Clinical approach to TOF physiology - cyanotic congenital heart disease with decreased pulmonary blood flow

1. DIFFERENTIAL DIAGNOSIS
of
TOF PHYSIOLOGY
Satyam Rajvanshi

2. CYANOTIC CHD CLASSIFICATION

3. Cyanotic CHD CLASSIFICATION
Anatomico-pathological Physiological

4. Cyanotic CHD with Increased PBF
• (5 Ts and 2 Ss)
– TAPVC – Single Ventricle
– TGA – Single (Common)
– Taussig-Bing Atrium
– Tricuspid Atresia
– Truncus Arteriosus

5. Cyanotic CHD with Increased PBF
• (5 Ts and 2 Ss)
Admixture Physiology
(Intercirculatory mixing)
• PRE-TRICUSPID
• Venous level – TAPVC
• Atrial level – Single atrium,
Tricuspid atresia, HLHS
• POST-TRICUSPID
• Ventricular level – Single
Ventricle
• Arterial level – Truncus
Transposition Physiology
• TGA
• Taussig Bing

6. Cyanotic CHD with Decreased PBF
RV Dominance
PAH
Acyanotic CHD
with ES
VSD
PDA, AP window
ASD
Cyanotic CHD
with PAH
DORV
TGA
TAPVC
Truncus
No PAH
RVOTO
Quiet Precordium
Single S2 ± PS murmur
TOF
DORV WITH PS
TGA WITH PS
L-TGA WITH PS
ASD with PS

7. Cyanotic CHD with Decreased PBF
LV dominance
LV type Apex (Exam/CXR)
No Parasternal Heave
LAD ± LV dominance on ECG
Tricuspid Atresia with PS
Pulmonary Atresia with intact IVS
Single Ventricle with PS
Ebstein’s

8. Cyanotic CHD with Near Normal PBF
• Pulmonary AV Fistula
• Unroofed coronary sinus into LA
• Anomalous drainage of vena cava to LA

9. CCHD Physiological classification
• TOF Physiology
• Transposition Physiology
• Admixture Physiology
• Eisenmenger Physiology
• Duct-dependent Physiology
– For PBF – Pulmonary atresia
– For SBF – Aortic atresia/HLHS

10. CCHD Physiological classification
• TOF Physiology
• Transposition Physiology
• Admixture Physiology
• Eisenmenger Physiology
• Duct-dependent Physiology
– For PBF – Pulmonary atresia
– For SBF – Aortic atresia/HLHS
• Near-normal
Physiology
– Pulmonary AVFs
• Miscellaneous
– Ebstein’s
– ASD with PS
– Unroofed CS into LA

11. • Symptom complex – guide to PHYSIOLOGY
• Examination – guide to ANATOMY
(Physical findings)
• Radiology, ECG – add to BOTH

12. TOF PHYSIOLOGY?
What is

13. TOF PHYSIOLOGY
• Cyanotic CHD with decreased PBF
having 2 key components anatomically
– Severe RVOTO – Decreasing PBF
– Large VSD – causing equalization of RV and LV
pressure with right to left shunt due to outflow
obstruction
(Acyanotic TOF not included)

14. TOF PHYSIOLOGY
• Cyanotic CHD with decreased PBF
having 2 key symptoms Physiologically
– History of Spells
– History of Squatting
– No CHF symptoms

15. Cyanotic CHD with Decreased PBF
RV Dominance
PAH
Acyanotic CHD
with ES
VSD
PDA, AP window
ASD
Cyanotic CHD
with PAH
DORV
TGA
TAPVC
Truncus
No PAH
RVOTO
Quiet Precordium
Single S2 ± PS murmur
TOF
DORV WITH PS
TGA WITH PS
L-TGA WITH PS
ASD with PS

16. Cyanotic CHD with Decreased PBF
LV dominance
LV type Apex (Exam/CXR)
No Parasternal Heave
LAD ± LV dominance on ECG
Tricuspid Atresia with PS
Pulmonary Atresia with intact IVS
Single Ventricle with PS
Ebstein’s

