CV Embryology

Question 1

What is the heart derived from

Answer 1

Splanchnic mesoderm (lateral plate)

Question 2

When do the 2 heart tubes fuse together

Answer 2

Late week 3

Question 3

How is the primitive heart tube anchored

Answer 3

// arterial trunks

// extensive venous channels

Question 4

What is the truncus arteriosus continuous with

Answer 4

Aortic sac (lies above)

• pulmonary trunk
• aorta

Question 5

What does the bulbus cordis become

Answer 5

Smooth part of outflow tract

Conus arteriosus

Question 6

What does the sinus venosus receive

Answer 6

Paired veins of the body

Question 7

What is formed as the heart bends on itself

Answer 7

Bulboventricular loop

Question 8

When does partition of the heart develop

Answer 8

Around the 4th week - essentially finished by the 5th

Question 9

3rd arch becomes

Answer 9

1. Common carotid
2. Proximal internal carotid
3. External branches of 3rd arch

Question 10

4th arch becomes

Answer 10

1. Arch of aorta (left)
2. Subclavian artery (right)

Question 11

6th arch becomes

Answer 11

1. Ductus arteriosus (left)
2. Pulmonary trunk

Question 12

Persistent Truncus Arteriosus

Answer 12

• Single outflow tract remains
• VSD - membranous part of septum fails to form
• Cyanosis (blue baby syndrome) - systolic murmur

Question 13

Transpositions of great vessels

Answer 13

• Conotruncal septum fails to spiral
• Cyanosis - usually a systolic murmur - not compatible with life unless another shunt is present

Question 14

Where did the smooth wall of right atrium come from

Answer 14

Sinus venosus

Question 15

What valve is important in foetal life

Answer 15

Valve of IVC

Question 16

What does the foramen ovale become

Answer 16

Fossa ovalis (in adults)

Question 17

Patent Foramen Ovale

Answer 17

Usually asymptomatic - suction stops mixing of blood

10-15% with ECHO

Question 18

Left -> right shunting of blood

1. What does it result in
2. Symptoms
3. Auscultation

Answer 18

1. Exercise intolerance in older children/adults // acyanotic heart disease
2. May be asymptomatic
3. Ejection systolic murmur

Question 19

Ostium primum defect

Answer 19

Septum primum fails to close ostium primum

Just above AV valves

Risk of associated valve defects

Question 20

Ositum secundum defects

1. Occurence
2. Where does it occur
3. What fails to fuse
4. Causes

Answer 20

1. Most common in 70% of ASDs
2. Occurs in region of fossa ovalis
3. Septum primum and secundum fail to fuse
4. Excessive resorption of septum primum // underdevelopment/absence of septum secundum

Question 21

What closes the interventricular foramen

Answer 21

Tissue from inferior endocardial cushion

Question 22

Ventricular septal defect

Answer 22

Spontaneous closure < 2 yrs, especially muscular VSDs

Membranous => likely valves

Question 23

Left -> right shunt of VSD

Answer 23

• Acyanotic
• Exercise intolerance in older children/adults
• Pansystolic murmur left lower sternal border
• May also have palpable thrill

Question 24

What is the ligamentum arteriosum

Answer 24

Remnant of ductus arteriosus

Question 25

Post-natal closure of ductus arteriosus

Answer 25

• Bradykinin releases
• SM contracts
• Physiological then anatomical closure of ductus arteriosus

Question 26

Patent Ductus Arteriosus (PDA)

Answer 26

• Post-natal blood flow left -> right
• Pulmonary hypertension
• Machine-like murmur (systole and diastole)

Question 27

Acyanotic

Answer 27

Left -> right shunt

Question 28

Cyanotic

Answer 28

Right -> left shunt

reduced flow to pulmonary circulation - patent truncus, Tetralogy of Fallot