CVS - congenital heart defects

Question 1

List some acyanotic congenital heart defects:

Answer 1

1. Left to right shunts: ASD, VSD, PDA

2. Obstructive lesions: aortic stenosis, pulmonary stenosis, coarction of aorta, mitral stenosis

Question 2

List some cyanotic congential heart defects:

Answer 2

1. Tetralogy of Fallot
2. Transposition of great arteries
3. Univentricular heart
4. Tricuspid atresia

Question 3

What is a cyanotic heart defect?

Answer 3

A heart defect that causes deoxygenated blood to be moved into the systemic circulation causing central cyanosis.

Question 4

What the four heart defects that occur together in tetralogy of fallot?

Answer 4

1. Over-riding aorta
2. Pulmonary stenosis
3. VSD
4. Right ventricular hypertrophy

Question 5

What is the patho-physiology of tricuspid atresia? Why does it cause central cyanosis?

Answer 5

Atresia means that there is no inlet into the right ventricle. Therefore the entire venous return is shunted from the right to left atrium. Blood flow to the lungs occurs via a VSD (or PDA).

Question 6

What is the pathophysiology of a hypoplastic left heart?

Answer 6

1. Left ventricle is underdeveloped
2. Ascending aorta is very small
3. Right ventricle supports systemic circulation
4. Obligatory right to left shunt
   For even short term survival there must be ASD and PDA.

Question 7

What is the pathophysiology of transposition of the great arteries?

Answer 7

1. RIght ventricle connected to aorta
2. Left ventricle connected to pulmonary artery
3. Not viable unless the two circuits communicate i.e. via atrial, ventricular or ductal shunts.
   This is an example of a bi-directional shunt.

Question 8

What is the pathophysiology of pulmonary atresia?

Answer 8

1. right ventricle outlet
2. Right to left atrial shunt of entire venous return
3. Blood flow to lungs via PDA

Question 9

What tends to be the history on presentation of a congenital ASD?

Answer 9

Usually asymptomatic late into adulthood. Late onset arrhythmias and right heart failure.

Question 10

What tends to be the history on presentation of a congenital VSD?

Answer 10

Unless very small (then asymptomatic with murmurs) it presents in infancy with left heart failure. Untreated, can lead to in-operable pulmonary hypertension.

Question 11

How does Coarction present?

Answer 11

1. In infancy or early childhood - associated with PDA, R to L shunt
2. Adult variety - complicated by renal hypertension, Left ventricular hypertrophy, often associated aortic valve stenosis

Question 12

How does tetralogy of fallot present?

Answer 12

Presents in infancy or early childhood with cyanotic spells. Mild cases compatible with adulthood.

Question 13

How does transposition of the great arteries/ hypoplastic left heart/ pre-ductal coarctation/ pulmonary atresia present?

Answer 13

Present as neonatal emergencies, often due to reduced pulmonary blood flow.

Question 14

What is the most common site for an ASD?

Answer 14

Foramen ovale (ostium secundum ASD)

Question 15

Why is a patent foramen ovale not a true ASD?

Answer 15

Because it is generally clinically silent, since the higher left atrial pressure causes functional closure of the flap valve. It may present in up to 20% of the population.

Question 16

What is a less common site for an ASD?

Answer 16

The inferior portion of the septum (ostium primum ASD).

Question 17

How may a paradoxical embolism occur?

Answer 17

It can occur when there’s a PFO and a transient increase in right atrial pressure which causes embolisms to move from the venous system to the systemic.

Question 18

What happens if the ductus arteriosus fails to close properly after birth?

Answer 18

PDA -> blood flows from the higher pressure aorta into the pulmonary artery

Question 19

What are consequences of chronic left to right blood shunting?

Answer 19

It can lead to vascular remodelling of the pulmonary circulation and an increase in pulmonary resistance. If the resistance of the pulmonary circulation increases beyond that of the systemic circulation the shunt will reverse direction as pressures on the right side of the heart increase (Eisenmenger syndrome).

Question 20

What is Eisenmenger syndrome?

Answer 20

This can occur as a consequence of chronic left to right blood shunting. If the resistance of the pulmonary circulation increases beyond that of the systemic circulation the shunt will reverse direction as pressures on the right side of the heart increase

Question 21

What is coarctation of the aorta?

Answer 21

A narrowing of the aorta lumen in the region of the ligamentum arteriosum. This increases the afterload on the left ventricle and can lead to left ventricle hypertrophy. This reduced blood flow to the body.

Question 22

Why does coarctation of the aorta not affect the head and upper limbs?

Answer 22

Because the vessels to the head and upper lumbs usually emerge proximal to the coarctation.

Question 23

What are symptoms of coarctation of the aorta?

Answer 23

The extent of the symptoms depends upon the severity of the coarctation. If very severe, an infant may present with symptoms of heart failure shortly after birth. In mild cases the defect may be detected in adult life.

Question 24

What are signs of coarctation of the aorta?

Answer 24

1. Weak, delayed femoral pulses

2. Upper body hypertension

Question 25

What is the underlying cause of tetralogy of fallot?

Answer 25

Its the result of a single developmental defect which places the outflow portion of the interventricular septum too far in the anterior and cephalad directions.

Question 26

Why does cyanosis occur with tetralogy of fallot?

Answer 26

Due to the pulmonary stenosis, right ventricular hypertrophy persists and blood is pumped at higher presssures though the pulmonary artery. This increased pressure along with the VSD and overirding aorta allows deoxygenated blood from the right ventricle to be shunted to the left ventricle and therefore into the systemic circulation.

Question 27

What affects the presentation of tetralogy of fallot?

Answer 27

The magnitude of the shunt and level of severity depend on the severity of pulmonary stenosis. Affected individuals may present with cyanosis or spells of cyanosis in infancy, but mild cases can present in adulthood.

Question 28

What is the cause of a hypoplastic left heart?

Answer 28

When the left ventricle and ascending aorta fail to develop properly