1. Congenital Heart Diseases
Special Pathology

2. Congenital heart diseases
abnormalities of the heart or great vessels that are present at birth
faulty embryogenesis during gestational weeks 3 through 8
major cardiovascular structures develop.
Congenital malformations of the heart encompass a broad spectrum of defects,
severe anomalies that cause death in the perinatal period,
mild lesions that produce only minimal symptoms, even in adult life.
Generally accepted incidence is approximately 1% of live births
higher in premature infants and in stillborns.
Most common type of heart disease among children.

3. Patients surviving with congenital heart disease is increasing rapidly
Because of clinical advances
by 2020 there will be an estimated 750,000 adults with congenital heart disease.
Surgery can correct the hemodynamic abnormalities
repaired heart may still not be completely normal
Although adaptive initially, such changes can elicit late-onset arrhythmias, ischemia, or myocardial dysfunction, sometimes many years after surgery
Myocardial hypertrophy and a cardiac remodeling brought about by the congenital defect may be irreversible.

4. General concepts regarding the etiology of congenital malformations
unknown in almost 90% of cases.
Environmental factors,
congenital rubella infection, are causal in many instances.
Genetic factors are also clearly involved,
as evidenced by familial forms of congenital heart disease
well-defined associations with certain chromosomal abnormalities (e.g., trisomies 13, 15, 18, and 21 and Turner syndrome).

5. Cardiac morphogenesis
involves multiple genes
tightly regulated to ensure an effective embryonic circulation.
Key steps involve specifying cardiac cell fate, morphogenesis and looping of the heart tube, segmentation and growth of the cardiac chambers, cardiac valve formation, and connection of the great vessels to the heart.
The molecular pathways controlling such cardiac development
provide a foundation for understanding the basis of some congenital heart defects.
Several congenital heart diseases are associated with mutations in transcription factors.
Mutations of the TBX5 transcription factor cause the atrial and ventricular septal defects seen in Holt-Oram syndrome.
Mutations in the transcription factor NKX2.5 are associated with isolated atrial septal defects (ASDs).

6. Since different cardiac structures can share the same developmental pathways,
dissimilar lesions may be related to a common genetic defect
The unifying feature of many outflow tract defects is the abnormal development of neural crest-derived cells,
whose migration into the embryonic heart is required for outflow tract formation.
In particular, genes located on chromosome 22 have a major role in forming the conotruncus, the branchial arches, and the human face;
Now known that deletions of chromosome 22q11.2 underlie 15% to 50% of outflow tract abnormalities.
can also cause developmental anomalies of the fourth branchial arch and derivatives of the third and fourth pharyngeal pouches
leading to thymic and parathyroid hypoplasia
resultant immune deficiency (Di George syndrome) and hypocalcemia.

7. Congenital heart diseases can be subdivided into three major groups:
Twelve disorders account for 85% of congenital heart disease; their frequencies are shown in Table.
Congenital heart diseases can be subdivided into three major groups:
Malformations causing a left-to-right shunt
Malformations causing a right-to-left shunt (cyanotic congenital heart diseases)
Malformations causing obstruction

8. Malformation
Incidence per Million Live Births %
Ventricular septal defect
4482 42
Atrial septal defect
1043 10
Pulmonary stenosis
836 8
Patent ductus arteriosus
781 7
Tetralogy of Fallot
577 5
Coarctation of the aorta
492
Atrioventricular septal defect
396 4
Aortic stenosis
388
Transposition of the great arteries
Truncus arteriosus
136 1
Total anomalous pulmonary venous connection
120
Tricuspid atresia
118
TOTAL
9757
Frequencies of Congenital Cardiac Malformations

9. Shunt abnormal communication between chambers or blood vessels.
Depending on pressure relationships, shunts permit the flow of blood from the left heart to the right heart (or vice versa).
Right-to-left shunt
dusky blueness of the skin (cyanosis) results
pulmonary circulation is bypassed
poorly oxygenated blood enters the systemic circulation.
Left-to-right shunts
increase pulmonary blood flow
not associated (at least initially) with cyanosis
expose the low-pressure, low-resistance pulmonary circulation to increased pressure and volume, resulting in right ventricular hypertrophy and-eventually-right-sided failure.
obstructive congenital heart disease
Some developmental anomalies obstruct vascular flow by narrowing the chambers, valves, or major blood vessels;
A complete obstruction is called an atresia.
In some disorders (e.g., tetralogy of Fallot), an obstruction (pulmonary stenosis) is associated with a shunt (right-to-left through a ventricular septal defect [VSD]).

