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AASM > 1 - Cardiovascular Embryology > Flashcards

1 - Cardiovascular Embryology Flashcards

1
Q

What does the umbilical vein do?

A

Carry oxygenated blood towards the fetus

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2
Q

What does the umbilical artery do?

A

Carry de-oxygenated blood back towards maternal circulation

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3
Q

What are the 3 important shunts exist in fetal circulation?

What is there overall function?

A

Ductus venosus
Foramen ovale
Ductus arteriosus

Increase oxygenation to the BRAIN.

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4
Q

What two vessels form the ductus venosus?

A

Left umbilical vein

Left branch of the hepatic portal vein

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5
Q

Where does the ductus venosus drain from, into?

A

Umbilical vein

Inferior vena cava

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6
Q

What are the 2 functions of the ductus venosus?

A

Shunts oxygenated blood past the sinusoids of the liver (already been cleansed by mother?)

Act as a mechanism to reduce right atrium venous return (in case of it being excessive)

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7
Q

What structure does the ductus venosus become after birth?

A

Ligamentum venosum (ligament continuous with the round ligament of the liver)

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8
Q

The left umbilical vein becomes what structure after birth?

A

Ligamentum teres

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9
Q

What % is shunted through the liver?

What controls it?

Why is this significant?

A

20-30%

Sphincter

Relatively small proportion in comparison to other animal species, which suggest underestimation in the function of the fetal liver.

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10
Q

How soon after birth does ductus venosus closure occur?

A

Functionally - minutes

Structurally - days/week

**Blood coagulates within the structure and becomes fibrosed with time.

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11
Q

What is the function of the foramen ovale?

A

Shunts oxygenated blood from the right to the left atrium.

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12
Q

What structure does it become following birth?

A

Fossa ovale / ovalis

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13
Q

What occurs following incomplete closure of the foramen ovale?

A

Patent foramen ovale

most common atrial septal defect

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14
Q

What clinical consequence occurs if this is the case?

A

Cyanosis (bluish tinge to skin / mucous membranes)

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15
Q

Where does the ductus arteriosus shunt blood from and to?

A

Shunt blood from pulmonary trunk to aorta

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16
Q

What are the functions of the ductus arteriosus?

A

1) Reduce pulmonary circulatory load (protect the lungs)

2) Enables right ventricle to strengthen

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17
Q

What does the ductus arteriosus become following birth?

What is its function?

A

Ligamentum arteriosum

Acts as a tether to hold the aorta and pulmonary trunk together

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18
Q

What feature of the lungs favours the blood’s passage to occur through the ductus arteriosus?

A

High pulmonary vascular resistance

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19
Q

Occlusion of the fetal circulation results in a drop in BP in which two connected areas?

A

IVC

Right atrium

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20
Q

What stimulates vasoconstriction of both ductus arteriosus / venosus?

A

Increasing oxygen content from first and subsequent breaths.

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21
Q

Aeration of the lungs is associated with 3 consequential changes?

A

1) Lung expansion reduces pulmonary resistance
2) Pulmonary blood flow increases
3) Left atrium pressure > IVC / right atrial pressure

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22
Q

Control of circulation is regulated by which two sets of receptors?

A

Peripheral baroreceptors (carotid sinus / aortic arch)

Central baroreceptors in cardiovascular centre of medulla

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23
Q

Through what mechanism does the foramen ovale close?

A

Before birth, RA pressure > LA pressure.

When born, venous return from placenta / IVC decreases, stops holding foramen ovale open.

Oxygenated blood return form pulmonary circulation stops passage of blood across shunt (due to pressure) because septum primum closes against relatively rigid septum secundum.

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24
Q

What ventricular changes also arise following birth?

A

In utero, right ventricle is stronger / thicker than left. Following shunt closure, the pressure in the left ventricle increases which encourages it to get stronger + RV demand is lower so lessens.

