Congenital heart diseases
• CHDs are abnormalities of the heart or great
vessels that are present at birth.
• Most such disorders arise from faulty
embryogenesis during gestational weeks 3
through 8, when major cardiovascular structures
• Overall incidence 1% of live births
• INCREASED owing to increased diagnostic
sensitivity via non invasive methods, e.g.,
ECHO, MRI, CT, etc.
• Ventricular septal defect
Atrial septal defect
Patent ductus arteriosus
Tetralogy of Fallot
Coarctation of aorta
Atrioventricular septal defect
Transposition of great arteries
Total anomalous pulmonary venous connection
• Unknown causes in almost 90% of cases.
• Genetic factors (8%) are clearly involved, as
evidenced by familial forms of congenital heart
disease and by well-defined associations with
certain chromosomal abnormalities (e.g.,
trisomies 13 (Patau, MR, AR), 15, 18 (Edward),
and 21(Down, ASD) and Turner syndrome
(Coarctation of aorta)
• Environmental factors (2%), such as congenital
• Trisomies 21, 13, 15, 18, XO
• Mutations of genes which encode for
• Region of chromosome 22 important in heart
development, 22q11.2 deletionconotruncus
(craniofascial & cardiac abnormalities), 4 th
branchial arch (thyroid) and 3rd and 4th pharyngeal
pouch derivative (thymus and parathyroid, Di
George syndrome and hypocalcemia) defect
Type of CHD
• LR SHUNTS: all “D’s” in their names
– NO cyanosis
– Pulmonary hypertension
– SIGNIFICANT pulmonary hypertension is
• RL SHUNTS: all “T’s” in their names
– VENOUS EMBOLI become SYSTEMIC
• A shunt is an abnormal communication between
chambers or blood vessels.
• Left-to-right shunts increase pulmonary blood
flow and are not associated with cyanosis.
• When there is a right-to-left shunt, a dusky
blueness of the skin (cyanosis) results because
the pulmonary circulation is bypassed and poorly
oxygenated blood enters the systemic
HYPERTENSION IS THE
• Prolonged left-to-right shunting has
produced pulmonary hypertension
sufficient to yield right-sided pressures
that exceed those on the left and thus
result in a reversal of blood flow through
the shunt. Such reversal of flow and
shunting of unoxygenated blood to the
systemic circulation is called Eisenmenger
• Therefore, Cyanosis is not an early feature
of these defects, but it can occur late.
• Opening in the atrial septum permitting the
shunting of blood between two atria
• Usually asymptomatic until adult hood
• Usually appear after 3rd decade of life
• The atrial septum begins as an ingrowth of the septum
primum from the dorsal wall of the common atrial
chamber toward the developing endocardial cushion; a
gap, termed the ostium primum, initially separates the
• Continued growth and fusion of the septum with the
endocardial cushion ultimately obliterates the ostium
• However, a second opening, ostium secundum, now
appears in the central area of the septum primum
(allowing continued flow of oxygenated blood from the
right to left atria, essential for fetal life).
• As the ostium secundum enlarges, the septum
secundum makes its appearance adjacent to the septum
primum. This septum secundum proliferates to form a
crescent-shaped structure overlapping a space termed
the foramen ovale
• The foramen ovale is closed on its left side by a flap of
tissue derived from the primary septum; this flap acts as
a one-way valve that allows right-to-left blood flow during
• At the time of birth, there will closure of the foramen
Type of ASD
• Ostium secundum ASD (90%), which occurs when the
septum secundum does not enlarge sufficiently to cover
the ostium secundum.
• Ostium primum ASDs (5%); these occur if the septum
primum and endocardial cushion fail to fuse and are
often associated with abnormalities in other structures
derived from the endocardial cushion (e.g., mitral and
• The sinus venosus ASDs (5%) are located near the
entrance of the superior vena cava and have been
associated with frameshift mutations in the NKX2.5
• Ostium secundum :Right atrial and ventricular dilation,
right ventricular hypertrophy, and dilation of the
pulmonary artery, reflecting the effects of a chronically
increased volume load on the right side of the heart.
