had to. They need to look at your electrolytes to check for an imbalance and get a Holter test. In the latter, you carry a little EKG recording box while hooked to plastic leads on your chest. When you feel palpitations, you record the time and feeling. A computer then reviews the 24 hours worth of recordings and helps the doctor judge the source and location of these rhythms. Further studies may then be done.
Dr. P. Aldea