Tof physiology

HISTORY
 Tetralogy of Fallot was first described by Niels
Stenson in 1671.
 Precise anatomical description by William
Hunter at St Georges Hospital Medical School in
London in 1784.

 Fallot physiology, was
defined by Etienne-Louis
Fallot in 1888 in his
description of L’anatomie
pathologique de la
maladie bleu.
 Term tetralogy of Fallot is
attributed to Canadian
Maude Abbott in 1924.

Fallot physiology
 Systemic venous return unable to reach lungs
 Shunted right to left away from pulm circulation
VSD essential for this to occur;
 Or a common chamber !
PLUS

 Obstruction at
- RA outlet - i.e Tricuspid atresia
- infundibular/valvular Pulmonary stenosis
- rarely branch PA stenosis.

FALLOT PHYSIOLOGY SYNDROMES
 Tetralogy of Fallot
 Tricuspid. atresia - PS
 Single ventricle - PS
 TGA with VSD – PS
 DORV – VSD – PS

EPIDEMIOLOGY
 About 3·5% of all infants born with a congenital heart
disease have tetralogy of Fallot.
 Corresponding to one in 3600 or 0·28 every 1000
livebirths, with males and females being affected equally.
Fyler et al . NE Regional Infant Cardiac Program. 1980
 Its precise cause is unknown, as for most congenital heart
diseases.
 Most cases seem sporadic, although the risk of recurrence
in siblings is about 2.5% if there are no other affected first-
degree relatives. Nora JJNora JJ Am J Med Genet 1988Am J Med Genet 1988

THE BALTIMORE-WASHINGTON INFANT
STUDY. (1981-1989) Ferencz et al.1997
 Tof - 0.33 per 1000 live births
 Fifth most common defect
 Most common form of cyanotic defect
 79.7% had tof with ps
 20.3% had tof with pa
 Tof with ps prevalence 0.26 per 1000 live births with male
predominance.

INDIAN DATA
Bhardwaj et al. Congenital heart disease · October 2014

GENETIC FACTORS
 Genetic causes of TOF are heterogeneous:
a)Monogenic or polygenic mode of inheritance.
b)Autosomal dominant mode of inheritance with reduced
penetrance,
c)An autosomal recessive mode of inheritance.
Moss & Adams' Heart Disease in infants
 Environmental factors:
Maternal diabetes [threefold increased risk], Retinoic
acids,Maternal phenylketonuria (PKU), and Trimethadione
Edward J et al .Edward J et al .N Engl J Med 1985; 313:837-841N Engl J Med 1985; 313:837-841

GENETIC SYNDROMES AND CHROMOSOMAL
ANOMALIES
 DiGeorge/Velocardiofacial
syndrome
 Down syndrome
 Alagille syndrome
 Cat's-eye syndrome
 CHARGE and
VATER/VACTERL
associations, Poland
syndrome
 Goldenhar’s
syndrome(oculo-auriculo-
vertebral dysplasia). THE
BALTIMORE STUDY.
Microdeletion 22q11….seen
in
8%-23% of TOF patients;
45% of TOF + PA;
 65% of those with TOF +
APV
Goldmuntz et al J Am CollGoldmuntz et al J Am Coll
Cardiol 1998Cardiol 1998

EMBRYOLOGY
 The aorta and pulmonary artery
start as a single tube the truncus
arteriosus which is then divided by
the spiral septum.
 The spiral septum grows down to
and attaches to the ventricular
septum which isolates the left and
right ventricles as well as isolating
the aorta and pulmonary artery.
 But in TOF Spiral septum gets
shifted over towards the right side
of the heart leading to large
opening of aorta and small
pulmonary artery opening with
spiral septum missing ventricular
septum with straddling of aorta
over malaligned vsd.

ANATOMYANATOMY
 Anterior and cephalad deviation of the infundibular septumAnterior and cephalad deviation of the infundibular septum..
 This results in a malaligned ventricular septal defect (VSD),This results in a malaligned ventricular septal defect (VSD),
with the aortic root overriding the defect and leading towith the aortic root overriding the defect and leading to
subsequent right ventricular outflow obstruction.subsequent right ventricular outflow obstruction.
 VSDVSD is most commonly located in the perimembranous regionis most commonly located in the perimembranous region
of the septum.of the septum.
 The VSD can extend into the muscular septum.The VSD can extend into the muscular septum.
 There are rarely other muscular ventricular septal defects.There are rarely other muscular ventricular septal defects.
Anderson et al. J thorac Cardiovasc Surg 1981