10. Left-to-right shunts;
most common type of congenital cardiac malformation (Fig.)
atrial and ventricular septal defects, and patent ductus arteriosus.
Atrial septal defects are typically associated with increased pulmonary blood volumes
ventricular septal defects and patent ductus arteriosus result in both increased pulmonary blood flow and pressure.
These malformations can be asymptomatic or can cause fulminant CHF at birth.
Cyanosis is not an early feature of these defects, but it can occur late,
Eisenmenger syndrome.
after 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
Rationale for early intervention, either surgical or nonsurgical
Once significant pulmonary hypertension develops,
structural defects of congenital heart disease are considered irreversible

12. ASDs normal atrial septation (Fig.)
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 two.
Continued growth and fusion of the septum with the endocardial cushion ultimately obliterates the ostium primum; however,
a second opening, ostium secundum, now appears in the central area of the primary septum
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 intrauterine life.
At the time of birth, falling pulmonary vascular resistance and rising systemic arterial pressure causes left atrial pressures to exceed those in the right atrium;
result is a functional closure of the foramen ovale.
In most individuals the foramen ovale is permanently sealed by fusion of the primary and secondary septa, although a
minor degree of patency persists in about 25% of the general population.

14. Abnormalities in this sequence result in the development of the various ASDs;
three types are recognized
ostium secundum ASD
The most common (90%) is the, which
occurs when the septum secundum does not enlarge sufficiently to cover the ostium secundum
Ostium primum ASDs are
less common (5% of cases); 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 tricuspid valves).
The sinus venosus ASDs
(5% of cases) are located near the entrance of the superior vena cava and have been
associated with frameshift mutations in the NKX2.5 transcription factor.

15. Pathophysiology of atrial septal defect
Pathophysiology of atrial septal defect. The net left-to-right shunt through the atrial septal defect results in volume overload of the right atrium, right ventricle, and pulmonary circulation. The volume of the shunt can be calculated from cardiac output and the amount of increase in oxygen saturation occurring at right atrial level. In the early stages, the pressures in the right side of the heart are not increased. With time, pulmonary vascular changes may occur, leading to increasing pulmonary arterial pressure. Reversal of the direction of flow through the shunt may occur with severe pulmonary hypertension.

17. Morphology Ostium secundum Ostium primum Sinus venosus
ASDs are typically smooth-walled defects near the foramen ovale,
usually without other associated cardiac abnormalities. Because of the
left-to-right shunt, hemodynamically significant lesions are accompanied by increased volume load on the right side of the heart
right atrial and ventricular dilation, right ventricular hypertrophy, and dilation of the pulmonary artery
Ostium primum
ASDs occur at the lowest part of the atrial septum
can extend to the mitral and tricuspid valves, reflecting the close relationship between development of the septum primum and endocardial cushion.
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.
In more severe cases, the ostium primum defect is accompanied by a VSD and severe mitral and tricuspid valve deformities, with a resultant common atrioventricular canal.
Sinus venosus
ASDs are located high in the atrial septum
often accompanied by anomalous drainage of the pulmonary veins into the right atrium or superior vena cava.

18. Clinical Features ASDs
most common defects to be first diagnosed in adults.
less likely to spontaneously close
left-to-right shunts, as a result of the
lower pressures in the pulmonary circulation and right side of the heart. well tolerated, especially if they are less than 1 cm in diameter; even larger lesions do not usually produce any symptoms in childhood.
With time, however, pulmonary vascular resistance can increase, resulting in pulmonary hypertension.
less than 10% of patients with uncorrected ASD.
The objectives of surgical closure of ASDs are;
reversal of the hemodynamic abnormalities and the
prevention of complications, including heart failure, paradoxical embolization, and irreversible pulmonary vascular disease.
Mortality is low
postoperative survival is comparable to that of a normal population.
Ostium primum defects are more likely to be associated with evidence of CHF, in part because of the high frequency of associated mitral insufficiency.

