Congenital Heart Disease

Question 1

What is a septal defect?

Answer 1

any defect which affects part of the wall between any of the chambers of the heart
defect in the septum, or wall, between two chambers

Question 2

Describe foetal development of the heart

Answer 2

It starts off as a tube that connects the pulmonary veins to the systemic arterial blood vessels.
-Arterial trunk, bulbous cordis, ventricular mass, atrial mass
The blood is going to flow from the venous end to the arterial end.
What’s going to happen is that this tube is going to fold and the segments dilate, to form different chambers
We still have a tube connecting the pulmonary veins to the arterial outflow, but parts of the tube have dilated to form almost separate chambers.
These are going to form, respectively, the atria, ventricles and arterial outflow tracts

Question 3

What is the name of the embryonic structure that when fails to close causes Atrial Septal Defect?

Answer 3

It’s the foramen ovale.
This particular structure is called the ostium secundum, which is the commonest type of ASD.
Heart murmur

Question 4

What is Patent Foreamen Ovale?

Answer 4

the higher pressure in the left side of the heart forces blood through the hole into the right atrium (a).
This means that extra blood comes into the right atrium and then the right ventricle has to pump this extra blood into the pulmonary artery.
So the ASD creates extra work for the right ventricle.

Question 5

What is a shunt?

Answer 5

the movement of blood from one side of the circulation to the other

Question 6

Describe ventricular septal defects

Answer 6

Most ventricular septal defects are high up, where the interventricular septum is fibrous rather than muscular.
Left to right shunt

Question 7

What is Patent ductus arteriosus?

Answer 7

The ductus arteriosus remains open.
Normally this embryological structure closes and remains behind as a dense ligament, the ligamentum arteriosum.
blood flows from the left side of the circulation (from the aorta) to the right side (to the pulmonary artery) (a), producing what’s termed a left to right shunt

Question 8

Explain the sequence of events that happen if there’s a significant left to right shunt

Answer 8

The right ventricle has to work harder to pump the extra blood into the pulmonary artery. So the pressure increases: pulmonary hypertension. Consequently the right ventricle tends to become hypertrophied.
The pulmonary hypertension leads to increased pulmonary resistance and in time there is permanent damage to the pulmonary arteries.
As the pressure in the right heart increases with time, it may exceed that in the left side of the heart. The flow of blood through the shunt then reverses and becomes right to left. This is particularly likely to occur with a large VSD or PDA. By this time, the pulmonary hypertension becomes irreversible, which is serious.
For these reasons, surgical intervention is required if a defect doesn’t close spontaneously.

Question 9

What is Eisenmenger’s syndrome/ complex?

Answer 9

the condition that results when there is a VSD with pulmonary vascular disease

Question 10

What is shunt reversal?

Answer 10

If the pressure in the pulmonary artery increases sufficiently, the pressure in the right ventricle will eventually exceed the pressure in the left ventricle.
Blood will then flow from the right side of the heart into the left side
push unoxygenated blood into the systemic circulation
Cyanosis

Question 11

How does pulmonary artery stenosis occur?

Answer 11

This set of defects is due to anterosuperior displacement of the infundibular septum during the development of the heart.
ventricular septal defect high up in the interventricular septum

Question 12

As a result of this pulmonary valve stenosis, what change would the wall of the right ventricle undergo?

Answer 12

The right ventricle would undergo hypertrophy, as it has to pump out blood against increased pressure from:
The stenosed pulmonary valve
The systemic blood pressure, transmitted through the ventricular septal defect.
So the child would develop right ventricular hypertrophy.

Question 13

What is Tetralogy of Fallot?

Answer 13

VSD.
pulmonary stenosis.
over-riding aorta.
right ventricular hypertrophy.

Question 14

What occurs as a result of Tetralogy of Fallot?

Answer 14

As the flow of blood into the pulmonary artery is diminished, due to the stenosed pulmonary valve, most of the blood from the right ventricle passes into the aorta.
The aortic blood is thus mixed with unsaturated blood coming from the right ventricle.

Question 15

What is transposition of the great arteries?

Answer 15

the aorta (a) comes off the right ventricle
the pulmonary artery (b) comes off the left ventricle

Question 16

What is correction transposition?

Answer 16

in addition to the main defect, the atria and ventricles were also mismatched

Question 17

How can transposition of the great arteries by corrected by a shunt?

Answer 17

Patent ductus arteriosus
As the pressure in the pulmonary artery, which comes off the left ventricle, is higher than that in the aorta, oxygenated blood from the pulmonary artery is pumped into the aorta through the ductus arteriosus.
This allows enough oxygenated blood to get into the systemic circulation to keep the child alive.

Question 18

What is the difference between a stable and unstable shunt?

Answer 18

A VSD tends to remain open and is called a stable shunt.
A PDA or ASD, however, tends to close (unstable shunt) and a surgeon must intervene early to create a stable shunt that will keep the child alive long enough to undergo more extensive surgery.

Question 19

What is coarctation of the aorta?

Answer 19

Narrowed segment of aorta

Question 20

What occurs due to coarctation of the aorta?

Answer 20

Coarctation tends to deprive the lower part of the body of blood, as the flow through the narrowed segment is reduced.
In addition, hypertension develops in the upper part of the body.

Question 21

What genetic condition is particularly associated with congenital heart disease?

Answer 21

Down’s syndrome

Question 22

In a pregnant woman, what are the recognised causes of congenital heart disease in the developing baby during the first 12 weeks (trimester) of pregnancy?

Answer 22

Excessive alcohol ingestion may damage the fetus. This particularly gives rise to ASD or VSD.
Infection of the mother with German measles, or, as we in the medical profession call it, rubella, is a classic cause of congenital heart disease in the baby, particularly PDA or ASD or stenosis of either the aortic or pulmonary valve.
Drugs of any sort should be avoided in the first part of pregnancy, especially anti-epileptics, lithium, sex hormones.