cardiotachometer

noun

car·​dio·​ta·​chom·​e·​ter ˌkärd-ē-(ˌ)ō-ta-ˈkäm-ət-ər, -tə-ˈkäm- 

: a device for prolonged graphic recording of the heartbeat

cardiotachometric

-ˌtak-ə-ˈme-trik 

adjective

cardiotachometry

-ta-ˈkäm-ə-trē, -tə-ˈkäm- 

noun

plural cardiotachometries