CV Development Flashcards
What pairs of tubes form the initial tube that becomes the heart?
Endocardial tubes
What derm layer forms around the initial tube that becomes the myocardial mantle?
Mesoderm
When does the myocardial mantle begin beating?
22 days
What are the 5 initial regions of the endocardial tube & myocardium?
Inferiorly to Superiorly:
Sinus Venosus (2)
Primitive atrium
Ventricle
Bulbus cordis
Aortic sac
What does the aortic sac eventually become?
Aorta & Pulmonary artery
What does the Bulbus cordis eventually become?
R ventricle, Proximal aorta & pulmonary trunk
What does the primitive ventricle eventually become?
L ventricle
What does the primitive atrium eventually become?
R & L auricles, L atrium
What does the left and right sinus venosus eventually become?
R atrium, Vena cavae, coronary sinus
What are the 4 steps to making a 4-chambered heart?
- Sinus venosus and primitive atrium separate into the R and L atrium.
- Primitive ventricle separates from bulbus cordis to form L and R ventricle.
- Primitive atrium separates from primitive ventricle.
- Conus cordis and truncus arteriosus develop internal partitions to become the proximal aorta and pulmonary trunk.
What is the hole between the atria known as?
Foramen ovale
What 4 things make up the wall that separate the atria?
Septum secundum and primum
Ostium secundum and primum
How much of the US population is estimated to still have a PFO? (patent foramen ovale)
25%
When is having a PFO a concern? What does it cause?
When you have increased R heart pressure. This can cause clots to skip from the R atrium straight to the L atrium, sending a clot into your arteries.
What separates the two ventricles from each other during development?
Muscular portion of the interventricular septum.
What two primitive structures become the L and R ventricles?
Primitive ventricle = L ventricle
Bulbus Cordis = R ventricle
What is the final key in separating the two ventricles during development?
Endocardial cushions, which make up the superior part of the interventricular septum and are made from the membranous portion of the interventricular septum.
Note: They also contribute to forming the pulmonary and aortic valves.
What is the most common congenital heart defect? (CHD)
A ventricular septal defect (VSD), estimated to make up 25% of all CHDs.
What are the 3 types of VSDs and who is most at risk?
Perimembranous (most common)
Muscular (less common)
Supracristal (rare)
Siblings have 3x the risk.
Expansion of what divides the common AV canal?
Endocardial cushions, separating it into L&R AV canals.
Note: imagine pinching a tube vertically in the center so it makes two holes, left and right.
What separates the primitive atrium and primitive ventricle from each other?
two endocardial cushions
Note: Imagine pinching a tube horizontally in the center, so it makes a hole above and below.
What shape/figure am I looking for to confirm chamber separation in a pre-natal screening?
A cross on the US.
What is an AV canal defect also known as?
Endocardial cushion defect.
What are the two types of AV canal defects? Whats the difference?
Partial means a severe low ASD or high VSD with AV valves affected but still present.
Complete means AV valves are not there, so the 4 chambers of the heart are one contiguous thing.
What kind of shunt causes cyanosis, why?
Right to left shunts, because RA blood is not oxygenated, so moving to the L atrium with deoxygenated blood will send mixed blood to the systemic circulation.
Hollowing out of what forms the chordae tendineae, papillary musceles, and AV valves?
Mesenchyme under the AV canals.
What 4 things make up the tetralogy of Fallot?
- Pulmonary stenosis
- R ventricular hypertrophy
- Overriding aorta
- VSD
Note: PROVe
What primitive structures form the proximal aorta and pulmonary artery?
Conus cordis & Truncus arteriosus
What structure splits the proximal aorta from the pulmonary artery?
Conotruncal ridges, which are swellings of truncuses.
What unique pattern do the conotruncal ridges travel in from the conus cordis and truncus arteriosus to the interventricular septum?
Spiral pattern
What is TGA?
Transposition of the great arteries.
Your aorta is now connected to the RV.
Your PA is now connected to the LV
There is also a vessel connecting the aorta and PA.
What is truncus arteriosus?
Failure of the PA and aorta to fully separate, so there is a large connection between both, as well as a connection between the two ventricles.
What are the 3 main pairs of aortic arches?
3, 4, 6
What are all the aortic arches connected to?
Aortic sac
What connects the aortic sac to the heart?
Truncus arteriosus
What do the 3rd aortic arches become?
Common carotid arteries
What do the 4th aortic arches become?
On the left, it is the part of the aorta between the L common carotid and L subclavian artery.
On the right, it is the part of the brachiocephalic artery before it becomes the R subclavian artery.
What do the 6th aortic arches become?
It becomes the branches of the pulmonary artery that go to the lungs.
What do the aortic sac and left dorsal aortae become?
Aortic sac becomes the ascending arch of the aorta & brachiocephalic artery.
Dorsal aortae becomes the descending arch of the aorta
What happens if the right dorsal aortae doesn’t fuse?
Double aortic arches, forming a subclavian sling and giving us two subclavian arteries right off our aorta.
What is coarctation of the aorta? Concerns?
A constricted area of the aorta, anywhere from the transverse arch to the iliac bifurcation.
98% are below the origin of the ductus arteriosus.
Mild forms are asymptomatic.
Major forms can cause severe obstruction and hypoperfusion/heart failure.
Where do all veins empty into as a fetus?
Sinus venosus.
What are the 3 main veins that we have as a fetus?
Vitelline veins, deoxygenated blood from yolk sac.
Cardinal veins, deoxygenated blood from the embryo.
Umbilical veins, oxygenated blood from the placenta.
What is TAPVR?
Total anomalous pulmonary venous return.
All the pulmonary veins empty into the superior vena cava, so there is mixed blood entering the heart.
Starting at the placenta, name the main pathway for blood to the pre and postductal aorta.
Placenta => umbilical vein => ductus venosus => IVC => RA => Foramen ovale => LA => LV => Pre-ductal aorta => post-ductal aorta & Head/upper limbs.
What structure is the precursor to the ligamentum arteriosum?
Ductus arteriosus.
Besides going through the foramen ovale and going to the LA, where else can blood go to from the RA?
RA => RV => Pulmonary trunk => Lungs (minor) & Ductus arteriosus.
What brings blood to the placenta?
Umbilical arteries
Where does oxygenated blood come from for a fetus?
Placenta
When a fetus is born, where does most of its oxygenated blood come from? What happens as a result?
Lungs are expanded, so more blood from the RA goes instead to the RV to the pulmonary artery to the lungs.
The ductus venosus starts closing, since there is no placenta to receive blood from anymore.