• Ostium primum : Abnormalities of the atrioventricular
valves are usually present, typically in the form of a cleft
in the anterior leaflet of the mitral valve or septal leaflet
of the tricuspid valve.
• Sinus venosus ASDs: Anomalous drainage of the
pulmonary veins into the right atrium or superior vena
• Most common CHD defect at birth. The
ventricular septum is normally formed by the
fusion of an intraventricular muscular ridge that
grows upward from the apex of the heart with a
thinner membranous partition that grows
downward from the endocardial cushion.
• Only 30% are isolated
• Often with TETRALOGY of FALLOT
• 90% involve the membranous septum
• If muscular septum is involved, likely to have
• The size and location of VSDs are variable,
ranging from minute defects in the muscular or
membranous portions of the septum to large
defects involving virtually the entire septum.
• In defects associated with a significant left-toright shunt, the right ventricle is hypertrophied
and often dilated. The diameter of the pulmonary
artery is increased because of the increased
volume ejected by the right ventricle.
• During intrauterine life, the ductus arteriosus permits
blood flow from the pulmonary artery to the aorta.
• In healthy term infants, the ductus is obliterated within 1
to 2 days after birth to form the ligamentum arteriosum.
• Ductal closure is often delayed in infants with hypoxia.
• PDAs account for about 7% of cases of congenital heart
90% of these are isolated defects. The remaining occur
with other congenital defects, most commonly VSDs and
coarctation of aorta.
• The DA arises from the left pulmonary artery and
joins the aorta just distal to the origin of the left
• In PDAs some of the oxygenated blood flowing
out from the left ventricle is shunted back to the
lungs. Because of the resultant volume overload,
the proximal pulmonary arteries, left atrium, and
ventricle can become dilated.
• With the development of pulmonary
hypertension, right heart hypertrophy and
dilation may develop.
• PDAs: audible as harsh "machinery-like" murmurs.
• Overload of pulmonary artery- Eisenmenger syndrome.
• With reversal of shunt, unoxygenated blood is delivered
distal to subclavian artery (differential cyanosis)
• Medical closure is by indomethacin
• Preservation of ductal patency (by administering PG E)
may be critically important for infants with various forms
of congenital heart disease wherein the PDA is the only
means to provide systemic or pulmonary blood flow
(e.g., aortic or pulmonic atresia).
• Ironically, then, the ductus can be either life threatening
• 90% isolated
• HARSH, machinery-like murmur
• LR, possibly RL as pulmonary
hypertension approaches systemic
• Closing the defect may be life saving
• Keeping it open may be life saving
(Prostaglandin E). Why?
• Associated with defective, inadequate
• Can be partial, or COMPLETE (ALL 4
CHAMBERS FREELY COMMUNICATE)
Tetralogy of Fallot
Transposition of great arteries
Total anomalous pulmonary venous
• Tricuspid atresia
Cyanosis present at or near the time of birth.
Clubbing of fingertips
Polycythemia (hypoxemia induced).
In addition, right-to-left shunts permit venous
emboli to bypass the lungs and directly enter the
systemic circulation (paradoxical embolism)
• More chance to develop Bacterial endocarditis
• septicemia and brain abscess
Tetralogy of Fallot
• The most common cause of cyanotic congenital
• The four features of the tetralogy are (1) VSD,
(2) obstruction to the right ventricular outflow
tract (subpulmonic stenosis), (3) an aorta that
overrides the VSD, and (4) right ventricular
• All of the features result from anterosuperior
displacement of the infundibular septum, so that
there is abnormal division into the pulmonary
trunk and aortic root.