17. Cyanotic CHD with Decreased PBF
LV dominance
LV type Apex (Exam/CXR)
No Parasternal Heave
LAD ± LV dominance on ECG
Tricuspid Atresia with PS
Pulmonary Atresia with intact IVS
Single Ventricle with PS
Ebstein’s

18. TOF

19. “Tetralogy of Fallot” History
• 1671: First reported by Niels Stenson a.k.a
Nicholas Steno
• 1777; 1784; 1839; 1866; 1872
Similar Case reports

20. • 1888:
Etienne Louis Arthur Fallot
– Anatomic diagnosis
at bedside
– Confirmed at
postmortem
– Coined term Tetralogie
(Fr.)

21. • 1894: Pierre Marie (French), first used term
“Tetralogie de Fallot”
• 1924: Maude Abbott, first used term
“Tetralogy of Fallot” &
“Fallot’s Tetralogy”

22. Pathology
• Van Praagh called TOF “Monology of Stenson”
• Central pathology –
Underdevelopment/hypoplasia of
Subpulmonary infundibulum
• Gives rise to 4 components of ‘tetralogy’
– Obstructive RVOT
– Large Malaligned VSD
– Aortic override
– Dominant RV hypertrophy

23. Pathology
• Van Praagh called TOF “Monology of Stenson”
• Central pathology –
Underdevelopment/hypoplasia of
Subpulmonary infundibulum
• Gives rise to 4 components of ‘tetralogy’
– Obstructive RVOT
– Large Malaligned VSD
– Aortic override
– Dominant RV hypertrophy

24. TOF
• 1 in 3600 live births
• M=F

25. Natural History
• Survival
– 66% 1st yr
– 50% 3rd yr
– 25% 1st decade
• Poor survival with PA
– 50% 1st yr
– 10% 1st decade

26. Symptoms/Presentation
• Cyanosis
– 1-2 weeks after birth
– More severe the PS, earlier the presentation
• Hypercyanotic Spells
– 2 months to 2 years of age
• Exertional dyspnoea
– Older child
• Squatting
– To alleviate a spell or dyspnoea

27. Physical Exam
• Physically underdeveloped
• Cyanosis (Depending on PBF)
• Pulse
– NORMAL (irrespective of PS severity)
– Wide PP – only in Large MAPCA/Severe AR

28. Physical Exam
• JVP
– NORMAL (Height and waveform)
(RAP stays normal unless significant TR present)

29. Physical Exam
Palpation
• RV impulse
– Gentle; like normal neonatal RV; but stays like that
even as child grows
– 4th LICS
– 5th LICS & Subxyphoid (if Sub-Infundibular stenosis)

30. Physical Exam
Palpation
• LV impulse
– ABSENT (Conspicuous feature)
– Absent even if MAPCAs present

31. Physical Exam
Palpation
• 2nd / 3rd LICS
– A2 maybe palpable
– Left upper ICS (Not right) (due to hypoplastic PA)

32. Physical Exam
Palpation
• Right sternoclavicular joint pulsation
– Right sided Aortic arch
• No thrill due to RVOTO
– BF goes uninterrupted to dilated Aorta

33. Physical Exam
Auscultation
• Aortic area (2nd RICS)
– Loud aortic EC from aortic root
– Maximum in expiration
• Pulmonary area
– Very delayed and soft P2
– EC and P2 almost inaudible (Bicuspid PV – decreased mobility)

34. Physical Exam
Auscultation
• 3rd LICS
– Superficial murmur starting with S1
Duration and intensity decreases with severity of PS
• No S4 (RA contraction not forceful, RAP normal)
• No S3 (No RVF)

35. Physical Exam
Auscultation
• Continuous murmurs
– In case of Pulmonary atresia/MAPCAs
• AR murmur ±
• PR murmur ±

36. ECG
• P wave
– Height normal, peaked
– Duration short
(LA underfilled)
• PR – Normal

37. ECG
• QRS
– RAD (Like newborns)
– Clockwise depn
– Normal duration
– No notching
– RVH
• Tall R in V1
• Sudden transition V1-2
• Q in V5,6 - PBF

