2. Objectives
โข Discuss anatomy and physiology of
fetal circulation
โข Define specialized structures of fetal
circulation
3. Anatomy and Physiology
Fetal Circulation
๏ฏ Umbilical cord
๏ฎ 2 umbilical arteries: return non-
oxygenated blood, fecal waste, CO2 to
placenta
๏ฎ 1umbilical vein: brings oxygenated blood
and nutrients to the fetus
โข Fetus depends on placenta to meet O2
needs while organs continue formation
โข Oxygenated blood flows from the placenta
4.
5.
6. โข To the fetus via the umbilical vein
โข After reaching fetus the blood flows through
the inferior vena cava
โข Blood continues to travel from the inferior
vena cava to the ductus venosis
โข Ductus Venosis
โ Small amount of blood routed to growing liver
โ Increased blood flow leads to large liver in
newborns
7. โข Blood continues to travel up the inferior vena cava
โข Empties into the right atrium of the heart
โข The blood then passes to the left atrium through the
foramen ovale
โข Foramen ovale
โ Small opening in the septum of the heart
โ Completely bypasses the non-functioning lungs
9. ๏ฏ Blood continues journey to the left ventricle blood
is then pumped into the aorta
๏ฏ Blood is circulated to the upper extremities
๏ฏ Blood then returns to the right atrium
โข From the right atrium, the blood goes to the right
ventricle then to the pulmonary arteries
โข Pulmonary arteries
โ Small amount goes to the maturing lungs
โข Rest of blood is shunted away from lungs by Ductus
ateriosus back to aorta
10.
11. โข Blood travels back from aorta to the two
umbilical arteries to the placenta
โข The placenta will re-supply the blood with
oxygen
12. What happens at birth?
Foramen ovale Closes shortly after birth,
fuses completely in first
year.
Ductus arteriousus Closes soon after birth,
becomes ligamentum
arteriousum in about 3
months.
Ductus venosus Ligamentum venosum
Umbilical arteries Medial umbilical ligaments
Umbilical vein Ligamentum teres
13. Problem with persistence
of fetal circulation
๏ฏ Patent (open) Ductus arteriousus and patent
foramen ovale each characterize about 8% of
congenital heart defects.
๏ฏ Both cause a mixing of oxygen-rich and oxygen-
poor blood; blood reaching tissues not fully
oxygenated. Can cause cyanosis.
๏ฏ Surgical correction now available, ideally
completed around age two.
๏ฏ Many of these defects go undetected until child
is at least school age.