Foetal Circulation and Congenital Heart Disease Flashcards Preview

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Flashcards in Foetal Circulation and Congenital Heart Disease Deck (60)
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1
Q

Describe the foetal circulation.

A

Blood foes from placental to heart (little bit to lungs) then to brain and body and back to placenta.

2
Q

Which of the umbilical vessels has oxygenated blood in it and moves away from the placenta?

A

Umbilical vein.

3
Q

What are the 3 shunts in the foetus and what do they connect?

A

Ductus venosus (umbilical vein to IVC [bypasses liver]), foramen ovale (opening in atrial septum), ductus arteriosus (pulmonary bifurcation to descending aorta).

4
Q

What is the function of the foramen ovale?

A

Allows best oxygenated blood to enter left atrium then onto LV, ascending aorta and carotids.

5
Q

What percentage of RV output goes to the lungs and where does the rest go?

A

7%, via ductus arteriosus to join descending aorta.

6
Q

What molecule maintains patency of the ductus arteriosus?

A

Prostaglandin E2 (produced by the placenta).

7
Q

What else keeps the ductus arteriosus open?

A

The low PO2 in foetal blood.

8
Q

What are the changes in the resistance of vessels when the baby is born?

A

Decreased pulmonary vascular resistance (baby breathes in physically expanding vessels), increased SVR.

9
Q

What is the change in pressure in the heart and what does this cause?

A

Pressure goes higher in the left than the right, closes the foramen ovale with flap.

10
Q

What causes the ductus arteriosus to close?

A

Less flow going across duct as pressure changes, PO2 increases, prostaglandins are metabolised in lungs.

11
Q

When does the ductus arteriosus close functionally and anatomically?

A

Functionally - within hours to days.

Anatomically - 7-10 days.

12
Q

What are the treatments of failure of duct closure?

A

Wait and see, NSAIDs (inhibit prostaglandin production) and surgery.

13
Q

What can be used to maintain duct patency if some congenital heart disease causes duct dependent circulation?

A

IV prostaglandin E2.

14
Q

Give an example of a duct dependent circulation?

A

Interruption of the aortic arch.

15
Q

When does pulmonary resistance reach normal adult type levels?

A

By 2-3 months.

16
Q

In what babies is persistent pulmonary hypertension of the newborn more likely?

A

In sick babies (sepsis, hypoxic ischaemic insult, meconium aspiration syndrome, cold stress).

17
Q

Give an underyling anatomical abnormality that persistent pulmonary hypertension of the newborn (PPHN) can be related to?

A

Congential diaphragmatic hernia.

18
Q

Why does blood continue to flow through the foramen ovale in PPHN?

A

The right sided heart pressure is greater than the left side.

19
Q

Why is there a large difference between pre and post ductal oxygen saturation in PPHN?

A

Because more deoxygenated blood is passed across ductus arteriosus so aortic blood oxygenation after the ductus arteriosus is lower.

20
Q

How would you treat PPHN?

A

Ventilation, oxygenation, high systemic blood pressure, inhaled nitric oxide, ECLS (extra cardiac life support).

21
Q

Where are the pre and post ductal saturations measured?

A

Pre measured in hands, post measured in foot.

22
Q

What is a congenital heart disease?

A

Abnormality of the structure of the heart that is present at birth.

23
Q

What is mild, moderate, severe and major congenital heart disease?

A

Mild - symptomatic, may resolve spontaneously.

Moderate - require specialist intervention and monitoring in a cardiac centre.

24
Q

What is the signs of a congential heart disease soon after birth?

A

Cyanosis.

25
Q

What signs might be there at the day 1-2 baby check?

A

Murmurs, abnormal pulses, cyanosis.

26
Q

What signs might be there at days 3-7?

A

Sudden circulatory collapse, shock, cyanosis, sudden death.

27
Q

What signs might be there at 4-6 weeks?

A

Signs of cardiac failure due to shunts - reduced feeding, failure to thrive, breathlessness, sweatiness.

28
Q

When does the GP check over the baby?

A

At 6-8 weeks.

29
Q

At what point is there antenatal screening for heart defects?

A

18-22 weeks gestation.

30
Q

What can you see on antenatal screening of the heart?

A

4 chamber heart view, outflow tract view.

31
Q

How would you describe the sensitivity of antenatal screening?

