A reviewer for nursing students

1. Tetralogy of Fallot
BY JERARD LLOYD B. DOMINGO
BSN 2A
#MCNCompilations #PediaDisorders

2. Tetralogy of Fallot
 Tetra – four
 Fallot - Etienne-Louis Arthur Fallot, the French
Physician that named the disease in 1888.
 Known historically “Stenofallot tetralogy”
 It is a most common form of Congenital Heart
Disease (CHD).
 A rare condition caused by a four heart defects that are
present at birth or congenital.
 Also known as “La Maladie Bleue” or “The Blue
Disease” or “Cyanose Cardiaque” or “Cardiac
Cyanosis”.
 Incidence: 5:10,000 live births.
Lloyd
2

3. Etiology/Risk Factors 3
1.Maternal History of TOF
2.Maternal Diabetes (Pre-gestational DM)
3.Maternal levels of Retinoic Acid
4.Maternal Phenylketonuria
5.Chromosomal Anomalies
6.Alagille Syndrome with JAG1 and NOTCH2 Gene
Mutations
7.Methylenetetrahydrofolate Polymorphism
8.Maternal Alcoholism during pregnancy
9.Poor Nutrition during pregnancy
10.Maternal Age >40
11.Viral Illness (Rubella) during pregnancy

4. 1. Maternal History of TOF 4
 Increases a five-fold chance of having TOF for its offspring.
 Since the etiology/risk factors are Autosomal, meaning there’s
a very high chance for the offspring to have CHDs or Tetralogy
of Fallot.

5. 2. Maternal DM (Pre-gestational) 5
 Hyperglycemia of mother during early embryogenesis may alter
gene expression in key cellular components of the developing heart
or cardiogenesis (AHAJournals.org).
 High blood sugar in the mother leads to high blood sugar in the
developing fetus, creating an abnormal biochemical environment
that can negatively affect genes responsible for normal
embryogenesis and fetal cardiogenesis.
 CHDs are highly associated with maternal diabetes in early
pregnancy. These include conotruncal abnormalities e.g. truncus
arteriosus, transposition of Great Arteries, TOF, double outlet right
ventricle, heterotaxy syndrome, and also VSD.
 AHA suggests that Pre-GDM women undergo a fetal
echocardiogram between 18 & 22 weeks of age to assess for fetal
CHD (pediatricheartspecialists.org).

6. 3. Maternal Levels of Retinoic Acid
6
*Retinoic acid (RA) – a derivative of Vitamin A involves a key role
during vertebrate development including cardiogenesis.
 Vitamin A deficiency – associated with heart malformations.
 Excessive Intake or High Levels – associated with fetal heart
toxicity.
 RA signaling alterations due to excessiveness or deficiency
may cause Congenital Heart Defects (CHD).

7. 4. Maternal PKU (Phenylketonuria)
7
 Phenylketonuria – a rare inherited disorder that causes a type
of amino acid called phenylalanine to buildup or increase in
amounts in the maternal body.
 Phenylalanine buildup has a teratogenic effects on
pregnancy.
 Phenylalanine Hydroxylase (PAH) – an enzyme responsible for
breaking down Phenylalanine. It is absent or deficient in
people with PKU caused by gene mutation of PAH.
*PKU mothers have a high chance of bearing children with heart
problems as high levels of phenylalanine causes
abnormal/aberrant cardiogenesis.

8. 5. Chromosomal Anomalies
8
5.1 Microdeletions of chromosome 22q11.2 or Digeorge Syndrome
 Occurs in 1:4000 births.
 Causes developmental abnormalities primarily in the heart and
craniofacial congenital defects.
 It is an inherited in autosomal dominant manner. Microdeletions
causes CATCH (C-Cardiac Defect, A – Abnormal Face, T-Thymic
Hypoplasia, C- Cleft Palate, H- Hypocalcemia.
*Chromosome 22 has 500 – 600 genes that provide for normal
protein synthesis. Microdeletion of Chromosome 22q.11 causes
dysregulation and abnormal protein synthesis that causes
malformations and congenital cases.

9. 5. Chromosomal Anomalies
9
5.2 Trisomy 21 or Down
Syndrome
 Incidence 1:700
*Trisomy of chromosome 21,
that is highly associated with
heart defects. Almost about
half of babies with Down
syndrome have heart
defects.

10. 6. Alagille Syndrome
10
 A genetic disorder that affects primarily the liver and the heart in an
autosomal dominant pattern.
 Prevalence: 1:100,000 live births.
 Named by French pediatrician Daniel Alagille in 1969.
 Other names: Alagille-Watson Syndrome & Hepatic Ductular Hypoplasia.
 S+S of the disease are due to hepatic and cardiac disorders.
*Pathophysiology: JAG1 & NOTCH2 Gene mutation
a. JAG1(Jagged 1) – encodes for surface binding ligand that regulates
notch signaling pathway. It plays a crucial role in cell signaling during
embryonic development. If the pathway is disrupted due to genetic
mutations the infant will not develop properly.
*Alagille Syndrome causes duct paucity characterized by narrow or
malformed bile ducts.

