foetal circulation and patent ductus arteriosus Flashcards
label the foetal circulation
describe the foetal circulation
blood is oxygenated in the placenta
→ baby via umbilical vein
umbilical vein → liver via ductus venosus
→ IVC → RA
SVC deoxy blood into RA → mixing of oxy and deoxy blood
blood passes through foramen ovale → LA
LA → LV → systemic circulation
some blood from RA → RV → pulmonary artery → lungs
pulmonary trunk → aorta (R - L shunt)
what does the ductus venosus become after the baby is born
ligamentum rotundum of the liver
why do the lungs require oxygen while the baby is still in the womb
the lungs require oxygen to grow and develop
pulmonary vascular resistance in foetal circulation
very high as lungs don’t need much blood
RV pressure > LV due to pulmonary vascular resistance
changes in the foetal circualtion at birth
- pulmonary vascular resistance falls
- pulmonary blood flow rises
- systemic vascular resistance increases
- Ductus arteriosus closes - within minutes after delivery
- foramen ovale closes
- ductus venosus closes
what does the foramen ovale become after birth
fossa ovalis
how common is patent ductus arteriosus (Botalli)
very common in pre-term infants
treatment of PDA
fluid restriction/diuretics
prostaglandin inhibitors
surgical ligation
in term babies - good chance of spontaneous closure within 1yr of life, not prostaglandin sensitive
what are 2 examples of prostaglandin inhibitors
indomethacin
ibuprofen
what controls the patency of ductus arteriosus
prostaglandins
what happens if ductus arteriosus is still patent at one year
no murmur - silent open duct (can only be demonstrated on echo, heamodynamically irrelevant) - no treatment necessary
symptomatic (murmur and present on echo) - catheter closure
