Embryology and Congenital Heart Defects

Question 1

what is the foramen primum?

Answer 1

the foramen between the atrium chambers

Question 2

before the foramen primum becomes obliterated what appears in the interatrial septum (septum primum)?

Answer 2

foramen secondum

Question 3

what does the development of the foramen secondum before the foramen primum has been fully obliterated allow?

Answer 3

the uninterrupted shunting of blood from right atrium to left atrium
(foramen secundum takes over the job of the foramen primum)

Question 4

where does the septum secondum grow in relation to the septum primum which has already formed?

Answer 4

to the right of it

Question 5

what is the function of the septum secondum?

Answer 5

partially covers the foramen secondum

Question 6

what is the small hole that appears as the septum secondum partially covers the foramen secondum?

Answer 6

foramen ovale

Question 7

what acts as a uni-directional flutter valve to ensure that blood flowing through the foramen ovale only moves from the right atrium to the left atrium?

Answer 7

septum primum

Question 8

what is the truncus arteriosus?

Answer 8

the original shared outflow track of the ventricles

Question 9

what embrylogical aortic arch forms the aorta?

Answer 9

4th

Question 10

what embryological aortic arch forms the pulmonary trunk?

Answer 10

6th

Question 11

what does bifurcation of the truncus arteriosus lead to?

Answer 11

aorta and pulmonary trunk

Question 12

why are the pulmonary arteries in an embryo constricted?

Answer 12

due to hypoxia in the pulmonary tissue

Question 13

what are the 2 major way the fetal circulation bypasses the lungs?

Answer 13

foramen ovale

ductus arteriosus

Question 14

what is the ductus arteriosus?

Answer 14

a connection from the pulmonary artery to the aorta to bypass the lungs

Question 15

how many umbilical veins is there?

Answer 15

1

Question 16

how many umbilical arteries are there?

Answer 16

2

Question 17

what blood does the umbilical vein carry?

Answer 17

oxygenated blood for the foetus

Question 18

what blood does the umbilical arteries carry?

Answer 18

deoxygenated blood from the foetus

Question 19

what is the ductus venosus?

Answer 19

a connection from the umbilical vein to the inferior vena cava to bypass the liver

Question 20

why does the ductus arteriosus close after birth?

Answer 20

1. increase in oxygen

2. decreased prostaglandins (which were from mother)

Question 21

why might the ductus arteriosus remain open after birth?

Answer 21

1. poor oxygen exchange (ie premature baby)
2. high prostaglandin plasma concentrations
3. increased sensitivity to prostaglandins
4. rubella infection

Question 22

what are the clinical signs of a patent ductus arteriosus?

Answer 22

1. specific murmur
2. widening pulse pressure
3. enlarged heart

Question 23

in a patent ductus arteriosus, which direction does the blood flow through this channel?

Answer 23

from aorta to pulmonary arteries

opposite direction to the way it was going in the foetus

Question 24

what is the treatment for PDA?

Answer 24

drugs: NSAIDs
surgery: PDA ligation, coil occlusion

Question 25

why are NSAIDs used in PDA?

Answer 25

they inhibit prostaglandins causing ductus arteriosus to close

Question 26

what is a patent ductus arteriosus?

Answer 26

a congenital defect where the ductus arteriosus hasn't closed after birth like it should

Question 27

what are the defects that make up tetralogy of Fallot? (congenital defect)

Answer 27

pulmonary stenosis right ventricular hypertrophy ventricular septal defect overriding aorta

Question 28

why is there right ventricular hypertrophy in tetralogy of Fallot?

Answer 28

because of the high resistance (due to the pulmonary stenosis) the right ventricle has to pump against

Question 29

what is an overriding aorta?

Answer 29

receives blood from both left and right ventricles | ie oxygenated and deoxygenated blood

Question 30

in tetralogy of Fallot, why is blood from the right ventricle more likely to go to the overriding aorta than the pulmonary trunk?

Answer 30

because of the pulmonary stenosis the pulmonary trunk has a much higher resistance than the aorta

Question 31

what do kids with tetralogy of Fallot do to relieve their symptoms?

Answer 31

squat suddenly

Question 32

why does squatting help relieve symptoms of tetralogy fallot?

Answer 32

increase oxygen content in veins | vasoconstriction to increase systemic resistance (less deoxygenated blood goes into the aorta)

Question 33

what is transposition of the great arteries?

Answer 33

a congenital defect where the aorta and pulmonary trunk are switched, so deoxygenated blood gets taken to systemic circulation and oygenated blood gets taken to the lungs (2 completely separate circuits)

Question 34

what usually comes with transposition of the great arteries?

Answer 34

ventricular septal defect

Question 35

why is the VSD life sustaining in the congenital defect of transposition of the great ventricles?

Answer 35

allows some oxygenated blood to go to the systemic circulation and some deoxygenated blood to go to the lungs

Question 36

what is truncus arteriosus? | present after birth

Answer 36

a congenital defect where there is no septum between aorta and pulmonary trunk so deoxygenated blood and oxygenated blood mixes

Question 37

what is coarction of the aorta?

Answer 37

a congenital defect where there is vasoconstriction just below the subclavian artery