Embryonic Cardiac Development Flashcards
What are the stages of embryonic cardiac developement?
Stage 1: single cardiac tube
Stage 2: further differentiation
Stage 3: absorption and septation
What happens in stage 1?
2 cardiac tubes combine to form 1, tube is lined with cardiac jelly and surrounded by myoepicardium mantle
When does stage 1 occur?
around day 22 of gestation
What are the different sections of the single tube?
-truncus arteriosus
-bulbis cordis (2 sections, conus cordis and truncus conus)
-primitive ventricle
-primitive atrium
-sinus venous
What does the truncus arteriosus become?
aorta and pulmonary artery
What are the sections of the bulbus cordis?
conus cordis and truncus conus
What does the conus cordis become?
LVOT and RVOT
What does the truncus conus become?
RV
What does the primitive ventricle become?
LV
What does the primitive atrium become?
RA and LA
What does the sinus venosus become?
inflow channels, IVC, SVC
What does the extra fold in the sinus venosus become?
eustachian valve
What is the order of blood flow in the primitive heart?
Enters through sinus venosus -> atrium -> primitive ventricle -> bulbus cordus -> truncus arteriosus
What happens in stage 2?
-the tube starts to loop, this is known as atrioventriculobulbo loop
-the top part bends anteriorly and to the right (dextro or d-looping)
When does stage 2 occur?
Tube starts to loops at day 23
Looping is complete at day 24
Stage 2 complete at day 28
What is the atrioventriculobulbo loop?
when the cardiac tube begins to loop at day 23
What us dextro or d-looping?
when the top part of the cardiac tube bends anteriorly and to the right
When does contraction of the heart begin?
28 days
When is a heartbeat sonographically visible?
6w5d
What is cardiac activity aka?
fetal heart motion (FHM)
fetal heart tones (FHT)
What is a normal 1st trimester heartrate?
around 120bpm
Is bradycardia or tachycardia more concerning?
bradycardia, indicator of embryonic demise
What happens during stage 3?
atria and ventricles get seperated by IVS and IAS and endocardial cushion
What divides the atria from ventricles?
endocardial cushion
What are the layers of the IAS?
1st Layer: septum primum
2nd Layer: septum secundum
When does the septum primum of the IAS develop?
day 30
What does the septum primum of the IAS consist of?
has 2 openings, ostium primum and ostium secundum that allow for communication between atria
When does the ostium secundum form?
day 33
When does the septum secundum of the IAS develop?
day 37
What does the septum secundum of the IAS consist of?
foramen ovale which remains open until birth, allows blood from RA to flow into LA, bypassing lungs
What was the foramen ovale formerly known as?
ostium secundum
How are the AV valves formed?
the fusion of the endocardial cushions
To ensure correct anatomy, what must happen to the aorta and PA?
they must TWIST
Where should the aorta be located?
posterior, connected to LV
Where should the pulmonary artery be located?
anterior, connected to RV
How many branches are there in the primitive aortic arch?
12 branches, 6 sets
What happens to the 1st set of the primitive aortic arch?
disappear
What happens to the 2nd set of the primitive aortic arch?
disappear
What happens to the 3rd set of the primitive aortic arch?
Right and left carotids
What happens to the 4th set of the primitive aortic arch?
Right branch: innominate and right subclavian
Left branch: aortic arch
What happens to the 5th set of the primitive aortic arch?
disappear
What happens to the 6th set of the primitive aortic arch?
Right branch: right pulmonary artery
Left branch: left pulmonary artery and ductus arteriosus
How are semilunar valves formed?
from tubercles from main truncus arteriosus