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25
Q

What is the most important factor for ductus arteriosus closure?

A

Increasing oxygen concentration

26
Q

What substance is made by the lungs to mediate ductus arteriosus closure?

A

Bradykinin

27
Q

What does bradykinin stimulate?

A

Vasoconstriction

28
Q

What two mediators that fall in concentration are also important in DA closure?

A

Prostaglandin E2

Prostacyclin

29
Q

Early in development, how many endocardial tubes are there?

A

4

2 medial, 2 lateral

30
Q

Which tubes fuse to form a single heart tube?

A

Medial endocardial tubes

31
Q

What structure does the truncus arteriosus become?

A

Roots of the outflow vessels

32
Q

What structure does the bulbus cordis become?

A

Right ventricle

33
Q

What structure does the primitive ventricle become?

A

Left ventricle

34
Q

From what embryological structure do the heart valves form from?

A

Endocardial cushions

35
Q

Congenital heart defects occurs in what % of births?

A

1%

36
Q

Trabeculae within the embryonic heart are important for what tissue?

A

Myocardial tissue

37
Q

At what point during pregnancy is the general morphology of heart made?

A

By the end of the 1st trimester

38
Q

Which two structures have been shown to arise from the secondary heart fields?

A

Right ventricle

Outflow tract

39
Q

Which two genes were important in discovering secondary heart fields being responsible for RV and OFT formation?

A

Isl1 (Islet 1)

TbX1

40
Q

What pathology occurs in Tetrology of Fallot

A

Inaccurate outflow septation - small pulmonary artery, normal aorta

41
Q

What pathology occurs in double-outlet RV?

A

Failure of rotation in outflow tract resulting in Aorta and Pulmonary artery leaving from the right ventricle

42
Q

What pathology occurs in Transposition of the great arteries?

A

Septation occurs but rotation doesn’t - wrong vessel to wrong ventricle

43
Q

What pathology occurs in persistent truncus arteriosus?

A

Septation fails completely, resulting in one outflow vessel.

44
Q

What is a specific genetic cause of persistent truncus arteriosus?

A

22q11.2 Deletion syndrome

45
Q

How does 22q11.2 deletion syndrome manifest?

A

Reduced cell proliferation in SHF. Fewer cells in OFT. Thus, OFT becomes thinner and shorter and results in inability to septate.

46
Q

The most common deletion involves how many genes?

A

30

47
Q

Second most common deletion quantity involves how many genes?

A

20

48
Q

What gene deletion do both most common deletions have in common?

A

TbX1 deletion

49
Q

TbX1 k/o results in what pathology with the OFT?

A

Lack of septation

OFT is shorter / narrower

50
Q

What does Tbx1 k/o result in such changes?

A

Reduction in cell proliferation

51
Q

In vitro, Tbx1 was shown to have effects on two other downstream genes - what are they?

A

FGF8

Srf

52
Q

Tbx1 has what effect on FGF8?

A

Stimulates proliferation

53
Q

Tbx1 has what effect on SRF

A

Inhibits Srf - a gene responsible for differentiation

54
Q

What does NAHR stand for?

A

Non-allelic homologous recombination

55
Q

Why is NAHR particularly relevant to the 22q11.2 area of the genome?

A

Plenty of low-complexity regions. More susceptible to deletions / duplications as a result of issues in non-complete meiotic divisions.

56
Q

What two general descriptive processes must occur for correct OFT anatomy?

A

Septation

Rotation

57
Q

What also sometimes happens to the ventricles alongside DORV?

A

Failure in ventricular septation

58
Q

Retinoic acid signalling (RARalpha/beta) duplication results in which two pathologies?

A

No septation (PTA/CAF)

Origin issues (DORV)

59
Q

Semi-lunar valves come from which heart field?

A

Secondary heart field

60
Q

What gene k/o showed semi-lunar development being assigned to secondary heart fields?

A

Calcineurin

AASM (8 decks)

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