Tetralogy of Fallot (TOF) is a congenital heart defect characterized by four anatomical features - ventricular septal defect, right ventricular outflow tract obstruction, overriding aorta, and right ventricular hypertrophy. It is the most common cyanotic heart defect in children beyond infancy. Patients typically present with cyanosis in infancy which worsens with activity due to right-to-left shunting through the ventricular septal defect. On examination, a systolic murmur may be heard due to the outflow tract obstruction. Without surgical repair, long-term outcomes are poor.

1. Tetralogy of Fallot
Dr. Yogesh Shilimkar

2. Introduction
• Tetralogy of Fallot (TOF) is a congenital heart defect, which has four
anatomical components—
• non-restrictive large subaortic ventricular septal defect (VSD),
• Infundibular stenosis,
• overriding aorta and
• right ventricular hypertrophy.
• TOF is the most common cyanotic heart defect seen in children
beyond infancy, accounting for a third of all congenital heart disease
(CHD) in this age group.
• Tetralogy of Fallot (TOF) occurs in 5% to 10% of all CHDs.
• This is the most common cyanotic heart defect.

3. History
• Neils Stensen – first mentioned this anomaly in 1671
• Sandifort – described Blue baby in 1777
• William Hunter – described cyanotic spell in 1785
• Etienne–Louis Arthur Fallot - first designated the four morphologic hallmarks
and outlined a clinical diagnosis in 1888 & coined the term tetrology
• The term tetralogy of Fallot was to take birth much later, in 1924, in the works
of Maude Abbot.
• Alfred Blalock, Viven Thomas and Helen Taussig - first surgical palliative
aortopulmonary shunt in 1945.
• Potts - described a descending aorta to pulmonary artery (Potts-Smith) shunt
in 1946
• Lillehei in 1954 did the first intracardiac repair (ICR) with controlled cross
circulation.
• Waterston - described an ascending aorta to pulmonary artery shunt in 1962
• Kirklin - in 1966 performed the first ICR using transannular patch and valved
conduits and he also proposed the 50% rule.

4. Spectrum Of TOF Anatomy (% For
Children’s Hospital, Boston)
• TOF - 66%
• TOF with pulmonary atresia ( PA with VSD) – 33%
• TOF with absent pulmonary valve (TOF with APV) – 3%
• TOF with AV canal defect – 3%

5. Genetics
• In most cases, TOF is sporadic and non-familial.
• The genes known to be involved in non-syndromic TOF are
• low-mutations in NKX2.5 (4% of TOF cases),
• JAGGED1 and
• FOG2 (4% of the cases).
• Frequency in the siblings is 3%
• If father has TOF – the recurrence risk is 1.4% and
• For mother – 2.6%

6. Recurrence rate (Nora-Nora series)
• Risk of recurrence in siblings:
• If 1 sibling is affected: 2.5%
• If 2 siblings are affected: 8%
• If 3 siblings are affected: >25%
• Risk of recurrence in offsprings
• If father is affected: 1.4%
• If mother is affected: 2.6%

7. • TOF could be a syndromic defect, often associated with
chromosomal anomalies and monogenic syndromes.
• Chromosomal anomalies are involved in about 12 percent of the
cases, e.g. trisomy 21 (Down syndrome), trisomy 13 (Patau
syndrome) and trisomy 18 (Edwards syndrome).
• Several conditions with multiple malformations have TOF as
their cardiac component. These include
• CHARGE (coloboma, heart defect, atresia choanae, retarded growth and
development, genital abnormality, ear abnormality) syndrome,
• VACTERL (vertebral defects, anal atresia, cardiac defects, tracheo-
esophageal fistula, renal anomalies, limb abnormalities) association and
• Goldenhar syndrome (oculoauriculovertebral spectrum).

8. • TOF can occur due to submicroscopic defects, such as the microdeletion
of chromosome 22q11.2 (DiGeorge/Velocardiofacial syndrome).
• Patients with TOF and 22q11 microdeletion frequently have additional
cardiac defects, like
• right or cervical aortic arch,
• hypoplasia or absence of the infundibular septum,
• absence of the pulmonary valve and discontinuity and
• diffuse hypoplasia of the pulmonary arteries (PAs).
• Among single gene defects, Alagille syndrome is known to be frequently
associated with TOF.
• This syndrome is due to mutations in the JAGGED1 gene.
• bile duct paucity + cardiac disease + skeletal & ocular abnormalities + abnormal
facies
• Patients with TOF and Down syndrome frequently have a particularly large
VSD in the inlet septum.

9. • Cardiac anomalies seen with 22q11.2 deletion
• 50% of interrupted arch
• 35% of truncus arteriosus
• 24% of isolated arch anomaly
• 15% of TOF
• 10% of VSD.
• Reasons to test for 22q11.2 deletion before surgery
• Prone to develop hypocalcemia
• May develop GVHD and so need to give irradiated blood products

10. Environmental risk factors:
• Maternal diabetes
• Retionic acid
• Maternal phenylketonuria
• Trimethadione

11. Embryology
• Van Praaghs view:
• underdevelopment of the sub pulmonary infundibulum is the primary pathology;
with all characteristics of TOF (including anterior cephalad deviation of the outlet
septum) being sequelae of this one pathologic feature
• Failure of normal growth of the sub pulmonary infundibulum results in an
obstructive pulmonary outflow tract.
• Because the sub pulmonary conus is too small, it fails to fill with the help of the
membranous septum—the interventricular foramen.
• Persistent patency of the interventricular foramen results in the typical malaligned
VSD of TOF.
• Due to the importance of the underdevelopment of the sub pulmonary
infundibulum, Van Praagh called TOF, the monology of Stensen.