19. VSDs
Incomplete closure of the ventricular septum allows left-to-right shunting
Most common congenital cardiac anomaly at birth
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.
The basal (membranous) region is the site of approximately 90% of VSDs
last part of the septum to develop
Overall incidence in adults is lower than that of ASDs
more common at birth than ASDs,
most VSDs close spontaneously in childhood,
Commonly associated with other cardiac malformations
Roughly 30% of VSDs occur in isolation

20. Pathophysiology of ventricular septal defect
Pathophysiology of ventricular septal defect. The defect results in a left-to-right shunt at the ventricular level, resulting in increased volume and pressure in the right ventricle, the magnitude of which depends on the size of the defect. The right ventricle undergoes hypertrophy because of volume and pressure overload. The left ventricle, which must handle the shunted blood in addition to the normal output into the aorta, also undergoes hypertrophy and dilation. Pulmonary arterial pressure may increase with time as a result of changes occurring in the pulmonary vasculature. This causes a progressive decrease in shunt volume and, if severe enough, may result in shunt reversal.

22. Morphology Size and location of VSDs are variable;
minute defects in the muscular or membranous portions of the septum
large defects involving virtually the entire septum.
Defects with a significant left-to-right shunt;
right ventricle is hypertrophied and often dilated
The diameter of the pulmonary artery is increased;
increased volume ejected by the right ventricle.
Vascular changes typical of pulmonary hypertension are common

23. Clinical Features Small VSDs; Larger defects;
may be asymptomatic
those in the muscular portion of the septum may close spontaneously during infancy or childhood.
Larger defects;
severe left-to-right shunt,
often complicated by pulmonary hypertension and CHF.
Progressive pulmonary hypertension;
resultant reversal of the shunt and cyanosis,
earlier and more common in patients with VSDs than ASDs;
Needs early surgical correction
Small- or medium-sized defects;
produce jet lesions in the right ventricle
prone to superimposed infective endocarditis.

24. Patent ductus arteriosus
During intrauterine life;
blood flow from the pulmonary artery to the aorta
bypassing the unoxygenated lungs
Shortly after birth; the ductus constricts in response to;
increased arterial oxygenation,
decreased pulmonary vascular resistance, and
declining local levels of prostaglandin E2.
In healthy term infants
functionally nonpatent within 1 to 2 days after birth;
complete, structural obliteration occurs within the first few months of extrauterine life to form the ligamentum arteriosum.
Ductal closure is often delayed (or even absent) in infants with hypoxia
resulting from respiratory distress or heart disease
PDAs account for about 7% of cases of congenital heart lesions;
90% are isolated defects
remaining occur with other congenital defects, most commonly VSDs.

25. Pathophysiology of patent ductus arteriosus
Pathophysiology of patent ductus arteriosus. Blood is shunted from the aorta to the main pulmonary artery via the patent ductus. This results in increased pressure and volume in the pulmonary artery, the magnitude of which depends on the size of the shunt. Pulmonary hypertension causes right ventricular hypertrophy. The left ventricle, which pumps a volume equal to the shunt plus the systemic output, also undergoes hypertrophy. Increasing pulmonary hypertension due to secondary pulmonary vascular changes may result in shunt reversal.

27. Morphology
The ductus arteriosus arises from the left pulmonary artery and joins the aorta just distal to the origin of the left subclavian artery.
Proximal pulmonary arteries, left atrium, and ventricle can become dilated
In PDAs some of the oxygenated blood flowing out from the left ventricle is shunted back to the lungs
resultant volume overload
Right heart hypertrophy and dilation.
With the development of pulmonary hypertension,
atherosclerosis of the main pulmonary arteries and proliferative changes in more distal pulmonary vessels

28. Clinical Features PDAs; A small PDA - no symptoms
high-pressure left-to-right shunts,
audible as harsh "machinery-like" murmurs.
A small PDA - no symptoms
larger bore defects - lead to the Eisenmenger syndrome with cyanosis and CHF.
The high-pressure shunt also predisposes affected individuals to infective endocarditis
There is general agreement that isolated PDAs should be closed as early in life as is feasible,
Preservation of ductal patency
by administering prostaglandin E
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 or lifesaving.

