Embryonic Cardiac Development

Question 1

What are the stages of embryonic cardiac developement?

Answer 1

Stage 1: single cardiac tube
Stage 2: further differentiation
Stage 3: absorption and septation

Question 2

What happens in stage 1?

Answer 2

2 cardiac tubes combine to form 1, tube is lined with cardiac jelly and surrounded by myoepicardium mantle

Question 3

When does stage 1 occur?

Answer 3

around day 22 of gestation

Question 4

What are the different sections of the single tube?

Answer 4

-truncus arteriosus
-bulbis cordis (2 sections, conus cordis and truncus conus)
-primitive ventricle
-primitive atrium
-sinus venous

Question 5

What does the truncus arteriosus become?

Answer 5

aorta and pulmonary artery

Question 6

What are the sections of the bulbus cordis?

Answer 6

conus cordis and truncus conus

Question 7

What does the conus cordis become?

Answer 7

LVOT and RVOT

Question 8

What does the truncus conus become?

Answer 8

RV

Question 9

What does the primitive ventricle become?

Answer 9

LV

Question 10

What does the primitive atrium become?

Answer 10

RA and LA

Question 11

What does the sinus venosus become?

Answer 11

inflow channels, IVC, SVC

Question 12

What does the extra fold in the sinus venosus become?

Answer 12

eustachian valve

Question 13

What is the order of blood flow in the primitive heart?

Answer 13

Enters through sinus venosus -> atrium -> primitive ventricle -> bulbus cordus -> truncus arteriosus

Question 14

What happens in stage 2?

Answer 14

-the tube starts to loop, this is known as atrioventriculobulbo loop
-the top part bends anteriorly and to the right (dextro or d-looping)

Question 15

When does stage 2 occur?

Answer 15

Tube starts to loops at day 23
Looping is complete at day 24
Stage 2 complete at day 28

Question 16

What is the atrioventriculobulbo loop?

Answer 16

when the cardiac tube begins to loop at day 23

Question 17

What us dextro or d-looping?

Answer 17

when the top part of the cardiac tube bends anteriorly and to the right

Question 18

When does contraction of the heart begin?

Answer 18

28 days

Question 19

When is a heartbeat sonographically visible?

Answer 19

6w5d

Question 20

What is cardiac activity aka?

Answer 20

fetal heart motion (FHM)
fetal heart tones (FHT)

Question 21

What is a normal 1st trimester heartrate?

Answer 21

around 120bpm

Question 22

Is bradycardia or tachycardia more concerning?

Answer 22

bradycardia, indicator of embryonic demise

Question 23

What happens during stage 3?

Answer 23

atria and ventricles get seperated by IVS and IAS and endocardial cushion

Question 24

What divides the atria from ventricles?

Answer 24

endocardial cushion

Question 25

What are the layers of the IAS?

Answer 25

1st Layer: septum primum 2nd Layer: septum secundum

Question 26

When does the septum primum of the IAS develop?

Answer 26

day 30

Question 27

What does the septum primum of the IAS consist of?

Answer 27

has 2 openings, ostium primum and ostium secundum that allow for communication between atria

Question 28

When does the ostium secundum form?

Answer 28

day 33

Question 29

When does the septum secundum of the IAS develop?

Answer 29

day 37

Question 30

What does the septum secundum of the IAS consist of?

Answer 30

foramen ovale which remains open until birth, allows blood from RA to flow into LA, bypassing lungs

Question 31

What was the foramen ovale formerly known as?

Answer 31

ostium secundum

Question 32

How are the AV valves formed?

Answer 32

the fusion of the endocardial cushions

Question 33

To ensure correct anatomy, what must happen to the aorta and PA?

Answer 33

they must TWIST

Question 34

Where should the aorta be located?

Answer 34

posterior, connected to LV

Question 35

Where should the pulmonary artery be located?

Answer 35

anterior, connected to RV

Question 36

How many branches are there in the primitive aortic arch?

Answer 36

12 branches, 6 sets

Question 37

What happens to the 1st set of the primitive aortic arch?

Answer 37

disappear

Question 38

What happens to the 2nd set of the primitive aortic arch?

Answer 38

disappear

Question 39

What happens to the 3rd set of the primitive aortic arch?

Answer 39

Right and left carotids

Question 40

What happens to the 4th set of the primitive aortic arch?

Answer 40

Right branch: innominate and right subclavian Left branch: aortic arch

Question 41

What happens to the 5th set of the primitive aortic arch?

Answer 41

disappear

Question 42

What happens to the 6th set of the primitive aortic arch?

Answer 42

Right branch: right pulmonary artery Left branch: left pulmonary artery and ductus arteriosus

Question 43

How are semilunar valves formed?

Answer 43

from tubercles from main truncus arteriosus