embolus vs heart attack

embolus

noun
  • An obstruction causing an embolism: a blood clot, air bubble or other matter carried by the bloodstream and causing a blockage or occlusion of a blood vessel. 

  • The structure on the end of the palp of male arachnids which contains the opening to the ejaculatory duct. 

heart attack

noun
  • An acute myocardial infarction, sometimes fatal, caused by the sudden occurrence of coronary thrombosis, which obstructs the blood supply to the heart and leads to necrosis of heart muscle tissue. 

  • Death or failure. 

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