coarctation of aorta, tetralogy of fallot, transposition of great vessels

1. Cardiovascular System I
PART II
Kishore S Rajan

2. Coarctation of Aorta
• The word coarctation has been derived from Latin
word ‘COACTERE’, meaning to contract.
• Definition: A congenital narrowing of upper
descending thoracic aorta adjacent to the site of
attachment of ductus arteriosus.
• Occurrence rate: 0.2-0.6/1000 live births.
• Represents 5-8% of all congenital heart disease.
• 8th most common congenital heart defect.

3. Pathophysiology
• This is due to arterial duct tissue encircling the aorta
just at the point of insertion of the duct.
• When the duct closes, aorta also constricts, causing
severe obstruction to the left ventricular outflow. This
is the commonest cause of collapse due the left
outflow obstruction.
• It is postulated that the coarctation maybe initiated in
the fetal life by the presence of a cardiac abnormality
that results in decreased blood flow anterograde
through the aortic valve.

4. • Preductal- proximal – infantile type
▫ very high load on left ventricle elevation of
both systolic & diastolic pressures absence
of collaterals  immediately symptomatic
with CCF from birth.
• Postductal type: distal to ductus/
ligamentum arteriosum or subclavian artery
- adult type.
▫ development of collaterals connecting
branches of subclavian artery to arteries
arising from aorta from in-utero life distal
level of coarctation spares infant from LVF.

5. Clinical features
• Coarctation of aorta recognized after infancy is rarely
associated with significant symptoms.
• Examination on the first day of life is usually normal.
• Neonates present with acute circulatory collapse at 2
days of age when the duct closes.
• The classical sign is a disparity in pulsation and blood
pressure in the arms and legs.
• The femoral, popliteal, posterior tibial and dorsalis
pedis pulses are weak or absent in contrast to the
bounding pulses of the arms and carotids.
• Metabolic acidosis due to kidney failure.

6. Investigations
• Chest X-ray
▫ Normal heart size with prominent ascending aorta and
aortic knuckle
• ECG
▫ Right or biventricular hypertrophy in neonates
▫ Normal in young children
▫ LVH in older children
• Echocardiography
▫ Cardiomegaly
▫ Visualization of coarctation.

7. Management
• Surgery is performed soon after diagnosis.
• Balloon angioplasty
• Resection of coarctation and end-to-end anastomosis
at any age but lowest risk at 1-10yrs.
• Medical includes management of complications like
CCF in infancy and hypertension.

8. Tetralogy of Fallot
• It is the most common cyanotic heart defect and the
most common cause of blue baby syndrome.
• It accounts for 6-10 percent of all CHDs
• This condition is characterized by the combination of
four defects:
▫ 1. Subpulmonary stenosis causing RV outflow obstruction thus,
▫ 2. Right ventricular hypertrophy
▫ 3. Overriding or dextroposed aorta, and
▫ 4. Ventricular septal defect (VSD)

10. Causes
• Unclear
• Children born to mothers with PKU are highly
susceptible as are mothers who drink during birth.
• Genetic

11. Pathophysiology
• Physiologically the pulmonary stenosis causes
concentric right ventricular hypertrophy without
cardiac enlargement and an increase in right
ventricular pressure.
• When the right ventricular pressure is as high as the
left ventricular or the aortic pressure, a right to left
shunt appears to decompress the right ventricle.

12. • Once the right and left ventricular become identical,
increasing severity of pulmonary stenosis reduces the flow
of blood into the pulmonary artery and increases the right
to left shunt.
• As the systolic pressures between two ventricle are
identical there is little or no left to right shunt and the
VSD is silent.
• The flow from the right ventricle into the pulmonary
artery occurs across the pulmonary stenosis producing an
ejection systolic murmur
• More severe the pulmonary stenosis, the less the flow into
the pulmonary artery and the bigger the right to left shunt,
more the cyanosis

13. • Thus the severity of cyanosis is directly proportional
to the severity of pulmonary stenosis
• The VSD of TOF is always large enough to allow
free exit to the right to left shunt
• Thus Congestive failure never occurs in TOF.

14. Clinical features
• Clinical manifestations depend on the size of the VSD and
the degree of LV outflow obstruction.
• SYMPTOMS:
▫ Severe cyanosis
▫ Hypercyanotic spells
 Associated with irritability or inconsolable crying because of
the hypoxia and
 Breathlessness and pallor due to acidosis
▫ Squatting on exercise.
• SIGNS:
▫ Clubbing in older groups
▫ Loud harsh ejection systolic murmur which will shorten as
RV outflow increases.

