Congential Heart Defects

Question 1

What are the classifications of congenital heart disease?

Answer 1

• Acyanotic, left to right shunts such as ASD, VSD, PDA. Obstructive lesions such as aortic stenosis, pulmonary stenosis.
• Cyanotic, complex right to left shunt . Such as tetratrology of fallot, transposition of the great arteries, total anamolous pulmonary venous drainage, univentricular heart.

Question 2

What are the shunts in the heart?

Answer 2

• atria
• ventricular
• atria-ventricular
• aorta-pulmonary (ductal)

Question 3

What are the haemodynamic effects of an atrial septal defect?

Answer 3

• increase pulmonary blood flow
• RV volume overload
• pulmonary hypertension is rare
• eventual right heart failure

Question 4

What are the haemodynamic effects of a ventricular septal defect?

Answer 4

• left to right shunt
• left ventricle volume overload
• pulmonary venous overload
• eventual pulmonary hypertension

Question 5

WHat are the four lesions of tetralogy of fallot?

Answer 5

1- pulmonary stenosis
2- ventricular septal defect
3-right ventricular hypertrophy
4- overriding aorta

Question 6

What are the three aitiologies of congenital heart disease?

Answer 6

• genetic
• environmental
• maternal infections

Question 7

How frequent are congenital heart defects of the heart and the great vessels associated?

Answer 7

6-8 per 1000 births

Question 8

What is the incidence of an atrial septal defect?

Answer 8

67 in 100,000 births

Question 9

Briefly describe an atrial septal defect:

Answer 9

An ASD is an opening in the septum between the two atria.

The foramen ovale exists prenatally to allow right to left shunting

Because pressure is higher is the left than the right postnatally then blood goes left to right making it an acyanotic disease.

Most common site of ASD is at the foramen ovale (Ostium Secundum) but can appear at Ostium primum at inferior part of septum.

Question 10

Briefly describe a patent foramen ovale:

Answer 10

PFOs are not true ASD.

May be present in 20% of the population but clinically silent due to higher left atrial pressure causing functional closure of the flap valve.

However, a PFO may be a route by which a venous embolism reaches the systemic circulation if the pressure in the right side of the heart increases transiently. This is called a paradoxical embolism.

Question 11

What is the prevalence of a ventricular septal defect?

Answer 11

1.5-3.5 per 1000 live births

Question 12

Where are the VSD most commonly found?

Answer 12

70% in the membranous part of the septum

30% in the muscular part of the septum

Question 13

What direction will the blood flow in a ventricular septal defect?

Answer 13

Left to right due to higher pressure in the left.

Acyanotic disease.

Question 14

What is the incidence rate of patent ductus arteriosus?

Answer 14

1 in 2500 to 5000 liver births

Question 15

Briefly describe patent ductus arteriosus:

Answer 15

The ductus arteriosus is the vessel that connects the left pulmonary artery to the aorta during fetal life.

PDA occurs when this hole fails to close after birth. Blood will flow from aorta to pulmonary artery.. High to low pressure.

Chronic left to right shunting here can lead to vascular remodelling of the pulmonary circulation and an increase in pulmonary resistance.

If resistance in pulmonary circulation increases beyond the systemic circulation the shunt will reverse in direction causing Eiseenmenger syndrome.

Question 16

Which way does blood flow through the DA prenatally? Does this change postnatally?

Answer 16

Prenatally right to left and then after birth changes to left to right due to increase in pressure at the aorta.

Question 17

What is the incidence of coarctation of the aorta?

Answer 17

1 in 6000 live births

Question 18

Briefly describe coarctation of the aorta:

Is it Cyanotic or acyanotic?

Answer 18

This is a narrowing of the aortic lumen in the region of the ligamentum arteriosum (former ductus arteriosus)

The narrowing of the aorta increases after load in the LV. Blood flow to the head and upper extremities preserves as vessels supplying these usually branch off the aorta proximal to the obstruction.

Question 19

If coarctation of the aorta doesn’t get corrected what complication may occur?

Answer 19

• Development of left ventricular hypertrophy
• dilatation of collateral blood vessels from intercostal arteries that bypass the coarctation and provide blood to the more distal descending aorta. Eventually, they enlarge and can erode the undersurface of the ribs.

Question 20

What happens to the femoral pulse in someone with coarctation of the aorta?

Answer 20

Weak and delayed femoral pulse

Upper body hypertension

Question 21

What effects do the lesions in tetralogy of fallot cause?

Answer 21

• The pulmonary stenosis causes persistence of the foetal right ventricular hypertrophy, as it must work harder to pump blood through the pulmonary artery
• The increase pressure on the RHS of the heart along with VSD and overriding aorta allow right to left shunting resulting in cyanosis.
• The magnitude of the shunt depends on level of severity of the pulmonary stenosis

Question 22

What is the incidence rate of tetralogy of fallot?

Answer 22

• Most common Cyanotic congenital heart disease

- 5 in 100,000 live births

Question 23

Is tricuspid atresia Cyanotic?

Answer 23

Yes

Question 24

Briefly describe tricuspid atresia:

Answer 24

This is the lack of development of the tricuspid valve.

This leaves no inlet to the right ventricle, there must be a complete right to left shunt of all blood returning to the right atrium ( via ASD or PFO)

and a VSD or PDA to allow blood to flow to the lungs.

Question 25

Briefly describe transposition of the great arteries?

Answer 25

• Each great vessel inappropriately arises from the opposite ventricle. So the aorta arises from the RV and the pulmonary artery from the LV.
• This condition is not compatible with birth unless a shunt exists to allow communication between the two vessels.
• The ductus arteriosus or patent/ASD can be formed to allow life

Question 26

What is hypo plastic left heart?

Answer 26

It is a Cyanotic defect

In some cases the left ventricle and ascending aorta fail to develop properly resulting in this condition.

A PFO or ASD are also present and blood supply to the systemic circulation is via a PDA. WITHOUT SURGERY = LETHAL