convulsion vs palpitation

convulsion

noun
  • An intense, paroxysmal, involuntary muscular contraction. 

  • An uncontrolled fit, as of laughter; a paroxysm. 

  • Violent turmoil. 

palpitation

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

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