RVOT OBSTRUCTION
 The right ventricular outflow obstruction is often at
multiple levels.
– The anterior and cephalad deviation of the
infundibular septum results in subvalvular obstruction.
– Hypertrophy of muscular bands in this region can
further accentuate subvalvular obstruction.
– The pulmonary valve annulus is usually hypoplastic,
although in some instances it is of normal size.
– The pulmonary valve itself is frequently bicuspid and
stenotic
Van praagh et al .Am J Cardiol 1970

 It is common to identify an area of supravalvularr
narrowing in the main pulmonary artery at the sinotubular
ridge.
 There may also be further obstruction at the branch
pulmonary arteries.
 These may be diffusely hypoplastic or have focal areas of
stenosis, most commonly at the proximal branch
pulmonary arteries.
Rao et al .Am J Cardiol 1971

Kirklin/Barratt-Boyes Cardiac Surgery

OVERRIDING AORTA
 Aorta is displaced to the right over the VSDAorta is displaced to the right over the VSD rather than the leftrather than the left
ventricle leading to blood flow from both ventricles into theventricle leading to blood flow from both ventricles into the
aorta.aorta.
 TheThe degree of aortic override of the VSDdegree of aortic override of the VSD can vary widely andcan vary widely and
is one of the major factors used by some groupsis one of the major factors used by some groups toto
differentiate between TOF and DORV.differentiate between TOF and DORV.
 If one defines double outlet right ventricle as the presenceIf one defines double outlet right ventricle as the presence
of aortic/mitral valve fibrous continuity, then the degree ofof aortic/mitral valve fibrous continuity, then the degree of
override is not relevant to diagnosis.override is not relevant to diagnosis.
 If, however, one defines double outlet right ventricle as aIf, however, one defines double outlet right ventricle as a
condition with greater than 50 percent aortic override, then, bycondition with greater than 50 percent aortic override, then, by
definition, the degree of aortic override in TOF is limited.definition, the degree of aortic override in TOF is limited.

ASSOCIATED ANOMALIES
Kirklin/Barratt-Boyes Cardiac Surgery

Kirklin/Barratt-Boyes CardiacKirklin/Barratt-Boyes Cardiac
SurgerySurgery

RV and LV pressures
becomes identical

RV and LV pressures
becomes identical
There is little
or no L to R
shunt

RV and LV pressures
becomes identical
There is little
or no L to R
shunt
Hence, VSD is silent

RV and LV pressures
becomes identical
There is little
or no L to R
shunt
Hence, VSD is silent
Right ventricle
into pulmonary
artery across
pulmonic
stenosis
producing
ejection systolic
murmur

Hence, the
more severe
the
pulmonary
stenosis

Hence, the
more severe
the
pulmonary
stenosis
The BIGGER
the Left to
RIGHT shunt

Hence, the
more severe
the
pulmonary
stenosis
The BIGGER
the Left to
RIGHT shunt
Less flow
into the
pulmonary
artery

Hence, the more
severe the
pulmonary
stenosis
The BIGGER
the Left to
RIGHT shunt
Less flow into
the pulmonary
artery
Shorter the
ejection systolic
murmur

Hence, the more
severe the
pulmonary
stenosis
The BIGGER
the Left to
RIGHT shunt
Less flow into
the pulmonary
artery
Shorter the
ejection systolic
murmur
More cyanosis because of less flow to the lung!

HENCE,
 Severity of cyanosis is directly proportional to the severity of
pulmonic stenosis.
 Intensity of the systolic murmur is inversely related to the
severity of pulmonic stenosis.

 One of the physiologic characteristics of TOF is that theOne of the physiologic characteristics of TOF is that the
RVOT obstruction can fluctuate.RVOT obstruction can fluctuate.
 An individual with minimal cyanosis can develop aAn individual with minimal cyanosis can develop a
dynamic increase in right ventricular outflow tractdynamic increase in right ventricular outflow tract
obstruction with a subsequent increase in right-to-leftobstruction with a subsequent increase in right-to-left
shunt and the development of cyanosis.shunt and the development of cyanosis.
 These episodes are often referred to asThese episodes are often referred to as "TET SPELLS"" oror
"HYPERCYANOTIC SPELLS".

 Typical spell begins with progressive increase in rate and
depth of respiration and culminates in paroxysmal hyperapnea,
deepening cyanosis, limpiness, syncope and occasionally in
convulsions, CVA and death.
 Peak incidence in between second and sixth month of life.
 Spells typically initiated by stress of feeding, crying or a
bowel movement, particularly after awakening from deep
sleep.

