[14] Atrial Septal Defect Flashcards
What is an atrial septal defect (ASD)?
A heart defect where blood flows between the two atria of the heart
What are the two main types of ASD?
- Secundum ASD
- Partial atrioventricular septal defects (AVSD or primum ASD)
What is the more common type of ASD?
Secundum ASD
Secundum ASD accounts for what percentage of ASD’s?
80%
What is a secundum ASD?
A defect of the atrioventricular septum involving the foramen ovale
What is the foramen ovale?
A foetal cardiac shunt that allows flow of blood from the right to left atrium
What may cause a secundum ASD?
- Failure of the septum secundum to develop
- Enlarged foramen ovale
What is a partial AVSD?
A defect in the inferior atrial septum (septum primum) and a regurgitant left atrioventricular valve leading to left to right communication
What are the risk factors for ASD?
- Female
- Family history
- Maternal alcohol consumption
- Down’s Syndrome
What is the common presentation of an ASD?
Commonly no symptoms
If symptoms are present, what might they be?
- Recurrent chest infections
- Wheeze
- Arrhythmias
What are the physical signs of an ASD?
- Ejection systolic murmur
- Fixed and widely split second heart sound
What sound is specifically heard in a partial AVSD?
Apical pansystolic murmur
Where is the ejection systolic murmur best heard?
Upper left sternal edge
What causes the ejection systolic murmur in ASD?
Increased flow across the pulmonary valve
What causes the increased flow across the pulmonary valve?
Left to right shunt
What causes the fixed, widely split second heart sound?
Right ventricular stroke volume being equal in inspiration and expiration
What causes the apical pansystolic murmur in AVSD?
Atrioventricular valve regurgitation
What investigations may be useful in assessing ASD?
- CXR
- ECG
- Echo
Which of the investigations is the mainstay of diagnosis?
Echo
Why is an echo most useful in diagnosis?
It will delineate the anatomy
What might a CXR show in ASD?
- Cardiomegaly
- Enlarged pulmonary arteries
- Increased pulmonary vascular markings
What might an ECG show in secundum ASD?
- Partial right bundle branch block
- Right axis deviation
What causes the right axis deviation seen on an ECG in secundum ASD?
Right ventricular enlargement
What might an ECG show in partial AVSD?
A ‘superior’ QRS axis (mainly negative in aVF)
What are some differentials for ASD?
- Partial anomalous pulmonary venous drainage
- VSD
- PDA
When is treatment require in ASD?
When it is significant enough to cause symptoms
When is treatment normally carried out?
Around 3-5 years of age
What does early treatment help to prevent?
Right heart failure and arrhythmias later in life
How are secundum ASDs usually treated?
Cardiac catheterisation with insertion of an occlusion device
How are primum ASDs usually treated?
Surgical correction
What are the complications of ASDs?
- Right atrial enlargement
- Cardiac arrhythmias
- Heart failure
