clinical pathology on congenital heart diseases and their pathophysiology. Causitive organism and other factors.

1. CONGENITAL HEART
DISEASES

2. • Congenital heart diseases result from interaction between genetic
and environmental factors.
• GENETIC
• Single classic Mendelian mutant genes account for 3% of congenital
heart diseases; 5% are caused by gross chromosomal aberrations, 3%
by known environmental factors (e.g. rubella, fetal alcohol syndrome),
and the rest by multifactorial gene effects or single gene effects
modulated by random events.
• Single mutant genes (autosomal dominant or recessive or X-linked)
usually cause congenital heart disease as part of a complex of
abnormalities.
• Chromosomal abnormalities also cause congenital heart diseases as
part of a complex of lesions

3. • Environmental factors:
• Fetal environment: Women taking lithium salts and Retinoic acid
used to treat acne during pregnancy may cause several types of
congenital heart lesions.
• Diabetic women or those taking progesterone in pregnancy have an
increased risk.
• Alcoholic mothers risk their babies having CHD (usually left-to-right
shunts).
• Infections: TORCHES. Rubella embryopathy is often associated with
peripheral pulmonic stenosis, patent ductus arteriosus, and valvar
pulmonic stenosis, coxsackieviruses and Mumps virus is responsible
for endocardial fibroelastosis.

4. Classification
• Congenital heart diseases are customary divided into noncyanotic and
cyanotic types.
• By convention, patients who have right-to-left shunts fall into the
cyanotic category whether or not they have readily recognizable
cyanosis.
• Patients who do not have right-to-left shunts-even if they are cyanotic
for other reasons, such as low cardiac output-are placed in the
Acyanotic category.

5. Classification
• Acyanotic: according to the predominant physiologic load placed on
the heart.
• Cyanotic: based on pathophysiology.
• Volume load: L-R shunts-ASD,VSD,PDA.
• Pressure load: Ventricular outflow obstruction; Pulmonary, aortic
valve lesions, aortic coarctation & pulmonary stenosis.
• Decreased pulmonary blood flow: TOF, Pulmonary atresia, Tricuspid
atresia, Single ventricle with pulmonic stenosis.
• Increased pulmonary blood flow: Transposition of great
vessels,Truncus arteriosus.

6. Heart defects
• Patent Ductus Arteriosus
• Atrial Septal Defect
• Ventricular Septal Defect
• Tetralogy of Fallot
• Transposition of the Great Arteries
• Coarctation of the Aorta
• Anomalous Venous Return
• Truncus Arteriosus
• Hypoplastic Left-Heart Syndrome

7. Acyanotic congenital heart diseases
• Left-to-Right Shunt Lesions
i) Atrial Septal Defect (ASD)
ii) Ventricular Septal Defect (VSD)
iii) Atrioventricular Septal Defect (AV Canal)
iv) Patent Ductus Arteriosus (PDA)

8. Atrio-Septal defect(ASD)

9. • ASD is an opening in the atrial septum permitting free communication
of blood between the atria. Seen in 10% of all CHD and 6-10% of all
births (1 of 1500 live births)
• 2 times more common in females than males.
• In 1950 most children with ASD did not reach the first grade.
• Today, first year surgery facilitates normal growth and development

10. • There are 3 major types:
• Sinus Venosus ASD – high in the atrial septum, associated with partial
anomalous venous return & the least common.
• Secundum ASD – at the Fossa Ovalis, most common.
• Primum ASD – lower in position & is a form of Atrial Septal Ventricular
Defect (ASVD), MV cleft.

11. Hemodynamics
• Small shunts may remain asymptomatic throughout life, or they may
be discovered in pregnancy due to volume overload.
• Large defects cause left to right shunts during late ventricular systole
or early diastole.
• This leads to diastolic overload of the right ventricle and increased
pulmonary blood flow causing increased pulmonary vascular
resistance and pulmonary hypertension that may cause a reversal of
shunt the Eisenmenger syndrome

12. Ventricular septal defect

13. • VSD – is an abnormal opening in the ventricular septum, which allows
free communication between the Rt & Lt ventricles. Accounts for
25% of CHD.
• There are 4 Types
• Perimembranous (or membranous) – Most common.
• Infundibular (subpulmonary or supracristal VSD) – involves the RV
outflow tract.
• Muscular VSD – can be single or multiple.
• AVSD – inlet VSD, almost always involves AV valvular abnormalities