Pediatric Cardiology for PractitionersPediatric Cardiology for Practitioners By Myung K. ParkBy Myung K. Park

MANAGEMENT OF ANOXIC SPELL
1. Calm the baby
2. Increase SVR
3. Knee chest position
4. Humidified O2
5. Morphine 0.1 -0.2 mg/Kg Subcutaneous
6. Correct acidosis – Sodium Bicarb IV
7. Inj phenyelphrine
8. Propranolol
1. 0.1mg/kg/IV during spells
2. 0.5 to 1.0 mg/kg/ 4-6hourly orally
9. Vasopressors:
10. Correct anemia

SQUATTING
Postural effects in tetralogy of fallot .Am J Med 15:297,1953

CLINICAL FEATURES
 Wide due to variable severity of RV outflow obstruction
 USGfetal diagnosis
 Newborn & infants…cyanosis and systolic murmur.
 Acyanotic TOFrarely CHF unless there is a large PDA
or aortopulmonary collateral arteries
 Pregnancy…poorly tolerated … gestational decrease in
SVR increases R-L shunt & the labile SVR during labor,
delivery leads to abrupt hypoxemia…..high fetal wastage /
immature offspring.

EXAMINATION
 Cyanosis, Clubbing
 Prominent a waves in jvp.
 Arterial pulses …normal in uncomplicated TOF
 Wide pulse pressure (arterial diastolic runoff)….
aortopulmonary collaterals, palliative surgical shunt or
PDA
 Accentuated precordial RV impulse
 S2 single& loud (anterior, dextroposed aorta)
 S3/S4 are unusual
 Aortic ejection click

 Systolic murmur - crescendo-decrescendo at LUSB.
 The intensity of the murmur inversely parallels the degree
of pulmonic obstruction.
 Diastolic murmurs are unusual.
 TOF with PA- no harsh, obstructive precordial murmurs
 TOF and APV syndrome - A harsh diastolic murmur, with
a harsh murmur of PS. [Harsh sawing, to-and-fro murmur]
 Continuous murmurs - PDA, aortopulmonary collaterals,
may be best heard in the back.

ECG
QRS axis … same as that of a normal newborn
RVH…Tall monophasic R in V1 with an abrupt
change to an rS pattern in V2 (Tall R extends into adj
precordial leads in TOF + APV)
Balanced shunt …qR in V5,V6

CXR
 Normal sized heart; [may be large in
PA]
 Upturned apex; attenuated & concave
left heart border (infundibular and PA
hypoplasia)….boot-shaped heart, or
coeur en sabot
 Diminished pulmonary vascularity in
proportion to the degree of cyanosis.
 Right atrial enlargement
 Right-sided aortic arch (20-25% of
patients) with indentation of leftward-
positioned tracheobronchial shadow.
 Absent thymic shadow in the newborn
may indicate associated chromosome
22q11.2 microdeletion (DiGeorge
syndrome).

ECHOCARDIOGRAPHY
 2-D echocardiography cornerstone for noninvasive diagnosis.
 Doppler analysis provides further data regarding
hemodynamic characteristics.
 The coronary arteries are also readily apparent in PSAX view
slightly superiorly.
 The origin and course of the left and right coronary arteries
should be determined, paying special attention to whether any
vessels take an anterior course across the infundibulum.
 Correct definition of the coronary artery anatomy was possible
in most patients with a sensitivity of 82%, specificity of 99%,
and accuracy of 98.5% in a study by Need et al.

LAD
RCC
NCC
RCA
LCx
Pulm.
Valve
MPA
The anomalous LAD crossing the RVOT in TOF is identified when the transducer
is swept superiorly in the parasternal short -axis view .
This allows visualization of the anomalous LAD that is situated anterior to the RVOT

CARDIAC CATHETERIZATION
 With the evolution of noninvasive technology, the
indications for diagnostic cardiac catheterization have
diminished substantially.
 Nonetheless, invasive study to obtain both hemodynamic
and anatomic information is, on occasion, helpful prior to
deciding on surgical strategy.
 Foremost goal …. clarification or better definition of
anatomic characteristics, such as pulmonary arterial or
coronary arterial anatomy.
 Coronary artery anatomy … either by aortic root angio,
selective coronary artery injection, or a combination of
both..

A: An ascending aortogram in the LAO projection demonstrates a right anterior
descending coronary artery arising from the right coronary artery.
B: A selective left coronary injection shows filling of only the circumflex coronary artery.