12. • Anderson's view,
• The characteristic abnormalities of TOF occur because the
components that normally unite to form the outlet of the RV
remain separate during development.
• He maintains that the defining morphology is anterior-cephalad
deviation of the outlet (infundibular) septum relative to the
septomarginal trabeculation (SMT) together with malformation of
the SMTs
• Whichever abnormality ultimately proves to be defining,
anterior-cephalad deviation of the outlet septum (which is a
much larger structure in TOF than in the normal heart) is
certainly a cardinal feature.

13. Pathology
• The central abnormality in TOF is the
• hypoplasia of the infundibular septum,
• which causes the septum to move anteriorly and create an
anterior malalignment type VSD.
• The crista supraventricularis is displaced anteriorly relative
to the parietal and septal bands, narrowing the right
ventricle outflow tract (RVOT).

14. RVOT obstruction in TOF
• Multiple level obstruction is
the rule
• Combination of infundibular
and valvar stenosis was
observed in 74% of cases
seen in GLH experience
• Pulmonary artery stenosis –
40% of cases and the origin of
LPA may have narrowing at
the ductus insertion site.

15. • VSD in TOF
• is a large perimembranous defect with extension into the sub
pulmonary region,
• is present just behind the anteriorly displaced crista
supraventricularis.
• Types:
• Subaortic – 80%
• Subpulmonic – 3%
• Doubly committed – 2%
• AV septal defect – 2%
• Multiple – 3-15%

16. • The right sinus of Valsalva is located at a higher position as
compared to normal hearts and the aorta can be easily entered from
the right ventricle (RV).
• When the infundibular stenosis is marked or severe the overriding of
aorta is to a very marked degree.
• The pulmonary valve is
• commonly stenotic.
• Very often it is bicuspid;
• in one fourth of cases, the pulmonary valve is atretic.
• In approximately 3% to 6% of patients with TOF, the pulmonary valve leaflets
are absent.
• Coronary abnormalities occur in 5 percent,
• anomalous origin of left anterior descending (LAD) artery from the right
coronary artery (RCA) being the most common.

17. Pulmonary valve in TOF

18. Associated anomalies in TOF

19. • TOF equivalents:
• Anatomy is different but physiology is same
• e.g.,
• TGA (d or l) + VSD + PS
• DORV + VSD + PS
• SV + PS
• TOF variants
• Anatomy is same but physiology is different
• TOF with pulmonary atresia
• TOF with absent pulmonary valve
• TOF with ASD
• Hoffman variant
• Pacific variant: obstruction predominantly at the level of valve

20. • Hoffman’s variant:
• It is a TOF, where the restrictive VSD is partially closed with tricuspid tissue, thus
the RV pressure is suprasystemic.
• Papillary muscles of RV:
• In normal RV there are three papillary muscles.
• The third one is small and attached to septum.
• In TOF, media papillary muscle may be absent.
• This muscle is called as muscle of Lanseri.
• Canal tet:
• Complete AV canal defect occurs in approximately 2% of patients with TOF, more
commonly among patients with Down syndrome, called “canal tet.”
• In these patients, the VSD has a large outlet component in addition to the inlet
portion associated with the AV canal.
• Pentology of Fallot: TOF with ASD
• Fallot’s triology: ASD+RVH+PS

21. Clinical features

22. History
• Tetralogy of Fallot is slightly more common in males than in
females.
• Patients with TOF most often present in infancy with cyanosis
due to right to left shunting of blood at the level of the VSD.
• The degree of right ventricular outflow tract obstruction
(RVOTO) often correlates with the degree of cyanosis and the
timing of presentation.
• Thus patients with mild pulmonary obstruction present late, perhaps
even in adulthood, the so-called “pink TOF”,
• while patients with severe obstruction may present soon after birth on
closure of the ductus arteriosus.
• In less severe cases, cyanosis is first noticed during crying.

23. Cyanosis
• 25% are cyanotic at birth and 75% are cyanotic by 1 year of
age.
• The late appearance of cyanosis is related to:
• Progressive increase in oxygen demand of the growing child
• Increasing PS/ progressive increase in infundibular stenosis
• After birth there is a slow change from HbF to HbA, which is a
better carrier of oxygen than later one

24. Cyanotic spell
• Also called hypoxic spell, hypercyanotic spell, “tet” spell
• Spell usually occurs in infants between 3 to 24 months of age.
• Initiated usually by crying, feeding or bowel movement, spells are
particularly common after getting up from sleep.
• Typical spell is characterized by progressive increase in the rate and depth
of respiration, deepening cyanosis, limpness or syncope.
• Convulsions, cerebrovascular accident and death are potential
complications.
• Spells are less common after 2 years.

25. • Mechanism of cyanotic spell

26. Theories for explanation of mechanisms
of cyanotic spells
• Wood's theory:
• Postulated that hypoxemic spells are caused by spasm of the infundibulum of
the right ventricle which precipitates a cycle of progressively increasing right to
left shunting and metabolic acidosis.
• Catecholamine release:
• Leads to increased myocardial contractility and infundibular stenosis (both
these theories do not explain the cause of cyanotic spells in patients with
tetralogy of Fallot with pulmonary atresia).
• Guntheroth's theory:
• Episodes of paroxysmal hyperpnoea are the cause rather than the effect of
cyanotic spells.
• Hyperpnoea increases the systemic venous return leading to right to left shunt
as well as oxygen consumption through increase work of breathing.