14. Hemodynamics
• The left to right shunt occurs secondary to PVR being < SVR, not the
higher pressure in the LV.
• This leads to elevated RV & pulmonary pressures & volume
hypertrophy of the LA & LV.
• Increased pulmonary overflow causes pulmonary oedema and
eventually increases pulmonary vascular resistance leading to
pulmonary hypertension.
• Elevated Pulmonary Vascular Resistance causes reversal of the shunt
to right-to-left shunt

15. • Clinical Signs & Symptoms Depend on size. Ranges from
Asymptomatic, growth, failure, recurrent LRTI, congestive heart,
failure, cyanosis and loud holosystolic murmurs.
• Small - moderate VSD, 3-6mm, are usually asymptomatic and 50% will
close spontaneously by age 2yrs.
• Moderate – large VSD, almost always have symptoms and will require
surgical repair.
• Today almost all VSD can be closed successfully, even in small babies.
• Large defects lead to pulm hypertension-Eissenmenger syndrome.

16. Atrioventricular Septal Defect
• AVSD results from incomplete
fusion the endocardial cushions,
which help to form the lower
portion of the atrial septum, the
membranous portion of the
ventricular septum and the
septal leaflets of the triscupid
and mitral valves.
• They account for 4% OF ALL
CHD.
• Common in downs Syndrome

17. Types of AVSD
Complete Form
• Low primum ASD continuous with a posterior VSD.
• Cleft in both septal leaflets of Tricuspid Valve/Mitral Valve.
• Results in a large L to R shunt at both levels, TR/MR, Pulm HTN with
increase in PVR.
Incomplete Form
• Any one of the components may be present.
• Most common is primum ASD, cleft in the MV & small VSD.
• Hemodynamics are dependent on the lesions.

18. Symptoms
• Incomplete AVSD maybe
indistinguishable from ASD - usually
asymptomatic.
• Congestive heart failure in infancy.
• Recurrent pulmonary infections,
Failure to thrive, Exercise intolerance,
easy fatigability.
• Late cyanosis from pulmonary
vascular disease with R to L shunt.
Clinical
• Hyperactive precordium
• Normal or accentuated 1st heart
sound
• Wide, fixed splitting of S2
• Pulmonary systolic ejection murmur
w/thrill
• Holosystolic murmur @ apex with
radiation to axilla
• Mid-diastolic rumbling murmur @ LSB
• Marked cardiac enlargement on CX-
Ray

19. PDA
• The Ductus Arteriosus Connects
Pulmonary Artery to Aorta Shunts
blood away from lungs in fetal
circulation.
• Maintained patent by low oxygen
pressures and presence of
prostaglandins
• Closes at Birth secondary to
Increase in PaO2 and Decrease in
level of prostaglandins.
• If this shunt persists post delivery
then its called PDA

20. PDA
• Normally closes in the 1st wk of life, within 48hrs post delivery.
• 5-10% of all births (1 of 2000 live births) occurs in 80% of premature
babies
• Accounts for 10% of all CHD, seen in 10% of other congenital heart
lesions and can often play a critical role in some lesions. Often
associated with coarctation & VSD.
• 2-3 times more common in females than males.
• 5th or 6th most common congenital cardiac defect.
• May be desirable with some defects. Morbidity/Mortality related to
degree of blood flow through PDA.

21. Hemodynamics of PDA
• As a result of higher aortic pressure and low pulmonary pressure,
blood shunts L to R through the ductus from Aorta to PA into the
lungs. This causes pulmonary overflow and systemic hypoperfussion.
• The pulmonary veins return excess blood to the left atria into left
ventricle thus increasing CO but with decreased systemic output and
hypoxia causing a heamodynamic paradox.
• Increased pulmonary overflow causes pulmonary oedema and
eventually increases pulmonary vascular resistance leading to
pulmonary hypertension.
• Increased pressures in the right will eventually reverse the flow and
the condition becomes cyanotic.

