Congenital heart disease refers to abnormalities of the heart present from birth that arise during embryonic development. The abnormalities fall into two categories: shunts, which are abnormal connections that allow blood to flow between chambers in the wrong direction, and obstructions, which are narrowings that block blood flow. Shunts can cause cyanosis if deoxygenated blood enters the systemic circulation from the right side of the heart. Over time, increased blood flow or pressure from shunts can lead to pulmonary hypertension and structural changes that are irreversible. Common types of congenital heart defects include atrial and ventricular septal defects, patent ductus arteriosus, tetralogy of Fallot, and transposition of the great

1. Congenital heart disease

2. Congenital heart disease is a general term
used to describe abnormalities of the heart or
great vessels that are present from birth. Most
such disorders arise from faulty
embryogenesis, during gestational weeks 3-8,
when major cardiovascular structures undergo
development.

3. Clinical consequences:
The various structural abnormalities in hearts
with congenital defects fall primarily into two
major categories:
i) shunts or
ii) obstructions.
Shunt--A shunt is an abnormal communication
between chambers or blood vessels (or both).
Abnormal channels permit the flow of blood
from left to right or the reverse, depending on
pressure relationships.

4. When blood from the right side of the heart
enters the left side (right-to-left shunt), a
dusky blueness of the skin and mucus
membranes (cyanosis) results because poorly
oxygenated blood enters the systemic
circulation.
Congenital heart defects that produce right-to-
left shunts from early infancy are known as
cyanotic congenital heart disease.
In contrast, left to right shunts are not initially
associated with cyanosis. But these can result

5. in progressive pulmonary hypertension and
right ventricular overload with hypertrophy.
The presence of a shunt may expose the
pulmonary circulation to increased volume or
pressure in congenital heart disease.
Shunts associated with increased pulmonary
blood flow include atrial septal defects(ASDs,)
and shunts associated with both increased
pulmonary blood flow and pressure include
ventricular septal defects (VSDs) and patent
ductus arteriosus(PDA).

6. The muscular pulmonary arteries first respond
to increased pressure by medial hypertrophy
and vasoconstriction. This maintains
relatively normal distal pulmonary capillary
and venous pressures and prevents pulmonary
edema.
Prolonged pulmonary arterial vasoconstriction
stimulates the development of irreversible
obstructive intimal lesions. Consequently the
pressure on the right side of the heart can rise
to exceed that on the left.

7. This may reverse the shunt to right-to left
which is called late cyanotic congenital heart
disease.
Once significant irreversible pulmonary
hypertension develops, the structural defects
of congenital heart disease are considered
irreparable. The secondary pulmonary
vascular changes eventually lead to the
patient’s death.

8. Clinical finding frequently associated with
severe long standing cyanosis include
clubbing of the tips of the fingers and toes and
polycythemia. Cerebral thrombosis in very
young children sometimes occurs in these
settings. This is due to polycythemia and
consequent increased blood viscosity and
dehydration.

9. Obstructions---Some developmental anomalies
of the heart produce obstructions to flow
because of abnormal narrowing of chambers,
valves or blood vessels. Prime examples are--
i) valvular stenoses (partial narrowing) or
ii) artresias (complete obstruction)
iii) coarctation of the aorta,
iv) aortic valvular stenosis and
v) pulmonary valvular stenosis
These are called obstructive congenital heart
disease.

10. In congenital heart disease, altered
hemodynamics usually cause cardiac
dilatation or hypertrophy (both).
A decrease in the volume and muscle mass of a
cardiac chamber is called hypoplasia if it
occurs before birth and atrophy if it develops
after birth. Children with significant congenital
cardiac defects may also fail to thrive, may
suffer from retarded development, and are at
greater risk of developing the usual disease of
childhood.

11. Left-to-right shunts (Late cyanosis)
1. Atrial Septal Defect (ASD):
An ASD represents an abnormal opening in the
atrial septum that allows free communication
of blood between the right and left atria. An
ASD is the most common congenital cardiac
anomaly that may first come to clinical attention
in adults.
ASDs result in a left to right shunt, because
pulmonary vascular resistance is considerably
less than systemic vascular resistance.