38. ECG
• T wave
– Maybe upright/inverted
– Deep inversion rare
(RVSP never
suprasystemic)

39. CXR

40. CXR
• Reduced PBF markings
• Lacy appearance in
Pulmonary Atresia
• Dilated Asc Ao
• Rt Ao arch 20-30%

41. CXR
• Coer-en-Sabot
• Heart resembling a
wooden boot
– Concave PA bay
– Small underfilled LV
above a horizontal IVS
– Concentric RVH

42. CXR
• Coer-en-Sabot
• Intrauterine life LV is
normal – so boot shape
develops after 1-2 mos
of birth
• TOF-PA – Boot even in
neonates if low PBF

43. DORV-VSD-PS

44. DORV
• Exact incidence unknown – Less than TOF
• Subaortic VSD 40-50% DORV
• PS 40-70% Subaortic VSD

45. DORV-PS
• History
• Physical Exam
• CXR
Same as TOF

46. DORV-PS
• Exceptions
- If restrictive VSD present (Subaortic stenosis)
• Long decrescendo systolic murmur at LPS area
(obligatory flow murmur)
• ECG - LVH

47. DORV-PS
• Differentiation from
TOF
- ECG
- PR Prolonged
- Counterclockwise depn
- RVH but no sudden
transition

48. D-TGA – VSD – PS

49. D-TGA
• 1 in 2500-5000 live births
• M>F 4:1
• VSD is most common communication
• PS (LVOTO) present in 15%

50. Symptoms/Presentation
• Cyanosis
– Since birth – 1st day of life
• Hypercyanotic Spells
– May be present occasionally
• Squatting
– Rare

51. Natural History
• Mortality rate in TGA without PS
– 30% 1st week
– 50% 1st month
– 90% 1st year
• Better survival with PS – may survive
adolescence

52. Physical Exam
• Birth weight > normal (Contrast to other CHDs)
• Deep Cyanosis
• Scalp & Arm varicose veins (Systemic volume
overload with desaturated blood)

53. • Pulse
– Full volume bounding pulse
– Warm extremities
• JVP
– Elevated RAP with dominant A wave
(Systemic volume overload with desaturated blood)

54. • Palpation
– RV impulse gentle at birth
– Soon after 1 week – Prominent RV impulse
(Systemic volume overload with desaturated blood)
– Rt sternoclavicular impulse – Rt arch
(11-16% in TGA-VSD-PS)
Just like TOF

55. • Auscultation
– Just like TOF

56. ECG
• P wave
– Tall, Peaked (Hypervolemic RA)
• RAD, RVH
• T
– Usually positive in ALL
precordial leads
– Taller in right precordial leads
• Counterclockwise depn

57. CXR
• Thymic shadow absent
(after 12 hrs of birth)
• Characteristic narrow
pedicle (egg on side)
ABSENT in severe PS –
due to dilated right
anterior aorta
• CXR like TOF

58. L-TGA – VSD – PS

59. L-TGA
• 1 in 13000 live births
• M>F 1.5:1
• VSD 80% L-TGA
• PS 50% L-TGA
80% of PS a/w VSD

60. Symptoms/Presentation
• Cyanosis appearance according to PS severity
• Spells and squatting uncommon
• Older adults – Stokes-Adams & Syncope
(High degree AV blocks)

61. Natural History
• Better survival with VSD-PS – may survive
adolescence

62. Physical Exam
• Like TOF

63. • Pulse
– Normal
– Bradycardia/Blocks
• JVP
– Normal
– 1st /2nd /3rd degree AV blocks

64. • Palpation
– IVS almost vertical and parallel to left sternal border
– Morph. RV – anterior & left position forming apex –
Systolic RV Impulse
– Morph. LV – posterior & right position behind
sternum – LV Impulse non-palpable (even if enlarged)
– Ao EC & A2 palpable 2nd LICS

65. • Auscultation
– Just like TOF
– In case of blocks
• Soft S1 – in 1st degree AVB
• Variable S1 – High degree AVB

