Cardiac Abnormalities

Question 1

What is ventricular septal defect?

Answer 1

When there is a hole in the septum causing oxygenated blood to be pumped back through the lungs

Question 2

What is coarctation of the aorta?

Answer 2

When the aorta is narrowed therefore increasing workload

Question 3

What is Tetralogy of Fallot?

Answer 3

Four defects:

1) Narrowed pulmonary trunk and valve
2) Hypertrophy of right ventricle
3) Ventricular septal defect
4) Aorta opens from both ventricles

Question 4

How does foetal circulation work?

Answer 4

• Oxygen is supplied by the placenta
  via the umbilical arteries
• The lungs are fluid filled and there is a great resistance to blood flow
• Oxygenated blood needs to enter the left side of the heart for systemic circulation
• The right side of the heart has a higher pressure than the left to allow this

Question 5

How does neonate circulation work?

Answer 5

In the neonate:
- The various foetal
openings and shunts
need to be closed
- The left side of the heart has a higher pressure than the right
- Failure to close or an error in development may result in a cardiac abnormality

Question 6

How does the heart develop?

Answer 6

• Heart develops from a ‘single’ muscular tube at day 22
• The heart needs to develop into four chambers and be able to function as both a foetal and neonatal heart
• Many abnormalities arise during development or during the transition from foetal to neonatal circulation

Question 7

How does the atria develop?

Answer 7

As a foetus, oxygenated blood flows from the right side with higher pressure to the left through the foramen ovale. In the neonate, the atrium separates into two completely different spaces when the septum closes. This is because the pressure is now higher on the left side.

Question 8

What are the steps of the development of the atria?

Answer 8

1) The septum primum starts to grow so as to separate the single atrium into two. Blood flows through the ostium primum right to left
2) The septum primum joins to the endocardial cushion and perforations, the ostium secundum, are made in septum primum to allow blood circulation.
3) The septum secundum forms with a foramen ovale to allow foetal circulation to continue
4) At birth the septum primum covers the foramen ovale

Question 9

How do the ventricle develop?

Answer 9

• The single ventricle is divided into two by the growth of a septum
• If the septum fails to grow and join with the endocardial cushion or part of the septum is reabsorbed then a hole will be present
• This hole is a ventricular septal defect (VSD)

Question 10

What is a cyanotic abnormality?

Answer 10

When deoxygenated blood enters the systemic circulation

Question 11

What is a acyanotic abnormality?

Answer 11

When oxygenation of the systemic circulation is relatively normal (some oxygenated blood may re-enter the pulmonary circulation)

Question 12

What are examples of cyanotic abnormalities?

Answer 12

• Tetralogy of Fallot

- Transposition of the Great Vessels

Question 13

What are examples of acyanotic abnormalities?

Answer 13

• Ventricular septal defects (VSDs)
• Atrial septal defects (ASDs)
• Aortic stenosis
• Coarctation of the Aorta

Question 14

What are ventricular septal defects (VDSs)?

Answer 14

• When the superior part of the interventricular
  septum fails to form
• Occurs in 1 in 500 births
• Acyanotic

Question 15

What are atrial septal defects (ASDs)?

Answer 15

• When there is a hole in the septum which should separate the two atria
• Caused by the septum being to short or the foramen ovale being to large or both
• Acyanotic

Question 16

What is the Patent Ductus Arteriosus?

Answer 16

• When a vessel connects the aorta and pulmonary artery
• Since the aorta has higher pressure, blood flows from there to the pulmonary artery
• Lower blood flow to the systemic circulation
• Increased blood flow to lungs can cause pulmonary oedema and right sided heart failure

Question 17

What is coarctation of the aorta?

Answer 17

• Narrowing of the aorta
• The muscle that closes the ductus arteriosus extends around the aorta
• Encourages collateral circulation
• Subclavian arteries may take blood to lower body

Question 18

How does the aorta and pulmonary artery form?

Answer 18

• A single vessel (truncus arteriosus) divides into the aorta and pulmonary artery
• In order to line up with the correct ventricles the truncus arteriosus must spiral 180 degrees
• Failure to spiral causes Transposition of the great vessels
• Failure to divide equally causes stenotic aorta or pulmonary artery

Question 19

What is the Transposition of the Great Vessels?

Answer 19

• When the aorta arises from the right side of the heart and the pulmonary artery from the left side
• Occurs when the truncus arteriosus doesn’t spiral
• Cyanotic
• Survival requires some form of septal defect or a patent ductus arteriosus
• Surgery is required to ‘switch’ the vessels back

Question 20

What happens if the truncus arteriosus divides unequally?

Answer 20

• Stenotic aorta or pulmonary trunk

- This will causes blood flow resistance and hypertrophy of the corresponding ventricle to overcome the resistance

Question 21

When do valve defects affect the individual?

Answer 21

Later in life when the valves become ‘stiff’

Question 22

How do semilunar valves mutate?

Answer 22

The left sided valve will have two cusps instead of three causing resistance to blood flow. Resistance causes the ventricle to contract harder and results in hypertrophy of the ventricle

Question 23

What is an aortic regurgitation murmur?

Answer 23

• A faulty aortic valve may cause a leaky valve
• During ventricular diastole blood may flow back into the ventricle causing a murmur
• “lubb” “dubb” “swish”

Question 24

What occurs in aortic valve stenosis?

Answer 24

• Resistance to blood flow through the aorta causes the left ventricle to contract harder
• This causes increased left ventricular pressure and then increased right atrial pressure, causing hypertrophy

Question 25

What occurs with mitral valve stenosis?

Answer 25

- There is resistance for blood to flow to the left ventricle therefore the atrium will contract harder. - This will increase the left atrial pressure and cause hypertrophy of the left atrium