Foetal Circulation & Congenital Diseases Flashcards Preview

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Flashcards in Foetal Circulation & Congenital Diseases Deck (46)
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1
Q

State eight functions of the placenta

A
  • foetal homeostasis
  • gas exchange
  • acid base balance
  • nutrient transport to foetus
  • waste transport from foetus
  • hormone production
  • transport of IgG
  • PGE2
2
Q

How can the foetal lungs be described prior to birth?

A

Unexpanded & filled with fluid

3
Q

Describe foetal blood supply

A

From the placenta oxygenated blood comes through the umbilical vein and leaves through the umbilical arteries which arise from the descending aorta

4
Q

Name the structure that connects the umbilical vein to the IVC

A

Ductus venosus

5
Q

What is the function of the ductus venosus?

A

Allows blood with nutrients to come from the placenta without being processed by the liver

6
Q

Name the opening in the atrial septum

A

foramen ovale - connects RA to LA

7
Q

What is the function of the foramen ovale?

A

The oxygenated blood enters LA then LV and flows to ascending aorta & carotids

8
Q

What is the function of the ductus arteriosus?

A

connects the pulmonary bifurcation to the descending aorta - only 7% of blood flows to foetal lungs

9
Q

How is the ductus arteriosus kept open?

A

prostaglandin E2 produced by the placenta

10
Q

What type of drugs inhibit prostaglandin E2?

A

NSAIDs - contraindicated in pregnancy

11
Q

What happens to the lungs after the baby is born?

A

They inflate and fill will oxygen, the baby turns from blue to pink, pulmonary vascular resistance decreases

12
Q

What is the result of circulating oxygen increase?

A

It is a vasodilator therefore decreases resistance

13
Q

At what age will pulmonary resistance reach adult levels?

A

2-3 months

14
Q

What happens to systemic vascular resistance?

A

When the cord is cut it increases as more cardiac output goes to the lungs

15
Q

After birth what happens to the foramen ovale?

A

It closes so there is no flow between the atria (this mechanism fails in 20% of the population)

16
Q

What happens to the ductus arteriosus after birth?

A

Constricts due to increased oxygen and reduced prostaglandins, ends up as fibrous ligament - ligamentum arteriosum

17
Q

What are oxygen sats when a baby is born?

A

60-70%

18
Q

Describe failure of ductus arteriosus closure

A

High incidence in premature babies, causes extra blood to flow to the lungs, increasing pulmonary BP leading to SOB and cardiac arrest

19
Q

Why is there increased blood flow to the lungs?

A

Blood shunts from the aorta to the pulmonary bifurcation

20
Q

When is persistent pulmonary hypertension common?

A
  • sepsis
  • hypoxic ischaemic insult
  • meconium aspiration syndrome
  • cold stress
  • prematurity
21
Q

What are the signs of PPH?

A

The baby will remain blue after birth and oxygen sats will be higher in the upper body compared to lower

22
Q

State the two management aims in babies with PPH

A
  • reduce pulmonary resistance

- increase systemic resistance

23
Q

How can pulmonary resistance be reduced?

A
  • ventilation & oxygenation
  • sedation
  • thermoregulation
  • correction of acidosis
  • treat sepsis
  • inhaled NO
24
Q

How can systemic resistance be increased?

A
  • increase BP
  • inotropes
  • support other organ function
  • heart bypass
25
Q

Describe the spectrum of severity

A

Mild - asymptomatic
Moderate - requires specialist intervention
Severe - presents severely unwell
Major - needs surgery within first year of life

26
Q

State the six different time periods for screening

A
  1. Antenatal
  2. Newborn (24 hours old)
  3. Day 1-2
  4. Day 3-7
  5. 4-6 weeks
  6. 6-8 weeks
27
Q

Describe antenatal screening

A

18-22 weeks gestation scan

28
Q

What are the management options if congenital heart disease is detected on an antenatal scan?

A

Prostaglandin E2 infusion, palliative care, termination

29
Q

What signs may present 1-2 days post birth?

A

murmurs, abnormal pulses, cyanosis, ductual sats

30
Q

What may present 3-7 weeks after birth?

A

sudden circulatory collapse, shock, cyanotic death

31
Q

How will 4-6 week year old babies with CHD present?

A

cardiac failure, reduced feeding, failure to thrive, SOB, sweating

32
Q

What is the most common congenital defect? How will it present?

A

Muscular ventricular septal defect - a murmur can be heard early in life due to blood shunting from left to right

33
Q

What causes cyanosis?

A

any condition that causes blood that is deoxygenated to pass the lungs and enter the systemic circulation

34
Q

What is the most common cause of cyanosis?

A

Transposition of the great arteries e.g the aorta arises from the RV

35
Q

What is the differential diagnosis for a baby with cyanosis?

A
  • cardiac disease (blue with no resp distress)
  • respiratory disease (increased work of breathing & x ray changes)
  • PPHN (very ill baby)
36
Q

State two reasons for collapse at the time of duct closure

A
  • duct dependent systemic circulation

- duct dependent pulmonary circulation

37
Q

What may cause duct dependent systemic circulation?

A
  • hypoplastic left heart syndrome
  • coarctation of the aorta
  • aortic stenosis
  • interruption of aortic arch
38
Q

What may cause duct dependent pulmonary circulation?

A
  • pulmonary atresia (valve not working )

- pulmonary stenosis

39
Q

What are the signs of a baby that has collapsed due to duct closure?

A
  • pallor
  • prolonged CRT
  • poor pulses
  • crepitations
40
Q

What is the differential diagnosis for a baby collapsed due to duct closure?

A

sepsis, metabolic disease

41
Q

What is the treatment for a baby collapsed due to duct closure?

A

ABC, prostaglandin E2, specialist support

42
Q

Why is a baby likely to present with cardiac failure?

A

Large left to right shunt increases pulmonary and ventricular flow, a few weeks later pulmonary pressure drops and blood moves right to left (shunt reverses)

43
Q

What are the clinical signs of VSD?

A
  • failure to thrive
  • slow/reduced feeding
  • SOB
  • sweatiness
  • hepatomegaly
  • crepitations
44
Q

How can a patent ductus arteriosus be repaired?

A

Catheter procedure which does not require bypass - insertion of a closure device

45
Q

How can VSD be repaired?

A

Involves closure with a patch that required bypass, thoracotomy and follow up through childhood

46
Q

Why is hypo plastic left heart syndrome repair difficult?

A

It is a three stage operation & is only palliative, transplant is eventually required as it involved the RV supplying the systemic circulation but this fails over time