29. Right-to-Left Shunts
Cardiac malformations associated with right-to-left shunts are distinguished by
cyanosis at or near the time of birth.
poorly oxygenated blood from the right side of the heart is introduced directly into the arterial circulation.
Two of the most important conditions associated with cyanotic congenital heart disease are;
tetralogy of Fallot
transposition of the great vessels (Fig.)
Clinical findings associated with severe, long-standing cyanosis;
clubbing of the fingertips (hypertrophic osteoarthropathy) and polycythemia
In addition, right-to-left shunts permit venous emboli to bypass the lungs and directly enter the systemic circulation
paradoxical embolism

30. Tetralogy of Fallot
5% of all congenital cardiac malformations, tetralogy of Fallot
most common cause of cyanotic congenital heart disease
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 hypertrophy
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.
Even untreated, some tetralogy patients can survive into adult life
Clinical severity largely depends on the degree of the pulmonary outflow obstruction.

31. Tetralogy of Fallot. The marked narrowing of the pulmonary outflow tract results in a right-to-left shunt through the ventricular septal defect, resulting in central cyanosis. The right ventricle is hypertrophied.

33. Morphology
The heart is large and "boot shaped" in tetralogy of Fallot as a result of;
right ventricular hypertrophy;
the proximal aorta is typically larger than normal, with a diminished pulmonary trunk.
The left-sided cardiac chambers are normal sized, while the right ventricular wall is markedly thickened and may even exceed that of the left.
The VSD lies in the vicinity of the membranous portion of the interventricular septum, and the aortic valve lies immediately over the VSD
The pulmonary outflow tract is narrowed, and, in a few cases, the pulmonic valve may be stenotic
Additional abnormalities are present in many cases, including PDA or ASD;
actually beneficial in many respects, because they permit pulmonary blood flow.

34. Clinical Features
The hemodynamic consequences of tetralogy of Fallot are;
right-to-left shunting,
decreased pulmonary blood flow,
increased aortic volumes.
The extent of shunting (and the clinical severity) is determined by the amount of right ventricular outflow obstruction.
If the pulmonic obstruction is mild, the condition resembles an isolated VSD,
because the high left-sided pressures on the left side cause a left-to-right shunt with no cyanosis.
More commonly, marked stenosis causes significant right-to-left shunting
consequent cyanosis early in life.
As patients with tetralogy grow, the pulmonic orifice does not enlarge, despite an overall increase in the size of the heart.
Hence, the degree of stenosis typically worsens with time resulting in increasing cyanosis.
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 erythrocytosis with attendant hyperviscosity, and hypertrophic osteoarthropathy; the right-to-left shunting also increases the risk for infective endocarditis, systemic emboli, and brain abscesses.
Surgical correction of this defect is now possible in most instances.

35. Transposition of the Great Arteries
Discordant connection of the ventricles to their vascular outflow
The embryologic defect
abnormal formation of the truncal and aortopulmonary septa;
aorta arises from the right ventricle and the
pulmonary artery emanates from the left ventricle (Fig.)
The atrium-to-ventricle connections are normal (concordant)
right atrium joining right ventricle and
left atrium emptying into left ventricle.

37. The functional outcome;
separation of the systemic and pulmonary circulations
a condition incompatible with postnatal life
shunt exists for adequate mixing of blood and delivery of oxygenated blood to the aorta.
stable shunt (35%)
Patients with TGA and a VSD
unstable shunts (65%)
Patients with only a patent foramen ovale or PDA
can close and often require surgical intervention within the first few days of life.

38. Morphology TGA has many variants;
abnormal origin of the pulmonary trunk and aortic root
patients surviving beyond the neonatal period;
Varying combinations of ASD, VSD, and PDA
Right ventricular hypertrophy;
functions as the systemic ventricle
Left ventricle becomes somewhat atrophic;
support the low-resistance pulmonary circulation

39. Clinical Features Early cyanosis
predominant manifestation of TGA
The outlook for neonates with TGA depends on;
the degree of the shunting
the magnitude of the tissue hypoxia
the ability of the right ventricle to maintain systemic pressures.
Procedures that enhance arterial oxygen saturation;
Infusions of prostaglandin E2
maintain patency of the ductus arteriosus
Atrial septostomy
create ASDs
Even with stable shunting, most uncorrected TGA patients still die within the first months of life.
Consequently, affected individuals usually undergo corrective surgery (switching the great arteries) within weeks of birth.

40. Congenital Obstructive Lesions
Obstruction to blood flow can occur at the level of the heart valves or within a great vessel.
Obstruction can also occur within a chamber
subpulmonic stenosis in tetralogy of Fallot.
Relatively common examples of congenital obstruction include;
pulmonic valve stenosis,
aortic valve stenosis or atresia
coarctation of the aorta.

