Module 8.1 : Normal Fetal Anatomy - Heart

Question 1

when does heart tube begin to develop

Answer 1

• develops from the mesoderm at 5th week LMP

Question 2

when is the heart tube fully formed

Answer 2

• 10th week LMP

Question 3

heart tube evaluations done when

Answer 3

• evaluated from 18 or 20 weeks to term or delivery

- best between 18-24 weeks

Question 4

fetal circulation - specialized structures

Answer 4

• ductus venosus
• foramen ovale
• ductus arteriosus
• 3 places where there is shunts

Question 5

heart position within the fetus

Answer 5

• sits completely horizontal in the fetal chest
• located left of midline
• apex points 45’ to left
• occupies 1/3 of chest

Question 6

chambers of the heart

Answer 6

• 2 atria sit posterior to 2 ventricles
• left atrium most posterior
• right ventricle most anterior

Question 7

moderator band

Answer 7

• thick muscle makes right ventricle chamber look smaller than left
• used to prove which chamber is right ventricle in abnormal hearts

Question 8

mitral valve

Answer 8

• aka bicuspid valve
• contains 2 cusps
• passes blood from left atrium to the left ventricle

Question 9

tricuspid valve

Answer 9

• contains 3 cusps
• passes blood from right atrium to the right ventricle
• mitral and tricuspid valves open and close together and at same level in heart

Question 10

aortic valve

Answer 10

• 3 cusps
• assess oxygenated blood from the left ventricle to the aorta to be distributed to the rest of the body
• seen in LVOT view

Question 11

pulmonary valve

Answer 11

• contains 3 cusps
• passes deoxygenated blood from right ventricle to pulmonary artery to be oxygenated by longs
• pulmonary artery sits more anterior than the aorta
• want to see it in long axis not short axis

Question 12

ductus arteriosis

Answer 12

• shunts blood from the pulmonary artery to the aortic arch to bypass the lungs during fetal life
• after deliver the ductus arteriosis closes

Question 13

foramen ovale

Answer 13

• opening between the atria
• blood flows from right atrium to the left atrium
• also helps bypass lungs
• ovale flaps open into left atrium

Question 14

IVC and SVC

Answer 14

• bring deoxygenated blood back from the body to the right atrium
• long horn vie you see both

Question 15

pulmonary veins

Answer 15

• 4 pulmonary veins the bring oxygenated blood from lungs to the left atrium in new born
• on ultrasound usually see 2

Question 16

routine images of heart

Answer 16

• 4 chamber heart (trans)
• left outflow tract (more superior)
• right outflow tract (more mores superior)
• 3 vessel view (most superior)
• cine clip
• fetal M mode
  + 120-160bpm in 2nd and 3rd trimester
  + can go higher but worrisome if goes lower

Question 17

4 chamber heart

Answer 17

• shows all 4 chambers with the septum
• valves closed = systole
• valves open = diastole

Question 18

LVOT

Answer 18

• demonstrates the left ventricle with the aorta

- anterior wall of the aorta should continue with the IVS

Question 19

RVOT

Answer 19

• demonstrates the right ventricle with the pulmonary artery
• LVOT and RVOT should cross eachother
• if parallel to each other the tubes didn’t twist

Question 20

3 vessel view

Answer 20

• should see pulmonary artery
• aortic arch
• SVC
• assess diameter

Question 21

cine clip 12 seconds

Answer 21

- begin at level of AC
  \+ demonstrate stomach for situs
- sweep cephalic 
- demonstrate 4 chamber
- then LVOT
- then RVOT
- then 3 vessel 
- sweep all the way to fetal neck

Question 22

heart tracing

Answer 22

• use M mode
• place cursor over the heart area where you catch wall of one atria and one ventricle
• usually one beat
• only way to prove viability
• assess if atria and ventricle beating at same rate

Question 23

tachycardia

Answer 23

• fetus won’t survive in tachycardia
• heart is quivering no blood into systems
• may see hydrops - end stage disease fluid in one or more cavities

Question 24

normal fetal heart rate

Answer 24

• 120-160bpm

Question 25

heart rate under 100 in first

Answer 25

• concerning
• early pregnancies heart may actually stop for a few seconds (conduction is weak)
• move to different area then go back

Question 26

third trimester heart rate

Answer 26

• up to 180 in third is normal with activity

Question 27

bradycardia

Answer 27

• under 100 sustained in 2nd 3rd trimester

Question 28

additional images

Answer 28

• short axis (circle and sausage)
• SVC IVC with right atrium
• aortic arch
• ductal arch
• pulmonary veins with left atrium

Question 29

short axis view

Answer 29

• demonstrates the right and left atrium
• right ventricle
• pulmonary artery
• ductus arteriosis
• all circling aorta

Question 30

SVC and IVC

Answer 30

• shown with right atrium

- steers head

Question 31

aortic arch

Answer 31

• candy cane
• see 3 vessels
  + brachiocephalic artery
  + left common carotid artery
  + left subclavian artery

Question 32

ductal arch

Answer 32

• right ventricle with ductus joining the aorta

- hockey stick

Question 33

pulmonary veins

Answer 33

• usually see 2 veins entering right atrium