27. • Kothari's theory:
• Argued against the other hypotheses and suggested the role of
stimulation of mechanoreceptors in the right ventricle to be the cause of
spells.
• Morgan’s theory:
• Vulnerable respiratory center which over-reacts to hypoxic stimuli like
crying, feeding & causes an increase in cardiac output and heart rate
which in turn increases venous return causing an increase in right to
left shunt across the ventricular septal defect which leads to a fall in
PaO2 and increase in PCO2.
• The respiratory center overreacts to this stimulus and causes
hyperpnea which again increases the venous return, thereby causing a
vicious cycle.
• Young’s theory:
• It was proposed that the spell was precipitated by an atrial tachycardia.

28. • Squatting:
• A characteristic posture older children with TOF assume to increase pulmonary
blood flow and to alleviate dyspnea is squatting.
• Squatting is of diagnostic significance in TOF.
• Squatting increases peripheral vascular resistance and thus decreases the
magnitude of the right to left shunt across the VSD.
• Locking up the more desaturated lower limb venous blood and displacing the
better oxygenated mesenteric venous blood into the right heart may be the
other benefits of squatting.
• Exertional dyspnea is common in the older child. Exertional dyspnea
usually worsens with age.
• Occasionally, hemoptysis may occur in the older child due to rupture
of bronchial collaterals.

29. • Squatting equivalents:
• Sitting with legs drawn downwards
• Legs crossed while standing
• Mother holding infant with legs flexed upon
• Lying down

30. • RV failure is uncommon in TOF patients but the various
circumstances in which the patient can present with RV
failure are
1. Pulmonary atresia with large systemic arterial collaterals
2. Accessory tricuspid leaflet tissue partially occluding the
ventricular septal defect making it restrictive and causing supra
systemic right ventricular pressure.
3. Absence of pulmonary valve causing combination of stenosis
(annular narrowing) and free pulmonary regurgitation.
4. Systemic hypertension
5. Acquired calcific aortic stenosis or regurgitation of the
biventricular aortic valve
6. Infective endocarditis affecting the aortic valve
7. Hyperdynamic circulatory status like due to anaemia,
thyrotoxicosis
8. Adult tetralogy of Fallot with aortic regurgitation

31. Clinical Examination
• Clubbing may be present after 3 months of life.
• General examination may reveal subtle features of 22q11
microdeletion.
• JVP: Normal
• A wave may become prominent with:
• Restrictive VSD
• Hypertension
• AS
• Right heart failure
• Precordium is quiet.
• A gentle RV impulse may be felt in 4th and 5th LICS
• Right sternoclavicular joint may show impulse in patients with right aortic arch

32. • Usually thrill is not present, but thrill may be palpable:
• If RVOT obstruction is mild
• If valvar or infundibular PS is present
• If restrictive VSD is present
• S1 is normal, while S2 is single due to a faint P2.
• Reasons for single S2
• Delayed and hesitant closure of the pulmonary valve due to the slow
pressure drop in the stenotic infundibular chamber,
• associated valvar stenosis and
• the overriding aorta.

33. • An aortic ejection click
• due to the dilated ascending aorta
• better heard in right 2nd LICS.
• It may heard over apex.
• It is respiratory phasic
• More prominent in expiration than inspiration
• Pulmonary ejection click is absent because:
• Stenosis is infundibular
• No poststenotic dilatation of PA
• Thickened pulmonary leaflet does not cause rapid opening of
valve.

34. • A prominent ejection systolic murmur, is heard at the mid and upper
left sternal border.
• The length and intensity of this murmur is inversely proportional to the severity
of stenosis.
• With more severe stenosis RV pumps more into the aorta and less across the
RVOT, decreasing the murmur.
• The murmur disappears during a spell.
• A continuous murmur
• below the left clavicle denotes a patent ductus arteriosus (PDA).
• If more widely heard, especially over the back, it is due to systemic-pulmonary
collaterals (type 3 of Rabinovitch systemic artery collaterals)
• Diastolic murmur in TOF: not a feature of uncomplicated TOF
• Early diastolic murmur in infancy: pulmonary regurgitation (absent pulmonary
valve)
• Early diastolic murmur in adolescent or adults: it is due to AR
• Mid diastolic rumble may be heard with large pulmonary flow

35. Adult TOF
• Males predominate, male to female ratio 2:1
• Dyspnea is most common symptom (95%).
• PND is rare and is related to severity of AR.
• Continuous murmur is more common and is found in 16%
of cases especially over infrascapular and axillary area (d/t
collaterals).

36. • The largest study on adult TOF patients was done by Abraham
et al in which he evaluated the presentation of 147 patients,
above the age of 18 with TOF. Cardiac catheterization and
selective cine angiography were performed in all.
• Cardiac enlargement was seen in 25.8% of the patients,
• congestive cardiac failure in 15.6%;
• systemic hypertension in 9.5 %, and
• aortic regurgitation was present in 6.7 %
• LVH on ECG – 0.7%
• Absence of RVH – 3.4%
• q in lateral leads – 8.8%
• The right atrial mean pressure was increased in 4.8% and a prominent
“a” wave greater than 10 mm Hg was present in 10.9%.
• The right ventricular end-diastolic pressure was increased in 23.8% and
the left ventricular end-diastolic pressure in 25.9% of the patients.

37. • A reticular pattern in the lung fields due to bronchial
collaterals was seen in 23.1 percent.
• The incidence of
• right aortic arch (19.9%),
• absent left pulmonary artery (2.8%),
• absent right pulmonary artery (0.7%) and
• dextrocardia (1.4%).
• This study clearly shows that a lot of clinical features
which are usually considered uncharacteristic in TOF
patients can be present in adult uncorrected TOF patients.

