Session 3 Lectures

Question 1

Which week does the embryo fold & does the position of carcinogenic field change?

Answer 1

In week 4 of embryonic period (embryonic period = week 3-8)

Yes the position changes

Question 2

Suggest a reason why congenital heart defects are one of the most common defects

Answer 2

There are different circulatory needs of the fetus and newborn baby - need to be able to create both and switch over immediately after birth

Question 3

What is at the inlet of the primitive heart tube?

Answer 3

Sinus venous and primitive atrium

Question 4

What is at the outlet of the primitive heart tube?

Answer 4

Aortic roots

Question 5

Suggest why cardiac looping takes place

Answer 5

To maximise the amount of space the heart has within the pericardial sac

Question 6

What is the primitive heart tube composed of?

Answer 6

Fusion of 2 endocardial tubes

Question 7

What does right atrium develop from?

Answer 7

Most of the primitive atrium and sinus venosus (inlet of heart tube)

Question 8

What does left atrium develop from? And why is it smoother?

Answer 8

A small portion of primitive atrium and proximal parts of the pulmonary veins
These are made of smooth muscle so left atrium is smoother

Question 9

In the fetus the lungs don’t work - where does oxygenation and removal of CO2 take place?

Answer 9

At the placenta

Question 10

When oxygenated blood enters the umbilical vein what does it reach first and how does it bypass this?

Answer 10

It reaches the liver first
Shunt of blood to go directly to inferior vena cava
This shunt is called the ductus venosus

Question 11

In the fetus oxygenated blood travelling from inferior vena cava reaches right atrium and is shunted across to pulmonary trunk. What is this shunt called?
Does some blood go into right ventricle first?

Answer 11

Foramen ovale

Yes some does reach right ventricle so that this muscle properly develops

Question 12

In the fetus blood eventually reaches pulmonary trunk and is shunted to aorta as it is already oxygenated. What is this shunt called?

Answer 12

Ductus arteriosus

Question 13

What nerve becomes hooked around the pulmonary trunk and aorta in development?

Answer 13

The left recurrent laryngeal nerve

Question 14

What does PDA stand for and what is the condition?

Answer 14

Patent ductus arteriosus
When the ductus arteriosus doesn’t close after birth - blood is now shunted from aorta to pulmonary trunk (down pressure gradient)

Question 15

What are the 2 septums called? What are the 2 hole called that form (1 in each)?

Answer 15

Septum primum and septum secundum

Ostium secundum and foramen ovale

Question 16

What happens to the foramen ovale in healthy newborns?

Answer 16

It is closed by the pressure of the left atrium (forcing the septum primum and septum secundum close together)

Question 17

What is hypoplastic left heart syndrome?

Answer 17

The left ventricle and ascending aorta fail to develop properly
A patent foreman ovale or atrial septum defect is also present and blood supply to systemic circulation is via a patent ductus arteriosus

Question 18

What are the 2 components of ventricular septum?

Answer 18

Muscular

Membranous

Question 19

What is the primary interventricular foramen?

Answer 19

The small gap left after muscular portion of ventricular septum has formed

Question 20

How is the primary interventricular foramen closed?

Answer 20

The membranous portion of the interventricular septum is formed by connective tissue and closes the gap

Question 21

In the fetus what does the blood flow out from?

Answer 21

The truncus arteriosus

Question 22

What are the 4 symptoms of tetralogy of fallot?

Answer 22

1) ventricular septal defect
2) Overriding aorta
3) Pulmonary stenosis
4) Can lead to right ventricular hypertrophy

Question 23

What are neural crest cells derived from and what do they contribute to creation of?
What can damage them in pregnancy?

Answer 23

They are derived from neurectoderm
They contribute to creation of endocardial cushions
They can be damaged in pregnancy if the mother drinks alcohol

Question 24

What is the oxygen saturation levels of oxygenated blood going through heart and deoxygenated blood going through heart?

Answer 24

100% when oxygenated

67% when deoxygenated

Question 25

What is the pressure (systolic and diastolic) in mm/hg in the left ventricle and right ventricle?

