maternal, fetal, and neonatal circulation Flashcards
what happens to materal blood volume and blood viscosity during pregnancy? Why?
- increase in blood volume
- decrease blood viscosity
- factilitates fetal perfusion and minimizes the increase in maternal stroke work
what happens to CO, HR, and SV during pregnancy
- CO increases
- SV increases
- HR increases
what happens to systemic vascular resistance during pregnancy
decreased up to 50%
- due to addition of low resistance uteroplacental circulation
- increased blood levels of estrogen and local mediators
what happens to maternal BP during pregnancy
- 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
where does gas exchange occur in fetus
placenta
fetal heart (rt and left side) work in parallel or series?
parallel
function of umbilical vein
carries oxygenated blood from the placenta to the fetus
function of umublical arteries
carries waste from fetus to placenta
does umbilical artery or vein carry higher o2 saturated blood
umbilical vein carries higher O2 saturated blood (to fetus)
function of ductus venosis
- 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
function of foramen ovale
- 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
function of ductus arteriosus
- shunts blood from the pulmonary artery to the aorta
- represents a right to left shunt
what is the combined cardiac output in fetal circulation
- 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
The CCO from both ventricles is 100% and decreases to what % in the thoracic aorta
69%
are fetal lungs at high or low resistance?
the lungs are a high resistance circuit due to low PO2 and compression by liquid and receive 7% of the CCO
is the placenta a low or high resistance?
the placenta is a low resistance vascular bed and receives 50% of the CCO
feal blood enters the placenta with a O2 sat of what? and returns to the IVC with a O2 sat of what?
- enters placenta at 60% O2 sat
- returns to IVC at 85% O2 sat
what is the % o2 saturation in the Right atrium in the fetus
- 55% because blood is mixed with cerebral venous return
what is the %O2 sat in the left atrium in the fetus?
- 65%
what is the major change that happens to the fetal lungs with the first breath
decrease in pulmonary resistance
what is a major change to the cardiovascular system with the cessation of the umbilical-placenta circulation?
increase in total peripheral resistance
lungs inflate by first breath resulting in:
- relaxation of pulmonary precapillary vessels by O2
- decreases pulmonary pressure and resistance
- increases blood flow in pulmonary circuit
what changes occur when blood flow to the left atrium increases in the newborn
- increases pressure in LA
- LA pressure exceed RA pressure
- closes the functional foramen ovale
cutting the umbilical cord has what affect on fetal atrial pressure
- decreases venous return to the RA
- reduces atrial pressures
what happens to flow through ductus arteriosis as the pulmonary pressure falls below aortic pressure
flow through the ductus arteriosis is reversed (now a left to right shunt)
perinatal changes in circulation: as the low resistance of the placental circulation is lost, what happens to the unique vascular channels
- closure of umbilical vessels, ductus arteriosus, ductus venosus and foramen ovale
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?
- 60% from arbohydrate metabolism, lactate, and glycolysis
- 40% from fatty acid oxidation?
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?
- 30% carbohydrate metabolism, lactate, and glycolysis
- 70% from fatty acid oxidation
what governs the myocardial energy metabolism shift in newborns
this switch is governed by full maturation of the carnitine carrier system
what is an atrial septal defect
- 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
what does an atrial septal defect lead to
- leads to RA, RV, and pulmonary vessel dilation
- pulmonary HTN
is a ventricular septal defect
- produces a L to R shunt
- sends oxygenated blood into the RV and provides more blood into the lungs
what conditions does ventricular septal defect lead to
- pulmonary HTN
- increased blood return to LA results in left heart remodeling
what is a patent ductus arteriosus
- failure of closure of ductus arteriosus
- produces a L to R shunt- flow from aorta to pulmonary artery
- systemic blood is normally oxygenated
