palpitation vs pounding

palpitation

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

pounding

noun
  • An act in which something or someone is pounded. 

adj
  • Characterized by heavy or loud throbs 

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