Answer 25

``` Left = 80/4 Right = 25/3 ``` The systolic pressure is the pressure needed to open the aortic and pulmonary valves

Question 26

What is cyanosis?

Answer 26

Presence of deoxygenated haemoglobin in arterial circulation

Question 27

What happens in a left to right shunt?

Answer 27

Blood travels from left ventricle back to the lungs instead of the body

Question 28

What happens in a right to left shunt?

Answer 28

Blood travels from right ventricle to circulate around body without being oxygenated by lungs

Question 29

Describe an atrial septal defect | - describe which direction blood flows and what it eventually leads to

Answer 29

``` Hole in septum separating two atrium Blood flows from left to right down pressure gradient (so no mixing of deoxygenated blood with oxygenated travelling around body) Leads to increased pulmonary blood flow Increased in RV volume Leads to right sided heart failure ```

Question 30

Where is the most common location for an atrial septal defect?

Answer 30

In the ostium secundum

Question 31

Why is a patent foreman ovale normally clinically silent?

Answer 31

Because the pressure of the left atrium keeps the flap closed

Question 32

Describe a ventricular septal defect | State which way blood flows and what it leads to

Answer 32

``` Abnormal opening in ventricular septum Blood flows from left to right down pressure gradient Leads to LV volume increase Pulmonary venous congestion Pulmonary hypertension ```

Question 33

Describe a patent ductus arteriosis What is its purpose in the fetus? Why does it normally close after birth? Which direction does blood flow if it fails to close after birth?

Answer 33

The ductus arteriosis is a vessel in the fetus that shines blood from pulmonary artery to aorta bypassing lungs It should close after birth as pressure in pulmonary artery drops following perfusion of lungs = patent ductus arteriosis is when it doesn't. Blood flows from aorta to pulmonary artery after birth (high to low pressure)

Question 34

What is eisenmonger syndrome?

Answer 34

Any untreated congenital heart defect that leads to pulmonary hypertension and cyanosis Blood flows from left to right down pressure gradient

Question 35

Describe coarction of the aorta - what can it lead to? - to where is blood flow reduced? - to where does blood flow remain the same and why?

Answer 35

It is a narrowing of the aortic lumen which increases afterload on LV and can lead to LV hypertrophy It affects blood flow to body (except head and upper limbs as the vessels leading here usually appear after coarctation)

Question 36

In which region of the aorta is coarction of the aorta? | What vessel appeared at this location in the fetus?

Answer 36

In the ligamentum arteriosum | It was the former ductus arteriosus in fetus (bypassing blood away from lungs from pulmonary arteries to aorta)

Question 37

In coarctation of the aorta what will the femoral pulses be like in either side of the body?

Answer 37

The femoral pulse only on the left will be weaker and there may be a delay in the pulse compared to the right

Question 38

What are the the four anomalies in tetralogy of fallot?

Answer 38

1) Pulmonary stenosis 2) ventricular septal defect 3) Right ventricular hypertrophy 4) Overiding aorta

Question 39

Is tetralogy of fallot a cyanosis defect and why?

Answer 39

Yes - there is mixing of deoxygenated blood with oxygenated blood leaving the aorta Increased pressure in the right ventricle (due to pulmonary stenosis and overiding aorta) means blood travels right to left

Question 40

What is tricuspid atresia? | By what method will blood be oxygenated?

Answer 40

Lack of development of the tricuspid valve There has to be a complete shunt of blood from right to left Blood oxygenated via a patent ductus arteriosis or a ventricular septal defect (allowing left to right movement of blood to lungs)

Question 41

In transposition of the great arteries - which vessels are connected to which ventricle?

Answer 41

Right ventricle to aorta | Left ventricle to pulmonary artery

Question 42

What is pulmonary atresia?

Answer 42

No right ventricle outlet Right to L atrial shunt of entire venous return and blood flows to lungs via a patent ductus arteriosis (blood flows from aorta to pulmonary artery)

Question 43

Name 3 acyanotic defects

Answer 43

``` Atrial septal defect ventricular septal defect patent foreman ovale coarction of the aorta patent ductus arteriosis ```

Question 44

Name 3 cyanotic defects

Answer 44

Tetralogy of fallot tricuspid atresia transposition of the great arteries hypoplastic left heart