Fallot's tetralogy is the most common form of cyanotic congenital heart disease. It consists of four anatomical abnormalities: a ventricular septal defect, pulmonary stenosis, an overriding aorta, and right ventricular hypertrophy. The degree of pulmonary stenosis determines the direction and magnitude of blood flow through the ventricular septal defect. In severe cases, hypoxic spells can occur due to an imbalance between systemic oxygen delivery and demand during times of increased cardiac output. Without surgical repair, long-term outcomes are poor with most patients not surviving past childhood.

1. TETROLOGY OF FALLOT
Dr Rijin Mohammad Thaju
Junior Resident
Internal Medicine

2. • VSD + RVOT Obstruction – seen in many different
anatomic malformations.
• Fallot’s tetralogy is the most common combination of
these two defects.
• The tetrology consists of RVOT obstruction, VSD,
overriding of the VSD by aorta and RVH.

3. • Danish monk, Nicholas Steno in
1672
• Described in detail by Fallot in
1888
• Most common congenital
cyanotic heart disease.
• Prevalence : 0.26 per 1,000 live
births

4. Genetic syndromes and associations
- DiGeorge/VCFS – CATCH 22 (25% have TOF)
- Down syndrome
- Alagille syndrome(15%)
- CHARGE and VATER/ VACTERAL associations
Genes identified :
- NKX2.5
- JAG1 in Alagille syndrome
- TBX5 in Holt-Oram syndrome.

5. Environmental Factors:
Maternal diabetes [3 fold increased risk of TOF]
Retinoic acids
Maternal phenylketonuria (PKU)
Recurrence risk:
-1 sibling affected: 2.5% ≥2 siblings affected: 8%
-Mother with TOF : 2% - Father with TOF: 1.4%

6. Anatomy of TOF

7. Embryology of heart – a brief note

12. Development of Inter ventricular
septum

14. Anatomy of TOF
Core Concepts

15. Mitral Opening
Tricuspid Opening
Pulmonary Trunk
Aorta
Right Ventricle Left Ventricle
Muscular Septum
Infundibular
Septum

16. 1.VSD
2.RVOT
obstruction
3.Overriding of
VSD by aorta
4.RVH

17. What happens in TOF?
• In the normal heart, division of the fetal bulboventricular cavity
(conotruncus) culminates in alignment of the infundibular septum
with the muscular trabecular septum.
• In Fallot’s tetralogy, the infundibular septum deviates anteriorly and
cephalad and is therefore not aligned with the trabecular septum.
• This creates a ventricular septal defect at the site of malalignment.
• The deviation of the infundibular septum encroaches on the right
ventricular outflow tract and causes infundibular stenosis and a
biventricular (overriding) aorta.
• The nonrestrictive malaligned ventricular septal defect accounts for
systemic systolic pressure in the right ventricle and concentric right
ventricular hypertrophy.

18. VSD in TOF
• A single large malaligned subaortic defect almost aprox
size of diameter of Aortic root
• Most common: perimembranous type (80%) followed
by muscular type.
• Malaligned VSDs are located in the perimembranous
septum with extension into the infundibular septum.
• Subarterial ventricular septal defects (more frequent
among Asians) are accompanied by aortic regurgitation
because a supporting infundibulum is absent.
• Muscular ventricular septal defects sometimes coexist
but usually close spontaneously in the first year of life.

20. RVOT obstruction in TOF
Causes of RVOT obstruction in TOF:
1. Malalignment of the infundibular septum
2. Hypertrophy of the septoparietal trabeculations
3. Hypertrophy of the trabecula septomarginalis
4. Hypertrophy of the infundibular septum
Anterior and cephalad malalignment of the
infundibular septum can narrow the entire right
ventricular outflow tract.

21. Levels of RVOT obstruction:
• The pulmonary valve is stenotic and bicuspid and
occasionally unicommissural and unicuspid.
• Occasionally, the main site of obstruction is a
hypoplastic pulmonary annulus or the ostium of
the infundibulum
• The pulmonary trunk, its bifurcation, and its right
and left branches may be segmentally or diffusely
hypoplastic
• Pulmonary atresia is the most severe form of
RVOT obstruction.