38. Investigations

39. Chest X-Ray
• Cardiac size is normal to decreased.
• Plain films may classically show a "boot shaped" heart (Coeur-
en-sabot) with
• an upturned cardiac apex due to right ventricular hypertrophy and
• concave pulmonary arterial segment.
• Lung vascularity is decreased.
• A right aortic arch is present in 25 %.

40. Electrocardiogram
• Right ventricular hypertrophy and right axis deviation are the
salient features of TOF.
• Older children and adults may show right atrial enlargement.
• Whereas the R wave in V1 is tall and usually monophasic, R
wave in V2 is much shorter – the so called “sudden transition”
is characteristic.
• In patients with pulmonary stenosis and restrictive VSD, right
precordial leads show deeply inverted T waves in right
precordial leads.

41. • Reasons for precordial pattern of QRS complex:
• R dominant in V1 – due to RVH
• S dominant in V2 – due to trabecular hypoplasia i.e. presence of VSD
• RS pattern in V3-V4 – due to septal hypertrophy
• S dominant in V5, V6 – due to LV hypoplasia.
• QRS axis:
• Is downward and right; mean axis is between +90 and +150
• TOF with AVSD – left axis.
• Depolarization is clockwise – rS complex in lead I and tall R in
lead II and III.
• When left axis and counter-clockwise depolarization is present
– suggest associated AV canal defect.

43. Echocardiography
A complete study must address:
1. The location and number of VSDs
2. The anatomy and severity of RVOTO.
a) The size and anatomy of the main pulmonary artery,
b) the pulmonary arterial confluence, and
c) the proximal branch pulmonary arteries, as far distally as possible, must be demonstrated.
3. The coronary arteries must be imaged, specifically looking for any major branch
crossing the RVOT. The LAD arises from the RCA and crosses the RVOT in 5
percent.
4. Aortic arch laterality must be shown.
5. Aortic override
6. The presence of any associated anomalies must also be looked for like
a) atrial septal defect
b) PDA,
c) additional VSDs.
7. Indices
8. RV & LV function

44. Cardiac catheterization
• May be needed in assessment of:
1) the levels of right ventricular outflow obstruction,
2) branch pulmonary artery stenosis or hypoplasia,
3) coronary artery anatomy,
4) presence of aortopulmonary collaterals (MAPCAs), and
5) Determination of number, size and relation of VSDs to great arteries
6) BT shunt function

45. • Views needed:
1) RAO cranial and lateral view: RVOT and PV annulus
2) Kattan’s view/Sitting up view (AP cranial 30):
MPA/RPA/LPA
3) LAO cranial (40/40) (4 chamber view): LPA
4) Views of additional VSDs:
a) Long axis oblique (LAO 60/cran 30): Membranous VSD
b) 4 chamber view: inlet VSD, mid-muscular VSDs
c) RAO view: Outlet (Subpulmonary) VSD
5) Descending aorta angiogram: MAPCAs

46. Angiographic assessment
• Biplane angiography is ideal.
• RV angiogram (anteroposterior [AP]
cranial, shallow left anterior oblique
[LAO] view) shows
• simultaneous opacification of aorta and
PA, RVOT obstruction and PA anatomy.
• Left ventriculography in LAO cranial
view (long axis oblique view)
• can visualize the number and size of
VSD and
• Detects degree of overriding of aorta

47. Salient features of oximetry run in tetralogy of
Fallot:
1. RA, RV and PA saturations are similar to that of vena cava
2. MVO2 is markedly reduced to about 20–40% in infants with severe
hypoxemia
3. PV saturation is near normal
4. LA saturation – slightly decreased to that of PV especially in
pentalogy of Fallot
5. LV saturation reflects LA saturation
6. Aortic saturation greater than that of RV and less than that of LV
(may be markedly reduced to 40–60%)
7. PA saturation higher than that of RV if PDA and/or multiple
collaterals are present
8. In patients with less severe infundibular stenosis the MVO2 is
nearly normal with a small increase in RVO2 and slight decrease in
LVO2

48. • The hemodynamic findings at catheterization typically
reveal normal or only mildly elevated filling pressures.
• The left and right ventricular systolic pressures are equal.
• Pulmonary artery pressures are normal or low.
• The degree of right-to-left shunting is best shown by the
degree of systemic desaturation.

49. • An aortic root injection in RAO or LAO view will
• usually provide adequate identification of the coronary arteries, although
selective injections may occasionally be needed.
• Sidedness of aortic arch and its branches
• Descending thoracic aortic angiography is usually unnecessary to
delineate collaterals in TOF patients, but is important in case of
pulmonary atresia with VSD.
• Multidetector computed tomography (MDCT) angiography
• is a safe and effective non-invasive technique to answer questions remaining
after echocardiography in patients with TOF.
• Major aortopulmonary collateral arteries (MAPCA) from all sources are best
shown by this technique.

50. Indices for prediction of success of
intracardiac repair
• Nakata index:
• Sum of the cross sectional areas of the left and right pulmonary arteries at their
prebranching points as related to body surface area.
• The normal Nakata index is + 330 mm2 /m2.
• An index of more than 150 mm2 /m2 is acceptable for complete repair without
prior palliative shunt.
• Tetralogy of Fallot with pulmonary stenosis should have an index of more than
100 for surgery.
• McGoon ratio:
• Ratio of the sum of the pre branching diameters of the left and right pulmonary
arteries to the diameter of the descending aorta just above the level of the
diaphragm.
• Normal – 2 to 2.5
• Ratio above 1.2 is adequate for ICR.

