Download Tetrology of fallot

Tetrology of Fallot
Dr. M. A. Sofi MD; FRCP (London);
FRCPEdin; FRCSEdin
TETROLOGY OF FALLOT
Tetralogy of Fallot, is one of the
most common congenital heart
disorders, comprises right
ventricular (RV) outflow tract
obstruction (RVOTO)
(infundibular stenosis),
ventricular septal defect (VSD),
aorta dextroposition, and RV
hypertrophy. The mortality rate
in untreated patients reaches
50% by age 6 years, but in the
present era of cardiac surgery,
children with simple forms of
tetralogy of Fallot enjoy good
long-term survival with an
excellent quality of life
Review blood flow through the
heart
 Discuss ToF anatomic
abnormalities
 Etiology
 Clinical Presentation
 Labs and Exams
 Two surgical interventions
TOF
4 anatomic malformations:
1. Right Ventricular
Hypertrophy
2.
Pulmonary Valve
Stenosis
3. Transposition of
the aorta
4. Ventricular Septal
Defect
ToF
 RVH
-secondary to PA Stenosis
-Increased P on RV leads to
RVH
 Transposition of Aorta
-aorta is displaced
 VSD
-”hole in the heart”
-mixing of oxygenated and
unoxygenated blood
-cyanosis
 PVS
-more severe, less blood
transported to the lungs and
more deoxygenated blood
will pass through VSD to
aorta to be circulated
throughout the body
Etiology
 Theory: destruction of the neuronal crest cells during
embryogenesis
 In the laboratory setting, destruction of these cells
reproduced results displayed with certain cardiac
malformations.
 This anomaly accounts for 10% of all congenital heart
disease and has an estimated prevalence of 1 in 2000
births
Signs and symptoms
The clinical features of tetralogy of Fallot are directly related to the
severity of the anatomic defects. Infants often display the following:
 Severe stenosis results in
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immediate cyanosis
following birth.
Mild stenosis will not present
until later.
Growth is retarded –
insufficient oxygen and
nutrients
SOA on exertion
Clubbing of fingers & toes
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Difficulty with feeding
Failure to thrive
Irritability
Episodes of bluish pale skin
during crying or feeding (ie,
"Tet" spells)
 Exertional dyspnea, usually
worsening with age
 Heart murmur
“Tet Spell”
 “Tet spells” at 2-3yo,
child becomes
cyanotic, may
experience syncope
Physical signs
 Physical findings include the
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following:
Most infants are smaller than
expected for age
Cyanosis of the lips and nail bed is
usually pronounced at birth
After age 3-6 months, the fingers and
toes show clubbing
A systolic thrill is usually present
anteriorly along the left sternal
border
A harsh systolic ejection murmur
(SEM) is heard over the pulmonic
area and left sternal border
 During cyanotic episodes, murmurs
may disappear
 In individuals with aortopulmonary
collaterals, continuous murmurs may
be auscultated
The following may also be noted:
 RV predominance on palpation
 A bulging left hemithorax
 Aortic ejection click
 Squatting position (compensatory
mechanism)
 Scoliosis (common)
 Retinal engorgement
 Hemoptysis
Diagnosis
Hemoglobin and hematocrit values are usually elevated in proportion to the
degree of cyanosis. Patients with significant cyanosis have the following, in
association with a tendency to bleed:
 Decreased clotting factors
 Low platelet count
 Diminished coagulation
factors
 Diminished total fibrinogen
 Prolonged prothrombin and
coagulation times
Arterial blood gas (ABG) results
are as follows:
 Oxygen saturation varies
 pH and partial pressure of
carbon dioxide (pCO2) are
normal unless the patient is in
extreme
Imaging studies include the following:
1. Echocardiography
2. Chest radiographs
3. Magnetic resonance imaging (MRI)
Echocardiography has the following
attributes:
 Color-flow Doppler
echocardiography accurately
diagnoses ductus arteriosus,
muscular VSD, or atrial septal
defect
 The coronary anatomy can be
revealed with some degree of
accuracy
 Valvar alterations can be detected
with ease
 In many institutions,
echocardiography is the only
diagnostic study used before surgery
