heart-strings (n.)youdaoicibaDictYouDict[heart-strings 词源字典]
also heartstrings, late 15c., in old anatomy, "the tendons and nerves that brace the heart;" from heart (n.) + string (n.). Transferred and figurative sense "strongest affections, most intense feelings" is from 1590s.[heart-strings etymology, heart-strings origin, 英语词源]