cardiovascular changes at birth Flashcards
fetal circulation
lungs do not do ventilation
placenta provides oxygenation
which is the most metabolically active organ?
brain
how is circulation changed after birth
3 shunts
streaming
vasoconstriction in pulmonary circulation
3 shunts
foramen ovale
ductus arteriosus
ductus venous
ductus arteriosus
blood bypasses lungs
carries blood from pulmonary arter
ductus venous
blood bypasses liver
pulmonary constriction in fetus
???
foramen ovale
allows flow from right atrium to left atrium
Pressure
P=flow x resistance
pulmonary vasoconstriction
maintains right atrial pressure high and keeps ductus arteriosus patent
reduces flow to lungs and diverts the pulmonary artery blood through the ductus arteriosus
what causes pulmonary vasoconstriction/ hypertension
hypoxia, if it continues after birth fetal circulation can persist
polycythaemia
increased concentration of haemoglobin
how is adequate oxygen delivery done in fetal tissues
fetal haemoglobin
polycythaemia
???
how is adequate oxygen delivery done in fetal tissues
fetal haemoglobin
polycythaemia
???
changes at birth
first breath> ppO2 increases and causes pulmonary vasodilation > fall in right heart pressure
placental circulation ceases > left heart pressure rises
Both cause foramen ovale closes > venous blood goes to lungs
what happens when placental circulation ceases?
systemic resistance increases
closure of ductus arteriosus
closes after birth within 2-3 days, final event in sequence
patency of ductus arteriosus
maintained by prostaglandin E2
what happens if there is no first breath
continued hypoxia and fetal circulation continues
what happens to foramen ovale
fossa ovalis
what happens to ductus arteriosus
ligamentum arteriosum
what happens to ductus venous
ligamentum venosum
treatment for patent ductus arteriosus
ibuprofen - blocks prostaglandin production
what causes a continuous murmur?
patent ductus arteriosus