15. • Squatting (a compensatory
mechanism) is uniquely
characteristic of a right- to-left
shunt that presents in the
exercising child.
• Squatting increases the
peripheral vascular
resistance, which diminishes
the right-to-left shunt and
increases pulmonary blood
flow.

16. Investigations
• Chest X-ray
▫ Small heart.
▫ Boot shaped heart (due
to ventricular
hypertrophy). It means
apex is lifted up.
▫ Concavity in the region
of pulmonary artery
▫ Right sided aortic arch.
▫ Oligaemic lung fields.
▫ Hilar vessels are few,
lung vessels also few.

17. • ECG- normal at birth. Right ventricular Hypertrophy
when older.
• Echocardiography- demonstrate the four cardinal
features

18. Management
• Initial management is medical with definitive surgery
at around 6 months of age.
• Surgical involves closing the VSD and relieving the
right ventricular outflow tract obstruction, sometimes
with a artificial patch.
• Infant, very cyanosed in the neonatal period, require a
shunt to increase Pulmonary blood flow.
• This is usually done by surgical placement of an
artificial tube between the subclavian artery and the
pulmonary artery (Blalock-Taussig shunt) or
sometimes by balloon dilatation of right ventricular
outflow tract.

20. • Hypercyanotic spells are usually self-limiting
followed by a period of sleep.
• If prolonged (>15min) – t/t
▫ Sedation and pain relief (morphine but watch out for SE)
▫ IV propranolol (or α adrenoceptor agonist) – peripheral
vasoconstrictor and relieve subpulmonary muscular
obstruction.
▫ IV fluids.
▫ Bicarbonates to correct acidosis.
▫ Muscle paralysis and artificial ventilation to reduce O2
demand.

21. Transposition of Great Arteries
• Transposition of the great arteries (TGA) is a serious heart
defect which the two main arteries leaving the heart are
reversed (transposed)
• 1 of 4000-5000 births, annual incidence 20-30 per 100.000
live birth.
• Second most common cause of cyanosis in infancy (5-7%
of congenital heart disease)
• No race predilection.
• History of diabetic mother.
• 60-70% male predominance.
• Cause is unknown.

22. • The transposition of
the great arteries,
ventriculo-arterial
discordance or
discordant VA
connection, in
which the aorta
arises from the
morphologic right
ventricle and the
pulmonary artery
arises from the
morphologic left
ventricle.

23. Pathophysiology
• The pulmonary and systemic circulations function in parallel
rather than in series
• Transposition of great arteries
• Oxygenated pulmonary venous blood returns to the left atrium
and left ventricle
• Re-circulated to the pulmonary vascular bed via the abnormal
pulmonary arterial connection to the left ventricle.
• Deoxygenated systemic venous blood returns to the right atrium
and right ventricle

24. • Pumped to the systemic circulation, effectively
bypassing the lungs
• Deficient oxygen supply to the tissues and an
excessive right and left ventricular workload.
• It is incompatible with prolonged survival unless
mixing of oxygenated and deoxygenated blood occurs
at some anatomic level like
• ASD or VSD or PDA or therapeutic interventions.

25. Clinical features
• Symptoms: Cyanosis – profound and life threatening.
• Presentation is usually on 2nd day when ductal closure
occurs
• Cyanosis will be less if other anomalies present, like
ASD, VSD etc.
• Physical signs: Cyanosis, Loud S2, may present with
a systolic murmur from increased flow or stenosis
within the left ventricle.

26. Investigations
• Chest X-ray
Classical finding
of a narrow upper
mediastinum with an
‘egg on side’
appearance of the
cardiac shadow. This is
due to anterior posterior
relationship of the great
vessels, narrow
vascular pedicle and
hypertrophied right
ventricle.

27. • ECG
This is usually normal.
• Echocardiography
This is essential to demonstrate the abnormal
arterial connections and associated abnormalities.

28. Management
• In the sick cyanotic neonate – key is to improve
Mixing.
• Maintaining the patency of the Ductus arteriosus is
important – Prostaglandin infusion.
• Balloon Atrial Septostomy
• Arterial switch in the neonatal period.

29. • Balloon Atrial Septostomy – life saving procedure.
• A catheter with an inflatable tip is passed through the
umbilical or femoral vein and then on through the
right atrium and foramen ovale.
• The balloon is inflated within the right atrium and
pulled back through the atrial septum.
• This tears the atrial septum, allowing mixing of
systemic and pulmonary venous blood within the
atrium.

31. • Arterial Switch Procedure.
• Performed in the neonatal period
• The pulmonary artery and the aorta are transected
above the arterial valves and switched over
• The coronary arteries have to be transferred across the
new aorta.

33. Thank you