Cardio Embryology

Question 1

What does the bulbs cordis give rise to?

Answer 1

smooth parts (outflow tract) of the left and right ventricles

Question 2

What does the endocardial cushions give rise to?

Answer 2

atrial septum
membranous interventricular septum
AV and semilunar valves

Question 3

What does the left form of sinus venosus give rise to?

Answer 3

coronary sinus

Question 4

What does the posterior, subcardinal, and supracardinal veins give rise to?

Answer 4

inferior vena cava (IVC)

Question 5

What does the primitive atrium give rise to?

Answer 5

trabeculated part of the left and right atria

Question 6

What does the primitive pulmonary vein give rise to?

Answer 6

trabeculated part of the left and right ventricles

Question 7

What does the right common cardinal vein and right anterior cardinal vein give rise to?

Answer 7

superior vena cava (SVC)

Question 8

What does the right horn of sinus venosus give rise to?

Answer 8

smooth part of right atrium (sinus venarum)

Question 9

What does the trunks arteriosus give rise to?

Answer 9

ascending aorta and pulmonary trunk

Question 10

When does the heart start to beat spontaneously?

Answer 10

1st functional organ

week 4 of development

Question 11

Cardiac looping

Answer 11

primary heart tube loops to establish left-right polarity; begins in week 4 of gestation

Question 12

Problems with cardiac looping can cause_____

Answer 12

Defect in the left-right Dynein (involved in L/R asymmetry) can lead to Dextocardia as seen in Kartagener syndrome (Primary Ciliary Dyskinesia)
DDDD

Question 13

What are the steps to separation of chambers?

Answer 13

1. septum primum grows towards the endocardial cushions, narrowing foramen premium
2. foramen secundum forms in septum premium (foramen primum disappears)
3. Septum secundum develops as foramen secumdum maintains right to left shunt
4. septum secundum expands and covers most of the foramen secundum. The residual foramen is the foramen oval.
5. remaining portion of septum primum forms valve of foramen ovale

Question 14

What fuse to form the atrial septum?

Answer 14

septum secundum and septum primum

Question 15

Why does the Forman oval usually close soon after birth?

Answer 15

due to increase pressure in the left atrium and decreased pressure in the right atrium.

Question 16

What is patent foramen ovale and what can it lead to?

Answer 16

1. caused by failure of septum primum and septum secundum to fuse after birth most are left untreated.
2. Can lead to paradoxical emboli (venouss thromboembolism that enter systemic arterial circulation) similar to those resulting from an ASD

Question 17

What are the step for ventricle morphogenesis?

Answer 17

1. muscular interventricular septum forms. Opening is called inter ventricular foramen.
2. aorticopulmonary septum rotates and fuses with muscular ventricular septum to form membranous inter ventricular septum closing inter ventricular foramen.
3. growth of endocardial cushions separates atria from ventricles and contributes to both atrial separation and membranous portion of the interventicular septum.

Question 18

What is the most common cardiac abnormality and where does it normally occurs?

Answer 18

1. ventral septal defect

2. membranous septum

Question 19

How does the outflow tract form?

Answer 19

neural crest and endocardial cells migrate

1. truncal and bulbar ridges that spiral and fuse to form aorticopulmonary septum
2. ascending aortal and pulmonary trunk

Question 20

What are the conotruncal abnormalities associated with failure of neural crest cells to migrate?

Answer 20

Transposition of great vessels
Tetralogy of Fallot
Persistent truncus arteriosus

Question 21

Where are the valves derived from?

Answer 21

aortic/pulmonary: derived from endocardial cushions fo outflow tract
Mitral/tricuspid: derived from fused endocardial cushions of the AV canal

Question 22

What could valvular abnormalities be like?

Answer 22

stenotic
regurgitant
atretic (e.g tricuspid atresia)
displaced (e.g Ebstein anomaly)

Question 23

What is the oxygen saturation and pressure in the umbilical vein during fetal circulation?

Answer 23

PO2 33mmHg

O2 sat: 80%

Question 24

What kind of oxygen saturation does the umbilical arteries have during fetal development?

Answer 24

low

Question 25

During fetal development what shut is the blood entering the fetus through the umbilical vein?

Answer 25

ductus venosus not the IVC bypassing hepatic circulation

Question 26

During fetal development what shut is the most highly oxygenated blood reaching the heart via the IVC directed through?

Answer 26

foramen ovale and pumped into the aorta to supply the head and body

Question 27

During fetal development what shut is the deoxygenated blood form the SVC pass through?

Answer 27

RA--RV--mian pulmonary artery--ductus arteriosus-- descending aorta; shunt is due to high fetal pulmonary artier resistance due to partly to low O2 tension.