51. • Z-Score:
• The branch pulmonary artery diameter Z-score is the most important
determinant of surgical strategy, with the worst figures being associated
with no surgical options or palliative surgery and the best figures
leading to corrective surgery
• Naito index:
• This index is derived from left ventricular end diastolic volume.
• Patients with an index < 30 ml/m2 are not adequate candidates for
complete repair and should undergo palliative surgery.
• Black Stone formula:
• This is derived from diameter of right and left pulmonary artery valve
annulus measured from preoperative cine angiogram normalized to
patients descending thoracic aorta.
• This ratio should be > 1.5:1

52. • Total Neo-pulmonary artery index (TNPAI):
• Nakata PA index was measured as described above.
• Then, APCs index was calculated by addition of CSA of all significant APCs
divided by the BSA.
• CSA of each APC was calculated from diameter of the respective vessels
measured on preoperative cineangiogram.
• The sum of total APC index and PA index is called TNPAI.
• A TNPAI index >200 mm2/m2 correlated well with low postoperative RV/LV
pressure ratio and identified patients who were clear candidates for VSD
closure at the time of single-stage surgical repair in TOF with pulmonary atresia

53. Natural History
• If left untreated, TOF results in
progressive right ventricular
hypertrophy and right
ventricular dilatation and
threatens survival.
• If pulmonary atresia is present
as well, survival is even poorer
with
• only 50 percent of patients
surviving to 1 year and
• only 8 percent of patients
surviving to 10 years.

54. Complications of TOF
• Brain abscess
• CVA
• Depressed IQ
• Scoliosis
• Gout
• Gallstones
• Infective endocarditis

55. Medical Management
• Medical management in TOF patients is directed towards
• preventing cyanotic spells,
• avoiding problems associated with anemia or polycythemia,
• preventing complications from infection like brain abscess or infective
endocarditis.
• The general measures include correction of anemia by iron
supplementation and nutritional supervision.
• The child is started on oral propranolol (1–4 mg/kg/day in three
or four divided doses) to prevent cyanotic spells until surgical
correction is done.

56. Treatment of cyanotic spell
• Hold the child in knee chest position.
• This increases the SVR and decreases the desaturated systemic venous return.
• Calm the child. The ideal sedative is morphine.
• It causes respiratory center suppression and sedation thereby reducing hyperpnea.
• It reduces the ventilatory drive and decreases systemic venous return (venodilator).
• This will decrease the release of catecholamines, increase the period of right ventricular filling by
decreasing the heart rate and relax the infundibulum.
• The dose of morphine is 0.1 mg/kg and it can be given intravenous (IV), intramuscular (IM) or
subcutaneous.
• It may be repeated after 5 minutes.
• The ventilation facilities should be at hand.
• The other alternative sedatives are:
• midazolam 0.05–0.1 mg/kg (IV, intranasal or intrarectal) or
• dexmedetomidine 0.5 -1 mcg/kg IV or infusion of 0.2 mcg/kg/hr or
• fentanyl 1–2 mcg/kg IV.
• Ketamine has dual benefit of causing sedation and increasing SVR. The dose is 0.25- 1.0 mg/kg IV or IM.

57. • 100% Oxygen supplementation.
• This causes pulmonary vasodilation and hence decreases the pulmonary
vascular resistance (PVR).
• The least aggravating method of delivery should be used.
• Fluids:
• Prompt administration of fluids will improve right ventricular preload.
• Initially, fluid is given as a bolus of 10-20 cc/kg, which may be increased to
60cc/kg.
• Bolus fluid should be isotonic saline or colloid.
• Sodium bicarbonate:
• in a dose of 1–2 meq/kg IV is given slowly to correct metabolic acidosis.
• This may reduce the respiratory center stimulating effect of acidosis and may
diminish the increase in pulmonary vascular resistance caused by hypoxia and
acidosis.
• It can be repeated in 10-15 minutes.

58. • Beta blockers:
• Like injection propranolol is given in a dose of 0.1-0.2 mg/kg IV over 5
minutes and can be repeated once after 15 minutes.
• It decreases the heart rate, infundibular spasm and increases SVR.
• If propranolol is not available then injection metoprolol can be given in
a dose of 0.1 mg/kg over 5 minutes.
• Another short acting beta blocker which can be given is injection
esmolol in a dose is 0.5 mg (500 mcg)/kg over 1 minute and then as an
infusion of 50 to 200 mcg/kg/min up to 48 hours.
• In refractory cases:
• vasopressors can be given to increase the SVR and promote the
redirection of blood flow through the pulmonary circulation.
• Phenylephrine can be given in a dose of 5 to 20 mcg/kg IV bolus,
followed by an infusion of 0.1 to 0.5 mcg/kg/min.

59. • Avoid any actions that agitate the baby like vigorous
examination, repeated attempts to venipuncture etc.
• The drugs to be avoided are inotropes (e.g. digoxin,
dopamine, or dobutamine) and diuretics.
• If the spell is persistent or refractory, then intubation and
mechanical ventilation maybe required.
• A emergency Blalock-Taussig (BT) shunt / pulmonary
balloon valvuloplasty (PBV) may be required in refractory
cases.

60. Primary repair vs Palliation
• Kirklin et al. have concluded that
• primary repair without a transannular patch is as safe as a two
stage procedure shunt – ICR, when infant is
• more than 6 months and
• BSA is 0.35 sqm.
• When transannular patch is required, two stage procedure
is safer if the infant is
• under 9 months old or
• has a BSA of less than 0.48 sqm.