COURSE AND COMPLICATIONS
1) Each anoxic spell is potentially fatal
2) Polycytemia
1) Cerebrovascular thrombosis
3) Anoxic infaction of CNS
1) Neurological complication

CNS COMPLICATIONS
 Paradoxic embolus
 Cerebral thrombosis
 Cerebral abcess
 Seizures
 Hypoxic damage
 Endocarditis & vegetations
 Postoperative strokes

TIMING OF SURGERY
 Infants with very severe RVOT stenosis and those with TOF + PA,
with SaO2<70%, should have surgery within a few weeks after birth.
 Infants with moderately severe stenosis and marked cyanosis (SaO2
70–90%) should have corrective surgery by 2–4 months.
 Corrective surgery should be performed in all other infants with
tetralogy of Fallot by 6 months.
Contraindications for repair in early infancyPalliation initially
 LAD from RCA crossing infundibulum
 Severely hypoplastic PAs
 Pulmonary atresia

PALLIATIVE PROCEDURES
Classic BT shunt[1945]…SCAPA on side opposite AA
Modified BT… esp in small infants <6 months…side to side anastomosis
with interposition graft of PTFE or Gore-Tex b/w SCA & PA [on the same
side of AA]
Waterston shunt : Side-side anastomosis of RPA to AA
Potts : Side - side anastomosis of LPA to DA
Waterston/Potts shunts : complications
Excessive PBF  HF [20%] & PHTN
Difficulty taking shunt down at time of correction
Distortion of Rt/Lt PA ; Right/Left PA aneurysm

BT shunt-advantages :
(a)low incidence of problems from excess PBF
(b)No pericardial adhesions as pericardium is not entered
(c)Easy to close at time of complete repair..ligating its distal part just proximal to
anastomoses with PA
(d)Less distortion of PAs
CENTRAL SHUNT :connecting a short tubular graft of Teﬂon or GoreTex from
the aorta to the MPA.
Advantages vs other shunts:
the size of the communication could be controlled by 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.

BLALOCK TAUSSIG SHUNT
 Subclavian artery – Pulmonary artery anastomosis

MODIFIED BLALOCK TAUSSIG SHUNT
 Goretex graft

AIM OF SURGERY
 Relieving all possible sources of RVOTO.
 If possible, pulmonary valve function is preserved by avoiding
a transannular patch.
 Closure of VSD (dacron patch)
 To relieve RVOTOpulmonary valvotomy, the insertion of
an outflow tract patch or a transannular patch are often
required.
 Surgery during early infancy, when the pulmonary annulus is
markedly stenotic, frequently requires the insertion of a long
and wide transannular patch.
Kirkln JW et al J Thorac Cardiovasc
Surg,1992

 Consequently, most patients acquire PR as a result of the
repair.
 PR may be well tolerated by many in the early
postoperative years.
 But in the long term chronic PR is associated with reduced
exercise capacity, RV dilatation, ventricular arrhythmias,
and sudden death.

POST REPAIR FOR TOF
 Current surgical survival, even for symptomatic infants <3Current surgical survival, even for symptomatic infants <3
months of age, is excellent.months of age, is excellent.
 Hospital and 1-month survival rates of 100% have beenHospital and 1-month survival rates of 100% have been
reported.reported.
 Earlier age at repair (<1 year of age) did not adverselyEarlier age at repair (<1 year of age) did not adversely
affect the rate of reintervention; so primary repair shouldaffect the rate of reintervention; so primary repair should
be regarded as the preferred management strategy.be regarded as the preferred management strategy.
 Twenty-year survival for hospital survivors, irrespective ofTwenty-year survival for hospital survivors, irrespective of
management strategy, was 98% for patients who have TOFmanagement strategy, was 98% for patients who have TOF
with PS and slightly lower for patients with PA, reflectingwith PS and slightly lower for patients with PA, reflecting
the overall excellent long-term survival of these patients.the overall excellent long-term survival of these patients.

COMPLICATIONS
 Residual VSDResidual VSD
 Pulmonary regurgitationPulmonary regurgitation
 Residual RVOT obstructionResidual RVOT obstruction
 RV wall motion abnormalitiesRV wall motion abnormalities
 RV dysfunction and RHFRV dysfunction and RHF
 Atrial tachycardiaAtrial tachycardia
 Ventricular tachycardia (VT)Ventricular tachycardia (VT)

Important findings
Conditions (RVH ON ECG) Important clinical findings
TOF (qrs axis between 90-150 degrees) Long systolic murmur , grade 2-3/6 at
ULSB
Soft continuous murmur in neonates
with tof with pulmonary atresia
Concave main PA segment on cxr
Right sided aortic arch on x ray film
DORV with PS (qrs axis > 150 degrees) Resemblance to TOF
Systolic murmur along LSB, Grade3-
4/6