Question 28

At birth what happens with the infant takes the first breath?

Answer 28

decrease resistance to pulmonary vasculature increase left atrial pressure vs right atrial pressure which leads to foramen ovale closure (now fossa ovals) increase O2 (from respiration) and decrease in prostaglandins (from placental separation) closure of ductus arteriosus

Question 29

What helps close the PDA?

Answer 29

indomethacin

Question 30

What keeps the PDA open?

Answer 30

prostaglandins E1 and E2 | kEEp PDA open

Question 31

What fetal structure does the median umbilical ligament derive from?

Answer 31

Allantosis-urachus | urachus is part of allantoic duct between the bladder and umbilicus

Question 32

What fetal structure does the ligament arteriosum derive from?

Answer 32

ductus arteriosus | near the left recurrent laryngeal nerve

Question 33

What fetal structure does the ligament venosum derive from?

Answer 33

ductus venosus

Question 34

What fetal structure does the fossa ovalis derive from?

Answer 34

foramen ovale

Question 35

What fetal structure does the nucleus pulposus derive from?

Answer 35

notochord

Question 36

What fetal structure does the medial umbilical ligaments derive from?

Answer 36

umbilical arteries

Question 37

What fetal structure does the ligamentum trees hepatic (round ligament) derive from?

Answer 37

umbilical vein | contained in the falciform ligament

Question 38

What are the symptoms and causes of right-to-left shunts seen in infants?

Answer 38

``` early cyanosis "blue babies" often diagnosed parentally or become evident immediately after birth usually require urgent surgical tx and/or maintenance of a PDA The 5 Ts 1. Truncus arteriosus (1 vessel) 2. Transposition (2 switch vessels) 3. Tricuspid atresia (3=Tri) 4. Tetralogy of Fallot (4=Tetra) 5. TAPVR (5 letters in the name) ```

Question 39

What is persistent truncus arteriosus

Answer 39

trucks arteriosus fails to divide not pulmonary trunk and aorta due to failure of aorticopulmonary septum formation. most pt have accompanying VSD

Question 40

What is D-transposition of great vessels?

Answer 40

Aorta leaves RV (anterior) and pulmonary trunk leaves LV (posterior)--separation of systemic and pulmonary circulations. Not compatible with life unless a shunt is present to allow mixing of blood (VSD, PDA or patent foramen ovale) Due to failure of the aorticopulmonary septum to spiral Without surgery most infants die within the first few months of life.

Question 41

What is tricuspid atresia?

Answer 41

absence of tricuspid valve of hypo plastic RV, requires both ADS and VSD for viability

Question 42

What is tetralogy of fallot?

Answer 42

Caused by anterosuperior displacement of the infundibular septum. 1. pulmonary infundibular stenosis (most important determinate for prognosis) 2. Right ventricular hypertrophy (RVH) boot shaped heart off CXR 3. Overriding aorta 4. VSD Pulmonary stenosis forces right-to-left flow across VSD-RVH "tet spell" (often caused by crying, fever, and exercise due to exacerbation of RV outflow obstruction)

Question 43

What congenital heart disease is the main cause of cyanosis in early childhood?

Answer 43

Tetralogy of Fallot

Question 44

What is total anomalous pulmonary venous return?

Answer 44

pulmonary veins drain into high heart circulation (SVC coronary sinus etc) associated with ADS and sometimes PDA to allow for right-to-left shunting to maintain cardiac output (CO)

Question 45

What is Ebsteins anomaly?

Answer 45

characterized by displacement of tricuspid valve leaflets downward into RV, artificially "atrializing" the ventricle. Associated with tricuspid regurgitation accessory conduction pathways and right sided HF. Can be caused by lithium exposure in utero.

Question 46

What can be caused by lithium exposure in utero?

Answer 46

Ebsteins anomaly

Question 47

What are symptoms and causes of left-to-right shunting?

Answer 47

acyanotic at presentation; cyanosis may occur years later Right-to-left shunts: eaRLy cyanosis Left-to-right shunts: LateR cyanosis

Question 48

What is ventricular septal defect?

Answer 48

asymptotic at birth, may manifest weeks later or remain asymptotic thought life. most resolve larger lesions may lead to LV overload and HF O2 saturation increases in RV and pulmonary artery

Question 49

What is atrial septal defect?

Answer 49

defect in interatrial septum, wide fixed split S2. Ostium secundum defects most common and usually an isolated finding; ostium primum defects rarer and usually occurs with other cardiac abnormalities. Sx range from non to HF. Different from patent foramen ovale in that septa are missing tissue rather than unfused O2 sat increased in RA, RV, and pulmonary artery. May lead to paradoxical emboli