Cardiovascular System - Heart Rate Development
|Heart rate (beats / minute) is a measurement that can be made from early in development (when the heart first starts) through embryonic and fetal stages into labor and birth. It is a common clinical diagnostic tool, but data can be variable between countries and institutions.
Early ultrasonographic measurement of embryonic heart rate (EHR) shows a steady increase from Stage 9-10 (75 beats/minute) to Stage 18 (130 beats/minute) and on to Stage 20, following which a gradual decrease in EHR occurs (More? Embryonic Heart Rate). This increase correlates with heart development and a low EHR is used as an indicator of developmental failure and likely abortion. Late stethoscope measurements of fetal heart rate can monitor fetal stress and identifies the characteristic "lub-dub" heart valve sounds.
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Chicken embryo heart beat.
Some Recent Findings
- Human Embryology (2nd ed.) Larson Ch7 p151-188 Heart
- The Developing Human: Clinically Oriented Embryology (6th ed.) Moore and Persaud Ch14: p304-349
- Before we Are Born (5th ed.) Moore and Persaud Ch12; p241-254
- Essentials of Human Embryology Larson Ch7 p97-122 Heart
- Human Embryology Fitzgerald and Fitzgerald Ch13-17: p77-111
Embryonic Heart Rate
In a 1996 study normal successful human gestations were defined by EHR criteria at different early embryonic (34-56 days from last menstrual period) developmental stages (at the earliest stages when embryo length is difficult to measure gestational sac diameters are included). 
- Stage 9-10 2 mm embryo (gestational sac diameter of 20 mm) EHR at least 75 beats / minute
- Stage 11-12 5 mm embryo (gestational sac diameter of 30 mm) EHR at least 100 beats / minute
- Stage 16 10 mm embryo EHR at least 120 beats / minute
- Stage 18 15 mm embryo EHR at least 130 beats / minute
Search May 2010
- Cardiovascular System Development All (63457) Review (10735) Free Full Text (15717)
Search Pubmed: Embryonic Heart Rate
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Cite this page: Hill, M.A. (2019, October 21) Embryology Cardiovascular System - Heart Rate Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Cardiovascular_System_-_Heart_Rate_Development
- © Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G