Important findings
Conditions (LVH ON ECG) Important clinical findings
Tricuspid atresia (qrs axis between -30
and -60 degree)
Severe cyanosis
Murmur of VSD or PDA
Superior QRS axis
Boot shaped heart
DORV with PS Resemblance to TOF
Systolic murmur along LSB, Grade3-
4/6

Important findings
Conditions (BVH ON ECG) Important clinical findings
TGA and PS Moderate cyanosis
No signs of CHF
Systolic murmur (of PS ) at ULSB
Single Ventricle and PS Resemblance to TOF
Systolic murmur along LSB.

PFO / ASD
VSD / PDA
Fallot physiology

 PREVALENCE
Tricuspid atresia accounts for 1% to 3% of congenital heart
defects.
 PATHOLOGY
1. The tricuspid valve is absent, and the RV is hypoplastic,
with absence of the inflow portion of the RV. The
associated defects such as ASD, VSD, or PDA are
necessary for survival.
2. Classified according to the presence or absence of PS and
TGA.
The great arteries are normal in 70% & transposed in 30%.
Transposition usually appears in the complete form.
In 3% of cases, the CCTGA occurs.

h
Heart Disease in Infancy
and Childhood , 3rd
ed.
New York,Macmillan,1978

CLINICAL MANIFESTATIONS
 History
1. Cyanosis is usually severe from birth. Tachypnea and poor feeding
usually manifest.
2. Hypoxic spells
Physical Examination
1. Cyanosis, either with or without clubbing, is always present.
2. A systolic thrill is rarely palpable when associated with PS.
3. The S2 is single. A grade 2-3/6 regurgitant systolic murmur of VSD is
usually present at the lower left sternal border. A continuous murmur
of PDA isoccasionally present.
4. Hepatomegaly may indicate an inadequate interatrial communication or
CHF.

ECG
 “Superior” QRS axis (between 0 and -90 degrees) is characteristic. It appears
in most patients without TGA .
 The “superior” QRS axis is present in only 50% of patients with TGA.
 LVH is usually present; RAH or combined atrial hypertrophy (CAH) is
common.

CXR
 The heart size is normal or
slightly increased, with
enlargement of the RA
and LV.
 Pulmonary vascularity
decreases in most patients
although it may increase
in infants with TGA.
 Occasionally, the concave
PA segment may produce
a boot-shaped heart, like
the x-ray findings of TOF.

ECHO
 Two-dimensional echo readily establishes the diagnosis of tricuspid
atresia.
 1. Absence of the tricuspid orifice, marked hypoplasia of the RV, and
a large LV can be imaged in the apical four-chamber view.
 2. The bulging of the atrial septum toward the left and the size of the
interatrial communication are easily imaged in the subcostal four-
chamber view.
 3. Patients with TGA should be examined for possible subaortic
stenosis and aortic arch anomalies.

TREATMENT
 Medical
1. Prostaglandin E1 to maintain the patency of the ductus before planned
cardiac catheterization or cardiacsurgery.
2. The Rashkind procedure (balloon atrial septostomy) may be performed
as part of the initial catheterization to improve the RA-to-LA shunt.
3. Treatment of CHF is rarely needed in infants with TGA without PS.
4. Infants with normally related great arteries and adequate PBF through a
VSD need close monitoring for decreasing oxygen saturation
resulting from spontaneous reduction of the VSD.
 Surgical
Most infants with tricuspid atresia require a palliative procedure before a
Fontan-type operation can be performed.

SINGLE VENTRICLE
 Occurs in <1%
 PATHOLOGY
 Both AV valves are connected to a main, single ventricular chamber
(i.e., double-inlet ventricle), and the main chamber is in turn connected
to a rudimentary chamber through the bulboventricular foramen.
 One great artery arises from the main chamber, and the other arises
from the rudimentary chamber .
 The main ventricular chamber has anatomic characteristics of the LV
(i.e., double-inlet LV).(80%)
 Either D-TGA or L-TGA is present in 85% of cases.
 Common is double-inlet LV with L-TGA and with the aorta arising
from the rudimentary chamber, occurring in 70% to 75% of cases .
The mitral valve is right sided; the tricuspid valve is left sided.
 PS or pulmonary atresia is present in about 50% of cases. COA and
interrupted aortic arch are also common.

