Transposition of the Great Arteries

Question 1

What are the two Great Arteries?:

Answer 1

• Pulmonary Artery: carries blood from the RV to the lungs
• Aorta: carries blood from the LV to the Body

Question 2

What is the Transposition of the Great Arteries?:

Answer 2

• When the RV is connected to the Aorta and the LV is connected to the Pulmonary Artery
• It is a cyanotic condition and therefore is incompatible with life.

Question 3

What is the typical presentation of the Transposition of the Great Arteries?:

Answer 3

• 60% The aorta is anterior and to the right of the pulmonary artery
  -40% The aorta is anterior and to the left of the pulmonary artery

Question 4

What is the Pathophysiology of Transposition of the Great Arteries?

Answer 4

• The switching of the Great Arteries causes a closed cyanotic system
• To compensate the body uses the Patent Ductus Arteriosus and the foramen ovale. There can be a ventricular septal defect

Question 5

What are the Risk Factors for TGA:

Answer 5

• Age >40
• Maternal Diabetes
• Rubella
• Poor Nutrition
• Alcohol Consumption

Question 6

How is it first picked up?:

Answer 6

• maternal antenatal scans

Question 7

What are the clinical features of TGA:

Answer 7

• Cyanosis within 24 hours (no mixing at the atrial level)
• Signs of Congestive Heart Failure (Tachypnoea, Tachycardia, Diaphoresis (excessive sweating), Failure to gain weight) due to increase in Pulmonary Blood Flow if large VSD

Question 8

What features on examination would you find in TGA?

Answer 8

• Right Ventricular Heave
• Second Heart Sound, loud A2
• Systolic Murmur potentially VSD
• No signs of respiratory distress

Question 9

What investigation would you request for TGA?

Answer 9

• Pulse Oximetry
• Capillary Blood Gas = Metabolic acidosis
• ECHO = abnormal position of aorta and pulmonary arteries
• CXR = “egg on a string” - cardiomegaly, increased pulmonary vascular markings

Question 10

What is the Managment of TGA?

Answer 10

• if there is a VSD this is positive as it allows for more mixing of the blood between the two systems
• 1. Emergency Prostaglandin E1 infusion - to keep the ductus arteriosus patent as a temporary solution that allows mixing of blood
     -2. Correct the metabolic acidosis
     -3. Atrial Balloon Septostomy - this allows the mixing of blood by feeding a catheter through the foramen ovale via the umbilical vein
     -4. Definitive and Long term Managment: Surgical correction via Arterial Switch Operation this is usually performed before the age of 4 weeks old.