Approach to TOF physiology

DIFFERENTIAL DIAGNOSIS of

TOF PHYSIOLOGY

Satyam Rajvanshi

CYANOTIC CHD CLASSIFICATION

Cyanotic CHD CLASSIFICATION

Anatomico-pathological Physiological

Cyanotic CHD with Increased PBF• (5 Ts and 2 Ss)

– TAPVC – Single Ventricle – TGA – Single (Common)– Taussig-Bing Atrium– Tricuspid Atresia– Truncus Arteriosus

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

Cyanotic CHD with Decreased PBF

RV Dominance

PAHAcyanotic CHD

with ES

VSDPDA, AP window

ASD

Cyanotic CHD with PAH

DORVTGA

TAPVCTruncus

No PAHRVOTO

Quiet PrecordiumSingle S2 ± PS murmur

TOFDORV WITH PSTGA WITH PS

L-TGA WITH PS

ASD with PS


LV dominanceLV type Apex (Exam/CXR)

No Parasternal HeaveLAD ± LV dominance on ECG

Tricuspid Atresia with PSPulmonary Atresia with intact IVS

Single Ventricle with PSEbstein’s

Cyanotic CHD with Near Normal PBF

• Pulmonary AV Fistula• Unroofed coronary sinus into LA• Anomalous drainage of vena cava to LA

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

• Symptom complex – guide to PHYSIOLOGY

• Examination – guide to ANATOMY(Physical findings)

• Radiology, ECG – add to BOTH

TOF PHYSIOLOGY?What is

TOF PHYSIOLOGY

• Cyanotic CHD with decreased PBF having 2 key components anatomically

– Severe PS – Decreasing PBF

– Large VSD – with right to left shunt due to outflow obstruction

(Acyanotic TOF not included)

TOF PHYSIOLOGY

• Cyanotic CHD with decreased PBF having 2 key symptoms Physiologically

– History of Spells

– History of Squatting

– No CHF symptoms


RV Dominance

PAHAcyanotic CHD

with ES

VSDPDA, AP window

ASD

Cyanotic CHD with PAH

DORVTGA

TAPVCTruncus

No PAHRVOTO

Quiet PrecordiumSingle S2 ± PS murmur

TOFDORV WITH PSTGA WITH PS

L-TGA WITH PS

ASD with PS


LV dominance

LV type Apex (Exam/CXR)No Parasternal Heave

LAD ± LV dominance on ECGTricuspid Atresia with PSPulmonary Atresia with intact IVS



LV dominance

LV type Apex (Exam/CXR)No Parasternal Heave

LAD ± LV dominance on ECGTricuspid Atresia with PSPulmonary Atresia with intact IVS


TOF

“Tetralogy of Fallot” History

• 1671: First reported by Niels Stenson a.k.a Nicholas Steno

• 1777; 1784; 1839; 1866; 1872Similar Case reports

• 1888:Etienne Louis Arthur Fallot– Anatomic diagnosis

at bedside– Confirmed at

postmortem– Coined term Tetralogie

(Fr.)

• 1894: Pierre Marie (French), first used term “Tetralogie de Fallot”

• 1924: Maude Abbott, first used term “Tetralogy of Fallot” &“Fallot’s Tetralogy”

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

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

TOF

• 1 in 3600 live births• M=F

Natural History

• Survival– 66% 1st yr– 50% 3rd yr– 25% 1st decade

• Poor survival with PA– 50% 1st yr– 10% 1st decade

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

Physical Exam

• Physically underdeveloped

• Cyanosis (Depending on PBF)

• Pulse– NORMAL (irrespective of PS severity)– Wide PP – only in Large MAPCA/Severe AR

Physical Exam

• JVP– NORMAL (Height and waveform)

(RAP stays normal unless significant TR present)

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)

Physical Exam

Palpation• LV impulse– ABSENT (Conspicuous feature)– Absent even if MAPCAs present

Physical Exam

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

Physical Exam

Palpation• Right sternoclavicular joint pulsation– Right sided Aortic arch

• No thrill due to RVOTO– BF goes uninterrupted to dilated Aorta

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)

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)

Physical Exam

Auscultation• Continuous murmurs– In case of Pulmonary atresia/MAPCAs

• AR murmur ±

• PR murmur ±

ECG

• P wave – Height normal, peaked– Duration short

(LA underfilled)

