Atrial septal defect

Question 1

What is the second most common congenital heart defect?

Answer 1

Atrial septal defect

Question 2

What is ASD?

Answer 2

Septum between left and right atrium is not formed completely

Question 3

What shunt occurs in ASD?

Answer 3

Left to right shunt

Pressure in left atrium is greater than in the right

Question 4

In terms of cyanosis, what is ASD?

Answer 4

Acyanotic congenital heart disease

Question 5

Why is ASD acyanotic?

Answer 5

Oxygenated blood from left atrium is forced into the right atrium

Question 6

What might happen to the ASD if it is very small?

Answer 6

May close on its own

Question 7

How many live births have an ASD?

Answer 7

9 in 1000

Question 8

What percentage of CHDs do ASDs account for?

Answer 8

5-10%

Question 9

Which sex is more prone to ASD and which one in particular?

Answer 9

Female

Ostium secundum

Question 10

Describe the pathophysiology of ASD in terms of atrial septum embryology

Answer 10

Formed from 2 separate endocardial cushions in the 4th week of gestation

Primary atrial septum = septum primum (grows cranial to caudal), this closes off the ostium primum

The ostium secundum develops again from the atrial roof and grows downwards towards the septum primum

Foramen ovale = space between the septum primum and secundum

Question 11

When does the foramen ovale close?

Answer 11

Shortly after birth

Question 12

Why does the foramen ovale close?

Answer 12

Change in vascular resistance

Systemic BP increases as pulmonary pressure decreases with a decrease in RA pressure

Question 13

List the 5 types of ASD in order of how commonly they occur

Answer 13

Patent foramen ovale 
Ostium secundum defect
Ostium primum defect
Sinus venosus defect
Coronary sinus defect

Question 14

Describe ostium secundum defect

Answer 14

When there is incomplete occlusion of ostium secundum by septum secundum or too much reabsorption of septum primum by the atrial roof

Question 15

Describe ostium primum defects

Answer 15

When septum primum fails to fuse with the endocardial cushions allowing blood to travel from LA to RA

Question 16

Name and describe the two types of ostium primum defects

Answer 16

Complete AVSD - Common AV valve but spanning from atria to ventricles
Partial AVSD - Defect just of the ostium primum with intact ventricular septum

Question 17

What can sinus venous defects be split into?

Answer 17

Superior

Inferior

Question 18

Describe superior sinus venous defect

Answer 18

When Superior vena cava opening runs on top of oval fossa of atrial septum
Renders SVC draining blood from both LA and RA

Question 19

Describe inferior sinus venous defect

Answer 19

Less common
Occurs with IVC orifice overrides LA and RA
Can coexist with abnormal communication between IVC and right superior pulmonary vein

Question 20

Describe coronary venous sinus defect

Answer 20

Absence of a roof in the coronary sinus
Partial or focal
Allowing for transmission between coronary sinus and left atrium

Question 21

List the risk factors for atrial septal defect

Answer 21

FH
Maternal smoking in 1st trimester
Maternal cocaine and alcohol use 
Maternal diabetes
Maternal rubella

Question 22

What inheritance pattern does ASD present?

Answer 22

Autosomal dominant

Question 23

What congenital conditions are ASDs linked with?

Answer 23

Treacher Collins syndrome

Thrombocytopenia absent radii (TAR) syndrome

Question 24

List the symptoms of large ASD in children

Answer 24

Tachypnoea
Poor weight gain
Recurrent chest infections

Question 25

List the symptoms of untreated large ASDs in adults

Answer 25

``` Exercise intolerance Palpitations Recurrent chest infections Fatigue Syncope ```

Question 26

What examination findings are there of an ASD?

Answer 26

Murmur - soft ejection systolic murmur, best heard over the pulmonary region, wide, fixed splitting second heart sound, diastolic rumble in the lower left sternal edge

Question 27

What is the differential of a ASD?

Answer 27

AVSD VSD Innocent murmur Pulmonary stenosis

Question 28

What is an innocent murmur?

Answer 28

Soft and musical

Question 29

Describe the pulmonary stenosis murmur

Answer 29

More turbulent

Question 30

What investigations would you do for an ASD?

Answer 30

ECG Transthoracic echocardiogram Cardiac MRI and CT CXR

Question 31

What are some possible ECG changes in a large ASD?

Answer 31

Tall P wave - RA enlargement Right bundle branch block Right axis deviation Atrial fibrillation or flutter

Question 32

What information does a transthoracic echocardiogram show?

Answer 32

Size of ASD | Direction of blood flow

Question 33

What can cardiac MRI measure?

Answer 33

Pulmonary vs systemic blood flow ratio | Informs us of how significant the shunt is

Question 34

Describe the management of ASD

Answer 34

If ASD <15mm then spontaneous closure should occur within 12 months of birth In adults with no signs of heart failure and a small defect - continue to monitor by echo every 2-3yrs If presenting with arrhythmia, control rhythm with drugs and anticoagulated before definitive surgical treatment Diuretics for children with heart failure Surgical closure is the definitive management - patients with ASD>1cm - percutaneous or open

Question 35

When is surgical closure not recommended?

Answer 35

For patients with pulmonary hypertension as this can induce RV failure if the ASD closes up

Question 36

What does percutaneous closure require?

Answer 36

Adequate septum to be present in order to hold device in place

Question 37

List the complications of percutaneous closure

Answer 37

Arrhythmia Atrioventricular block Thromboembolism

Question 38

List the indications for surgical closure

Answer 38

TIA/stroke Ostium primum defects Sinus venous defects Coronary sinus defects

Question 39

What are the complications of large atrial septal defects

Answer 39

``` Arrhythmia Pulmonary hypertension Eisenmenger syndrome Cyanosis Peripheral oedema TIA/stoke ```

Question 40

What is the life expectancy for a child with an ASD diagnosed in childhood?

Answer 40

The same as normal