[20] Transposition of Great Arteries

Question 1

What is transposition of the great vessels?

Answer 1

A group of congenital heart defects involving an abnormal spatial arrangement of any of the great vessels

Question 2

What are the great vessels?

Answer 2

• Superior and inferior vena cavae
• Pulnonary artery
• Pulmonary veins
• Aorta

Question 3

What is the name of the sub-group of conditions only involving the aorta and pulmonary artery?

Answer 3

Transposition of the Great Arteries

Question 4

What happens in transposition of the great arteries?

Answer 4

• The aorta is connected to the right ventricle

- The pulmonary artery is connected to the left ventricle

Question 5

What does transposition of the great arteries result in?

Answer 5

Two parallel circulations

Question 6

What does the two parallel circulations result in?

Answer 6

Oxygnetated blood is returned to the lungs and de-oxygenated blood is returned to the body

Question 7

What is required for transposition of the great arteries to be compatible with life?

Answer 7

Mixing of blood

Question 8

What are the risk factors for transposition of the great arteries?

Answer 8

• Pre-existing DM of pregnant mother
• History of rubella or other viral illness during pregnancy
• Drinking alcohol during pregnancy

Question 9

What is the most prominent symptom of transposition of the great arteries?

Answer 9

Cyanosis - may be profound and life-threatening

Question 10

When is presentation of transposition of the great arteries most common?

Answer 10

On day 2 of life

Question 11

Why is presentation of transposition of the great arteries most common on day 2?

Answer 11

This is usually the point by which the ductus arteriosus closes and mixing of saturated and desaturated blood stops

Question 12

Is there a murmur in transposition of the great arteries?

Answer 12

Not usually but there can be a systolic murmur

Question 13

How does the second heart sound sound?

Answer 13

Loud and single

Question 14

What is seen on a CXR in transposition of the great arteries?

Answer 14

• Narrow upper mediastinum
• ‘Egg on side’ appearance of cardiac shadow
• Increased pulmonary vascular markings

Question 15

How does the ECG appear in transposition of the great arteries?

Answer 15

Normal

Question 16

Why is an echo essential in investigation of transposition of the great arteries?

Answer 16

To demonstrate abnormal arterial connections and associated abnormalities

Question 17

What are the differentials for transposition of the great arteries?

Answer 17

• Tricuspid or pulmonary atresia

- Tetralogy of Fallot

Question 18

What is the key to managing the sick cyanosed neonate?

Answer 18

Improve mixing of blood

Question 19

What is mandatory to achieve mixing in patients with transposition of the great arteries?

Answer 19

Maintaining the patency of the ductus arteriosus with prostaglandin infusion

Question 20

What procedure can often be life saving in transposition of the great arteries?

Answer 20

Balloon atrial septostomy

Question 21

What happens in a balloon atrial septostomy?

Answer 21

A catheter with a balloon at its tip is passed through the umbilical or femoral vein and through the right atrium and foramen ovaleand inflated in the left atrium before being pulled back through the foramen ovale

Question 22

What effect does balloon atrial septostomy have?

Answer 22

The balloon tears the atrial septum rendering the foramen ovale patent and aloows mixing of blood

Question 23

What do all patients with transposition of the great arteries require eventually?

Answer 23

Surgical correction

Question 24

What is the usual procedure in the neonatal period?

Answer 24

Arterial switch procedure

Question 25

What occurs in the arterial switch procedure?

Answer 25

The pulmonary artery and aorta are transected above the arterial valves and switched over

Question 26

What also has to happen in an arterial switch procedure?

Answer 26

The coronary arteries have to be switched to the new aorta

Question 27

What are the potential complications of transposition of the great arteries?

Answer 27

• Hypoxia
• Heart failure
• Lung damage