Congenital Heart Disease and other Abnormalities

Question 1

What is the cardiac embryology?

Answer 1

• clusters of angiogenic cells from mesodermal cardiogenic plate arising from right and left endocardial tubes
• day 21: lateral folding brings tubes together forming primitive heart tube
• day 23: heart beats
• tube lengthens and folds further into bulboventricular loop
• day 28: septation of the atria, ventricles and outflow tract
• over 2nd and 3rd trimester: long periods and maturation

Question 2

What does failure of the septation of the atria cause?

Answer 2

CHD

• early (AVSD from endocardial cushion)
• late (simple ASD or VSD)

Question 3

What are the anatomical connections in fetal circulation?

Answer 3

• foramen ovale (bypasses pulmonary circulation)
• ductus arteriosus
• ductus venosus (1/3 of blood supply from umbilical vein)

Question 4

What is the purpose of anatomical connections in fetal circulation?

Answer 4

• high resistance pulmonary circulation

- low resistance systemic circulation

Question 5

What is the purpose of high pressure in fetal circulation?

Answer 5

High pressure pulmonary circulation forces most blood through ductus arteriosus into systemic circulation (diverts it from pulmonary circulation)

Question 6

What closes during pregnancy?

Answer 6

• closure of ductus arteriosus
• closure of foramen ovale
• closure ductus venosus

Question 7

What is the purpose of the ductus arteriosus closing?

Answer 7

• increased oxygen levels

- in utero ductus is kept open under PG E1 influence

Question 8

What is the purpose of formen ovale closing?

Answer 8

• drop in pressure in pulmonary circulation/right side of heart
• shunting reversed and valve closes

Question 9

What is the purpose of ductus venosus closure?

Answer 9

• decrease in blood flow in IVC

Question 10

What is persistent pulmonary hypertension of the newborn?

Answer 10

• if problems with lungs (pneumonia, aspirate meconium(
• increased pressure in pulmonary artery keeping foramen ovale open
• shunting of deoxygenated blood into systemic circulation
• cyanotic baby

Question 11

What is cyanosis?

Answer 11

• patient blue
• blue produced by amounts of deoxygenated Hb (g/l) not percentage saturation
• Hb>50g/l in capillaries OR 34/l in arterial blood

Question 12

How does CHD present?

Answer 12

• normal alveolar gas exchange
• no dyspnoea
• normal pulmonary venous saturations
• results from shunting of deoxygenated blood from right to left

Question 13

How does lung disease present?

Answer 13

• impaired alveolar gas exchange
• tachypnoea and recession
• reduced pulmonary venous saturations
• results from oxygen diffusion problems or ventilation-perfusion mismatch within the lung

Question 14

What is the main difference between lung disease and CHD?

Answer 14

CHD - no problem with functioning of lungs so normal oxygenation
Lung disease - limited gas exchange so body not perfused

Question 15

What occurs in transposition of great vessels?

Answer 15

• aorta connected to RV, pulmonary connected to LV forming 2 separate connections
• baby stays alive because of blood mixing in foramen ovale and ductus arteriosus

Question 16

What is teratology of fallot?

Answer 16

• ventricular septal defect
• overriding aorta (aorta above septal defect)
• right ventricular hypertrophy
• stenosis of RV (narrow outflow)

Question 17

What are other forms of CHD?

Answer 17

• tricuspid atresia (complete valve closure)
• pulmonary valve atresia
• critical pulmonary stenosis
• truncus arteriosus (single artery from heart, large ventricular septal defect below valve of trunk)
• total anomalous pulmonary venous drainage (pulmonary veins not connected to LA but to one of veins draining back to RA)

Question 18

Define acyanotic?

Answer 18

Patient pink

Question 19

What are the 2 major groups of acyanotic congenital problems?

Answer 19

• left to right shunts: increase pulmonary blood flow = pulmonary oedema/hypertension
• left heart outflow tract obstruction: pulmonary oedema/impaired tissue perfusion/lactic acidosis (increased back pressure on pulmonary veins -> pulmonary circulation)

Question 20

How can cyanosis occur as a secondary feature of acyanosis?