22. PDA
• With increase LV output and low systemic perfussion, hypoxia triggers
cardiac support neuro-humoral effects i.e the sympathetic system and
RAAS which cascades to promote heart failure.
• There will be left atria and ventricular enlargement, aortic and
pulmonary vein and arteries dilatation with pulmonary hypertension.
• Cerebral and systemic hypoxia lead to cerebral damage and multi-
organ failure.

23. PDA
Small PDA’s are usually asymptomatic
Large PDA’s can result in symptoms of Congestive Heart Failure, growth
restriction, Failure to Thrive.
Bounding arterial pulses
Widened pulse pressure
Enlarged heart, prominent apical impulse
Grade 1-2 Classic continuous machinery systolic murmur (washing
Machine)
Mid-diastolic murmur at the apex

24. Obstructive Heart Lesions
• Pulmonary Stenosis
• Aortic Stenosis
• Coarctation of the Aorta

25. Pulmonary Stenosis
• Pulmonary Stenosis is
obstruction in the region of
either the pulmonary valve or
the subpulmonary ventricular
outflow tract.
• Accounts for 7-10% of all CHD.
• Most cases are isolated lesions
• Maybe biscuspid or fusion of 2
or more leaflets.
• Can present w/or w/o an intact
ventricular septum.

26. Hemodynamics
• Right Ventricular volume overload, RV pressure hypertrophy ->Right
Ventricular failure.
• Right Ventricular pressures maybe more than systemic pressure.
• Post-stenotic dilation of main Pulmonary Artery.
• In severe stenosis without intact septum lead to R-L shunt through
Pertent foramen ovale causing cyanosis.
• Cyanosis is indicative of Critical PS.

27. Pulmonary Stenosis
Clinical Signs & Symptoms
• Depends on the severity of obstruction.
• Asymptomatic with mild PS < 30mmHg.
• Mod-severe: 30-60mmHg, > 60mmHg
• Prominent jugular a-wave, RV lift
• Split 2nd heart sound with a delay
• Ejection click, followed by systolic murmur.
• Heart failure & cyanosis seen in severe cases

28. Aortic Stenosis
• Aortic Stenosis is an obstruction to the outflow from the left ventricle
at or near the aortic valve that causes a systolic pressure gradient of
more than 10mmHg. Accounts for 7% of CHD.
• 3 Types
• Valvular – Most common.
• Subvalvular(subaortic) – involves the left outflow tract.
• Supravalvular – involves the ascending aorta is the least common.

29. Hemodynamics
• Pressure hypertrophy of the LV and LA with obstruction to flow from
the LV.
• Mild AS 0-25mmHG
• Moderate AS 25-50mmHg
• Severe AS 50-75mmHg
• Critical AS > 75mmHg

30. Aortic Stenosis
Symptoms
• Mild AS may present with
exercise intolerance, easy
fatigabiltity, but usually
asymptomatic.
• Moderate AS – Chest pain,
dypsnea on exertion, dizziness &
syncope.
• Severe AS – Weak pulses, left
sided heart failure, Sudden
Death.
Clinical Signs
• LV thrust at the Apex.
• Systolic thrill @ right
base/suprasternal notch.
• Ejection click, III-IV/VI systolic
murmur @ Right sternal border
(RSB)/Left Sternal Border (LSB)
with radiation to the carotids.

31. Coarctation of the Aorta
• Coarctation- is narrowing of the
aorta at varying points anywhere
from the transverse arch to the
iliac bifurcation.
• 98% of coarctations are
juxtaductal.
• Male: Female ratio 3:1.
• Accounts for 7 % of all CHD
• Associated with Bicuspid Aortic
Valve and Turner’s Syndrome

32. Location of Coarctation
Pre-Ductal
• Less common but more serious
• Associated with VSD, PDA, Transposition
Post-Ductal
• More common
• Often associated with collateral circulation beyond coarctation, which
minimizes effect.
• Diagnosed by a difference in blood pressure between lower extremities
and upper ones.
• Pressure in upper extremities > lower

33. Hemodynamics
• There is obstruction of left ventricular outflow -> severely reduced
systemic blood flow and pressure hypertrophy of the LV.
• Increased work on the heart leading to CHF and cardiovascular
collapse.

