For Undergraduate students of Medicine (MBBS)

1. Congenital Heart Disease
CSBR.Prasad, MD.,
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2. Congenital Heart Disease - CHD
• CHD is a general term designating abnormalities of the heart or great
vessels that are present at birth
• CHD arises from faulty embryogenesis during 3-8 weeks of gestation
• Incidence - 5%
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3. Twelve disorders account for about 85% of cases
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5. Congenital Heart Disease –
Cardiac Development
• The fetal heart consists of a single chamber until the fifth week of
gestation
• Then, it is divided by the development of interatrial and
interventricular septa and by the formation of atrioventricular valves
from endocardial cushions
• A muscular interventricular septum grows upward from the apex
toward the base of the heart. It is joined by the down-growing
membranous septum, thereby separating right and left ventricles
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6. CHD - Cardiac Development
Day 15: Multipotent progenitor cells originate in
lateral mesoderm and migrate to the midline
Day 20: beating tube
Day 28:
Migration of neural crest cells, out flow tract & aortic
arch formation
Endocardial cushion formation
Day 50: Formation of four chambered heart
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7. CHD - Cardiac Development
• This well orchestrated event involves many genes, transcription
factors, signaling pathways
• Each heart field is differentially marked by the expression of distinct
set of genes
• 1st heart field: Hand1
• (most of the left ventricle derived from this field)
• 2nd heart field: Hand2 and FGF-10
• (Out flow tract, right ventricle and atria are derived from this field)
• Pathways involved: Wnt, Hedghog, Notch-Delta
• Growth factors involved: VEGF, TGF-beta, FGF
• Specific micro-RNAs
• Others: Hemodynamic forces in the developing heartJAN-2015-CSBRP

8. CHD - Cardiac Development
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9. CATCH-22
Down’s syndrome
Trisomies (13,18, 21)
Most common genetic cause of
congenital heart disease is
Trisomy 21 (Down’s Syndrome)
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10. Congenital Heart Disease – Environmental factors
• Mutations in Csx/Mkx2-5
• Down syndrome (trisomy 21) and other trisomies
• Turner syndrome and
• Di George syndrome
• Intrauterine influences
• Rubella
• Alcohol
• Phenytoin
• Amphetamines
• Lithium
• Estrogenic steroids and,
• Thalidomide (historical)
• Maternal diabetes
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11. Congenital Heart Disease - gist
• CHD is a consequence of faulty embryonic
development
• Either as misplaced structures OR
• Eg: transposition of the great vessels) or
• As an arrest in the progression of a normal structure
(from an early stage to one that is more mature)
• Eg: ASD
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12. Congenital Heart Disease –
Clinical features
CHDs can be organized into three major categories:
1. Malformations causing a left-to-right shunt
2. Malformations causing a right-to-left shunt
3. Malformations causing an obstruction
Definition:
SHUNT: is an abnormal communication between chambers or blood vessels.
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13. Congenital Heart Disease –
Clinical features
CHDs can be organized into three major categories:
1-Malformations causing a left-to-right shunt
• Not initially associated with cyanosis
• However, over the course of years, the patient may
develop right to left shunt – EISENMENGER syndrome
Left to right shunt results in pulmonary hypertension and associated changes in
the pulmonary circulation. After the development of PHT the structural defects in
CHDs are considered irreparable.