22. Pulmonary atresia with TOF
• Pulmonary atresia with Fallot’s tetralogy is the ultimate
expression of severity.
• The right ventricle terminates blindly against an atretic
pulmonary valve or against imperforate muscle.
• The pulmonary trunk is either a vestigial cord or a
hypoplastic funnel-shaped channel that widens as it
approaches the bifurcation.
• The proximal pulmonary arteries are hypoplastic and
may be discontinuous.
• The entire right ventricular output enters the systemic
circulation via the nonrestrictive malaligned ventricular
septal defect.

23. • The biventricular aorta is dilated and often
continues as a right aortic arch.
• The lungs are perfused by systemic-to-pulmonary
arterial collaterals, on which survival depends.
• Exceptionally, the pulmonary circulation is
supplied primarily, if not exclusively, by a long,
narrow sigmoid-shaped ductus arteriosus that is
structurally a muscular systemic artery similar to
a systemic arterial collateral, directed from the
aorta into the pulmonary artery.
Pulmonary atresia with TOF

24. Systemic to pulmonary collaterals in
TOF
• Fallot’s tetralogy with pulmonary atresia - pulmonary
circulation is supplied entirely by collateral arteries that
serve both a nutritive function and a respiratory function.
• 3 types of arterial blood supply to the lungs
1. Systemic arterial collaterals
2. Ductus arteriosus
3. Small diffuse pleural arterial plexuses.
• Systemic arterial collaterals are classified according to their
origins as:
1. Bronchial, from bronchial arteries
2. Direct systemic arterial collaterals, from the descending aorta
3. Indirect systemic arterial collaterals, which originate from the
internal mammary, innominate, and subclavian arteries.

25. Systemic to pulmonary collaterals in
TOF
• Systemic arterial collaterals anatomose with pulmonary
arteries in three locations: (1) intrapulmonary; (2)
extrapulmonary; and (3) hilar.
• All three major types of collaterals are present when
Fallot’s tetralogy occurs with pulmonary atresia, but
only bronchial collaterals are present when the
tetralogy occurs with pulmonary stenosis.
• Systemic arterial collaterals have a strong tendency to
harbor intimal cushions (proliferations) that serve as
sites of potential segmental stenosis

26. Aortic regurgitation in TOF
• AR in TOF occurs because the malaligned VSD
is partially roofed by the aortic valve.
• Herniation of aortic cusps is more frequent
with an isolated subarterial ventricular septal
defects than with Fallot’s tetralogy
• In cyanotic Fallot’s tetralogy, the aortic valve is
not subjected to turbulent flow because the
left ventricle ejects directly into the aorta
without generating a left-to-right jet.

27. Anomalous origin of coronary arteries
• It is of no functional importance but of
considerable surgical importance.
• The most common anomalies are origin of a
conus artery or the left anterior descending
artery from the right coronary artery or from
the right sinus of Valsalva.

28. ASD in TOF
• An atrial septal defect occasionally coexists
with Fallot’s tetralogy (5%) , but the term
pentalogy is longer used.
• PFO is seen in 83% cases.

29. TOF- Aortic arch
- Right Aortic arch : 25%
- Double aortic arch
- Aberrant Left SCA from
descending Aorta
- Cervical aortic arch
- Vascular ring with and
without bronchial compression

30. Physiology of TOF

31. • The magnitude and direction of the shunt in TOF
depend essentially on two variables:
1. The degree of RVOT obstruction (PAH)
2. The degree of Systemic vascular resistance. (Systemic
HTN)
• When pulmonary stenosis offers lesser resistance, the
shunt is left-to-right.
• When the resistances are equal, the shunt is balanced.
• When right ventricular outflow resistance exceeds
systemic resistance, the shunt is right-to-left.