34. Rib Notching

35. Cyanotic Heart Diseases
• Tetralogy of Fallot
• Complete Transposition of the Great Arteries.
• Anomalous Venous Return
• Truncus Arteriosus
• Hypoplastic Left Heart Syndrome

36. Tetralogy of Fallot
• Most common of the cyanotic cardiac
diseases.
• Mortality increases with age (1 year-
old has a 25% mortality, 40 year-old
has 95%).
• Four Defects
• Pulmonary infandibular Stenosis
(determinant factor related to
severity) i.e narrowing of RV outflow
• VSD (usually large)
• Overriding Aorta
• RV hypertrophy

37. TOF hemodynamics
• Due narrowed pulmonary infandibula and overriding Aorta, both RV
and LV ejects blood into the Aorta.
• VSD is restrictive thus no gradient across the chambers
• Systolic pressure in LV and RV are the same
• RV persists its dorminance as in fetal life preferentially ejects into the
aorta. With increased flow it dilates giving a boot shape on X-ray.
• RV pressure never exceeds systemic pressure.
• With the narrowed pulmonary infandibula, very minimal blood is
delivered to the lungs for oxygenation, thus the cyanosis and finger
clubbing.

38. Complete Transposition of the Great Arteries
• Second most common form of
CHD. Causes blue baby
syndrome
• Aorta arises from RV and
Pulmonary Arteries from LV.
• Without an abnormality, life
would not be possible.
• ASD
• VSD (30-40%)
• PDA

39. Hemodynamics
• Oxygen poor blood returns to the RA, to RV then into the
misconnected Aorta back to the system.
• Oxygen rich blood returns to the LA from lungs into the LV then into
the PA back to the lungs
• Two separate circutes are formed, one of oxygen poor and oxygen
rich blood.
• Other heart defects associated with TGA help mitigate the problem.
PDA, VSD and ASD facilitate mixing of this blood thus allowing some
oxygen to reach tissues.

40. Anomalous Venous Return
• Return of pulmonary venous
blood to the right atrium instead
of the left or in the systemiv
veins. Can also be partial or
complete.
• ASD is present to sustain life.

41. Hemodynamics of TVR
• Pulmonary veins pours into the RA causing volume overload and thus
pressure overload to thr RA and RV.
• There is incread blood flow to the lungs leading to pulm oedema, and
increased pulm vascular resistance then pulmonary hypertension.
• Without a ASD, life is not sustainable.
• LA and LV receive less and pump less. Reduced CO triggers neuro-
humoral cardiac response which cascades to CHF

42. Truncus Arteriosus
• Defect in which one large vessel(
usually pulmonary trunk) arises
from right and left heart over a
large VSD.
• Cyanosis is often present.
• CHF common

43. • Outflow from both ventricles is directed to this one trunk.
• Resistances to flow is determined by both systemic and pulmonary
resistance.
• Subnormal arterial oxygen concentration, pulmonary flow is elevated
causing over circulation and deprived systemic circulation.
• This caused increased myocardial workload and failure.

44. Hypoplastic left heart syndrome
• It’s a condition where the left heart
does not form normally during
embryogenesis.
• Features are:
• -under developed LV
• Unformed or underdeveloped
mitrial valve
• Unformed or underdeveloped
Aortic valve
• Underdeveloped or very small
ascending aorta
• Atrioseptal defect

45. hemodynamics
• In the first few days of life, the right side pumps blood to both the
lungs and the system via the PDA.
• Pulmonary venous return drains into the right heart via ASD
• Closure of the two is fatal therefore they must be kept open using
prostaglandins.

46. Dextrocardia
• Dextrocardia is a radiographic term used when the heart is on the right side of
the chest.
• When dextrocardia occurs with reversal of position of the other important organs
of the chest and abdomen (e.g. liver, lungs, and spleen), the condition is called
situs inversus totalis and the heart is usually completely normal.
• When dextrocardia occurs with otherwise normal organs (situs solitus), the heart
usually has severe defects.
• Rarely, the abdominal organs and lungs are neither in situs solitus or situs
inversus, these states are called situs ambiguous.
• The liver is central and anterior in the upper abdomen with the stomach pushed
behind
• There may be bilateral right-sidedness (asplenia syndrome) or bilateral left-
sidedness (polysplenia syndrome), but in virtually all cases of situs ambiguous,
severe congenital heart disease is present.

