This document provides an overview of tetralogy of Fallot (TOF), one of the most common cyanotic congenital heart diseases. It discusses the history, epidemiology, pathophysiology, clinical presentation, investigations, management, and prognosis of TOF. Key points include: TOF is characterized by pulmonary stenosis, ventricular septal defect, overriding aorta, and right ventricular hypertrophy. Clinical features include cyanosis, clubbing, and systolic murmur. Investigations include CXR, ECG, echocardiogram and cardiac catheterization. Management involves medical treatment of spells, palliative shunt procedures, and complete repair surgery. Long-term prognosis depends on severity of pulmonary stenosis and associated anomalies,

1. WELCOME
Dr. A.K.M. Kamruzzaman
FCPS Student, BSMMU.

2. Tetralogy of Fallot

3. Overview
Epidemiology
Pathophysiology
Hemodynamic
Clinical presentation
Blue spell
Evaluation
Complication
Management
Prognosis

4. History
1671 Danish
anatomist Nils
Steno
The first description
1777 Sandifort described a .“blue boy.” with the
anatomic features of TOF
1784 William Hunter cyanotic spells and poor growth in a
boy with TOF
Louis-Etienne Fallot ( A French physician) in 1888 , first correlate
the clinical and pathological features of TOF
1924 Maude Abbott coined the term“tetralogy of
Fallot.”
1936 produced the first illustrations of the pathologic and circulatory
features, and described x-ray and electrocardiographic features of TOF

5.  One of the conotruncal family of heart lesions
 Primary defect is an anterior deviation of the
infundibular septum
- Obstruction of RVOT(PS)
- VSD
- Overriding of aorta
- RVH
Tetralogy of fallot

7.  Most common congenital cyanotic heart disease
 Occurs in 3 of every 10,000 live births, and
 Accounts for 7–10% of all congenital cardiac
malformations.
Epidemiology

8.  Multifactorial
 But associations include
untreated maternal diabetes, phenylketonuria, &
intake of retinoic acid.
 Associated chromosomal anomalies include
trisomies 21, 18, and 13
 The risk of recurrence in families is 3%.
Etiology
Recent experience points to the much more frequent association of
microdeletions of chromosome 22. 22q11.2 deletion syndrome

9. Developmental Fault
• Defective embryonic neural crest migration- abnormal
conotruncal development.
• Incomplete rotation and faulty partitioning of the
conotruncus during separation.
• Malrotation of truncal-bulbar ridges results in mis-
alignment of the outlet and trabecular septum and
consequent straddling of the aorta over the malaligned
VSD.
• Abnormally anterior septation of the conotruncus by the
bulbotruncal ridges- subpulmonic obstruction.

10. Lesion Frequency in TOF
Structural
Pulmonary atresia
Atrial septal defect
Additional VSD
Atrioventricular septal defect
PDA
Dextrocardia
12%
20%
5%
1-3%
4-6%
2%
Vascular
Right aortic arch
Congenital absence of Pul valve
Coronary artery anomaly
Aberrant subclavian artery
MAPCAS
15-25%
3%
3-8%
2%
Additional structural and vascular lesions in TOF

11. Hemodynamic

12. Tetralogy Of Fallot
• Obstruction of RVOT(PS)
• Ventricular septal defect
• Overriding of aorta
• Right ventricular hypertrophy

13. Pathophysiology
Owing to right ventricular obstruction
during ventricular systole
deoxygenated blood of right ventricle
shunts through VSD to the left ventricle,
mix with oxygenated blood and this
mixed blood passes through the aorta
to different parts of the body.

14. • The flow occurs across the pulmonic stenosis
producing an ejection systolic murmur --
more severe the pulmonic stenosis, the less the
flow into the pulmonary artery and the bigger
the right to left shunt
• more severe the pulmonic stenosis, the shorter
the ejection systolic murmur and the more the
cyanosis
• the severity of cyanosis is directly proportional
to the severity of pulmonic stenosis, but the
intensity of the systolic murmur is inversely
related to the severity of pulmonic stenosis

15. • the right ventricular
outflow obstruction
results in the delay in the
P2 -- since the
pulmonary artery
pressure is reduced, the
P2 is also reduced in
intensity -- the late and
soft P2 is generally
inaudible in TOF -- the
S2 is , therefore, single and
the audible sound is A2 --
 since the aorta is
somewhat anteriorly
displaced, the audible
single A2 is quite loud.