32. When Subpulmonary Obstruction
Is Minimal at Birth
– Uncommon
– present at 4 - 6 wks
– with features indistinguishable
from large VSD
– babies are breathless, feed
poorly, gain weight poorly, and
are not cyanosed
– Pink TOF or Acynotic TOF
– Later with increasing RVH, &
RVOT obstrucn, shunt gets
reversed & cyanosis+

33. • When Subpulmonary
Obstruction Is moderate
at Birth
– Acyanotic at birth.
– Systolic murmur during
routine examination.
– The development of
cyanosis is dependent on
increasing infundibular
stenosis, and not on the
degree of aortic override.

34. • When Subpulmonary
Obstruction Is Severe
from Birth
– Persistent cyanosis
becomes apparent within
the first few hours or
days of life.
– pulmonary circulation is
duct-dependent.
– Spontaneous closure of
the duct results in death.
Maintenance of ductal
patency, by PG E infusion
is crucial.
SYSTEMIC -
PULMONARY
COLLATERALS
PATENT DUCTUS

35. Presentation with Absent Pulmonary Valve
– Presentation is classical
– Respiratory symptoms of inspiratory and expiratory
stridor, dyspnoea
– caused by lobar collapse, lobar emphysema.
– reflect compression of the bronchial tree by the
grossly dilated proximal pulmonary arteries.

36. Physiology of Pulmonary atresia with
TOF
• The ultimate expression of right ventricular outflow
obstruction is pulmonary atresia, which commits the
entire right ventricular output to the aorta.
• Pulmonary blood flow then depends on systemic
arterial collaterals, which provide the lungs with
normal or increased flow, so cyanosis can be mild or
even absent.
• Unobstructed flow through arterial collaterals sets the
stage for pulmonary vascular disease.
• Stenoses at intimal cushions in arterial collaterals
protect the pulmonary vascular bed, but at the price of
reduced pulmonary blood flow.

37. Why is heart failure less common in
TOF?
• When right ventricular blood preferentially flows
into the aorta, pulmonary blood flow falls
reciprocally, so the left side of the heart is
underfilled, reduced in size with reduced stroke
volume. So, left heart failure is unlikely in TOF.
• Irrespective of the degree of RVOT obstruction,
right ventricular systolic pressure cannot exceed
systemic because the ventricular septal defect is
nonrestrictive. So, right heart failure is also
unlikely in TOF.

38. Causes of heart failure in TOF
1. Anemia
2. Infective endocarditis in incompetent aortic valve
3. Acquired calcific aortic valve
4. Systemic hypertension
5. Unrelated myocarditis
6. Aortic or pulmonary regurgitation
7. Severe pulmonary stenosis with Restrictive VSD
8. Accessory tricuspid leaflet tissue partially occluding
the malaligned VSD
9. TOF with pulmonary atresia due to excessive
collateral blood flow.

39. Effect of systemic Hypertension
• Irrespective of the degree of RVOT obstruction, right
ventricular systolic pressure cannot exceed systemic
because the ventricular septal defect is nonrestrictive.
• Accordingly, a systemic ceiling is placed on the pressure
overload that pulmonary stenosis can impose on the right
ventricle.
• When pulmonary stenosis is severe, right ventricular
pressure overload is determined by systemic vascular
resistance.
• Increased resistance associated with systemic hypertension
or, less commonly, with acquired calcific aortic stenosis
improves pulmonary blood flow but increases right
ventricular afterload.

40. Other morphologic changes in TOF
• Tricuspid leaflets develop fibrous thickening
because right ventricular systolic pressure is
systemic, but the thickened leaflets are
seldom incompetent.
• Low pressure and low flow in the pulmonary
circulation alter the small muscular arteries
and arterioles and cause thinning of the media
with interruption of elastic tissue and
widespread thromboses.

41. History

42. • Most common cyanotic congenital heart disease
after 4 years of age.
• Gender distribution in Fallot’s tetralogy is
approximately equal.
• Birth weight tends to be lower than normal, and
growth and development are generally retarded.
• Familial tetrology: the jagged 1 gene,71 with
NKX2.5 mutations,72 and with chromosome
22q11.2 deletion.

