Early Devolopment:The human embryonic heart (HEH)

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dipjyoti
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Early Devolopment:The human embryonic heart (HEH)

Post by dipjyoti » Tue Sep 26, 2006 8:18 am

At 21 days after conception, the human heart rate begins beating at 75-80 beats per minute and accelerates linearly for the first month of beating.
The human embryonic heart (HEH) begins beating approximately 21 days after conception, or five weeks after the last normal menstrual period (LMP), which is the date normally used to date pregnancy. The human heart begins beating at a rate near the mother’s, about 75-80 beats per minute (bpm). It then accelerates linearly for the first month of beating, peaking at 165-185 bpm during the early 7th week, (early 9th week after the LMP). This acceleration is approximately 3.3 bpm per day, or about 10 bpm every three days, an increase of 100 bpm in the first month. [1]

After peaking at about 9.2 weeks after the LMP, it decelerates to about 150 bpm (+/-25 bpm) during the 15th week after the LMP. After the 15th week the deceleration slows reaching an average rate of about 145 (+/-25 bpm) bpm at term. The regression formula which describes this acceleration before the embryo reaches 25 mm in crown-rump length or 9.2 LMP weeks is:

Age in days = EHR(0.3)+6

There is no difference in male and female heart rates before birth.[1]

DIP JYOTI CHAKRABORTY.
FORMER NATIONAL CHILD SCIENTIST. MEMBER OF RAMSAR, GLAND;SWITZERLAND. MEMBER OF Epilepsy Foundation 8301 Professional Place Landover.
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