Symposium - congenital heart disease

Question 1

What are lungs full of before birth?

Answer 1

Fluid containing chloride, protein, mucus, surfactant

Question 2

What produces surfactant?

Answer 2

Type 2 pneumonocytes from 24 weeks

Question 3

What is the consequence of breathing movements occurring before birth?

Answer 3

Causes aspiration of some amniotic fluid

Question 4

How is respiratory fluid removed from the foetal lungs?

Answer 4

Prelabour hormonal changes 40ml/kg to 10ml/kg
Compression of vaginal birth removes - 1/3
Adrenaline secreted in labour promotes reabsorption - 2/3

Question 5

What motivates a baby to take their first breath?

Answer 5

Temperature change
Light stimulation
Physical stimulation
Lack of oxygen supply
Negative pressure in chest cavity from recoil after birth

Question 6

What happens to the pulmonary blood vessels at birth?

Answer 6

Dilation of pulmonary vascular bed due to fall in capillary pressure

Question 7

What is the ductus venosus?

Answer 7

Allows oxygenated blood from the placenta to bypass the liver

Question 8

What causes the circulatory changes at birth?

Answer 8

Loss of placental blood flow

Start of respiration

Question 9

What are the main circulatory changes that occur at birth?

Answer 9

Closure of:

• foramen ovale
• ductus arteriousus
• ductus venosus
• umbilical vessels

Question 10

What is the foramen ovale?

Answer 10

Opening between the atria allowing oxygenated blood to by-pass the lungs

Question 11

What changes occur to the foramen ovale at birth?

Answer 11

Functional closure which increases left atrial pressure and decreases right atrial pressure
Flexible septum primum is pressed against rigid septum secundum

Question 12

What leads to the final fusion of fossa ovalis?

Answer 12

Apoposition of septa around 6-12 months

Question 13

What is the ductus arteriosus?

Answer 13

Vessel connecting pulmonary trunk to arch of aorta

Question 14

What is the function of the ductus arteriosus?

Answer 14

Protects lungs against circulatory overload by shunting 90% of blood away from the lungs

Question 15

What happens if the ductus arteriosus isn’t present?

Answer 15

Too much blood flow into the lungs leading to pulmonary oedema

Question 16

What mediates closure of the ductus arteriosus?

Answer 16

Bradykinin from the lung during initial inflation (requires high O2)

Question 17

When does the ductus arteriosus close?

Answer 17

Initial closure at 6-48 hours

Full anatomical closure may take 1-3 months

Question 18

What is the function of fetal iliac arteries?

Answer 18

Carries deoxygenated blood to placenta

Question 19

What does the umbilical vein become?

Answer 19

The round ligament of the liver

Question 20

What does the umbilical artery become?

Answer 20

The anterior division of internal iliac arteries

Question 21

What is the function of the PDA in utero?

Answer 21

Bypass the lungs to prevent pulmonary oedema

Question 22

How can the PDA be kept open?

Answer 22

Prostaglandins PGE2

Question 23

What are the types of murmurs in paediatrics?

Answer 23

Innocent
Systolic
Pan or ejection
Diastolic
Continuous

Question 24

What are some symptoms of right sided paediatric heart failure?

Answer 24

Hepatomegaly

Techypnoea

Question 25

What are some symptoms of left sided paediatric heart failure?

Answer 25

Oedema - pedal, sacral

Tachypnoea

Question 26

How does ASD often present?

Answer 26

Children often have recurrent chest infections