 The bulboventricular foramen is frequently obstructive.
 Anomalies of the AV valves, which include stenosis, in
addition to overriding or straddling, are frequent.
 In double-inlet RV, either right or left atrial isomerism
and straddling and/or overriding of the AV valves are
common.
 Most common ventriculoarterial connection is a double
outlet from the main chamber.
 PS is frequently found.

 Physical findings depend on the magnitude of PBF.
 1. With increased PBF, physical findings resemble those
of TGA and VSD or even of large VSD:
 a. Mild cyanosis and CHF with growth retardation are
present in early infancy.
 b. The S2 is single or narrowly split with a loud P2. A
grade 3-4/6 long systolic murmur is audible along the left
sternal border.
 c. A diastolic murmur of PR may be present along the
upper left sternal border as a result of pulmonary
hypertension.

 2. With decreased PBF, physical findings resemble those
of TOF.
 a. Moderate to severe cyanosis is present. CHF is not
present. Clubbing may be seen in older infants and
children.
 b. The S2 is loud and single. A grade 2-4/6 ejection
systolic murmur may be heard at the upper right or left
sternal border

 Electrocardiography
An unusual ventricular hypertrophy pattern with similar QRS complexes
across most or all precordial leads is common (e.g., RS, rS, QR
pattern).
Abnormal Q waves (representing abnormalities in septal depolarization)
are also common and take one of the following forms: Q waves in the
right precordial leads, no Q waves in any precordial leads, or Q waves
in both the right and left precordial leads.
Either first- or second-degree AV block may be present.
Arrhythmias occur (e.g., SVT, wandering pacemaker).

CXR
 1. With increased PBF the heart size enlarges and the
pulmonary vascularity increases.
 2. When PBF is normal or decreased, the heart size is
normal and the pulmonary vascularity is normal or
decreased.
 3. A narrow upper mediastinum suggests that TGA may be
present.

ECHO
 The following anatomic and functional information is important .
 a. Morphology of the single ventricle (e.g., double-inlet LV? double-
inlet RV?).
 b. Location of the rudimentary outflow chamber, which is usually left
and anterior.
 c. Size of the bulboventricular foramen and whether there is an
obstruction at the foramen.
 d. Presence or absence of D-TGA or L-TGA, stenosis of the
pulmonary or aortic valve, and size of the PAs.
 e. Anatomy of the AV valves.
 f. Size of the ASD.
 g. Associated defects such as COA, interrupted aortic arch, or PDA.

MANAGEMENTMANAGEMENT
• Palliative Procedures – BT shunt , PA banding ,
DKS operation
• Second stage palliation procedures – bidirectional
glenn shunt
• Definitive procedure – fontan operation

DOUBLE OUTLET RIGHT VENTRICLEDOUBLE OUTLET RIGHT VENTRICLE
 PREVALENCEPREVALENCE
 DORV occurs in <1% of all congenital heart defects.DORV occurs in <1% of all congenital heart defects.
 PATHOLOGYPATHOLOGY
 1. Both the aorta and the PA arise from the RV. The only1. Both the aorta and the PA arise from the RV. The only
outlet from the LV is a large VSD.outlet from the LV is a large VSD.
 2. The great arteries usually lie side by side. The aorta is2. The great arteries usually lie side by side. The aorta is
usually to the right of the PA, although one of the greatusually to the right of the PA, although one of the great
arteries may be more anterior than the other.arteries may be more anterior than the other.
 The aortic and pulmonary valves are at the same level.The aortic and pulmonary valves are at the same level.
Conus septum is present between the aorta and the PA.Conus septum is present between the aorta and the PA.
There is no fibrous continuity between the semilunarThere is no fibrous continuity between the semilunar
valves and the AV valves.valves and the AV valves.

 3. Classified according to position of VSD and presence or absence of
PS
 a. SUBAORTIC VSD (TOF type). The VSD is closer to the aortic
valve than to the pulmonary valve and lies to the right of the conus
septum .
 Most common type, (55% to 70%) PS is common, especially the
infundibular type, and it occurs in about 50% of patients with this type
of DORV
 b. SUBPULMONARY VSD (I.E., TAUSSIG-BING ANOMALY).
The VSD is closer to the pulmonary valve than to the aortic valve, and
it usually lies above the crista supraventricularis and to the left of the
conus septum. (10% to 30% )
 c. DOUBLY COMMITTED VSD. The VSD is closely related to both
semilunar valves and is usually above the crista supraventricularis
(<5% of cases).
 d. REMOTE OR NONCOMMITTED VSD. The VSD is clearly away
from the semilunar valves (about 10% of cases). It most commonly
represents the AV canal-typeVSD

