Congenital Heart Disease

Question 1

Outline the embryological development of the heart

Answer 1

1. There is a cluster of angiogenic cells that is present in the mesodermal cardiogenic plate
2. The right and left endocardial tubes fuse to form a single cardiac tube
3. Folding into the bulboventricular loop occurs
4. Atrial, ventricular and outflow tract septation
5. There is then postnatal closure of the foetal connections

Question 2

When do the left and right endocardial tubes fuse?

Answer 2

Day 21

Question 3

When does the heart start beating?

Answer 3

Day 23

Question 4

When does atrial, ventricular and outflow tract separation occur?

Answer 4

Day 28

Question 5

What is the function of the foramen ovale in foetal circulation?

Answer 5

Connects the atria, and allows right to left shunting

Question 6

What is the function of the ductus arteriosus in the foetal circulation?

Answer 6

Connects the descending aorta with the pulmonary artery to allow shunting from the pulmonary artery to the aorta to bypass the high resistance lungs (which are currently non-functional)

Question 7

What is the function of the ductus venosus in the foetal circulation?

Answer 7

To bypass the liver

Question 8

What is persistent pulmonary hypertension of the newborn?

Answer 8

Where there continues to be a greater pulmonary pressure, and therefore blood continues to be shunted from the right to left side of the heart (through foramen ovale) which may cause cyanotic heart condition

Question 9

What are cyanotic heart lesions?

Answer 9

Where blood from the right side of the heart goes to join the left (deoxygenated blood goes to the oxygenated region)

Question 10

What are acyanotic heart lesions?

Answer 10

Where blood from the left side of the heart goes to join the right (oxygenated goes to the deoxygenated region)

Question 11

Name three cyanotic heart disorders

Answer 11

Tetralogy of Fallot, persistent TRUNCUS arteriosus, transposition of the great vessels

Question 12

Name four acyanotic heart disorders

Answer 12

Atrial septal defect, ventricular septal defect, patent DUCTUS arteriosus, coarctation of the aorta

Question 13

Describe Tetralogy of Fallot

Answer 13

> Ventricular septal defect
Narrow right ventricular outflow (due to infundibular senses)
Right ventricular hypertrophy (due to high right ventricular pressure)
An over-riding aorta directly above the septal defect (so carries mixed blood)

Question 14

Describe persistent truncus arteriosus

Answer 14

Only one artery (truncus) arising from the heart; usually due to a large VSD below the truncal valve

Question 15

Describe transposition of the great vessels

Answer 15

The conotruncal septum fails to follow the spiral course, and instead runs straight down; this leads to the incorrect vessel-ventricle pairing

Question 16

How is transposition of the great vessels treated?

Answer 16

Fossal ovalis is opened to allow greater mixing of the blood

Question 17

How may you re-open the ductus arteriosus therapeutically?

Answer 17

Using prostaglandin E

Question 18

How do atrial septal defects present?

Answer 18

Usually asymptomatic for first 30 years of life, but may occur on exertion

Question 19

Describe patent ductus arteriosus

Answer 19

Persistent opening between the descending aorta and the pulmonary artery, leading to greater oxygenated blood travelling to the lungs

Question 20

What are the potential complications of a patent ductus arteriosus?

Answer 20

Increases the risk of getting bacterial endocarditis

Question 21

How is patent ductus arteriosus treated?

Answer 21

Adminstration of a prostaglandin inhibitor or surgical clipping

Question 22

What is coarctation of the aorta?

Answer 22

Where there is constriction of the aorta; either above or below the ductus arteriosus.

Pre-ductal allows the ductus arteriosus to persist and allow blood flow. Post-ductal requires collateral circulation to form for proper perfusion of the body and legs

Question 23

What’s the difference between pre-ductal and post-ductal coarctation of the aorta?

Answer 23

Pre-ductal allows the ductus arteriosus to persist and allow blood flow. Post-ductal requires collateral circulation to form for proper perfusion of the body and legs

Question 24

How may coarctation of the aorta present?

Answer 24

Hypertension and decreed lower extremity pulses

Question 25

Why may diuretics and ACE inhibitors be used to treat acyanotic heart lesions?

Answer 25

To prevent too much blood going across the foramen oval by reducing the blood pressure exerted on the structure

Question 26

Define atresia

Answer 26

Absence or abnormal narrowing of an opening or passage in the body

Question 27

What can neural tube defects lead to?

Answer 27

Spina bifida occulta, meningocoele, myelomeningocoele (spina bifida), encephalocoele and anencephaly

Question 28

What is spina bifida occulta?

Answer 28

Closed, asymptomatic neural tube defect in which some of the vertebrae are not completely closed

Question 29

What is meningocele?

Answer 29

Where there is protrusion of the meninges (filled with CSF) due to a defect in the skull of spine due to neural tube defect

Question 30

What is myelomeningocoele?

Answer 30

Where there is an open spinal cord with a meningeal cyst

Question 31

What is anencephaly?

Answer 31

Where there is an open brain and lack of skull vault due to neural tube defect

Question 32

What is encephalocele?

Answer 32

Where there is herniation of the meninges and brain due to a neural tube defect

Question 33

What is gastroschisis?

Answer 33

Where there is a small defect in the full thickness of the abdominal wall just lateral to the umbilicus (bowel is exposed)

Question 34

What is exomphalos/omphalocoele?

Answer 34

A wide-based defect where a membrane covers herniated viscera

Question 35

What is the cause of cleft lip and palate?

Answer 35

Failure of the maxillary and frontonasal processes fusing