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14. Common congenital
left-to-right shunts
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15. Congenital Heart Disease –
Clinical features
CHDs can be organized into three major categories:
2-Malformations causing a right-to-left shunt
• Associated with cyanosis
• Paradoxical embolism
• Hypertrophic osteoarthropathy
• Polycythemia
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16. Congenital Heart Disease –
Clinical features -Hypertrophic osteoarthropathy
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1. Tetralogy of Fallot
2. Transposition of the great
arteries
3. Persistent truncus arteriosus
4. Tricuspid atresia, and
5. Total anomalous pulmonary
venous connection
Common congenital right-to-left shunts

18. Congenital Heart Disease –
Clinical features
CHDs can be organized into three major categories:
3-Malformations causing an obstruction
• Abnormal narrowing of chambers, valves or blood vessels
• Complete obstruction is called Atresia
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19. Aortic
coarctation with
and without PDA
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20. Atrial Septal Defect - ASD
• Abnormal fixed opening in the atrial septum caused by incomplete
tissue formation
• Atria communicate with each other
• Cf: Patent foramen ovale – PFO
• Failure to close foramen that is a part of normal development
• Both ASD & PFO result from defects in the formation of interatrial
septum
• Usually asymptomatic until adulthood
• Common genetic variation near a gene MSX1 is strongly associated
with the risk of an ASD
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21. Atrial Septal Defect
Development of interatrial septum
• Septum primum - originates posteriorly
• Ostium primum
• During fetal development, this opening allows blood to be shunted from the right atrium
to the left
• Ostium secundum
• The ostium secundum allows continued shunting of blood from the right atrium to the
left
• Septum secundum - originates anteriorly
• Foramen ovale
• The foramen ovale is continuous with the ostium secundum, again providing for
continued shunting of blood
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22. Atrial Septal Defect
Development of interatrial septum
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23. Atrial Septal Defect
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24. Atrial Septal Defect
Classification
According to their location:
• Secundum ASD:
• 90% of all ASDs
• Deficient septum secundum
• No other associated anomalies
• May be of any size, may be fenestrated
• Primum anomalies
• 5% of ASDs
• AV valve abnormalities
• Sinus venosus defects
• 5% of ASDs
• Located near the entrance of SVC
• Associated with anomalous venous return to RAJAN-2015-CSBRP

25. Atrial Septal Defect
• The most common type of ASD: The ostium secundum type,
comprises 6–10% of all congenital heart diseases
• Mechanisms:
• Enlarged foramen ovale
• Inadequate growth of the septum secundum, or
• Excessive absorption of the septum primum
• 10-20% of individuals may have MVP
• Lutembacher's syndrome: Ostium secundum ASD + acquired MS
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26. Patent Foramen Ovale
• FO closes permanently in 80% of people by 2 years of age
• In the remaining 20%, the unsealed flap can open if right-sided
pressures become elevated
• Pulmonary hypertension or even transient increases in right-sided
pressures can produce brief periods of right-to-left shunting, with the
possibility of paradoxical embolism
• During a bowel movement
• coughing or
• Sneezing
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27. Patent Ductus Arteriosus - PDA
Ductus Arteriosus
• The ductus arteriosus (DA) arises from the PA and joins the aorta
• During intrauterine life, DA shunts blood from the PA to the aorta
• Shortly after birth DA constricts and is closed after 1 to 2 days
• This occurs in response to:
• Increased arterial oxygenation
• Decreased pulmonary vascular resistance and
• Reduced levels of PGE2 locally
• After a few months - ligamentum arteriosum
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28. Patent Ductus Arteriosus - PDA
Ductus Arteriosus
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29. Ductus Arteriosus
Ligamentum arteriosum
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30. Patent Ductus Arteriosus - PDA
• Constitute 7% of cases of CHDs (and 90% of them are isolated)
• Maternal Rubella infection
• PDA produces a characteristic continuous harsh “machinery-like”
murmur
• Complications: PHT, IE
• Isolated PDA should be closed as early in life as is feasible
• Preservation of ductal patency may be necessary in some CHDs
• Eg: Aortic valve atresia
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32. Ventricular Septal Defect - VSD
Ventricular septal defects occur as:
1. A small hole in the membranous septum
2. A large defect involving more than the membranous region
(perimembranous defects)
3. Multiple defects in the muscular portion, which are more common
anteriorly but can occur anywhere in the muscular septum or
