Flashcards in Exam #3 Cardiac Deck (114)
When we are in the uterus, we do not need our lungs. So they are collapsed down, but they still make surfactant.
since we do not use lungs as a fetus, we get oxygenated blood via the placenta.
From the placenta… oxygenated blood flows through the umbilical vein to the fetus.
Once it enters the fetus….it goes to the liver where we have something that is called the DUCTUS VENOSUS.
What does the ductus venosus do?
It shunts the oxygenated blood straight into the inferior vena cava.
Once the blood has been shunted from the ductus venosus into the inferior vena cava…..Where does it go next?
Into the right atrium.
In a fetus, the problem is that we do not need it to go to the lungs….because of the pressure…we have a trap door that opens called the Foramen ovale.
What does the foramen ovale do?
It is literally a hole between the atriums with a little flap. So blood goes from the right atrium into the left atrium and bypasses the lungs.
And because the pressure is stronger coming from the mother…it keeps it open.
After the blood enters the right atrium and travels through the foramen ovale into the left atrium….where does it go next.
It goes through the mitral valve into the left ventricle and out through the aorta.
Most of it goes from the aorta to the brain.
This is where most of it is shunted
Even though fetal circulation bi-passes the lungs….there is still a little bit of leakage through the tricuspid valve into the right ventricle…into the lungs.
Even though the fetus does not use the lungs….they still need a little bit of blood in order to make surfactant.
Most of the blood needed is given to the brain due to its rapid growth.
This is done though a shunt called the ductus arteriosis.
What does the ductus arteriosus do?
The ductus arteriosus takes most of mommas blood that did
Go through the foramen ovale and shunts it over to the pulmonary vein…to the left atrium….and left ventricle and out to the brain.
When the fetus is done getting the oxygenated blood from momma, how is the blood returned to the fetus to be reoxygenated?
Through the umbilical arteries.
Name the 2 shunting systems that deliver oxygenated blood to the fetus….
Which one shunts blood into the pulmonary veins?
Which one shunts blood into the inferior vena cava?
Which one carries oxygenated blood to the fetus?
Which one carries unoxygenated blood away from the the fetus?
Name the 5 fetal circulation structures.
Fetal Circulation through the heart….
liver, ductus venosus
inferior vena cava
back through umbilical artery
return to the placenta
leak through tricuspid
back through umbilical artery
return to the placenta
When you are born you come out of the vagina…..you take your first breath of life….it is about 40-60 sonometers of pressure that expands the lungs.
When you expand the lungs for the first time….you have changed the whole system.
Meanwhile, when the cord is cut, the pressure of the whole system changes.
The body now has a higher pressure in the lungs, and the placenta is gone.
So the foramen ovale closes.
Why does the foramen ovale close shortly after birth?
because we have more pressure from the lungs expanding for the first time.
Now the blood travels through the heart like it is supposed to.
Change Happens in about 1 min.
A fetus is used to getting ___% oxygen from the mother
Once the cord is cut and the baby is breathing on their own…What percent of oxygen are they now getting?
So when we look at congenital heart problems, we are looking at something that has gone wrong with the setup of ____ ______.
Most babies will do just fine with a congenital heart condition as long as the fetus is in the uterus getting all of their oxygen from the placenta.
True or false
When you put them in their own world, that is when any defects in their heart start showing up.
Congenital defects are classified by what?
Increased blood flow to the lungs and decreased blood flow to the lungs.
After the baby is born, and the cord is cut….
What stimulates the ductus arteriosus to close?
The ductus arteriosus will close slowly ( it constricts) in reaction to the fact that the baby is breathing 21% oxygen.
Also closes in response to a decrease in prostaglandins.
So if we have a good healthy baby (that has not been recusitated), the ductus arteriosus closes and we may hear a _____ in the first 1 - 2 hours of life.
Because it closes slowly
If we have a sick baby, especially a preterm baby…..they will not be getting enough oxygen…This means that their _____ _____ will stay open/patent.
It stays open because they baby is not getting enough oxygen and this is what stimulates it to close (along with dropping prostaglandin levels)
If a newborn baby that was fine originally gets sick later on 4-5 hours later….will their ductus arteriosus open again?
because the body thinks that it is without oxygen and back in the uterus
What are the Pediatric Indicators of Cardiac Dysfunction. (6 of them)
Failure to thrive, poor weight gain
Developmental delays esp. gross motor
Positive family history of cardiac disease
What are we looking for on a cardiac assessment of a child?
History – prenatal and postnatal
Blood pressure – 4 extremity