61. Palliative Shunt Procedures
• Indications: When the following situations are present, a
shunt operation may be chosen usually rather than primary
repair.
1. Neonates with TOF and pulmonary atresia
2. Infants with hypoplastic pulmonary annulus, which requires a
transannular patch for complete repair
3. Children with hypoplastic Pas
4. Unfavorable 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

62. • Blalock-Taussing shunt (classical):
• Subclavian artery to pulmonary artery anastomosis (end-to-side), usually on the side opposite the descending aorta
• Infrequently, this may lead to pulmonary hypertension
• It is usually performed for infants older than 3 months because it is often thrombosed in young infants.
• Advantages
• It requires no prosthetic material
• Subclavian artery diameter prevents the excessive flow to pulmonary arteries and prevents congestive heart failure
• Ease of closure during corrective surgery
• Potential adaptive growth of anastomosis
• Disadvantages
• Requires careful, lengthy dissection
• Can cause distortion of the peripheral pulmonary artery
• Blood supply to the ipsilateral arm is compromised which may result in a discrepancy in growth and strength.
• Thrombosis of shunt (small size)
• Subclavian Steal syndrome
• Neurologic (rare):
• recurrent laryngeal nerve injury,
• phrenic nerve injury,
• Horner syndrome

63. • Blalock-Taussing shunt (modified):
• Interposition graft between subclavian artery and ipsilateral pulmonary artery.
• Controlled augmentation of pulmonary blood flow.
• Usually a 4mm Gore-Tex shunt is required early in infancy.
• Larger shunts would be required for older patients, although the possibility of repair should always be explored
first.
• This is the most popular procedure for any age, especially for infants younger than 3 months of age.
• Advantages
• Can be performed on either side
• Subclavian blood supply to the arm is preserved
• Kinking of the subclavian artery is not a problem
• Excellent patency rates: 90% at 2 years
• Prevent mutilating effects of CBTS
• Pulmonary artery distortion less likely
• Can be performed < 3 months age
• Disadvantages
• May be more difficult than classic BT shunts to take down
• Leakage of serous fluid through PTFE in chest – forming seroma.
• Pseudoaneurysm formation which can lead to fatal hemoptysis

64. • Waterston shunt:
• Ascending aorta-to-main or right pulmonary artery (side-by-side).
• No artificial material used; shunt grows with the patient.
• May lead to pulmonary hypertension.
• Infrequently, problems have been encountered with pulmonary artery
disruption, requiring extensive arterioplasty.
• Potts shunt:
• Descending aorta-to-left pulmonary artery (side-by-side).
• Frequent complication with narrowing and kinking of the left pulmonary
artery at the site of the anastomosis.
• The latter necessitates reconstructive surgery during repair,
occasionally through an additional thoracotomy, which made this shunt
unpopular.

65. • Melbourne shunt
• End to side shunt between MPA and aorta
• Described by Dr. Mee from Melbourne
• Davidson shunt:
• Central shunt
• Prosthetic graft material is inserted between ascending aorta and MPA
• Usually performed when pulmonary arteries are hypoplastic
• Sano shunt:
• Extracardiac allograft valved conduit is inserted directly from RV to
pulmonary artery
• This shunt is created to avoid reduced diastolic blood flow in the
coronary circulation a/w BT shunt

66. • Central interposition tube graft:
• A Gore-Tex graft is often used for patients not suitable for early repair.
• Between ascending aorta and MPA.
• May be indicated in neonates and children younger than 3 months
• It can be performed only in infants with PDA or some other source of
pulmonary blood flow
• Brock procedure:
• Infundibular resection or closed pulmonary valvotomy
• Often effective palliative procedure from an earlier surgical era.
• Relief of RVOT obstruction without VSD closure or with fenestrated VSD
closure:
• In patients with multiple pulmonary artery stenoses or hypoplasia.

67. • Classical Glenn:
• SVC to RPA
• End to end
• Bidirectional Glenn:
• End to side connection between cranial end of SVC and RPA
• Advantage: does not increase volume load on ventricle
• Kawashima operation:
• Modification for those with bilateral SVCs
• Each SVC is anastomosed to ipsilateral pulmonary artery

68. Catheter interventions in TOF
1. Balloon dilatation of pulmonary stenosis.
2. Balloon dilatation and/or ductal stenting.
3. The coil closure of MAPCAs.
4. Balloon dilatation of peripheral pulmonary artery stenosis with or without
stenting.
5. Balloon dilatation of blocked BT shunt.
6. Stenting of RVOT for infundibular stenosis by balloon expandable
stainless steel stents (Johnson & Johnson).
7. Transcatheter pulmonary valve replacement.

69. Pulmonary Balloon Valvuloplasty
• In patients with TOF, balloon dilatation of pulmonary stenosis
may be an effective palliative procedure in a subset of patients,
obviating the need for a palliative shunt.
• The PBV is recommended
• if the patient’s size or cardiac anatomy makes that patient an unsuitable
candidate for total surgical correction.
• The valvar obstruction should be a significant part of the RVOTO.
• The supravalvular pulmonic stenosis, if discrete, can be relieved by
balloon dilatation.
• Also due to the multiple obstructions in the RVOT, the subvalvar
obstruction still remains thus preventing flooding of the lungs
after PBV.