43. • Usually diagnosed in neonates and infants.
• When the shunt is left-to-right, initial
suspicion is a prominent systolic murmur.
• When the shunt is balanced, the murmur
persists in addition to mild, intermittent, or
stress-induced cyanosis.
• When the shunt is reversed, the prominence
of the systolic murmur is inversely
proportional to the degree of cyanosis.

44. • Early infancy - uneventful
• Cyanosis may be delayed for months and
develops due to increased oxygen
requirements of the growing infant
• Patients seldom remain acyanotic after the
first few years of life, and by 5 to 8 years of
age, most children are conspicuously cyanotic.

45. • Survival: About two thirds of patients reach their first
birthday, approximately half reach 3 years, and
approximately a quarter completed the first decade
of life.
Life expectancy of unoperated patients with TOF
based on data from the Danish populations study.

46. Hypoxic spells
(Paroxysmal hyperpnea, syncopal attacks, hypoxic or hypercyanotic spells)
• Exercise-induced hypoxemia and increased carbon dioxide content
stimulate the respiratory center and the carotid body, provoking
hyperventilation that is subjectively perceived as dyspnea
• A hypoxic spell begins with a progressive increase in the rate and
depth of breathing and culminates in paroxysmal hyperpnea,
deepening cyanosis, limpness, syncope, and occasionally
convulsions, cerebrovascular accidents, and death.
• Peak incidence is between the second and sixth month of life, with
an occasional spell as early as the first month but comparatively few
spells after age 2 years, and only rarely in adults.
• Spells in infants are typically initiated by the stress of feeding,
crying, or a bowel movement, particularly after awakening from a
long deep sleep.

47. Hypoxic spells
Mechanism
• Vulnerable respiratory control mechanisms, which are especially
sensitive after prolonged deep sleep
• React to the sudden increase in cardiac output provoked by feeding,
crying, or straining, by initiating the following vicious cycle.
• As heart rate and cardiac output increase, venous return increases
in the face of fixed obstruction to right ventricular outflow, so the
right-to-left shunt increases.
• Infundibular contraction reinforces this pattern but does not initiate
it.
• The increased right-to-left shunt causes a fall in systemic arterial
pO2 and pH and a rise in pCO2, a blood gas composition to which a
sleep-sensitive respiratory center and carotid body overreact,
provoking hyperpnoea, which in turn further increases the cardiac
output and perpetuates the cycle.

48. Sudden
increase C.O
Vulnerable
respiratory
control
mechanisms
right-to-left
shunt
increases
venous return
increases
Hyperapnoea

49. (1) An acceleration in heart rate
(2) An increase in cardiac output and venous return;
(3) An increase in right-to-left shunt;
(4) Vulnerable respiratory control centers
(5) Infundibular contraction.
 Manual compression of the abdominal aorta
can abort a spell by decreasing cardiac output
and venous return.

50. How does squatting help?
The mechanisms by which squatting exerts its beneficial
effects are as follows:
1. Counter acting post exertion orthostatic hypotension
2. Increases systemic vascular resistance
3. Isotonic leg exercise reduces the oxygen saturation of the
venous return.
4. Right ventricular blood shunted into systemic circulation has
a higher oxygen content and pH and a lower pCO2 content.
5. The higher pO2 and pH and the lower pCO2 reduce the
stimulus to the respiratory center and carotid body and
reduce the hyperventilatory dyspnea.

52. Complications of Hypoxic spells
• Brain damage and Mental retardation.
• Cerebral venous sinus thromboses and small occult
thromboses
• Hypernasal resonance or nasal speech (velopharyngeal
insufficiency)
• Brain abscess and cerebral embolism. Iron deficiency in
patients less than 4 years of age increases the risk of
CVT.
• Wheezing and stridor have been attributed to tracheal
compression by an enlarged aorta.
• A stenotic pulmonary valve and an incompetent aortic
valve are substrates for infective endocarditis.