12. Besides, the compliance (distensibility) of the
right ventricle is much greater than that of the
left. Pulmonary blood flow may be 2-4 times
normal. A murmur is often present which is
due to excessive flow thought the pulmonary
valve.

15. 2. Ventricular Septal Defect (VSD):
A VSD represent an abnormal opening in the
ventricular septum that allows free
communication between right and left
ventricles. It is the most common congenital
cardiac anomaly. Frequently VSD is associated
with other structural defects, particularly
tetralogy, transposition, PDA, ASD and aortic
coarctation.

16. The functional significance of a VSD depends
on the size of the defect or the presence or
absence of pulmonary stenosis.
Small defects (<0.5 cm in diameter) close
spontaneously (50%) and the remainder are
generally well tolerated for years. They induce
a loud murmur during systole.
Large defects generally remain patent and
permit a significant left-to-right flow. They also
induce cardiac murmur at birth. Right
ventricular hypertrophy and pulmonary
hypertension are present from birth.

17. Overtime, irreversible pulmonary vascular
disease develops in all patients with large
unoperated VSDs, leading to shunt reversal,
cyanosis, clubbing and polycythemia.
Surgical closure of incidental VSD is generally
not done during infancy, in hope of spontaneous
closure. But correction is indicated in older
children with large defects, before obstructive
pulmonary vascular disease develops and
renders the lesion inoperable.

20. 3. Patent Ductus Arterious (PDA):
PDA results when the ductus arteriosus, a
normal aortopulmonary vascular channel
during intrauterine life remains open after
birth. In a full term infant, the ductus usually
closes functionally within the first day or two
of life. In contrast, in premature infants with
respiratory distress syndrome at birth, the
ductus may remain patent. In full-term infants
with PDA there may be a true structural defect
in the wall.

21. A PDA should be close as early in life as is
feasible. Up to the recent past, operative
closure was recommended. Currently
indomethacin (suppress vesodilatory PGE
synthesis) have proved promising. Ironically
the ductus may be either life threatening or life
saving.

24. 4. Atrio-Ventricular Septal Defects (AVSD):
AVSDs result from abnormal development of
the embryologic AV canal, in which the
superior and inferior endocardial cushions fail
to fuse adequately resulting in incomplete
closure of the AV septum. All four cardiac
chambers freely communicate, inducing
volume hypertrophy of each. More than one-
third of all patients with the complete AV
septal defect have Down syndrome. Surgical
repair is possible.

25. Right-to-left shunts (Early cyanosis)
1. Tetralogy of Fallot:
The four features of Fallot tetralogy are--
i) VSD
ii) obstruction to the right ventricular outflow
tract (sub pulmonary stenosis)
iii) an aorta that overrides the VSD
iv) right ventricular hypertrophy.
The clinical consequences of tetralogy of Fallot
depend primarily on the severity of
subpulmonary stenosis.

26. The severity of obstruction to right ventricular
outflow determines the direction of blood flow.
If the sub pulmonary stenosis is mild, the shunt
may be left-to-right without cyanosis. As the
obstruction increase in severity,
right-to-left shunting predominates along with
cyanosis.
As the child grows and the heart increases in
size, the pulmonic orifice does not expand
proportionally, making the obstruction ever
worse. Thus most infants with tetralogy are
cyanotic from birth or soon thereafter.

29. 2. Transposition of great arteries:
Transposition represents ventriculo-arterial
discordance, such that the aorta arises from
the right ventricle and the pulmonary artery
arises from the left ventricle.
This is an embryologic defect and occurs due
to the abnormal formation of the truncal and
aortopulmonary septa. Thus the aorta arises
from the right ventricle and lies anterior to the
right of the pulmonary artery (in the normal
heart the aorta is posterior and to the right).

30. The result is separation of the systemic and
pulmonary circulation. This condition is
incompatible with post natal life, unless a
shunt exists for adequate mixing of blood. This
malformation is particularly common in
offspring of diabetic mother, causes cyanosis
from birth.
Patients with transposition and VSD have a
stable shunt. Patients with only PDA have
unstable shunts that tend to close.

31. This patient therefore require immediate
intervention to open an right to left
communication within the first few days of
life.
Risk factors:
Expecting mother
i) having diabetes
ii) having rubella
iii) having poor nutrition
iv) consuming alchol
v) being >40 years old

33. Thanks