Cardiac Embryology Flashcards
The primitive heart consist of what parts?
Truncus arteriosus Bulbus cordis ventricle atria sinus venosus
What parts of the primitive heart becomes which parts in developed heart?
Truncus arteriosus --> aorta and PA Bulbus cordis --> smooth RV and LV ventricle --> trabeculated LV/RV atria --> trabeculated RA/LA sinus venosus --> RA smooth [sinus veranum] (right horn), coronary sinus (left horn)
Where do neural crest cells migrate?
to truncal-bulbar ridge –> forms aorta and PA
What happens if the neural crest cells fail to migrate?
Transposition of the great vessels (failure to spiral)
Tetralogy of Falot (Skewed AP septum development)
Persistent truncus arteriosus (partial AP septum development)
Describe the steps in ventricular septum formation:
1) aorticopulmonary septum forms (eventually will devide the LVOT and RVOT)
2) muscular ventricular septum forms
3) Membranous septum forms on top; AP twists
4) Endocardial cushions arise –> separate R/L atrium and ventricles
Which syndrome is related to endcardial defects?
Down syndrome
What some pathologies with ventricular septum malformation?
ASD and VSD (higher risj with endocardial cushion defects)
Which structure grows superiorly of the endocardial cushion in atrial septum formatoon?
Septum prinum
What happens when the septum prinum divides and one part regresses?
foramen secundum develops (a hole) and foramen primum –> leads to ASDs if persists in adulthood
List the steps of atrial septum formation after the septum prinum and endocardial cushion fuse:
1) foramen secondum still present
2) septum secundum develops right to the septum prinum (covers the foramen secondum) BUT a foramen ovale forms that lets blood from RA to LA
3) postnatally the LA pressure increases and the structure formed from endocardial cushion+septum prinum is pushed and fuses with the septum secundum —> foramen ovale closed
Why is the RA pressure high in fetus?
PA have really high resistance
HOw does the fetus receive oxygenated blood?
from umbilical cord
Where does the umbilical blood go?
to RA (bypasses liver via ductus venosus IMP)
How does the blood bypass the pulmonary circulation?
Blood travels through the foramen ovale
T or F: in the fetus some blood can go directly to RV via SVC
T
How does blood from RV circulate in a fetus?
Ductus arteriosa connects PA to aorta, and blood drains through here
When the foramen ovale closes what is called?
Fossa ovalis
What maintains the DA open?
low O2, and high prstaglandins
What structures form the SVC/IVC?
cardinal veins:
R common cardinal vein and R anterior cardinal vein –> SVC
Posterior veins –> IVC
What is cardiac looping?
heart tube loops at 4 weeks of gestation and establishes left-right orientation in chest
What things is required for cardiac looping?
Cilia and dynein
The endocardial cushions contribute to which structures?
- atrial septum
- ventricular septum
- AV valves
- semilunar valves
What is a patent foramen ovale?
when septum prinum and secondum fal to fuse found on 25%
When does the cardiac development start?
3 weeks
Which two layers start the development?
Epiblast (dorsal) –> later ectoderm
Hypoblast (ventral) –> later endoderm
Where does the primitive streak begin?
epiblast
Which layer gives the heart?
Mesoderm (visceral)
What happens at the embryo’s head?
Results to the primary heart field (horseshoe shape with two limbs)
What does the endoderm layer do at the primary heart field?
Secretes vascular endothelial growth factor (VEGF)
Whats the function of VEGF?
signals cells in the limbs to organize intwo two heart tubes
T or F: the limbs have two pericardial cavity
T
What does the inferior pericardial CAVITY CONNECT TO?
Vitelline vein from yolk sac
Where does the blood from vitelline vein exit?
via dorsal aorta
What is the lateral folding?
flat embryo to cylindrical shape –> the two heart tubes fuse anteriorly –> primitive heart tube
What happens to the vitelline veins when the two heart tubes fuse?
They fuse to become the sinus venosus (inflow tract to heart tube)
What happens to the two dorsal aorta when the two tubes fuse?
BEcomes the aortic sac (ie. outflow tract)
How does the dorsal mesocardium appeare?
Fusing of the pericardial cavities that then elongate at the midline and hangs and has a cavity
- the inner cells of the cavity –> endocardium
the outer cells –> cardiac myoblasts –> myocardium
Where does the initial electric discharge come from?
sinus venosus
What folding causes the heart to go down the chest?
craniocaudal folding at week 4
What gives rise to the epicardium?
visceral pericardium
T or F: the aortic arches stay intact in adulthood
F:
Aortic arch V regresses
I becomes the maxillary artery
II becomes the stapedial
III gives rise to common carotids (and part of internal carotid)
Left IV becomes the aortic arch, right IV become right subclavian artery
VI becomes the PA (and left become ductus arteriosus)