• TETRALOGY of FALLOT most COMMON
– 1) VSD, large
– 2) OBSTRUCTION to RV flow
– 3) Aorta OVERRIDES the VSD
– 4) RVH
– SURVIVAL DEPENDS on SEVERITY of
– Can be a “PINK”
tetralogy if pulmonic obstruction
– but the greater the obstruction, the greater is the
• The heart is large and "boot shaped" as a result
of RVH; the proximal aorta is typically larger
than normal, with a diminished pulmonary trunk.
• The left-sided cardiac chambers are normal
• The VSD lies in the vicinity of the membranous
portion of the interventricular septum.
• The pulmonary outflow tract is narrowed.
• Additional abnormalities may present: PDA or
Clinical Features (TOF)
• Marked subpulmonic stenosis causes cyanosis early in
• The lungs are protected from hemodynamic overload by
the pulmonic stenosis, so that pulmonary hypertension
does not develop.
• As with any cyanotic heart disease, patients develop
polycythemia with hyperviscosity, and hypertrophic
• The right-to-left shunting also increases the risk for
infective endocarditis, systemic emboli, and brain
Transposition of the Great Arteries
• TGA is a discordant connection of the ventricles
to their vascular outflow.
• The aorta arises from the right ventricle and the
pulmonary artery arises from the left ventricle.
• The atrium-to-ventricle connections, however,
are normal (concordant), with right atrium joining
right ventricle and left atrium emptying into left
• The functional outcome is separation of the
systemic and pulmonary circulations.
• The fundamental lesion is the abnormal origin of the
pulmonary trunk and aortic root.
• Incompatible with life unless VSD, ASD or PDA present
• Varying combinations of ASD, VSD, and PDA are seen
in patients surviving beyond the neonatal period.
Right ventricular hypertrophy becomes prominent
because this chamber functions as the systemic
• The left ventricle becomes somewhat atrophic, since it
only has to support the low-resistance pulmonary
Clinical Features (TGA)
• Early cyanosis.
• Infusions of prostaglandin E2 and atrial
septostomy are performed to create ASDs
that enhance arterial oxygen saturation.
• Even with stable shunting, most
uncorrected TGA patients still die within
the first months of life.
of GREAT ARTERIES)
• NEEDS a SHUNT for survival
– PDA or PFO (65%), “unstable” shunt
– VSD (35%), “stable” shunt
– RV>LV in thickness
– Fatal in first few months
– Surgical “switching”
• Developmental failure of separation of
embryogenic TA into aorta and pulmonary
• Single great vessel receive blood from
COARCTATION of AORTA
• Aortic coarctation is common obstructive congenital
• Males are affected twice as often as females, although
females with Turner syndrome frequently have aortic
• Two classic forms have been described : an "infantile
(preductal)" form with hypoplasia of the aortic arch
proximal to a PDA, and an "adult (postductal)" form in
which there is a discrete ridgelike infolding of the aorta,
just opposite the ligementum artreriosum.
• With PDA: differential cyanosis, CHF
• Adult form: May be asymptomatic, high BP
in upper limb, weak pulse and lower BP in
lower limb, notching of rib on X-ray
COARCTATION of AORTA
But XO’s frequently have it
INFANTILE FORM (proximal to PDA) (SERIOUS)
ADULT FORM (CLOSED DUCTUS)
Bicuspid aortic valve 50% of the time
• If 100% atretic, hypoplastic RV with
• Clinical severity ~ stenosis severity
CHD result in shunting of blood between the right and left circulation
or cause outflow obstructions.
Left-to-right shunts involve ASDs, VSDs, or a PDA. These lesions
result in chronic right-sided pressure and volume overload that
eventually causes pulmonary hypertension with reversal of flow and
right-to-left shunts with cyanosis (Eisenmenger syndrome).
Right-to-left shunts are caused by TOF or transposition of great
vessels. These are cyanotic lesions from the outset and are
associated with polycythemia, hypertrophic osteoarthropathy, and
Obstructive lesions include aortic coarctation; the clinical severity of
the lesion depends the degree of stenosis and the patency of the