palpitation vs throbbing

palpitation

noun
  • An abnormal beating of the heart that may be perceived by the patient, a result of excitement, exertion, or illness. 

throbbing

noun
  • That which throbs. 

adj
  • Beating or pounding strongly. 

How often have the words palpitation and throbbing occurred in a corpus of books? (source: Google Ngram Viewer )