71. • Advantages of Pulmonary Balloon Valvuloplasty
1. Substantial increase in saturation (SO2).
2. Growth of pulmonary valve annulus and pulmonary arteries.
3. The need for transannular patch is reduced by 40%.
4. The high risk intracardiac repair (ICR) is postponed in infants.
5. PBV in TOF acts as a safe bridge to surgery.
• Disadvantages of Pulmonary Balloon Valvuloplasty
1. Pulmonary balloon valvuloplasty may not be successful in all
patients.
2. Very rarely in severely hypoxic and sick patients with very low
SO2 the very attempt to cross the infundibulum can precipitate
the cyanotic spell.
3. The mortality can occur due to either cyanotic spell or
tamponade in very sick infants.

72. Interventions in Blalock-Taussig shunt
• In patients with a narrowed BT shunt, balloon angioplasty with
or without stent may
• improve pulmonary oligemia,
• improve systemic arterial hypoxemia and
• obviate the need for a second systemic-to-pulmonary artery shunt.
• The BT stenosed anastomosis can be opened up with
thrombolytic therapy or balloon dilatation.
• Complicated cases like pulmonary atresia or hypoplastic
pulmonary valve and pulmonary artery and collaterals can
benefit from a series of interventions prior to surgery.

73. Surgery
• The diagnosis of TOF in general is an indication for repair.
• Most centers prefer primary elective repair between 3 months
and 12 months of age, even if they are asymptomatic, acyanotic
(i.e., “pink tet”), or minimally cyanotic.
• Appropriate age for ICR: 6 months if TAP is required
• 9 months if TAP is not required
• Advantages cited for early primary repair include:
• avoiding risks associated with a shunt operation
• diminution of hypertrophy and fibrosis of the RV,
• Normal growth of the PAs and alveolar units, and
• reduced incidence of postoperative ventricular arrhythmias and
possible sudden death.

74. • The occurrence of hypoxic spell is generally considered an
indication for operation, even in conservative centers.
• Mildly cyanotic infants who have had previous shunt
surgery may have total repair 1 to 2 years after the shunt
operation.
• Patients with coronary artery anomalies may have an early
surgery at the same time as those without anomalous
coronary arteries.
• In the past, surgery for these patients was delayed until after 1
year of age because a conduit placement may be required
between the RV and the PA.

75. Surgical techniques for intracardiac repair
1. Transventricular approach:
a) This was the earliest approach which was used for
RVOT resection but fell into disrepute due to
The high incidence of ventricular arrhythmias,
conduction system defects and
right ventricular dysfunction.
b) This difference from other surgical approaches has
been proven in various follow up studies.

76. 2. Transatrial approach:
a) The transatrial approach for tetralogy of Fallot repair was
proposed by Hudspeth et al in 1963.
b) This method has significant advantages as over the
transventricular approach for intracardiac repair.
c) The salient features of this method are:
Preservation of ventricular function
Decreased severity of PR
No risk of injuring branches of RCA
No scar on ventricle
Decreased arrhythmias
Adequate annulus is a must

77. • Combined transatrial and transpulmonary approach:
The salient features of this approach are:
1) Small ventriculotomy
2) Minimizes RV dysfunction
3) Excellent exposure
4) Lower RVEDP, higher RVEF during isoprenaline infusion
5) Lower incidence of ventricular arrhythmias
6) Suitable for all patients

78. Procedure
• Total repair of the defect is carried out under
cardiopulmonary bypass, circulatory arrest, and
hypothermia.
• The procedure includes
• patch closure of the VSD, preferably through transatrial and
transpulmonary artery approach (rather than right
ventriculotomy),
• widening of the RVOT by division or resection of the infundibular
tissue, and
• Pulmonary valvotomy, avoiding placement of a transannular fabric
patch

80. • At the present time, surgeons aim to avoid right ventriculotomy
and placement of transannular patch whenever possible.
• Widening of the RVOT without placement of patch is more likely
to be accomplished if the repair is done in early infancy.
• However, if the pulmonary annulus and main PA are
hypoplastic, transannular patch placement is unavoidable.
• Some centers advocate placement of a monocusp valve at the
time of initial repair, but others advocate pulmonary valve
replacement at a later time if indicated.

82. Annular Patch
• According to Kirklin, postoperative right to left ventricular pressure
ratio (PRV/LV) of < 0.75 will be associated with good functional results if
VSD is adequately closed and the pulmonary valve ring is intact.
• If the PRV/LV ratio is > 0.75 intraoperative measurement of the
pulmonary annulus by means of Hegar dilators has been used. A
pulmonary valve annulus that is < 50% of the diameter of ascending
aorta or less than a minimal acceptable diameter from a table of
normal values has been used as an for transannular patch repair.
• Z score > - 3: ICR, no need of transannular repair
• Z score -3 to -7: Transannular repair can be done
• Z score less than -7: transannular repair not feasible, shunt surgery to be done

83. Contraindications to intracardiac repair
• Weight less than 3 kg (arbitrary and relative)
• Severe hypoplasia of pulmonary annulus (Z value < 4)
• Associated anomalies
• Multiple ventricular septal defects
• Anomalous coronaries especially if the left coronary artery
crosses the right ventricular outflow tract
• Small pulmonary arteries are a relative contraindication

84. Mortality and Complications
• For patients with uncomplicated TOF, the mortality rate is
1% to 2% during the first 2 years.
• Patients at risk are those
• Those younger than 3 months and older than 4 years
• those with severe hypoplasia of the pulmonary annulus and trunk,
• multiple VSDs,
• large aortopulmonary collateral arteries
• Down syndrome.

