Interrupted Aortic Arch​ (IAA)

Question 1

What is interrupted aortic arch (IAA)?

Answer 1

A congenital anomaly where there is interruption or discontinuation of a segment of the aortic arch.

IAA can lead to significant cardiovascular complications if not addressed.

Question 2

What congenital defects are frequently associated with IAA?

Answer 2

• Ventricular septal defects (VSD)
• Bicuspid aortic valve

These associations can complicate the clinical management of patients with IAA.

Question 3

What is IAA type B specifically associated with?

Answer 3

A posterior malalignment ventricular septal defect (VSD), narrowing of the left ventricular outflow tract (LVOT), and hypoplasia of the aortic valve.

IAA type B represents a specific clinical presentation that may require tailored surgical intervention.

Question 4

How common is IAA among patients with congenital heart disease?

Answer 4

Occurs in approximately 1% of the time.

IAA type B is the most prevalent form of this anomaly.

Question 5

What genetic deletion is associated with IAA type B?

Answer 5

22q11 deletion (DiGeorge syndrome).

This genetic association is less frequently seen in IAA types A or C.

Question 6

Fill in the blank: IAA occurs in about ______ of patients with congenital heart disease.

Answer 6

1%

This statistic highlights the relative rarity of this condition within the broader category of congenital heart defects.

Question 7

True or False: IAA type A is more commonly associated with 22q11 deletion than type B.

Answer 7

False

IAA type B has a higher incidence of 22q11 deletion compared to type A or C.

Question 8

What is the most common form of interrupted aortic arch?

Answer 8

IAA type B

Understanding the prevalence of IAA types can aid in clinical diagnosis and management.

Question 9

What are the consequences of posterior malalignment in IAA type B?

Answer 9

Narrowing of the left ventricular outflow tract (LVOT) and hypoplasia of the aortic valve.

These anatomical changes can lead to significant hemodynamic challenges.

Question 10

What is Type A interruption?

Answer 10

Interruption occurs after the aortic isthmus, just beyond the left subclavian artery and proximal to the ductal insertion.

Type A interruptions account for approximately 33% of cases.

Question 11

What is Type B interruption?

Answer 11

Interruption occurs between the left common carotid artery and the left subclavian artery. An aberrant right subclavian artery may be seen in this type.

Type B interruptions are the most common, accounting for about 66% of cases.

Question 12

What is Type C interruption?

Answer 12

Interruption occurs between the innominate (or brachiocephalic) artery and the left common carotid artery.

Type C interruptions are very rare, accounting for less than 1% of cases.

Question 13

Fill in the blank: Type A interruption occurs after the _______.

Answer 13

aortic isthmus

Question 14

True or False: Type B interruption is the least common type.

Answer 14

False

Question 15

What percentage of interruptions are classified as Type A?

Answer 15

Approximately 33%

Question 16

What percentage of interruptions are classified as Type C?

Answer 16

Less than 1%

Question 17

What is the purpose of prenatal diagnosis in relation to interrupted aortic arch (IAA)?

Answer 17

To identify the interruption site and vessels arising from the ductal arch

Prenatal diagnosis can reveal an unusual configuration of the aorta proximal to the site of interruption.

Question 18

What happens if IAA is not diagnosed prenatally?

Answer 18

Infants will present in the neonatal period with ductal dependent systemic blood flow

Question 19

What is required for neonates with IAA after birth until surgical repair?

Answer 19

Prostaglandin-E1 (PGE) administration

Question 20

What is differential cyanosis in neonates with IAA?

Answer 20

Cyanosis due to right to left shunting at the duct

Question 21

In type A IAA, where are the higher saturations observed?

Answer 21

In both arms compared to the legs

Question 22

In type B IAA, which arm has normal saturation?

Answer 22

The right arm

Question 23

What happens when a neonate’s ductus arteriosus (PDA) begins to close?

Answer 23

Signs of poor perfusion and cardiogenic shock develop

Question 24

What are the signs of poor perfusion in neonates with IAA?

Answer 24

Hypotension, poor pulses, decreased urine output, lactic acidosis

Question 25

What may BP measurements proximal to the site of interruption be?

Answer 25

Normal or even hypertensive

Question 26

In interrupted aortic arch Type B with an aberrant subclavian artery, what is unique about blood pressure measurements?

Answer 26

There may not be an upper extremity to lower extremity blood pressure gradient

Question 27

Fill in the blank: Neonates with IAA may require _______ for systemic blood flow.

Answer 27

Prostaglandin-E1 (PGE)

Question 28

What type of probe should be used for neonates in echocardiography?

Answer 28

A high frequency probe for optimal resolution.

Question 29

What is the initial imaging modality used to diagnose IAA?

Answer 29

Echocardiography.

Question 30

What should be assessed regarding arch interruption?

Answer 30

Identify the following: * Arch sidedness * Site of interruption * Head and neck vessel anatomy * Branching pattern (especially for aberrant right subclavian artery in type B) * Location of arch receiving prograde vs retrograde flow.

Question 31

What aspects should be evaluated for a VSD?

Answer 31

Size, directionality of flow, and mal-alignment.

Question 32

What should be assessed for LVOT obstruction?

Answer 32

Degree of LVOT narrowing and obstruction, often secondary to mal-aligned VSD.

Question 33

What features of the aortic valve should be evaluated?

Answer 33

Size and anatomy, including: * Number of commissures * Stenosis * Hypoplasia in setting of mal-aligned VSD.

Question 34

What should be ensured regarding the PDA?

Answer 34

That it is patent and has right to left flow to the descending aorta.