maternal, fetal, and neonatal circulation

Question 1

what happens to materal blood volume and blood viscosity during pregnancy? Why?

Answer 1

• increase in blood volume
• decrease blood viscosity
• factilitates fetal perfusion and minimizes the increase in maternal stroke work

Question 2

what happens to CO, HR, and SV during pregnancy

Answer 2

• CO increases
• SV increases
• HR increases

Question 3

what happens to systemic vascular resistance during pregnancy

Answer 3

decreased up to 50%

• due to addition of low resistance uteroplacental circulation
• increased blood levels of estrogen and local mediators

Question 4

what happens to maternal BP during pregnancy

Answer 4

• MAP decreases until mid-pregnancy then returns to the non-pregnant state
• decrease in MAP is due to a drop in total peripheral vascular resistance

Question 5

where does gas exchange occur in fetus

Answer 5

placenta

Question 6

fetal heart (rt and left side) work in parallel or series?

Answer 6

parallel

Question 7

function of umbilical vein

Answer 7

carries oxygenated blood from the placenta to the fetus

Question 8

function of umublical arteries

Answer 8

carries waste from fetus to placenta

Question 9

does umbilical artery or vein carry higher o2 saturated blood

Answer 9

umbilical vein carries higher O2 saturated blood (to fetus)

Question 10

function of ductus venosis

Answer 10

• arises from umbilical vein
• shunts blood flow directly into the inferior vena cava
• allows oxygenated blood from placenta to bypass the liver
• carries 50% of blood from placenta

Question 11

function of foramen ovale

Answer 11

• ovale hole in the septum dividing the atria
• shunts blood that enters the right atrium into the left atrium
• represents a right-to-left shunt

Question 12

function of ductus arteriosus

Answer 12

• shunts blood from the pulmonary artery to the aorta
• represents a right to left shunt

Question 13

what is the combined cardiac output in fetal circulation

Answer 13

• the R and L sides of the fetal pump are in parallel and because the inputs and outputs of these sides mixes, the sum of the outputs is the CCO

Question 14

The CCO from both ventricles is 100% and decreases to what % in the thoracic aorta

Answer 14

69%

Question 15

are fetal lungs at high or low resistance?

Answer 15

the lungs are a high resistance circuit due to low PO2 and compression by liquid and receive 7% of the CCO

Question 16

is the placenta a low or high resistance?

Answer 16

the placenta is a low resistance vascular bed and receives 50% of the CCO

Question 17

feal blood enters the placenta with a O2 sat of what? and returns to the IVC with a O2 sat of what?

Answer 17

• enters placenta at 60% O2 sat
• returns to IVC at 85% O2 sat

Question 18

what is the % o2 saturation in the Right atrium in the fetus

Answer 18

• 55% because blood is mixed with cerebral venous return

Question 19

what is the %O2 sat in the left atrium in the fetus?

Answer 19

• 65%

Question 20

what is the major change that happens to the fetal lungs with the first breath

Answer 20

decrease in pulmonary resistance

Question 21

what is a major change to the cardiovascular system with the cessation of the umbilical-placenta circulation?

Answer 21

increase in total peripheral resistance

Question 22

lungs inflate by first breath resulting in:

Answer 22

• relaxation of pulmonary precapillary vessels by O2
• decreases pulmonary pressure and resistance
• increases blood flow in pulmonary circuit

Question 23

what changes occur when blood flow to the left atrium increases in the newborn

Answer 23

• increases pressure in LA
• LA pressure exceed RA pressure
• closes the functional foramen ovale

Question 24

cutting the umbilical cord has what affect on fetal atrial pressure

Answer 24

• decreases venous return to the RA
• reduces atrial pressures

Question 25

what happens to flow through ductus arteriosis as the pulmonary pressure falls below aortic pressure

Answer 25

flow through the ductus arteriosis is reversed (now a **left to right shunt**)

Question 26

perinatal changes in circulation: as the low resistance of the placental circulation is lost, what happens to the unique vascular channels

Answer 26

* closure of umbilical vessels, ductus arteriosus, ductus venosus and foramen ovale

Question 27

in a newborn, what percentage of ATP production is derived from carbohydrate metabolism, lactate, and glycolysis and how much is derived from fatty acid oxidation?

Answer 27

* 60% from arbohydrate metabolism, lactate, and glycolysis * 40% from fatty acid oxidation?

Question 28

in a 7 day old newborn, what percentage of ATP production is derived from carbohydrate metabolism, lactate, and glycolysis and how much is derived from fatty acid oxidation?

Answer 28

* 30% carbohydrate metabolism, lactate, and glycolysis * 70% from fatty acid oxidation

Question 29

what governs the myocardial energy metabolism shift in newborns

Answer 29

this switch is governed by full maturation of the carnitine carrier system

Question 30

what is an atrial septal defect

Answer 30

* failure of foramen ovale to close * produces a **Lt to Rt shunt** * sends oxygenated blood into the RA and provides more blood into the lungs

Question 31

what does an atrial septal defect lead to

Answer 31

* leads to RA, RV, and pulmonary vessel dilation * pulmonary HTN

Question 32

is a ventricular septal defect

Answer 32

* produces a L to R shunt * sends oxygenated blood into the RV and provides more blood into the lungs

Question 33

what conditions does ventricular septal defect lead to

Answer 33

* pulmonary HTN * increased blood return to LA results in left heart remodeling

Question 34

what is a patent ductus arteriosus

Answer 34

* failure of closure of ductus arteriosus * produces a L to R shunt- flow from aorta to pulmonary artery * systemic blood is normally oxygenated