85. Postsurgical follow up
• In a group of 490 children who survived past the first year of
surgery in Germany, actuarial survival rates were:
• 10 years: 97%
• 20 years: 94%
• 30 years: 89%
• 36 years: 85%
• The most common cause of death was sudden death (n = 13),
followed by congestive heart failure (n = 6).
• Nollert G, Fischlein T, Bouterwek S, et al. Long-term survival in
patients with repair of tetralogy of Fallot: 36-year follow-up of
490 survivors of the first year after surgical repair. J Am Coll
Cardiol. 1997;30:1374-83

86. • Long term complications:
1. Pulmonary regurgitation : 60-90%
2. RVOT aneurysm
3. Residual PS
4. Residual VSD
5. Aortic root dilatation with increasing age – 6.6% have increased
size and diameter may be more than 40mm in 30% adults
6. AR
7. Arrhythmias – SCD – 2%
8. Heart failure

87. • The incidence of bradyarrhythmias after TOF repair has been drastically
reduced in recent years.
• The incidence of late atrial arrhythmias after TOF repair is relatively high,
about 30 %, including atrial fibrillation, flutter, focal or reentrant atrial
tachycardia.
• Therefore, lifetime surveillance is recommended to assess and monitor these risks
and to recommend treatment.
• TOF patients are at risk for sudden cardiac death with 1 - 5 % lifetime
incidence.
• Risk factors for sudden cardiac death include
• older age at repair,
• male sex,
• advanced NYHA class,
• repair via atriotomy,
• complete heart block beyond the third postoperative day and
• QRS duration greater than 180 milliseconds
• Significant LV dysfunction

88. How to follow up patient after TOF surgery
• Infants and children up to 10 years of age need
yearly echo.
• Adults:
• MRI
• once in 3 years after the age of 10 years
• Velocity encoded
• MRI can accurately quantify pulmonary regurgitation

89. Indications for re-intervention in
tetralogy of Fallot
1) Symptoms of right heart failure
2) RV enlargement or evidence for RV dysfunction, especially if pulmonary
regurgitation is present
3) Progressive aneurysmal dilation of an RV outflow tract patch
4) Clinically significant arrhythmias (atrial or ventricular)
5) Onset or progression of tricuspid regurgitation
6) Residual VSD with shunt > 1.5 : 1
7) Residual patent arterial-pulmonary shunts leading to LV volume overload
8) Residual RV outflow tract obstruction or pulmonary stenosis with
systolic RV/LV 0.67
9) Significant aortic insufficiency with evidence of LV dysfunction
10) Dilated aortic root > 5.5 cm

90. Reoperation
• Reoperation may be required in 7 to 10 percent of patients after TOF
repair.
• Freedom from reoperation is 88 percent at 30 years.
• Reoperation is indicated for
• residual RVOTO,
• residual VSD or
• PR.
• The most common reason for reoperation is progressive pulmonary
regurgitation for which pulmonary valve replacement is done.
• PR results from transannular patching or pulmonary valvotomy.

91. Pulmonary regurgitation after TOF repair
• Significant, and usually progressive, pulmonary regurgitation
may develop after repair of TOF.
• Although the PR is well tolerated for a decade or two, moderate
to severe PR may eventually lead to significant volume overload
to the RV and RV dysfunction.
• For a period of time, RV dysfunction remains reversible with
intervention to abolish PR by insertion of a homograft
pulmonary valve by either a transcatheter technique or
surgically.

92. • Severe PR left untreated may result in irreversible anatomic
and functional changes in the RV.
• Ideal timing of the valve replacement has been
controversial.
• Although the procedural mortality rate is low, the functional
integrity of all available bioprosthesis valves deteriorates
within 10 years, posing continuing problems.

93. Pulmonary valve replacement
• Indications: (Geva, journal of
cardiovascular MRI):
• In presence of severe PR – regurgitation
fraction ≥ 25% AND
I. Asymptomatic patient with 2 or more
of the following criteria:
a. RV end diastolic volume index: > 150
ml/m2 or Z score > 4
b. RV end systolic volume index: > 80
ml/m2
c. RVEF < 47%
d. LVEF < 55%
e. Large RVOT aneurysm
f. QRS duration > 140 ms
g. Sustained tachyarrhythmias
related to right heart volume load
h. Other hemodynamically
significant abnormalities
i. RVOT obstruction with RVSP ≥
2/3rd of systemic
ii. Severe branch pulmonary artery
stenosis(<30% flow to affected
lung
iii. ≥Moderate TR
iv. L to R shunt from residual atrial
or ventricular defects with shunt
ratio of ≥ 1.5
v. Severe AR
vi. Severe aortic dilatation
(diameter ≥5cm)

94. II. Symptomatic patients:
• symptoms and signs attributable to severe RV volume overload
documented by CMR or alternative imaging modality, fulfilling ≥ 1 of the
quantitative criteria described before.
• Examples of symptoms and signs include
• (1) exertional intolerance not explained by extracardiac causes,
• (2) signs and symptoms of heart failure, and
• (3) syncope attributable to arrhythmia.
III. Special considerations:
a) Due to higher risk of adverse clinical outcomes in patients who
underwent TOF repair at the age ≥ 3 years – PVR may be considered
if fulfil ≥ 1 of the criteria in section I
b) Women with severe PR with RV dilatation and/or dysfunction may be
at risk for pregnancy related complications. PVR may be considered
if fulfilling ≥ 1 of the quantitative criteria in section I.

95. Methods used for PVR
• Stented bioprosthesis
• Hybrid procedure:
• mini thoracotomy at 3 LICS: 29 mm porcine valve stented through
an incision of PA
• Tissue valve replacement