53. Natural History
• The clinical picture initially resembles an isolated
nonrestrictive ventricular septal defect with large left-
to-right shunt.
• With the development of right ventricular outflow
obstruction, excessive pulmonary blood flow and
volume overload of the left ventricle are decreased,
symptoms related to the left-to-right shunt diminish,
and physical development improves.
• Obstruction to right ventricular outflow may progress
sufficiently to reverse the shunt, resulting in late onset
cyanosis.

54. Natural History
• When a restrictive ventricular septal defect is
accompanied by severe pulmonary valve
stenosis, the clinical picture resembles
isolated pulmonary stenosis with intact
ventricular septum.
• A restrictive ventricular septal defect with
mild pulmonary stenosis is associated with a
conspicuous murmur and few or no symptoms
but with the risk of infective endocarditis.

55. • Underdeveloped
• VSD with pulmonary atresia – patients will be in chronic heart failure
• Cyanosis maybe absent, mild or severe, or appear only on exertion.
Associated syndromes:
1. CATCH 22 monosomy 22q11
2. Down trisomy 21
3. Velocardiofacial (Shprintzen-Goldberg) syndrome
4. Goldenhar’s syndrome (oculo-auriculo-vertebral dysplasia)
5. Absent thumb and first metacarpal
6. Absence of a pectoralis major muscle (congenital pectoral dysplasia or
Poland’s syndrome
7. Syndactyly, Brachydactyly with Hypoplasia of the ipsilateral hand
8. Underdevelopment of the left arm secondary to an isolated left
subclavian artery
Physical Appearance

56. • The arterial pulse is normal, irrespective of the
severity of pulmonary stenosis
– When the shunt is balanced, the left ventricle
maintains a normal stroke volume
– In severe pulmonary stenosis or atresia, a reduced
left ventricular stroke volume is supplemented by
right ventricular blood ejected directly into the
aorta.
• High volume pulse- large systemic arterial
collateral flow or aortic regurgitation.
Arterial Pulse

57. JVP
• Usually normal
– Reason: The right ventricle can eject at systemic
resistance without increasing its filling pressure
because the VSD decompresses it. Hence right atrial
pressures are not affected.
• When is JVP elevated in TOF?
– Accessory tricuspid leaflet partially occluding the VSD
– Systemic HTN
– Acquired aortic stenosis
– Persistent Left SVC (hence prominent left JVP)

58. Precordial movement and palpation
• Right ventricular impulse felt in 4th and 5th left
ICS and subzyphoid area.
• Impulse at the right sternoclavicular junction.
-Dilated right aortic arch.
• Palpable A2 in the 2nd left ICS because a
hypoplastic anterior pulmonary trunk is all
that guards the enlarged aortic root.
• Systolic thrill only in mild Pulmonary stenosis
or restrictive VSD.

59. Auscultation
1. Aortic ejection click – maximal at the upper RSB, but when loud, it is heard
along the LSB and toward the apex.
2. ESM of PS - maximal in the 3rd left ICS because the stenosis is infundibular.
Subinfundibular stenosis results in a lower location of the murmur. As the
severity of PS increases, the ESM becomes shorter and softer, and cyanosis
worsens. During a hypoxic spell, the ESM of PS shortens and disappears.
3. PSM of VSD - maybe present initially, but as PS worsens, it becomes silent.
4. Continuous murmurs- seen in VSD with pulmonary atresia originate in
direct and indirect systemic arterial collaterals. Heard beneath the
clavicles, in the back, to the right and left of the sternum, and in the right
and left axillae.
5. PSM of TR - right ventricular failure caused by systemic hypertension or
acquired aortic stenosis or partial occlusion of the ventricular septal defect
by tricuspid leaflet tissue.
6. Diastolic murmurs - aortic regurgitation, or much less frequently, by
absent pulmonary valve

60. Auscultation
1. Loud A2
2. P2 will be absent since pulmonary blood
flow is very low.
3. S4 usually absent since atrial contraction is
not increased.
4. RVS3 present if RVF occurs
5. LVS3 occurs if there is increased LV filling by
systemic pulmonary collaterals.

