Congenital heart disease Flashcards
Fetal lung maturation
Before birth, the lungs are full of fluid
- Chloride
- Protein
- Mucus
- Surfactant
Breathing begins before birth
- Amniotic fluid aspirated
60% fluid removed from lungs before delivery
Breathing movements of fetus
Helps to develop lungs
- Like respiratory muscles
Removal of respiratory fluid in fetus
Hormonal changes pre-labour
Vaginal birth
- Compression
Adrenaline secretion [2/3]
- Increases reabsorption of fluid
Factors that stimulate baby to take first breath
Temperature change
Stimulation from light
Physical stimulation
Lack of O2 supply
- Separation of placenta
Negative pressure in chest cavity
Amniotic fluid
- Synthesis
- Function
Synthesis
- Made from maternal plasma via placenta
- Fetal urine
Function
- Cushions against trauma
- Contains growth factors
- Inhaled at birth
Changes in the lungs at birth
Inflation of pulmonary sacs [alveoli]
- Decreases pressure = dilation of pulmonary vascular bed.
Circulatory differences pre-birth
Umbilical vein/ Artery
Ductus venosus
Foramen ovale
Ductus arteriosus
Umbilical vessels
Vein
- Brings blood from the placenta and is shunted from the left portal vein into the IVC
Artery
- Paired
- Carries deoxygenated blood to the placenta
- Develops into internal iliac arteries
Ductus venosus
Vessel in fetal circulation that shunts blood from the umbilical vein, into the IVC.
Bypasses the liver as the blood from placenta is already cleared from mother’s liver.
Closes to form ligamentum venosum
Ductus arteriosus
Vessel that causes a right to left shunt
- Blood from pulmonary trunk shunted into aorta arch
- Bypasses lungs
- Kept open via prostaglandins secreted from placenta
Closes to form ligamentum arteriosum
Foramen ovale development
- Septum primum + intermedium
- Septum degrades to form ostium secundum
- Septum secundum
- Foramen ovale forms in septum secundum
Foramen ovale
Hole in the septum between the atria
- Allows right to left shunt
- Bypasses the lungs
Closes at birth –> Fossa ovalis
- Increases pressure in left atrium
- Decreases pressure in right atrium
Takes 6-12 months for f.Ovalis to form
Ductus arteriosus pre and post closure
Pre-closure
- Prevents circulatory overload of lungs [oedema]
Post-closure
- Initially 6-48 hours, then 1-3 months.
- Requires high oxygen levels during lung inflation–> bradykinin mediated
- Muscular contraction causes vasoconstrction
When does the PDA close
Initially
- 6-48 hours
Fully
- 1-3 months
Innocent murmurs
Also called flow murmurs
- Caused by tachycardia
Changes with position
- Supine and upright