Chest radiographs have the following:
 Often normal initially
 Diminished vascularity in the lungs
and diminished prominence of the
pulmonary arteries gradually become
apparent
 The classic boot-shaped heart (coeur
en sabot) is the hallmark of the
disorder
MRI has the following attributes:
 Provides good delineation of the aorta,
RVOT, VSDs, RV hypertrophy, and
the pulmonary artery and its branches[1]
 Can also be used to measure
intracardiac pressures, gradients, and
blood flows
Plain films may
classically show a
"boot shaped" heart
with an upturned
cardiac apex due to
right ventricular
hypertrophy and
concave pulmonary
arterial segment. Most
infants with TOF
however may not show
this finding
Boot Shaped Heart
Cardiac catheterization
 Cardiac catheterization is
extremely useful in any of the
following instances:
 The anatomy cannot be
completely defined by
echocardiography
 Disease in the pulmonary
arteries is a concern
 Pulmonary vascular
hypertension is possible
 Cardiac catheterization
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findings include the
following:
Assessment of the pulmonary
annulus size and pulmonary
arteries
Assessment of the severity of
RVOTO
Location of the position and
size of the VSD
Ruling out possible coronary
artery anomalies
Angiography & MR and CT angiography
 Diagnostic angiography is required
to identify the origins and
contributions of all major
aortopulmonary collateral arteries
(MAPCAs).
 All communications between
MAPCAs and the true pulmonary
artery system must be identified, as
surgical planning depends on
whether each lung segment receives
blood flow from MAPCAs, true
pulmonary arteries (isolated
supply), or both (dual supply).
 In addition, all points of stenosis in
each MAPCA need to be identified
 MR and CT angiography —
Both magnetic resonance (MR)
and computed tomographic
(CT) angiography may provide
accurate detailed images of the
pulmonary architecture.
 As radiographic technology
evolves, it is likely that CT will
become more important in
delineating complex pulmonary
artery anatomy, and may
replace or become adjunctive to
neonatal cardiac catheterization.
Management
 The great news about ToF is that many
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people born with ToF do very well
over time.
Many are now in their 60s, 70s and
even 80s.
The first surgery for ToF, called a
Blalock-Taussig shunt (B-T shunt),
was first done in 1944.
This was followed by the development
of open heart surgery to repair the
defects in 1954.
The B-T shunt helps babies born with
ToF get enough oxygen to their body.
Then the baby can have open heart
surgery to repair the defects.
Primary correction is the ideal
operation and is usually performed
under cardiopulmonary bypass.
Palliative procedures (eg,
placement of the modified
Blalock-Taussig shunt) may be
necessary in patients with
contraindications to primary
repair, which include the
 The presence of an anomalous
coronary artery
 Very low birth weight
 Small pulmonary arteries
 Multiple VSDs
 Multiple coexisting intracardiac
malformations
Management: The management of patients with tetralogy of Fallot with
pulmonary valve atresia (TOF/PA) is challenging given the wide spectrum of
pulmonary artery architecture.
 Initial medical management to
maintain sufficient pulmonary
blood flow for survival.
 Subsequent management focused
on complete separation of the
pulmonary and systemic
circulations. This is accomplished
by restructuring pulmonary blood
flow to create a low pressure
system, establishing antegrade
pulmonary blood flow from the
right ventricle (RV), and closing
the ventricular septal defect
(VSD).
The surgical steps include:
 Unifocalization, which involves
detachment of collateral vessels
from their aortic origins and
anastomosis to the central
pulmonary arteries, resulting in
creation of a low pressure
pulmonary arterial system.
 Reconstruction of the right
ventricular outflow tract
(RVOT) using an allograft valved
conduit from the RV to pulmonary
artery that results in antegrade
pulmonary blood flow from the
RV into the pulmonary vascular
system.
 VSD closure