47. Cardiomyopathy
• Its an acquired or hereditary progressive disease of the myocardium.
• The muscle weakens and it is unable to pump blood to the systems
• There are 3 types of cardiomyopathy
• i) Dilated
• ii) Restrictive
• Iii) Hypertrophic
• Treatment depends on the type.

48. Dilated Cardiomyopathy-Pathology
• Gradual four chamber hypertrophy and dilation. can occur at any age
as slow progressive CHF but mostly affects middle aged people.
• Leads to impaired myocardial contractility and CHF.
• The following gross changes may be observed
• The heart is flabby.
• Cardiomegaly (to 900gm) is typical, although wall thickness may not
reflect the degree of hypertrophy due to dilation
• Poor contractile function and stasis can predispose to mural thrombi
• Valves and coronary arteries are generally normal

49. Hypertrophic cardiomyopathy
• Characterised by abnormal thickening of the myocardium
• Affected people have Fhx of the disease, linked to genetic mutations.
• characterized by heavy, muscular, hypercontractile, poorly compliant
hearts with poor distolic relaxation. Has increased risk of Sudden
death.

50. Pathology of Hypertrophic cardiomyopathy
• marked cardiomegaly owing to hypertrophy, left ventricle greater
than right ventricle, often with atrial dilation.
• Classically, there is disproportionate thickening of the interventricular
septum (asymmetric septal hypertrophy) although many cases have
concentric or symmetric hypertrophy
• The left ventricular cavity is compressed into a banana-like
configuration by the symmetric bulging of the septum
• Septal thickening at the level of the mitral valve compromises left
ventricular systolic outflow by contact of the anterior mitral leaflet
with the septum.

51. • Microscopically, there is marked myofibre hypertrophy; 25-50% of the
septum classically shows helter-skelter myocyte disarray,
accompanied by myofilament disorganization within muscle cells
• There are abnormal thick-walled intramyocardial arterioles, as well
aspatchy replacement fibrosis, the later presumably due to focal
ischemic injury.

52. Restrictive Cardiomyopathy
• Relatively rare. The myocardium becomes rigid and less elastic so it
cant expand to fill with blood in diastole. Often occurs in old age.
• It is characterized by ventricular subendocardial fibrosis extending
from the apex to the ventricular inflow tracts, often with superiposed
mural thrombus
• The atrioventricular valves may be involved
• Restrictive physiology results with reduced ventricular chamber
volume and reduced CO

53. Arrythmogenic Right ventricular
cardiomyopathy
• Arrythmogenic right ventricular cardiomyopathy is a recently
recognized cardiomyopathy with distinct presentation and
morphology
• It is typically a familial disorder characterized by predominantly right
sided failure (occasionally left sided) and various rythmic
disturbances, particularly ventricular tarchcardia and sudden death.
• Morphologically the right ventricular wall is severely thinned with
myocyte loss and profound fatty infiltration.
• Death occurs secondary to progressive CHF, embolism of mural
thrombi of fatal arrythmias.

54. Myocarditis
• It is characterized by myocardial inflammation as the principle feature
• Most cases are thought to be of viral origin (e.g. coxsackie A and B,
echovirus). Cardiac involvement occurs days to weeks after a primary
viral infection, which can be in the heart or solely at another site
• The cardiac involvement can be a direct infection or an immunological
reaction to a myocardial antigen triggered by the infectious agent
• Rare cases are secondary to bactereamia e.g. staphylococci,
tuberculosis trypanosome cruzi

55. pathology
• Gross
• Gross manifestations include a flabby heart often with four chamber
dilation and patchy heamorrhagic mottling.
• Mural thrombi can form in dilated chambers
• Endocardium and valves are unaffected
• After the acute stage, there may be residual dilation or hypertrophy

56. • Microscopically
• There is a myocardial inflammatory infiltrate with associated myocyte
necrosis or degeneration. Lesions are typically focal and may be
missed by routine endomyocardial biopsy.
• In viral infections, associated myofibre necrosis is seen with interstitial
edema and a mononuclear cell infiltrate. After the acute stage,
inflammatory lesions may resolve, leaving either no residual or
variable interstitial and replacement fibrosis
• Depending on cause, bacteria, other organisms and cellular infiltrates
may be demonstrated.

57. Read about:
• Pericarditis
• Tumours of the heart