Atrial septal defect

Question 1

What is atrial septal defect?

Answer 1

Atrial septal defect is a hole between the left and right atria (caused by a defect in septum secundum during development) causing a left-right shunt

=> common cardiac malformation

=> most likely congenital heart defect found in adults

Question 2

What are the two types of atrial septal defect?

Answer 2

1. Ostium secundum - most common

2. Ostium primum

Question 3

What is the aetiology of atrial septal defect?

Answer 3

ASD causes flow from the higher pressured left atrium into the lower pressured right atrium.

=> this increase in blood volume in the right atrium increases the flow across the tricuspid valve, which causes a low pitched diastolic rumble in the tricuspid area (lower left sternal border, not seen in this patient) and a flow murmur over the pulmonary valve.

=> the increased volume in the right ventricle takes longer to push across the pulmonary valve. This means that there is a flow murmur across the pulmonary valve (ejection systolic murmur at upper left sternal edge) and a delay in closing of the pulmonary valve. The delay makes a significant gap between hearing the aortic and the pulmonary valve close, which causes a split second heart sound. This split second heart sound is fixed, i.e. does not vary with inspiration or exhalation.

Question 4

What is the clinical feature of atrial septal defect?

Answer 4

=> mostly asymptomatic

or

=> present with late-onset cyanosis or heart failure

=> ejection soft systolic murmur, fixed splitting of S2, upper left sternal edge

=> embolism may pass from venous system to left side of heart causing a stroke

Question 5

What is ostium secundum associated with?

What are the ECG findings?

Answer 5

Associated with Holt-Oram syndrome (tri-phalengeal thumbs)

ECG: right bundle branch block with right anterior descending coronary artery (RAD).

Question 6

What is ostium primum associated with?

What are the ECG findings?

Answer 6

Associated with abnormal AV valves

ECG: Right bundle branch block with left anterior descending coronary artery (LAD).

*presents earlier than ostium secundum defects

Question 7

How is atrial septal defect managed?

Answer 7

Management depends on severity.

Most are managed conservatively.

Severe cases closed by surgery or cath lab.

Question 8

What is the prognosis of atrial septal defect?

Answer 8

Significant mortality - 50% of patients die at 50 years.

Question 9

Left to right shunts features:

=> abnormal mixing from left (red blood) to right (blue blood)

=> pink and breathlessness

=> heart failure

=> increased risk of pulmonary HTN

=> Eisenmengers is an end stage complication (right to left shunting)

Answer 9

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