Embryology

Question 1

cardiogenic mesoderm

Answer 1

gives rise to endo, epi, and myocardium

- does not form fibrous skeletal elements or valves

Question 2

Cardiac looping

Answer 2

induced by rapid growth of ventricles

caudal end folds up and posterior –>puts venous and atrial things posterior

Question 3

Sinus venosus

Answer 3

most caudal structure in heart tube (receives all blood form embryo)
Becomes RA
L sinus horn–>coronary sinus
R sinus horn–> sinus venarum

Question 4

Primitive atrium

Answer 4

will become the pectinate regions of the LA and RA (i.e. auricle regions)

Question 5

Primitive ventricle

Answer 5

will form the trabeculated portions of the LV

Question 6

bulbus cordis

Answer 6

becomes the trabeculated portion of RV, root of ascending aorta an pulmonary trunks, outflow parts of both RV and LV

Question 7

conus cordis

Answer 7

part of bulbous cordis that becomes smooth walled outflow of both LV and RV

Question 8

Truncus arteriosus

Answer 8

part of bulbous cordis that becomes ascending aorta and pulmonary trunk

Question 9

Septum Primum

Answer 9

forms first in atrial partitioning

has a small opening in inferior part called ostium primum (very short lived)

Question 10

Osteium secundum

Answer 10

second step in atrial partitioning
forms in septum primum
allows blood to flow from RA to LA and bypass the lungs

Question 11

Septum secundum

Answer 11

3rd step
forms laterally to primum, thicker and more muscular, will become interatrial septum
contains foramen ovale which is the definitive blood shunt (sealed at birth)
septum primum is the valve for foramen ovale

Question 12

Patent foramen ovale

Answer 12

common, lack of fusion of foramen ovale and primum
usually asymptomatic, unless there is a pathology that increases pressure in RA, when it can open up

example of ASD (10% of all defects)

Question 13

Neural crest cells

Answer 13

migrate into heart and form a ring of tissue around the IV septum called endocardial cushions, creating a right and left atrioventricular canal

will form the heart valves and membranous portion of ventricle wall

Question 14

VSD (ventricular septal defect )

Answer 14

30% of all congenital defects
- holes in either muscular or membranous (more common) septa
severity depends on size
L–>R shunting of blood
sx= pulmonary hypertension, decreased systemic blood flow, LV hypertrophy

Question 15

endocardial cushion (neural crest) disorders

Answer 15

cause persistent AV canal
ASD (ostium primum defect)
Membranous VSD

Question 16

Aortic stenosis

Answer 16

narrowing of great vessel lumen due to stenosis of heart valve (usually semilunar)

Question 17

Tetralogy of fallot

Answer 17

caused by unequal division of truncus arteriosus

1) narrowing of pulmonary trunk
2) overriding aorta (very large)
3) Membranous VSD
4) RV hypertrophy

due to pulmonary stenosis

** common cause of cyanosis of newborn

Question 18

Transposition of great vessels

Answer 18

Aorta exits from RV, PT comes from LV

due to conotruncal ridges failing to spiral

Question 19

Persistent truncus arteriosus

Answer 19

1 artery that leaves from both RV and LV–> mix of oxygenated and deoxygenated blood to systemic circulation

from conotruncal ridges failing to form
another cause of cyanosis in the newborn

Question 20

dextrocardia

Answer 20

looping disorder that causes a right sided heart

Question 21

ectopic cordis

Answer 21

body wall defect in which there is no fusion of the thoracic wall–> heart forms externally

Question 22

DiGeorge syndrome

Answer 22

neural crest disorder--> cardiac valve defects, 
CATCH-22
Chromosome 22 deletion
abnormal face
thymic aplasia (immunocompromised), 
cleft palate
hypocalcemia (PTH defect)

Question 23

3rd Aortic arch

Answer 23

R= Common Carotid a. 
L= Common Carotid a.

Question 24

4th Aortic arch

Answer 24

R=  R Subclavian . 
L= Arch of aorta

Question 25

6th Aortic arch

Answer 25

R= Pulmonary a. 
L= Pulmonary a. and ductus arteriosus

Question 26

7th aortic arch

Answer 26

R= Subclavian a.
L= Subclavian a.

Question 27

Patent ductus arteriosus

Answer 27

ductus arteriosus does not close
L--> R blood shunt 
pulmonary overflow 
R side hypertrophy 
decreases systemic flow

Question 28

Preductal coarctation of aorta

Answer 28

Infantile, presents immediately
bypass the constriction via ductus arteriosus prenatally, but at birth there is no diversion
–> tachycardia, cyanosis of LOWER LIMBS, low femoral pulse

Question 29

Postductal coarctation of aorta

Answer 29

adolescent, present later,

during development there is no way to divert the block unless collateral circulation is developed via posterior and anterior intercostals which brings blood to descending aorta

presents as individual becomes more active
Sx= fatigue, HA, HT upper limg, weak femoral pulse, hypotension in lower limbs

Question 30

Retroesophageal R subclavian a.

Answer 30

R subclavian passes behind esophagus

can compress the esophagus–> dysphagia lucoria

Question 31

double aortic arch

Answer 31

aortic arch persists on both sides compressing the esophagus and causing dysphagia

Question 32

Tracheoesophageal Fistula

Answer 32

development of an abnormal fistula (opening) b/w trachea and esophagus due to lack of septum formation

proximal esophageal atresia

sx: infant that can’t eat (vomits immediately)
stomach become distended with air

Question 33

Fetal survivability based on lung development

Answer 33

6-16 weeks= non-survivable due to lack of lungs and surfactant

surfactant production begins at week 21, becomes survivable

preemies suffer from respiratory distress syndrome due to lack of surfactant