Symposium - congenital heart disease Flashcards
(26 cards)
What are lungs full of before birth?
Fluid containing chloride, protein, mucus, surfactant
What produces surfactant?
Type 2 pneumonocytes from 24 weeks
What is the consequence of breathing movements occurring before birth?
Causes aspiration of some amniotic fluid
How is respiratory fluid removed from the foetal lungs?
Prelabour hormonal changes 40ml/kg to 10ml/kg
Compression of vaginal birth removes - 1/3
Adrenaline secreted in labour promotes reabsorption - 2/3
What motivates a baby to take their first breath?
Temperature change Light stimulation Physical stimulation Lack of oxygen supply Negative pressure in chest cavity from recoil after birth
What happens to the pulmonary blood vessels at birth?
Dilation of pulmonary vascular bed due to fall in capillary pressure
What is the ductus venosus?
Allows oxygenated blood from the placenta to bypass the liver
What causes the circulatory changes at birth?
Loss of placental blood flow
Start of respiration
What are the main circulatory changes that occur at birth?
Closure of:
- foramen ovale
- ductus arteriousus
- ductus venosus
- umbilical vessels
What is the foramen ovale?
Opening between the atria allowing oxygenated blood to by-pass the lungs
What changes occur to the foramen ovale at birth?
Functional closure which increases left atrial pressure and decreases right atrial pressure
Flexible septum primum is pressed against rigid septum secundum
What leads to the final fusion of fossa ovalis?
Apoposition of septa around 6-12 months
What is the ductus arteriosus?
Vessel connecting pulmonary trunk to arch of aorta
What is the function of the ductus arteriosus?
Protects lungs against circulatory overload by shunting 90% of blood away from the lungs
What happens if the ductus arteriosus isn’t present?
Too much blood flow into the lungs leading to pulmonary oedema
What mediates closure of the ductus arteriosus?
Bradykinin from the lung during initial inflation (requires high O2)
When does the ductus arteriosus close?
Initial closure at 6-48 hours
Full anatomical closure may take 1-3 months
What is the function of fetal iliac arteries?
Carries deoxygenated blood to placenta
What does the umbilical vein become?
The round ligament of the liver
What does the umbilical artery become?
The anterior division of internal iliac arteries
What is the function of the PDA in utero?
Bypass the lungs to prevent pulmonary oedema
How can the PDA be kept open?
Prostaglandins PGE2
What are the types of murmurs in paediatrics?
Innocent Systolic Pan or ejection Diastolic Continuous
What are some symptoms of right sided paediatric heart failure?
Hepatomegaly
Techypnoea