Answer 20

• pulmonary oedema impairs gas exchange
• pulmonary hypertension causes right to left shunting as there is higher pressure on right side = Eisenmenger shunt
• dangerous = if closed will develop right heart failure

Question 21

What is ventricular septal defect?

Answer 21

• pressure in left ventricle is higher than right -> shunt

Question 22

What is preductal coarctation of the aorta?

Answer 22

• causes pulmonary oedema as increased pulmonary pressure

- preductal: before ductus arteriosus

Question 23

What are other forms of cyanotic CHD?

Answer 23

• atrial septal defect
• atrioventricular septal defect
• critical aortic stenosis
• patent ductus arteriosus

Question 24

What are the main complex mixed presentations?

Answer 24

Hypoplastic left heart

Double outlet right ventricle (aorta connects to right ventricle instead of left)

Question 25

What is hypoplastic left heart?

Answer 25

- no blood flow through left ventricle to aorta - patient reliant on fetal circulation to stay alive - blood flows through foramen ovale into right ventricle -> pumped to rest of body

Question 26

How may ductus arteriosus and foramen ovale delayed presentation/treatment?

Answer 26

- bypass obstruction (teratology of fallot, pulmonary atresia, coarctation, hypoplastic left heart) - allow mixing (transposition) - both delay presentation as mild cyanosis easily missed and only get symptoms once ductus closes - reopen ductus with PG E/enlarge foramen ovale with balloon septostomy transposition

Question 27

How do you treat CHD?

Answer 27

- depends on condition - monitoring - diuretics for pulmonary oedema - re-open ductus arteriosus with PG E - surgery and catheter procedures

Question 28

Symptoms of acyanotic CHD?

Answer 28

- expectant small vascular VSDs PDA and ASD/PFO may close spontaneously - diuretics and prostaglandins

Question 29

What would definitely correct acyanotic CHD?

Answer 29

- percutaneous catheter closure of PDA - balloon dilatation of valvular stenosis - repair of coarctation - open heart surgery for VSD/ASD

Question 30

What are the limiting factors in treatment of CHD?

Answer 30

- anatomical@ disuse atrophy (cannot grow new ventricles) | - functional: chronically elevated pulmonary blood flow (irreversible pulmonary hypertension)

Question 31

What neural tube defects are there?

Answer 31

- failure of normal zipping of neural tube - spina bifida occulta (failure of one or more vertebrae in spine to form properly) - meningocoele (meninges protrude form spinal column) - encephalocoele (protrusion of neural tissue from head) - anencephaly (absence of major portion of brain, skull and scalp)

Question 32

What is the most serious form of spina bifida occulta?

Answer 32

- myelonmengocoele: neural tissue exposed on babies back

Question 33

How is myelomeningocele treated?

Answer 33

- closure reduces risk of infection but does not restore neural function - closure may lead to hydrocephalus (plastic catheter through valve running under skin into peritoneal cavity to be rapidly absorbed into circulation)

Question 34

What are the neurological consequences of lumbar myelomeningocele?

Answer 34

- mixed sensory, motor and autonomic problems (dependent on level of lesions and degree of neural disruption) - loss of bladder control, faecal incontinence and loss of sensation in legs

Question 35

What are the abdominal wall defects?

Answer 35

Gastroschisis | Exomphalos

Question 36

What are the features of gastrochisis?

Answer 36

- full thickness small defect in abdominal wall lateral to umbilicus (bowel free within abdominal cavity) - surgical closure possible - bowel may take 1-3 months to start functioning normally

Question 37

What is exomphalos?

Answer 37

- wide based defect - membrane covers herniated viscera - may be associated with other abnormalities/genetic disorders

Question 38

What is cleft lip?

Answer 38

- common defect where maxilla fail to fuse with frontonasal process - complete surgical correction possible - can affect eustachian tube function (risk of conductive hearing loss)

Question 39

What is cleft palate?

Answer 39

- common defect - failure of secondary palate to fuse - philtrum formed - tongue too large and stops plated from turning horizontally - general failure of rotation - can affect eustachian tube function (risk of conductive hearing loss)