16. The VSD of TOF is always large enough to allow free exit to
the right to left shunt --- since the right ventricle is
effectively decompressed by the VSD --- congestive failure
almost never occurs in TOF.
As the systolic pressures between two ventricle are
identical there is little or no shunt and the VSD is silent

17. The degree of RVOT obstruction determines
 The timing of the onset of symptoms
 Severity of cyanosis
 Degree of RVH
RVOT obstruction
Mild- moderate
Balanced shunt across the VSD
No visibly cyanosed-Pink TOF
Severe
Cyanosis will be present
from birth

18. Clinical Features
From History
• Exertional dyspnea
• Cyanosis
• Paroxysomal blue
spells
• Growth failure
• Developmental
delay

19.  Cyanosis , clubbing
 Conjunctival congestion
 Pulse: Normal
 Blood pressure : Normal
 Normal sized heart with parasternal impulse, a
systolic thrill in less than 30 % patients.
Physical examination

20. Normal first sound, Single second sound
 An ejection systolic murmur : Loud & harsh, most
intensity at the left sternal border
 Occasionally continuous murmur ( if prominent
collaterals are present)
Physical examination

21. Paroxysmal hypercyanotic attack
Hypoxic, blue or tet spell
 Particular problem during the 1st 2 years of life
 Hyperpneic, restless, cyanosis increases,
gasping respiration & syncope
 Frequently occur in the morning on awakening or
after episodes of vigorous crying
 Last for few min to hrs
 Onset is spontaneous & unpredictable

23. Paroxysmal hypercyanotic attack
 Short episodes are followed by generalized
weakness & sleep
 Severe spell progress to unconsciousness,
occasionally to convulsion/ hemiparesis
 Temporary disappearance /↓ in intensity of the
systolic murmur
Occurs due to already compromised pulmonary blood flow as a result
of severe hypoxia & metabolic acidosis

24. Investigation
CBC with PBF
Polycythemia
Feature of iron deficiency anemia

25. 1. Boot shaped heart(“coeur en
sabot”) : apex is lifted up, narrow
base & there is a concavity in the
region of pulmonary artery
2. Normal heart size
3. Oligaemic lung fields
4. Hilar vessels are few, lung
vessels also few
X ray chest

26. ECG
Right axis deviation
RVH
Tall peaked p wave may be present

27.  The extent of aortic
override of the septum
 Location & degree of the
RVOT obstruction
 The size of pulmonary
valve annulus
 The side of aortic arch
Echocardiography

28. Cardiac catheterization
 Presence of multiple VSDs
 Degree &levels of stenosis in
right ventricular outflow
tract, pulmonary arteries,
coronary artery anomaly.

29. Complication
 Hypercyanotic spell
 Cerebral thrombosis
 Cerebral abscess
 Infective endocarditis
 Hyperuremia & gout : 2ndary to polycythemia
 Relative iron deficiency anemia
 Bleeding disorder
 Coagulopathy

30. Treatment
 General measure
 Management of hyper cyanotic spell
 Surgery
 Treatment of complication
 Prophylaxis

31. Treatment depends upon the RVOT
obstruction
Severe tetralogy require urgent
medical treatment & surgical
intervention in neonatal period
Less severe obstruction,
stable & waiting for surgery
1. Oxygenation
2. Prevention of hypothermia
3. I/V PG E1 (.01-.02
micro/kg/min)
4. Monitoring of blood
glucose
1. Oral propanolol (0.5-1
mg/kg every 6hr)
2. Prevention/prompt
treatment of
dehydration
3. Iron supplementation

32. Management of cyanotic spell
1.Knee chest position:
1) Constriction of Femoral artery PVR left
ventricular presser Rt- Lt shunt improves
pulmonary blood flow better oxygenation &
improves cyanosis
2) Constriction of femoral vein venous return
Rt- Lt shunt

33. • It is difficult to achieve to
knee-chest position. It is
favorable to hold the child
in parents shoulder with
knees bent and oxygen is
administered by another
person from behind.