61.  Adult TOF :
- Continuous murmur – due to syst. to pulm. collaterals
- AR
- Cardiomegaly (AR, HT, collaterals)
 Post operative TOF:
Single S2 (A2)
MSM of residual PS often
Low frequency EDM of PR often
PSM if residual VSD

62. Working rule
• When a loud continuous murmur is heard in
the neonatal period,-
– originate from flow through large major Aorto
pulmonary collaterals than the PDA.
– Likely to have co-existing pulmonary atresia.
– Cyanosis may not be so marked, since pulmonary
blood flow is more adequately maintained
through the collateral arteries

63. ECG
• Electrocardiogram from a 2-year-
old girl with cyanotic Fallot’s
tetralogy.
– P waves in leads 1, 2, 3, and V2-
3 are peaked but not tall.
– Moderate right axis deviation
– RVH: Tall R in V1 with rapid
transition to rS in V2
– Right precordial T waves were
normal because right ventricular
systemic pressure did not
exceed systemic.
– Q waves are absent in left
precordial leads because the left
ventricle was underfilled.
– Post operative – RBBB in 45% ,
LAHB in 15%

64. Chest X-ray
• X-ray from a 4-year-old girl with
classic cyanotic Fallot’s tetralogy.
• The heart is typically boot-shaped
because a small underfilled left
ventricle (LV) lies superior to a
relatively horizontal ventricular
septum and an elevated
interventricular sulcus (unmarked
arrowhead) inferior to which lies the
concentrically hypertrophied apical
right ventricle (RV).
• The ascending aorta (Ao) is
prominent, the main pulmonary
artery segment (PA) is concave, and
the lungs are oligemic.

65. • X-rays from two patients 55 years apart in age.
• A, A 20-day-old male infant with Fallot’s
tetralogy and pulmonary atresia.
• The boot-shaped apex is emphasized by the
concave main pulmonary artery segment
(arrow) and the right aortic arch (Ao).
• The lung fields show the lacy appearance of
systemic arterial collaterals. B, X-ray from a 55-
year-old woman with Fallot’s tetralogy,
pulmonary atresia, and acquired calcific stenosis
and aortic regurgitation. Death was from
biventricular failure.
• The lung fields show the lacy appearance of
systemic arterial collaterals. The dilated
ascending aorta (AAo) continues as a left aortic
arch that deviates the trachea to the right
(arrowheads) and descends along the left side
of the vertebral column.
• The main pulmonary artery segment is concave
(arrow). An enlarged right atrium (RA) occupies
the lower right cardiac border. The apex-forming
right ventricle (RV) is convex and not boot-
shaped because the left ventricle was well-
developed.

66. • Pulmonary vascularity is reduced and the middle and outer thirds of the lung fields
display a paucity of vascular markings because of a reduction in size of
intrapulmonary arteries and veins.
• The concave main pulmonary artery segment of pulmonary atresia stands out in
bold contrast to the dilated right aortic arch.
• The size of the heart in cyanotic Fallot’s tetralogy is normal. The right atrium and
right ventricle cope with systemic resistance without dilating, and the left atrium
and left ventricle are underfilled and are therefore small.
• In pulmonary atresia, there will be cardiomegaly due to increased collateral blood
flow.
• The boot shape results from the combination of a small underfilled left ventricle
• that lies above a horizontal ventricular septum, inferior to which is a concentrically
hypertrophied but nondilated right ventricle. The coeur en sabot is uncommon in
neonates because intrauterine left ventricular volume is normal.

67. TOF with Absent pulmonary valve
• The combination of:
– absent pulmonary valve
– ventricular septal defect
– Pulmonary annular stenosis
– Dilation of the pulmonary trunk and its
branches.
• the right ventricle, which is subjected to the
massive volume overload of severe
pulmonary regurgitation in addition to the
resistance to discharge incurred by annular
obstruction.
• RV failure develops followed by RA dilation.
• The malformation causes respiratory distress
(tracheobronchial obstruction) and right
ventricular failure soon after birth.
• Emphysema, atelectasis, and pulmonary
infection are common.

