[14] Atrial Septal Defect

Question 1

What is an atrial septal defect (ASD)?

Answer 1

A heart defect where blood flows between the two atria of the heart

Question 2

What are the two main types of ASD?

Answer 2

• Secundum ASD

- Partial atrioventricular septal defects (AVSD or primum ASD)

Question 3

What is the more common type of ASD?

Answer 3

Secundum ASD

Question 4

Secundum ASD accounts for what percentage of ASD’s?

Answer 4

80%

Question 5

What is a secundum ASD?

Answer 5

A defect of the atrioventricular septum involving the foramen ovale

Question 6

What is the foramen ovale?

Answer 6

A foetal cardiac shunt that allows flow of blood from the right to left atrium

Question 7

What may cause a secundum ASD?

Answer 7

• Failure of the septum secundum to develop

- Enlarged foramen ovale

Question 8

What is a partial AVSD?

Answer 8

A defect in the inferior atrial septum (septum primum) and a regurgitant left atrioventricular valve leading to left to right communication

Question 9

What are the risk factors for ASD?

Answer 9

• Female
• Family history
• Maternal alcohol consumption
• Down’s Syndrome

Question 10

What is the common presentation of an ASD?

Answer 10

Commonly no symptoms

Question 11

If symptoms are present, what might they be?

Answer 11

• Recurrent chest infections
• Wheeze
• Arrhythmias

Question 12

What are the physical signs of an ASD?

Answer 12

• Ejection systolic murmur

- Fixed and widely split second heart sound

Question 13

What sound is specifically heard in a partial AVSD?

Answer 13

Apical pansystolic murmur

Question 14

Where is the ejection systolic murmur best heard?

Answer 14

Upper left sternal edge

Question 15

What causes the ejection systolic murmur in ASD?

Answer 15

Increased flow across the pulmonary valve

Question 16

What causes the increased flow across the pulmonary valve?

Answer 16

Left to right shunt

Question 17

What causes the fixed, widely split second heart sound?

Answer 17

Right ventricular stroke volume being equal in inspiration and expiration

Question 18

What causes the apical pansystolic murmur in AVSD?

Answer 18

Atrioventricular valve regurgitation

Question 19

What investigations may be useful in assessing ASD?

Answer 19

• CXR
• ECG
• Echo

Question 20

Which of the investigations is the mainstay of diagnosis?

Answer 20

Echo

Question 21

Why is an echo most useful in diagnosis?

Answer 21

It will delineate the anatomy

Question 22

What might a CXR show in ASD?

Answer 22

• Cardiomegaly
• Enlarged pulmonary arteries
• Increased pulmonary vascular markings

Question 23

What might an ECG show in secundum ASD?

Answer 23

• Partial right bundle branch block

- Right axis deviation

Question 24

What causes the right axis deviation seen on an ECG in secundum ASD?

Answer 24

Right ventricular enlargement

Question 25

What might an ECG show in partial AVSD?

Answer 25

A ‘superior’ QRS axis (mainly negative in aVF)

Question 26

What are some differentials for ASD?

Answer 26

• Partial anomalous pulmonary venous drainage
• VSD
• PDA

Question 27

When is treatment require in ASD?

Answer 27

When it is significant enough to cause symptoms

Question 28

When is treatment normally carried out?

Answer 28

Around 3-5 years of age

Question 29

What does early treatment help to prevent?

Answer 29

Right heart failure and arrhythmias later in life

Question 30

How are secundum ASDs usually treated?

Answer 30

Cardiac catheterisation with insertion of an occlusion device

Question 31

How are primum ASDs usually treated?

Answer 31

Surgical correction

Question 32

What are the complications of ASDs?

Answer 32

• Right atrial enlargement
• Cardiac arrhythmias
• Heart failure