Historical clue formulations

• Rhythmic part of a heartbeat — 2022-01-16
• Part of a heartbeat — 2021-04-04
• Cardiac contraction — 2019-01-12
• Part of a heartbeat — 2008-07-09
• Part of a heartbeat — 2006-05-07
• Normal rhythmical contraction of the heart — 2003-11-13
• Part of a heartbeat — 2003-09-07
• Heart contraction — 1999-06-13