Congenital Heart Disease - Embryology & Situs

Question 1

The heart is formed between ___ - ___ weeks gestation.

Answer 1

3-7

Question 2

The truncus arteriosus is is superior and forms what?

Answer 2

The semilunar valves

The aortic root and pulmonary artery form as the truncus separates

Question 3

Which way should the heart tube fold?

Answer 3

Rightward

Question 4

What does leftward folding result in?

Answer 4

L-TGA

Question 5

Stage 1 of atrial septal formation

Answer 5

Septum primum. Foramen primum forms in the lower portion of the IAS

Question 6

Stage 2 of atrial septal formation

Answer 6

Foramen secundum

Question 7

Stage 3 IAS formation

Answer 7

Secundum septum. Overlaps the Foramen secundum and forms foramen ovale

Question 8

What closes the foramen ovale at birth?

Answer 8

Increased pressure in the LA pushes the valve against the septum secundum

Question 9

Where do the following atrial septal defects occur? Primum ASD, secundum ASD, Sinus venosus ASD

Answer 9

Primum ASD- inferior
Secundum ASD- middle
Sinus venosus ASD- superior

Question 10

Stage one of IVS formation

Answer 10

Trabecular IVS grows from apex halfway up

Question 11

Stage 2 IVS formation

Answer 11

Tricuspid and mitral orifice formation

Question 12

Stage 3 of IVS formation

Answer 12

Truncus formation-> conotruncal septum forms in a spiral fashion to form prox aorta and pulmonary artery

Question 13

Stage 4 of IVS formation

Answer 13

Membranous septum forms to complete the IVS

Question 14

What do the 2 medial endocardial cushions form?

Answer 14

Septal leaflet of TV

Anterior MVL

Question 15

What do the 2 lateral endocardial cushions form?

Answer 15

Anterior and posterior tricuspid leaflets

Posterior MVL

Question 16

What do the atrioventricular valves form from?

Answer 16

Endocardial cushions

Question 17

What do the semilunar valves form from?

Answer 17

Truncus arteriosus

Question 18

There are originally 6 sets of aortic arches in the fetus. Which one develops into the adult aorta?

Answer 18

The 4th

Question 19

Where does the fetus get its oxygenated blood from?

Answer 19

The placenta -> umbilical vein -> ductus venosus & onward

Question 20

What are the 3 steps in the segmental approach to CHD?

Answer 20

• visceral atrial situs & atrial connections
• orientation of the ventricles & connections
• orientation of the great vessels & connections

Question 21

Define dextroposition, mesoposition, levoposition

Answer 21

Dextro: reversed (right)
Meso: middle
Levo: normal (left)

Question 22

Dextrocardia situs inversus totalis

Answer 22

All organs are mirrored

Question 23

Describe the 3 visceral situs formats

Answer 23

• situs solitus (normal)
• situs inversus (mirror image)
• situs ambiguous (cant tell)

Question 24

What are some defining features of the RT atria?

Answer 24

eustachian valve, vena cavae, coronary sinus, Chiari network, RAA

Question 25

What are some defining features of the LA?

Answer 25

Pulmonary veins, LAA

Question 26

Defining features of the morphologic RV

Answer 26

-crescent shaped, 3 leaflet valve, larger trabeculations, multiple paps, moderator band, infundibulum, septal leaflet apically displaced

Question 27

Defining features of the morphologic LV

Answer 27

-bullet shaped, 2 leaflet valve, two paps