68. • Early cyanosis due to respiratory distress, and a right-
to-left shunt diminishes with age because a fall in
pulmonary vascular resistance decreases pulmonary
regurgitant flow, decreases volume overload of the
pressure-overloaded right ventricle, and decreases the
right-to-left shunt.
• Arterial pulse volume decreased due to RVF.
• JVP raised with prominent a wave due to RVF. V wave
becomes prominent when TR develops.
• Prominent right ventricular impulse.
• A systolic thrill is common
• A diastolic thrill of pulmonary regurgitation is common

69. • Auscultation:
• Diffuse wheeze due to tracheobronchial obstruction
• Absent pulmonary ejection click since there is no pulmonary valve
• P2 must be absent
• A2 is muted by anterior interposition of the dilated pulmonary
trunk.
• Mid systolic murmer in 2nd left ICS due to ejection of blood across a
stenotic pulmonary annulus
• Diastolic murmer of pulmonary regurgitation
• The combination of a long, loud, harsh systolic murmur followed by
a shorter harsh diastolic murmur creates the auscultatory
impression of “sawing wood”.

70. • ECG:
– RVH with RAD
– The main differnece in ECG between TOF with
absent pulmonary valve and classic cyanotic TOF is
the chest lead pattern of RVH.
– When the pulmonary valve is absent, the tall
monophasic R wave in lead V1 extends to adjacent
precordial leads, in contrast to Fallot’s tetralogy in
which the tall right precordial R wave is confined
to lead V1.

71. • X-ray from a 6-month-old male
with Fallot’s tetralogy and
absent pulmonary valve.
• The right pulmonary artery
(RPA) is aneurysmal.
• A dilated left pulmonary artery
(arrow) is partially obscured by
the large pulmonary trunk
(PT).
• The ascending aorta (AAo) is
dilated.
• A large right atrium (RA)
occupies the right lower
cardiac border, and an
enlarged right ventricle (RV)
occupies the apex.

72. • Fallot’s tetralogy with absent left pulmonary
artery is characterized by
– Relatively small left hemithorax
– Elevated left hemidiaphragm
– Ipsilateral decrease in pulmonary vascularity.
– The murmur of pulmonary stenosis radiates
preferentially into the right pulmonary artery and
the right upper chest.

73. Management of TOF

74. Hypercyanotic spells
Treatment strategy:
- lowering pulmonary blood flow impedance
- increasing systemic vascular resistance
- Infant held in a knee-chest position
- Morphine : (0.2 mg/kg S/C or IM)
- Oxygen
- Sodium bicarbonate : (1 mEq/kg IV) .
- Phenylephrine : (0.02 mg/kg IV)
- Ketamine : ( 2mg/kg IV)
- Propranolol : ( 0.05 mg/kg IV)
Refractory to above …..
- Balloon angioplasty of pulm. annulus
- Emergent surgical palliation or repair

75. Before the advent of surgical intervention about 50% of patients
with TOF died in the first few years of life
The goal of repair :
- Closure of VSD
- Relieve RVOT obstruction.
Two basic approaches
to repair
a) Early total repair
b) Palliative shunt creation → definitive repair.

76. Timing…
• Stable, minimally cyanosed: Total correction at 1-2 years of age or earlier
according to the institutional policy (Class I). Preferably – <6m-1yr
• If significant cyanosis (SaO2< 70%) or history of spells despite therapy
<3 months: systemic to pulmonary artery shunt (Class I).
>3 months: shunt or correction depending on anatomy and surgical
centers’experience (Class I).

77. Palliative Shunt Procedures
Situations → Shunt operations chosen rather than
primary ICR:
1. Neonates with TOF and PA
2. Infants with hypoplastic pulmonary annulus → requires
a trans annular patch for complete repair
3. Children with hypoplastic PAs
4. Unfavourable coronary artery anatomy
5. Infants younger than 3 to 4 months old who have
medically unmanageable hypoxic spells
6. Infants weighing less than 2.5 kg

78. Palliative shunts
1. Classic Blalock-Taussig (BT) shunt
2. Modified Blalock-Taussig (BT) shunt
3. Waterston shunt
4. Pott’s shunt
5. Central shunt

