Entries related to heart-beat
Old English heorte "heart (hollow muscular organ that circulates blood); breast, soul, spirit, will, desire; courage; mind, intellect," from Proto-Germanic *hertan- (source also of Old Saxon herta, Old Frisian herte, Old Norse hjarta, Dutch hart, Old High German herza, German Herz, Gothic hairto), from PIE root *kerd- "heart."
Spelling with -ea- is c. 1500, reflecting what then was a long vowel, and the spelling remained when the pronunciation shifted. Most of the modern figurative senses were present in Old English, including "memory" (from the notion of the heart as the seat of all mental faculties, now only in by heart, which is from late 14c.), "seat of inmost feelings; will; seat of emotions, especially love and affection; seat of courage." Meaning "inner part of anything" is from early 14c. In reference to the conventional heart-shape in illustration, late 15c.; heart-shaped is from 1744.
Heart attack attested from 1875; heart disease is from 1864. The card game hearts is so called from 1886. To have one's heart in the right place "mean well" is from 1774. Heart and soul "one's whole being" is from 1650s. To eat (one's own) heart "waste away with grief, resentment, etc." is from 1580s.
c. 1300, "a beating, whipping; the beating of a drum," from beat (v.). As "throb of the heart" from 1755. Meaning "regular route travelled by someone" is attested from 1731, also "a track made by animals" (1736), from the sense of the "beat" of the feet on the ground (late Old English), or perhaps that in beat the bushes to flush game (c. 1400), or beat the bounds (1560s). Extended to journalism by 1875. Musical sense is by 1842, perhaps from the hand motion of the conductor and the notion of "beating the time":
It is usual, in beating the time of a piece of music, to mark or signalize the commencement of every measure by a downward movement or beat of the hand, or of any other article that may be used for the purpose .... ["Godfrey Weber's General Music Teacher," 1842]
Earlier in music it meant a sort of grace note:
BEAT, in music, a transient grace note, struck immediately before the note it is intended to ornament. The beat always lies half a note beneath its principal, and should be heard so closely upon it, that they may almost seem to be struck together. ["The British Encyclopedia," London, 1809]