34. 2. Oxygen: Oxygen to improve oxygenation. It is better given
in nebulized form .
3. Morphine: Depresses respiratory center→abolishes
hyperpnea→ decreases Systemic Venous Return. 0.2mg/kg
SC.
4. IV fluids: to correct dehydration
5. Inj NaHCO3: (1-2 meq/kg intravenously slowly). To
correct metabolic acidosis

35. 6. Propanolol: 0.1-0.2 mg/kg I/V over 5 min.
 Reduces dynamic RVOT obstruction and slow the HR
thereby decreasing R→L shunting.
 Increase SVR by antagonizing the vasodilating effects
of β2 adrenergic stimulation.

36. 7. Phenylephrine Hydrochloride: 0.01 mg/kg IV (slowly) or
0.1 mg/kg SC or IM (Improve RV outflow, ↓R→L shunt
8. Ketamine: 0.25- 1.0 mg/kg. IV or IM→ has dual benefit
causes sedation and ↑ SVR
9. Premature attempts to obtain blood samples should be
avoided.

37. Long Term medical Management
1. Educate the parents to recognize the spell and know what
to do.
2. Oral propanolol therapy ,0.5-1.5 mg/kg every 6 hr
3. Maintenance of good dental hygiene and practice of
antibiotic prophylaxis against SBE are important.

38. Long Term medical Management (cont’)
4. A relative iron deficiency state should be
detected and treated.
5. Hct values are usually normal so RBC indices and PBF
should be monitored.

39. Surgical tratment

40. Surgical
Palliative Shunt Procedures :
-To increase pulmonary blood flow
Indications:
1. Neonates with TOF and pulmonary atresia.
2. Infants with hypoplastic pulmonary annulus.
3. Infants younger than 3-4 months with medically
unmanageable hypoxic spells.

41.  Classic Blalock-Taussing shunt-(SA-PA)
 Modified B-T shunt- A Gore-Tax interposition is placed
between the Subclavian Artery and the ipsilateral
Pulmonary Artery
 Potts operation- between the descending aorta and left PA.
 Waterson Shunt-a between ascending aorta and right PA.

43. Corrective /Complete Repair Surgery:
Indications
1. Oxygen saturation <75 to 80%.
2. Occurrence of hypoxic spell
3. Mildly cyanotic infants who have had
previous shunt surgery
4. Asymptomatic children with coronary artery
anomalies.

44. Timing
Symptomatic infants may have primary repair at 4-
6months.Most centers prefer primary elective repair by 1 to
2years of age .
The procedure include
- Patch closure of VSD
- Relief of RVOT obstruction by resecting
obstructive muscle bundle
- And Pulmonary valvotomy
Surgical mortality rate is <5%

45. Natural course/Prognosis
Depends upon
- Severity of RVOT obs
- Associated other malformation
- Management

46. NATURAL HISTORY
1. Infants with acyanotic TOF gradually become cyanotic.
Patients who are already cyanotic become more cyanotic
as a result of the worsening condition of the infundibular
stenosis and polycythemia.
2. Polycythemia develops secondary to cyanosis.
3. Development of relative iron-deficiency state (i.e.,
hypochromia)

47. NATURAL HISTORY(contd.)
4. Hypoxic spells may develop in infants
5. Growth retardation may be present if cyanosis is
severe
6. Brain abscess and cerebrovascular accident rarely
occur
7. SBE is occasionally a complication.
8. Some patients, particularly those with severe
TOF, develop AR.
9. Coagulopathy is a late complication of a long-
standing cyanosis.

48. • The survival for untreated Tetralogy of Fallot is
approximately 75% after the first year of life, 60%
by four years, 30% by ten years, and 5% by forty
years.

49. TOF with RVOT
obstruction
Clinical course Survival
Mild
Obstruction
Cyanosis appear in
childhood
3rd-4th decade
Moderate Cyanosis since early
infancy
2nd-3rd decade
Severe Cyanosed since birth Seldom survive
beyond 2nd decade

50. Without surgery around 50% of children with TOF will
die within the first few years of life and survival beyond
30 years is uncommon.
With corrective surgery in childhood, survival is 95-
99%, and almost all children can be expected to survive to
adulthood.