79. Management of TOF
Core Concepts

80. AoA
(L)CCA (L)SCA
(R)SCA
(R)CCA
BCA
Classic Blalock-Taussig
(BT) shunt
(1950s)

81. AoA
(L)CCA (L)SCA
(R)SCA
(R)CCA
BCA
Modified Blalock-
Taussig (BT) shunt
(1960s)

83. AoA
(L)CCA (L)SCA
(R)SCA
(R)CCA
BCA
Reparative Surgery
(1960s – 1990)
Transannular Patch
VSD closure

84. AoA
(L)CCA (L)SCA
(R)SCA
(R)CCA
BCA
Reparative Surgery
(1990s – present)
VSD closure
Supravalvular
Patch
Infundibular
patch

85. Classic Blalock-Taussig shunt
- Performed on the side opposite to that of the aortic arch.
(SCA arises from brachiocephalic artery→kinking is less likely to
occur at its origin when it is turned down to become a shunt.)
- Infants more than 3 months
Modified Blalock-Taussig (BT) shunt
- Gore-Tex interposition shunt is placed between the subclavian
artery and the ipsilateral PA
- Most popular procedure for any age (especially < 3 months)
- Performed on the same side of the aortic arch
- Surgical mortality rate is 1% or less

86. BT shunt-advantages :
- Low incidence of problems from excess PBF
- No pericardial adhesions as pericardium is not entered
- Easy to close at the time of complete repair
- Less distortion of PAs
Central shunt :
- Connecting a short tubular graft of Teflon or GoreTex from the
aorta to the MPA.
Advantages over other shunts:
- Size of the communication could be controlled selecting a tube
with a diameter appropriate for the patient
- Branch PAs are not disturbed so that reconstruction is not
required at the time of corrective surgery.
Waterston/Potts shunts – complications:
- Excessive PBF  HF [20%] & Pulmonary HTN
- Difficulty in taking down shunt at time of correction
- Distortion of RPA/LPA
- RPA/LPA aneurysm

87. Interventional Catheterization Procedures
- Balloon Valvuloplasty
- RVOT stent placement
TOF with severe annular hypoplasia→ palliation of cyanosis
(Improvement in antegrade flow → enhance pulmonary
arterial growth by augmenting pulmonary blood flow)
- Coil embolization of APCs
- Reduce LV volume overload
Balloon valvuloplasty of the pulmonary valve annulus:
- Preferable to a shunt procedure
- less traumatic , it avoids a thoracotomy
- less distortion of the pulmonary arteries

88. Total repair of Tetralogy of Fallot
Best age for repair: 3-6 months of age
Circulation. 2000;102 -123
(III-129)
Primary repair in babies < 3 months of age →longer intensive care
and hospital stay than in those older than 3 month
Median time to cessation of mechanical ventilation
and discharge from the intensive care unit (ICU) by age.

89.  Surgery within a few weeks after birth:
- Infants with very severe RVOT stenosis
- TOF + PA
- SaO2<70%
 Surgery by 2–4 months:
- Infants with moderately severe stenosis
- marked cyanosis (SaO2 70–90%)
 Corrective surgery should be performed in all other
infants with TOF by 6 months.
Guidelines for corrective surgery

90. Aim of surgery
- Relieve all possible sources of RVOTO
(Preservation of PV function by avoiding a transannular patch)
- Closure of VSD (Dacron patch)
- RA or RV approach
RVOTO relieved by:
- Pulmonary valvotomy
- ( Insertion of an outflow tract patch or a transannular patch)
Long trans annular patch → PR
Chronic PR:
- Reduced exercise capacity
- RV dilatation
- Ventricular arrhythmias
- Sudden death

91. Actuarial survival of 105 patients discharged from
the hospital after repair of TOF.
93% at 10ys after Sx
Long term follow up -survival
Annals of Surgery. 204(4):490, October 1986

92. Pathophysiology after TOF repair

93. He is a three-time Olympic gold medalist.
He holds the record for the most X-Games gold medals
and most Olympic gold medals by a snowboarder
Shaun White