FALLOT-TYPE DOUBLE-OUTLET RIGHTFALLOT-TYPE DOUBLE-OUTLET RIGHT
VENTRICLE WITH PULMONARY STENOSISVENTRICLE WITH PULMONARY STENOSIS
 Even though the VSD is subaortic, in the presence of PS (i.e., FallotEven though the VSD is subaortic, in the presence of PS (i.e., Fallot
type), some desaturated blood goes to the aorta. This causes cyanosistype), some desaturated blood goes to the aorta. This causes cyanosis
and a decrease in PBF.and a decrease in PBF.
 Clinical pictures resemble those of TOFClinical pictures resemble those of TOF
 1. Growth retardation, cyanosis, and clubbing are all common.1. Growth retardation, cyanosis, and clubbing are all common.
The S2 is loud and single.The S2 is loud and single.
A grade 2-4/6 ejection systolic murmur along the left sternal border isA grade 2-4/6 ejection systolic murmur along the left sternal border is
present, either with or without a systolic thrill.present, either with or without a systolic thrill.
 2. The ECG shows RAD, RAH, RVH, or RBBB. First-degree AV2. The ECG shows RAD, RAH, RVH, or RBBB. First-degree AV
block is frequent.block is frequent.
 3. Chest x-ray images show normal heart size with an upturned apex.3. Chest x-ray images show normal heart size with an upturned apex.
Pulmonary vascularity is decreasedPulmonary vascularity is decreased

ECHO
 In the parasternal short-axis view, a “ DOUBLE
CIRCLE,” rather than the normal “circle and sausage”
appearance of the great arteries, may be seen.
 Either the great arteries are side by side with the aorta to
the right, or the aorta is anterior and slightly to the right of
the PA.
 Differentiation of DORV from TOF with a markedDifferentiation of DORV from TOF with a marked
overriding of the aorta or from TGA is necessary. There isoverriding of the aorta or from TGA is necessary. There is
mitral-semilunar continuity in TOF and TGA (i.e., mitral-mitral-semilunar continuity in TOF and TGA (i.e., mitral-
aortic continuity in TOF, and mitral-pulmonary continuityaortic continuity in TOF, and mitral-pulmonary continuity
in TGA), but no mitral-semilunar continuity is present inin TGA), but no mitral-semilunar continuity is present in
DORV.DORV.

MANAGEMENT
 Palliative Procedures
 1. PA banding for symptomatic infants with increased PBF
and CHF is occasionally performed..
2. For infants with the Taussig-Bing type, enlarging the
interatrial communication is important for better mixing
and for decompressing the LA, which causes pulmonary
venous congestion.
Balloon atrial septostomy or blade atrial septostomy
should be considered.
3. In infants with PS and decreased PBF with cyanosis, a
systemic-to-PA shunt procedure is needed.

 Definitive Surgeries –Definitive Surgeries –
 An intraventricular tunnel between the VSD and the aorta, in additionAn intraventricular tunnel between the VSD and the aorta, in addition
to relief of PS by a patch graft, is carried out between 6 months and 2to relief of PS by a patch graft, is carried out between 6 months and 2
years of age.years of age.
 If preoperative studies indicate the need for a homograft valvedIf preoperative studies indicate the need for a homograft valved
extracardiac conduit, the corrective repair is deferred until age 4 or 5extracardiac conduit, the corrective repair is deferred until age 4 or 5
years, with a shunt operation performed in infancy.years, with a shunt operation performed in infancy.

TETRALOGY OF FALLOT WITH
PULMONARY ATRESIA
 PREVALENCE -15% to 20% of patients with TOF.
 PATHOLOGY
Resembles that of TOF in all respects except for the
presence of pulmonary atresia, the extreme form of right
ventricular outflow tract obstruction. The atresia may be at
the infundibular or valvular level.
 2. The PBF is most commonly mediated through a PDA
(70%) and less commonly through multiple systemic
collaterals MAPCA’s (30%).
 The ductus is small and long and arises from the left aortic
arch at an acute angle (instead of the normal oblique
junction) and courses downward (“vertical” ductus)

 3. PA anomalies are common in the form of hypoplasia,
nonconfluence, and abnormal distribution.
 a. The central PA is hypoplastic in most patients with TOF
 b. The central PAs are confluent in 85% of patients; they
are nonconfluent in 15%. Confluent PAs are usually found
in patients with PDA (70%).
 c. Among patients with confluent PAs, 50% have
incomplete arborization (distribution) of one or both PAs.
About 80% of patients with nonconfluent PAs have
incomplete arborization

CLINICAL MANIFESTATIONS
 Cyanotic at birth. The degree of cyanosis depends on patency of
ductus and systemic collateral arteries .
 Murmur cannot be heard.
 However, a faint, continuous murmur may be audible from the PDA or
collaterals. The S2 is loud and single. A systolic click is occasionally
present.
 ECG - RAD and RVH.
 CXR- normal heart size. The heart often appears as a boot-shaped
silhouette and the pulmonary vascularity is markedly decreased (i.e.,
“black” lung field).
 Echo studies show all the anatomic findings of TOF plus the absence
of a direct connection between the RV and the PA. The small branch
PAs and “vertical ductus” are well imaged from a high parasternal or
suprasternal transducer position.