66. ECG
• AV Blocks maybe present
– CHB – ventricular activation sequence normal;
QRS narrow
• LAD (d/t LAFB)
• RVH

67. • Q /q
– Present in right precordial leads / absent in left
(Septal activation right to left directed)
– Present in III, avf (III>avf) / absent in I, aVL
(Septal activation superiorly directed)
• T
– Usually positive in ALL precordial leads
• Clockwise depn

68. CXR
• Thymic shadow absent
• Ao & PA side by side
• Ao left and Anterior
• Straight left border
• Hump shaped heart
• RPA and LPA at same
level

69. TRICUSPID ATRESIA – PS

70. Tricuspid Atresia (TA)
• 1 in 17000 live births
• 90% TA
– No TGA
• 90% have Restrictive VSD – Physiologically PS
• 10% TA
– TGA
• 90% have no PS – Increased PBF

71. Symptoms/Presentation
• Just like TOF

72. Natural History
• TA-NRGA-PS
– 80% mortality in 1st yr
– Already restrictive VSD – decreases in size and
closes! (Like a PM-VSD!)
– Acquired Pulmonary atresia without
embryological collaterals – fatal!

73. Physical Exam
• Like TOF
• No left precordial bulge – RV underdeveloped

74. • Pulse
– Normal
• JVP
– Height increased
– A prom – PFO/Restrictive ASD/Decr LV compliance
– V prom – MR

75. • Palpation
– IVS almost vertical and parallel to left sternal border
– Systolic LV Impulse (present even if low PBF)
– RV Impulse non-palpable

76. • Auscultation
– Single S1 (M1)
– Single S2 (A2); P2 soft & delayed – maybe heard
– LVS4 if unrestrictive VSD/LVH
– Obligatory VSD holosystolic murmur
• 3rd-4th LICS
• Radiates to 2nd LICS
• Duration shortens in closing VSD

77. ECG
• P wave
– Tall, Peaked (RAE)
• LAD
• LVH with adult precordial
progression
• Counterclockwise depn

78. CXR
• RAE – prominent rt.
Upper border
• Small RV – Flat
receding rt. Inferior
border
• LV apex
• Prominent Ao/small PA

79. SINGLE VENTRICLE – PS

80. Single ventricle (SV)
• 1 in 20000 live births
• M>F 2-4:1
• 80% SLV
• 10% SRV
• 10% Indeterminate
• SLV OC inverted (left); Noninverted (right)
TGA present (Ao from OC; PA from SLV)

81. Symptoms/Presentation
• Cyanosis since birth
• Spells and squatting maybe present

82. Natural History
• SLV 50% mortality before 14 yrs
• SRV 50% mortality before 4 yrs

83. Physical Exam
• Like TOF

84. • Pulse
– Normal
• JVP
– Normal
– V prom – if Rt AV valve regurgitant

85. • Palpation
– Systolic LV Impulse at apex
– 3rd LICS – palpable impulse due to inverted OC maybe
present

86. • Auscultation
– Like TOF

87. ECG
• P wave
– Tall, Peaked (RAE)
• Inverted OC – RAD,
Clockwise depn
• Noninverted OC – LAD,
Counterclockwise depn
• Stereotyped rS or RS
complexes V2-V5
• Tall R in V1 despite LVH

88. CXR
• Non-inverted OC
• Doesn’t form left
border – just like D-TGA
• LV apex
• Characteristic waterfall
appearance of RPA –
NOT present in PS –
Low PBF

89. CXR
• Inverted OC
• Form left border – just
like L-TGA
• Maybe visible as
convexity on left
• Left straight border
• LV apex

90. APPROACH?

91. • Incidence acccording to age and natural
history
– Age of presentation?
– Survival?

92. • PRESENTATION
– Timing of cyanosis appearance?
– Characteristic spells/squatting?

93. • Physical Exam
– LV or RV predominent?

94. • ECG
– LAD/RAD
– Clock/Counterclock
– LVH/RVH
– AV Blocks

95. • CXR
– Less helpful
– LV/RV apex
– Left Straightening