CV embryology

Question 1

What gave rise to the ascending aorta and pulmonary trunk? The smooth parts (outflow tract) of the left and right ventricles? SVC?

Answer 1

truncus arteriosis

bulbus cordis

right common cardinal vein and right anterior cardinal vein

Question 2

When does the heart start to spontaneously beat? What happens in kartageners syndrome? When?

Answer 2

4 weeks

Defect dynein side arms leads to the lack of an establishment of left right polarity by the primary heart tube, which normally occurs at 4 weeks

Question 3

What are the steps in the septation of the atria? Describe what happens in PFO. What can they lead to?

Answer 3

septum primum grows toward cushions, which narrows foramen primum

foramen secundum forms in septum primum

septum secundum develops as foramen secundum maintains right to left shunt

septum secundum expands and covers most of foramen secundum—>foramen ovale

Remaining portion of septum primum forms the valve of FO

septum secundum and septum primum fuse to form the atrial septum

FO usually closes soon after birth due to LA pressure

Failure to fuse of septum secundum and primum leading to PFO. Paradoxical emboli

Question 4

Describe the steps of the septation of the ventricles. Where does a VSD occur?

Answer 4

Muscular ventricular septum forms (inferior). The opening is called interventricular foramen

Aorticopulmonary septum rotates and fuses with muscular septum to form membranous interventricular septum, closing foramen

Growth of cushions separates atria from ventricles and contributes to both atrial septation and membranous portion of interventr. septum

Membranous septum

Question 5

Describe the formation of the outflow tract. What are some abnormalities in this process?

Answer 5

Truncus arteriosus roates

Neural crest and endocardial cell migrations

truncal and bulbar ridges that spiral and fuse to form aorticopulmonary septum

Transposition of great vessels

Tetralogy of fallot

Persistent truncus arteriosus

Question 6

What are the aortic/pulm valves derived from? Mitral/tricuspid?

Answer 6

AP: endocardial cushions of outflow tract

M/t: fused endocardial cushions of AV canal.

Question 7

Where does fetal erythropoesis occur (3-8 wks, til birth, 10-28 weeks, 18 weeks til adulthood)? What are the early embryonic globins? Fetal hemoglobin globins? How does fetal hemoglobin differ physiologically from HbA1? Why?

Answer 7

Young Liver Synthesizes blood

yolk sac
liver
spleen
bone marrow

Zeta and epsilon
HbF: alpha and gamma

HbF has higher affinity for O2 due to less avid binding of 2,3 BPG, allowing it to extract more O2.

Question 8

What is the fetal circulation? PO2 of umbilical vein? saturation? What happens at birth with the vasculature? What helps close PDA? What is its remnant? Remnant of FO? What does the allantois/urachus become? ductus venosus? notochord? umbilical arteries? umbilical vein? Where is it found?

Answer 8

Po2=30mmhg, 80% saturated

Umbilical vein to ductus venosus (shunt past liver) to IVC.

Highly oxygenated blood from IVC enters FO (shunt past pulm. circ.) to aorta to head and body

Deoxygenated blood from SVC passes through RA to RV to main pulmonary artery to PDA (shunt past pulm. circ.) to descending aorta.

Breaths leads to decr. resist. in pulm. vasc. leading to incr. left atrial pressure than RA pressure leading to FO closure.
Increase in O2 leads to decr. in prostaglandins leads to closure of ductus arteriosus.

Indomethacin helps close PDA (decr. PGE1 and 2) leading to ligamentum arteriosum

FO becomes fossa ovalis

allantois: median umbilical ligament
ductus venosus: ligamentum venosum
notochord: nucleus pulposus
Umbilical arteries: medial umbilical ligaments
Umbilical vein: ligamentum teres hepatis (falciform ligament)

Question 9

What are the branches of the RCA? LCA? What do they supply? What supplies SA and AV nodes? What is right dominant circulation? left? mixed? Where does coronary artery occlusion most commonly occur? When does coronary blood flow peak? What is the most posterior part of the heart? What can its enlargement lead to?

Answer 9

Right dominant: RCA supplies the posterior descending artery
Left dominant: LCA supplies it
Mixed: both supply it

Right marginal artery: right ventricle
RCA: SA and AV nodes
PDA: posterior 1/3 of IV septum, posterior walls of ventricles and posteromedial papillary muscle

Left anterior descending: anterior 2/3 of IV septum, anterolateral papillary muscle, anterior surface of left ventricle
Left marginal artery
Left circumflex coronary artery: lateral and posterior walls of left ventricle, anterolateral papillary muscle.