• PR – Normal

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

ECG

• T wave – Maybe upright/inverted – Deep inversion rare

(RVSP never suprasystemic)

CXR

CXR

• Reduced PBF markings• Lacy appearance in

Pulmonary Atresia• Dilated Asc Ao• Rt Ao arch 20-30%

CXR

• Coer-en-Sabot• Heart resembling a

wooden boot– Concave PA bay– Small underfilled LV

above a horizontal IVS– Concentric RVH

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

DORV-VSD-PS

DORV

• Exact incidence unknown – Less than TOF

• Subaortic VSD 40-50% DORV

• PS 40-70% Subaortic VSD

DORV-PS

• History• Physical Exam• CXR

Same as TOF

DORV-PS

• Exceptions- If restrictive VSD present (Subaortic stenosis)• Long decrescendo systolic murmur at LPS area

(obligatory flow murmur)• ECG - LVH

DORV-PS

• Differentiation from TOF- ECG

- PR Prolonged- Counterclockwise depn- RVH but no sudden

transition

D-TGA – VSD – PS

D-TGA

• 1 in 2500-5000 live births• M>F 4:1

• VSD is most common communication

• PS (LVOTO) present in 15%

Symptoms/Presentation

• Cyanosis– Since birth – 1st day of life

• Hypercyanotic Spells– May be present occasionally

• Squatting– Rare

Natural History

• Mortality rate in TGA without PS– 30% 1st week– 50% 1st month– 90% 1st year

• Better survival with PS – may survive adolescence

Physical Exam

• Birth weight > normal (Contrast to other CHDs)

• Deep Cyanosis

• Scalp & Arm varicose veins (Systemic volume overload with desaturated blood)

• Pulse– Full volume bounding pulse– Warm extremities

• JVP– Elevated RAP with dominant A wave

(Systemic volume overload with desaturated blood)

• 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

• Auscultation– Just like TOF

ECG

• P wave – Tall, Peaked (Hypervolemic RA)

• RAD, RVH• T– Usually positive in ALL

precordial leads– Taller in right precordial leads

• Counterclockwise depn

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

L-TGA – VSD – PS

L-TGA

• 1 in 13000 live births• M>F 1.5:1

• VSD 80% L-TGA

• PS 50% L-TGA80% of PS a/w VSD


• Cyanosis appearance according to PS severity• Spells and squatting uncommon• Older adults – Stokes-Adams & Syncope

(High degree AV blocks)

Natural History

• Better survival with VSD-PS – may survive adolescence

Physical Exam

• Like TOF

• Pulse– Normal– Bradycardia/Blocks

• JVP– Normal– 1st /2nd /3rd degree AV blocks

• 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

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

ECG

• AV Blocks maybe present– CHB – ventricular activation sequence normal;

QRS narrow• LAD (d/t LAFB)• RVH

• 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

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

TRICUSPID ATRESIA – PS

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


• Just like TOF

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!

Physical Exam

• Like TOF• No left precordial bulge – RV underdeveloped

• Pulse– Normal

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

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

• 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

ECG

• P wave – Tall, Peaked (RAE)

• LAD• LVH with adult precordial

progression• Counterclockwise depn

CXR

• RAE – prominent rt. Upper border

• Small RV – Flat receding rt. Inferior border

• LV apex• Prominent Ao/small PA

SINGLE VENTRICLE – PS

Single ventricle (SV)

• 1 in 20000 live births• M>F 2-4:1

• 80% SLV• 10% SRV• 10% Indeterminate

• SLV OC inverted (right); Noninverted (left)TGA present (Ao from OC; PA from SLV)


• Cyanosis since birth

• Spells and squatting maybe present

Natural History

• SLV 50% mortality before 14 yrs

• SRV 50% mortality before 4 yrs

Physical Exam

• Like TOF

• Pulse– Normal

• JVP– Normal– V prom – if Rt AV valve regurgitant

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

present

• Auscultation– Like TOF

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

CXR

• Non-inverted OC• Doesn’t form right

border – just like D-TGA• LV apex

• Characteristic waterfall appearance of RPA – NOT present in PS – Low PBF

CXR

• Inverted OC• Form left border – just

like L-TGA• Maybe visible as

convexity on left• Left straight border• LV apex

APPROACH?

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

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

• Physical Exam– LV or RV predominent?

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

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

Health & Medicine

Approach to TOF physiology