Fetal Circulation

What is the Placenta?

Most important organ; “Fetomaternal organ”

What type of blood goes through the umbilical vein?

Oxygenated; full of nutrients

What type of blood goes through the umbilical arteries?

Deoxygenated blood; Full of waste

How many shunts are there?

3 Shunts

What is the first shunt?

Oxygenated & nutrient rich blood leaves the placenta and travels through the fetus via the umbilical vein

How much blood goes through the liver in the first shunt?

About half of the blood is shunted into the liver

Where does the rest of the blood in the first shunt?

The rest is shunted through the Ductus Venosus into the IVC

What is the second shunt?

Blood drains from the IVC & SVC into the RA of the heart

What happens to the blood in the 2nd shunt?

Half of the blood is shunted from the RA to the LA; via FORAMEN OVALE

What is the 3rd shunt?

Blood will enter the PA after passing through the RV

What happens to the blood in the 3rd shunt?

90% of blood gets shunted to the aorta; 10% of the remaining blood enters the pulmonary system

What does the 3 shunts bypass?

Ductus Venosus - Liver - connects UV to IVC

Foramen Ovale - RV - Hole B/n RA & LA

Ductus Arteriosus - Lung - Hole B/n PA & Aorta

What affects vascular resistance?

Diameters of the blood vessel

Pressure, Diameter, Resistance

What is Pulmonary vascular resistance?

How much blood gets from point A to point B

What is the Systemic vascular resistance?

Reflection of how hard the LV must work hard to push blood through the body

What is Fetal Lung Fluid?

Combination of plasma ultrafiltrate from the fetal pulmonary microcirculation, components of the pulmonary surfactant, and other fluids from the pulmonary epithelial cells and the developing fetus

What happens to the fluid before birth?

It stops; 1/3 is released after vaginal squeeze

How much does it take for a baby to take its first breath/cry?

40 cm H20

What does the Ductus Venosus becomes?

Ligamentum Venosum; bypass liver

What does the Foramen Ovale become?

Fossa Ovalis; Bypass RV

What does the Ductus Arteriosus?

Ligamentum Arteriosum; closes within 7 days; bypass Lungs

What is cyanotic?

Blood shunts on the right side of the heart to the left

What is acyanotic?

Blood shunts from the left side of the heart to the right

What is Tetralogy of Fallot

Cyanotic; Pulmonary stenosis > PA tube is narrow; vessels push harder; x-ray shows “boot-shaped”

Transportation of the Great Vessels

Cyanotic; PA & aorta are swapped; x-ray shows “egg-shaped”

What is Ventricular Septal Defect (VSD)?

Acyanotic; Most common acyantoic defect

What is Atrial Septal Defect (ASD)?

Acyanotic; Most commonly caused by a patent foramen ovale not closing

What is Patent Ductus Arteriosus (PDA)

Commonly seen in infants with underlying respiratory disorder: Reflex pulmonary vasoconstriction