41. Aortic Coarctation relatively common structural anomaly
most important form of obstructive congenital heart disease.
Males are affected twice as often as females;
females with Turner syndrome frequently have aortic coarctation
Two classic forms have been described (Fig):
"infantile" form with hypoplasia of the aortic arch proximal to a PDA, and an
"adult" form in which there is a discrete ridgelike infolding of the aorta, just opposite the ligamentum arteriosum distal to the arch vessels.
Coarctation of the aorta may occur as a solitary defect
more than 50% of cases, it is accompanied by a bicuspid aortic valve.
Congenital aortic stenosis, ASD, VSD, or mitral regurgitation may also occur.
In some cases berry aneurysms in the circle of Willis coexist.

43. Morphology Preductal ("infantile") coarctation;
tubular narrowing of the aortic segment between the left subclavian artery and the ductus arteriosus
usually patent
main source of blood delivered to the distal aorta.
Because the right side of the heart must perfuse the body distal to the narrowing, the
right ventricle is typically hypertrophied and dilated
pulmonary trunk is also dilated to accommodate the increased blood flow.
Postductal ("adult") coarctation;
more common
sharply constricted by a ridge of tissue at or just distal to the ligamentum arteriosum
made up of smooth muscle and elastic fibers that are continuous with the aortic media and are lined by a thickened layer of intima.
The ductus arteriosus is closed.
Proximal to the coarct, the aortic arch and its branch vessels are dilated and, in older patients, often atherosclerotic
left ventricle is hypertrophic.

44. Clinical Features
depend almost entirely on the severity of the narrowing and the patency of the ductus arteriosus.
Preductal coarctation of the aorta with a PDA;
usually leads to manifestations early in life, hence the older designation of infantile coarctation
cause signs and symptoms immediately after birth.
delivery of poorly oxygenated blood through the ductus arteriosus produces cyanosis localized to the lower half of the body.
Femoral pulses are almost always weaker than those of the upper extremeties.
Many such infants do not survive the neonatal period without intervention
Postductal coarctation of the aorta without a PDA;
usually asymptomatic, and the disease may go unrecognized until well into adult life
upper extremity hypertension, due to poor perfusion of the kidneys, but weak pulses and a lower blood pressure in the lower extremities.
Claudication and coldness of the lower extremeties result from arterial insufficiency.
Adults tend to show exuberant collateral circulation "around" the coarctation involving markedly enlarged intercostal and internal mammary arteries;
expansion of the flow through these vessels leads to radiographically visible "notching" of the ribs.

45. SUMMARY Congenital Heart Disease
Defects of cardiac chambers or the great vessels;
Shunting of blood between the right and left circulation or cause outflow obstructions.
Left-to-right shunts
most common and typically 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
tetralogy of Fallot or transposition of great vessels
cyanotic lesions from the outset and are associated with polycythemia, hypertrophic osteoarthropathy, and paradoxical emboli.
Obstructive lesions include aortic coarctation; the
clinical severity of the lesion depends the degree of stenosis and the patency of the ductus arteriosus.

46. Congenital Heart Disease
A general term to describe abnormalities of the heart or great vessels that are present from birth.

47. Congenital Heart Disease
Three major categories:
left-to-right shunt (Acyanotic heart disease)
right-to-left shunt (Cyanotic heart disease)
obstruction (Stenosis / Atresia) 47

48. Acyanotic Heart Disease
Atrial Septal Defect (ASD),
Ventricular Septal Defect (VSD),
Patent Ductus Arteriosus (PDA), and
Atrioventricular Septal Defect (AVSD). 48

49. Ventricular Septal Defect (VSD)49

50. Atrial Septal Defect (ASD)50

51. Cyanotic Heart Disease
Tetralogy of Fallot (TOF)
Transposition of great arteries (TGA)
Truncus Arteriosus
Tricuspid Atresia
Total Anomalous Pulmonary Venous Connection (TAPVC) 51

52. Tetralogy of Fallot 52

53. Transposition of the Great Arteries53

54. Tricuspid Atresia 54

55. Truncus Arteriosus 55

56. Obstructive Congenital Anomalies
Coarctation of Aorta
Pulmonary Stenosis and Atresia
Aortic Stenosis and Atresia 56

57. Pulmonary Valve Stenosis and Atresia57

58. Hypoplastic Left Heart Syndrome58

59. Teachers open the door but you must walk through it yourself.

61. Thanks