A

Very variable but generally pretty low.

32
Q

What is the potential management of antenatally diagnosed congential heart disease?

A

May decide to deliver in cardiac surgical centre, prostaglandin infusion if duct dependent lesion.

33
Q

What do you check for in a newborn screening?

A

Femoral pulses, heart sounds and presence of murmurs.

34
Q

Why may newborn screening not be very effective?

A

Murmurs are common in normal babies.

35
Q

Give an example of and describe a condition that could cause a murmur at baby check.

A

Small muscular VSD, causes murmur early in life. No haemodynamic consequences and many close spontaneously. The smaller they are the noiser they are and the earlier they present.

36
Q

What 2 types of conditions can cause cyanosis?

A
  1. Any condition causing deoxygenated blood to bypass the lungs and enter the systemic circulation.
  2. Any condition where mixed oxygenated and deoxygenated blood enters the systemic circulation from the heart.
37
Q

How can you tell cardiac cyanosis from respiratory cyanosis in babies?

A

Cardiac babies tend to be blue with little or no respiratory distress.

38
Q

What is it called when the right ventricle pumps into the aorta and the left ventricle pumps into the pulmonary arteries?

A

Transposition of the great arteries.

39
Q

Why will a bigger foramen ovale be an advantage to a baby with transposition of the great arteries?

A

There will be more mixing of blood so baby will be less blue.

40
Q

What will be the symptoms if the duct doesn’t close?

A

Severe cyanosis or pallor, tachypnoea, distress, rapid deterioration to death.

41
Q

At what time would a ductus arteriosus closure cause symptoms?

A

Between 2 and 7 days.

42
Q

What would be the clinical signs of duct closure?

A

Pallor, prolonged CRT, poor or absent pulses, hepatomegaly, crepitations, increased work of breathing.

43
Q

What would you get in an ABG of duct closure?

A

Profound acidosis.

44
Q

What would be the differential diagnosis of duct closure?

A

Sepsis, metabolic conditions.

45
Q

What is the treatment of duct closure?

A

ABC, IV prostaglandin E2, multisystem supportive treatment, transfer to cardiac surgical centre for definitive management.

46
Q

What are some conditions that cause duct dependent systemic circulation?

A

Hypoplastic left heart, critical aortic stenosis, interrupted aortic arch, critical coarctation of aorta.

47
Q

What are some conditions that cause duct dependent pulmonary circulation?

A

Tricuspid atria, pulmonary atresia.

48
Q

Describe hypoplastic left heart.

A

Large foramen ovale, very small LV and ascending aorta. Very little blood coming through left ventricle. Systemic circulation is provided by duct.

49
Q

What effect can hypoplastic left heart have on the pulmonary circulation?

A

Leads to backpressure into lungs.

50
Q

Describe pulmonary atresia and where does the pulmonary circulation come from in this?

A

Pulmonary arteries very thin and usually associated with a VSD. Pulmonary circulation supplied by aorta through ductus arteriosum.

51
Q

What conditions will cause a baby to present with heart failure?

A

Moderate to large left to right shunts - increased pulmonary flow, increased ventricular load.

52
Q

What are the clinical sings of heart failure in babies?

A

Failure to thrive, slow/reduced feeding, breathlessness (esp when feeding), sweatiness, hepatomegaly, crepitations.

53
Q

Why would a big VSD not be found at baby check?

A

There is less pressure gradient so often no murmur.

54
Q

Why do ventricular septal defects cause congestive cardiac failure?

A

It causes increased pulmonary circulation.

55
Q

Why does the murmur in VSD develop over time?

A

Pulmonary pressure drops over first weeks.

56
Q

What is meant by palliative surgical management of congenital heart disease?

A

They are not putting the heart back into normal configuration.

57
Q

How is a patent ductus arteriosus repaired?

A

Catheter procedure leaves a closure device. Need a couple of follow up appointments to ensure flow has stopped and device is in correct position.

58
Q

Even when a VSD is repaired why would you need follow up?

A

Can still have rhythm problems or valve problems.

59
Q

Describe hypoplastic left heart surgery and the risks of this.

A

3 stage complex surgery, significant mortality at each stage and between.

60
Q

What is the end point of hypoplastic left heart surgery and will this last forever?

A

Ends with right ventricle supplying circulation, will fail over time.