Atrial Septum Defects

Question 1

What is a true ASD?

Answer 1

An abnormal opening in the atrial septum allowing blood to flow either way.

Question 2

How are ASDs discovered?

Answer 2

By a surface echo, a TEE, or a bubble study.

Question 3

Which way does blood primarily shunt through ASDs?

Answer 3

From left to right.

Question 4

What are the 4 types of ASDs?

Answer 4

1. Ostium Secundum
2. Sinus Venosus
3. Ostium Primum
4. Common Atrium

Question 5

Which ASD is the most common type?

Answer 5

Ostium Secundum ASD

Question 6

With an ostium secundum ASD what goes wrong in fetal development?

Answer 6

The proliferations that form in the septum secundum become exaggerated and most of the septum primum disappears, and the foramen ovale never closes.

Question 7

What is the surgical correction for an Ostium Secundum ASD?

Answer 7

Patches to close the ASD.

Question 8

With a large ASD what happens to the right atrium and ventricle?

Answer 8

They both dilate and become hypertrophic due to the volume overload. This causes pulmonary blood flow to increase and pulmonary arteries to dilate.

Question 9

What negative effects do ASDs have on the left heart?

Answer 9

Blood flow in the left atrium is increased, and the left ventricle becomes hyperdynamic to maintain cardiac output. Systemic blood flow is diminished.

Question 10

Where is a Sinus Venosus ASD located?

Answer 10

It is located high within the IAS, near or at the level of the SVC and pulmonary veins.

Question 11

What are other congenital lesions associated with Sinus Venosus ASDs?

Answer 11

1. Abnormal pulmonary veins
2. Ventricular septal defects
3. Abnormal drainage from pulmonary veins

Question 12

What are the surgical corrections for Sinus Venosus ASDs?

Answer 12

Pericardial patch to reroute the anomalous venous return and close the ASD.

Question 13

What causes an Ostium Primum ASD?

Answer 13

The septum primum does not meet the endocardial cushion in fetal development.

Question 14

What can an Ostium Primum be associated with?

Answer 14

A membranous VSD.

Question 15

Which ASD involves the complete absence of the IAS?

Answer 15

Common Atrium ASD.

Question 16

What goes wrong during fetal development leading to a Common Atrium ASD?

Answer 16

The truncus is not finished over the roof of the atria and the sinus venosus fails to produce folds.

Question 17

Why may there be low O2 sats associated with Common Atrium ASD?

Answer 17

Because there is arterial and venous blood mixing. The atria act as one chamber causing slight arterial desaturation.

Question 18

What Sx may be present in a Pt with a hemodynamically significant ASD?

Answer 18

• SOB
• Pulmonary HTN
• increased HR & BP
• Right heart failure
• Venous congestion & distended neck veins
• Neonates experience nausea, restlessness, and loss of appetite

Question 19

What murmurs may a Pt with an ASD have?

Answer 19

Murmurs are heard at atrial contraction (if it is a large defect), and an ejection murmur in the PA due to an increased amount of blood passing through the PA valve.

Question 20

What will a Pt with an ASD chest X-ray look like?

Answer 20

It will show signs of pulmonary congestion, a dilated right heart, pulmonary infiltrates, a dilated PA, and/or a primary left heart defect.

Question 21

How does an ASD effect the heart?

Answer 21

• dilated right heart
• incompetent tricuspid valve
• pulmonary HTN
• venous congestion
• LV compression
• Low return to left heart
• Left heart becomes hyperdynamic to maintain stroke volume.