4. Complete absence of the muscular septum (leaving a single
ventricle)
NOTE: A small septal defect may have little functional significance and
may actually close spontaneously as the child matures
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33. VSD
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34. VSD
• VSDs are classified according to their size and location
1. Membranous VSD
2. Infundibular VSD
• Membranous VSD: Single
• Infundubular VSD: Multiple, small
• 70-80% are associated with other CHD
• 20-30% occur in isolation
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35. VSD
• Large VSDs
• cause PHT / RVH
• Shunt reversal, cyanosis and death
• Small VSDs
• Present much later in life
• 50% may close spontaneously
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36. VSD (membranous type)
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37. VSD (Infundibular type)
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38. TETRALOGY OF FALLOT:
• DOMINANT RIGHT-TO-LEFT SHUNT
• IT IS THE MOST COMMON CYANOTIC CHD
• Four cardinal features are:
1. VSD
2. Obstruction to right ventricular out flow i.e. PS
3. Over riding of aorta
4. Right ventricular hypertrophy (RVH)
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41. TETRALOGY OF FALLOT:
• Heart is usually enlarged – boot shaped
• Due to marked right ventricular hypertrophy
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42. Persistent Truncus Arteriosus
• A common trunk for the origin of the aorta, pulmonary arteries
• Results from absent / incomplete partitioning of the truncus
arteriosus by the spiral septum
• Truncus overrides the VSD and receives blood from both the
ventricles
• Clinical Features:
• Recurrent pulmonary infections
• Cyanosis
• PCV / clubbing of fingers
• PHT / heart failure / early death
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44. Truncus Arteriosus
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45. Transposition of the Great Arteries - TGA
• Ventriculoarterial discordance: The aorta arises from the
right ventricle, while the pulmonary artery emanates from
the left ventricle
• Concordant AV connections: RA joining the RV and the LA
emptying into the LV
• Embryology: TGA results from abnormal formation of the
truncal and aortopulmonary septa
• Result: Separation of pulmonary and systemic circulation
• A condition incompatible with postnatal life unless a shunt exists
for adequate mixing of blood
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46. Transposition of the Great Arteries - TGA
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47. Transposition of the Great Arteries - TGA
• The outlook for infants with TGA depends on the
degree of blood “mixing”
• Patients with TGA and a VSD often have a stable shunt
• Patients with TGA and ASD / PDA have unstable shunt as
they many close early in life
• RVH
• Left ventricle may become thin walled
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48. Coarctation of the Aorta
• F:M = 1:2
• Females with Turner syndrome are also frequently affected
• There are two classic forms:
• Infantile form (symptomatic in early childhood)
• Adult form (with a ridge like infolding of the aorta)
• 50% of cases accompanied by a bicuspid aortic valve
• Patients may have berry aneurysms
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49. Coarctation of the
Aorta
Pathogenesis
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50. Coarctation of the Aorta
• Clinical manifestations depend on:
• Severity of the narrowing and
• Patency of the ductus arteriosus
• Coarctation of the aorta with a PDA: Cyanosis localized to the lower
half of the body
• Coarctation of the aorta without PDA: Unless the aortic constriction is
severe most children are asymptomatic
• Typically there is hypertension in the upper extremities with weak
pulses and hypotension in the lower extremities
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51. Coarctation of the Aorta
• Development of collateral circulation:
• Intercostal and
• Internal mammary arteries
• X-ray - “notching” of the undersurfaces of the ribs
• Pan systolic murmurs / thrill
• Concentric LVH
• Treatment:
• Surgical resection and end-to-end anastomosis or
• Replacement of the affected aortic segment by a prosthetic graft
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52. Coarctation of the Aorta
Collaterals, Notched ribs
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53. Coarctation of the Aorta
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54. CHDs - Gist
• Congenital heart disease represents defects of cardiac chambers or the great
vessels
• These either result in shunting of blood between the right and left circulation or
cause out flow obstructions
• Lesions range from relatively asymptomatic to rapidly fatal
• Both Environmental (toxic or infectious) and genetic factors contribute
• Left-to-right shunts are most common and are typically associated with ASDs,
VSDs, or a PDA
• Right-to-left shunts are most commonly caused by TOF or TGA
• Obstructive lesions include aortic coarctation
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