palpitating vs pit-a-pat

palpitating

adj

  • Very exciting 

pit-a-pat

adv

  • With a quick tapping sound 

noun

  • A series of quick tapping sounds 

verb

  • To make a series of quick tapping sounds; to palpitate 

How often have the words palpitating and pit-a-pat occurred in a corpus of books? (source: Google Ngram Viewer )