 NATURAL HISTORY
Most neonates who have this condition die during the first 2 years of
life;
However, infants with extensive collaterals may survive for a long
time, perhaps for more than 15 years.

MANAGEMENTMANAGEMENT
Pediatric Cardiology for Practitioners By Myung K. Park

TETRALOGY OF FALLOT WITH ABSENTTETRALOGY OF FALLOT WITH ABSENT
PULMONARY VALVEPULMONARY VALVE
 2% of patients with TOF
 PATHOLOGY AND PATHOPHYSIOLOGY
 The pulmonary valve leaflets are either completely absent or have an
uneven rim of rudimentary valve tissue present. The annulus of the
valve is stenotic and displaced distally.
 A massive aneurysmal dilatation of the PAs is present.
 The massive PA aneurysm results from severe pulmonary
regurgitation (PR) and an associated increase in RV stroke volume.
The aneurysmal PAs compress anteriorly the lower end of the
developing trachea and bronchi throughout fetal life, producing
hypoplasia of the compressed airways.
 This produces signs of airway obstruction and respiratory distress
during infancy.

CLINICAL MANIFESTATIONSCLINICAL MANIFESTATIONS
 1. Mild cyanosis may be present as a result of a
bidirectional shunt during the newborn period when the
pulmonary vascular resistance is relatively high. Cyanosis
disappears, and signs of CHF may develop, after the
newborn period.
 2. A to-and-fro murmur (with “sawing-wood” sound) at
the upper and mid-left sternal borders - characteristic .This
murmur occurs because of mild PS and free PR. The S2 is
loud and single.
 The RV hyperactivity is palpable.

 The ECG shows RAD and RVH.The ECG shows RAD and RVH.
 Chest x-ray images reveal a noticeably dilated main PAChest x-ray images reveal a noticeably dilated main PA
and hilar PAs. The heart size is either normal or mildlyand hilar PAs. The heart size is either normal or mildly
enlarged, and pulmonary vascular markings may beenlarged, and pulmonary vascular markings may be
slightly increased.slightly increased.
 Echo reveals a large, subaortic VSD with overriding of theEcho reveals a large, subaortic VSD with overriding of the
aorta, distally displaced pulmonary annulus and giganticaorta, distally displaced pulmonary annulus and gigantic
aneurysm of the PA and its branches.aneurysm of the PA and its branches.
 Doppler studies reveal evidence of stenosis at the annulusDoppler studies reveal evidence of stenosis at the annulus
and PR.and PR.

 NATURAL HISTORY
 1. More than 75% of infants with severe pulmonary
complications (e.g., atelectasis, pneumonia) die during
infancy if treated only medically.
 2. Infants who survive infancy without serious pulmonary
problems do well for 5 to 20 years and have fewer
respiratory symptoms during childhood.
 They become symptomatic later and die from intractable
right-sided heart failure.
 Management is early surgical repair.

ConclusionsConclusions
 Tetralogy of Fallot is the most common form of cyanoticTetralogy of Fallot is the most common form of cyanotic
congenital heart disease, and one of the first to be successfullycongenital heart disease, and one of the first to be successfully
repaired by congenital heart surgeons.repaired by congenital heart surgeons.
 Since the first procedures in the 1950s, advances in theSince the first procedures in the 1950s, advances in the
diagnosis, perioperative and surgical treatment, anddiagnosis, perioperative and surgical treatment, and
postoperative care have been such that almost all those born withpostoperative care have been such that almost all those born with
tetralogy of Fallot can now expect to survive to adulthood.tetralogy of Fallot can now expect to survive to adulthood.
 The care of children with tetralogy of Fallot and their transitionThe care of children with tetralogy of Fallot and their transition
to adult life has been a success of modern medicine.to adult life has been a success of modern medicine.
 Most of them now survive early repair and have an essentiallyMost of them now survive early repair and have an essentially
normal childhood.normal childhood.

Tof physiology

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