11. 6. Alagille Syndrome
11
b. NOTCH2 Gene Mutation
- NOTCH2 Gene is responsible for NOTCH-gene signaling
cascade and cell to cell recognition. Involves gen regulation
mechanisms that controls multiple cell differentiation processes
during embryonic and adult life. It is vital for;
Atrioventricular, Ventricular, Angiogenesis, Pancreatic, intestinal,
bone respiratory, neuron cell differentiation, neurite
development, gliogenesis and adult brain function.
*Alagille Syndrome is a strongly causative factor for liver
problems due to narrow bile ducts, and heart disorders caused
by pulmonary Stenosis and tetralogy of fallot.

12. 6. Alagille Syndrome
12

13. 7. Methylenetetrahydrofolate
Reductase(MTHFR) Polymorphism 13
 Genetic polymorphism/Polymorphism - is a term used
somewhat differently by geneticists and molecular biologists to
describe certain mutations in the genotype.
 What does MTHFR do?
-MTHFR is an enzyme that converts Vitamin B9 or Folate. It
converts an inactive form of folate called 5,10
methylenetetrahydrofolate into 5 methylenetetrahydrofolate.
- 5 methylenetetrahydrofolate – is the primary form of folate
found in the blood. It converts the amino acid HOMOCYSTEINE
into METHIONINE.
- Methionine – is essential for making proteins and other
important compounds.

14. 7. Methylenetetrahydrofolate
Reductase(MTHFR) Polymorphism 14
Methylenetetrahydrofolate Reductase and Association with CHD
- Mutation of MTHFR is associated with a 50% reduction of MTHFR
enzyme activity and increase in homocysteine concentrations
and decrease in plasma folic acid concentration.
*Maternal MTHFR Polymorphism results to Hyperhomocystenemia
and Low folate levels in bloodstream = Increased Risk of CHD in
offsprings.

15. 8. Maternal Alcoholism during pregnancy
15
 Excessive intake of alcoholic beverages prior to and during gestation has
increase the chance of having Fetal Alcohol Syndrome.
 Fetal Alcohol Syndrome (FAS) – Fetal Alcohol Syndrome. Alcohol, which is
lipid soluble and has a molecular weight between 600 and 1000, passes
freely across the placental barrier; concentrations of alcohol in the fetus
are at least as high as in the mother. Unlike other teratogens, the harmful
effects of alcohol are not restricted to the sensitive period of early
gestation, but extend throughout pregnancy. Prenatal exposure to
alcoholism can exert a wide range of adverse effects on the developing
fetus, such as; craniofacial abnormalities, growth deficiencies, CNS
Dysfunctions and neurobehavioral disabilities or collectively known as
Fetal Alcohol Syndrome or Fetal Alcohol Spectrum Disorders.
 Increased exposure to alcohol during the gestational period increases
incidence of heart anomalies (e.g. Ventricular Septal Defect (VSD), Atrial
Septal Defect (ASD), and other forms of CHD.

16. 9. Poor Nutrition
16
Poor Nutrition causes inadequacy of important nutrients, vitamins
and minerals that is essential for the progression of fetal
development and embryogenesis.

17. 10. Maternal Age >40
17
Increasing age is associated with high risk of adverse pregnancy
outcomes and a high chance of miscarriage and birth defects
like chromosomal abnormalities that contributes for fetal
anomalies and CHD’s.

18. 11. Viral Illness (Rubella) during Pregnancy
18
 Women who contrast rubella or German Measles, have a high risk
of having a baby with Congenital Rubella Syndrome (CRS).
 CRS will cause effects such as miscarriage, stillbirths, and series of
birth defects. The risk of fetal infection varies according to the time
and onset of maternal infection.
Note: Infection rates are highest in first trimester.
-CRS manifestations are cataracts, sensorineural deafness, and CHDs
especially Patent Ductus Arteriosus (PDA), VSD, ASD, and Pulmonary
Stenosis (PS).
*When the fetal heart is targeted by the virus, there is a direct viral
damage to the myocardium, affecting primarily the left atrium, the
heart septa leading to thrombosis, necrosis and hemorrhage that
causes PDA, PS, ASD, and VSD.

19. 12. Maternal Drug and Medical Use
19
 Thalidomide - a medication used to treat a number of cancers
including multiple myeloma, graft-versus-host disease, and a
number of skin conditions including complications of leprosy.
 Isotretinoin - a medication primarily used to treat severe acne.
 Thalidomide and Isotretinoin can interfere with normal fetal
cardiogenesis.
* Certain Drugs are classified as non-safe or a “teratogen” for the
conceptus.

20. Tetralogy of Fallot
1. Pulmonary Valve Stenosis
2. Right Ventricle Hypertrophy
3. Overriding Aorta or Aortic Displacement
4. Ventricular Septal Defect
Tetralogy of Fallot occurs during fetal growth, when the baby's heart is developing. While
factors such as poor maternal nutrition, viral illness or genetic disorders might increase the
risk of this condition, in most cases the cause of tetralogy of Fallot is unknown.

21. 1. Pulmonary Valve Stenosis
21
*Also known as Right Ventricular Outflow Tract
Obstruction (RVOTO).
 Pulmonary valve stenosis is a narrowing of the
pulmonary valve — the valve that separates the
lower right chamber of the heart (right ventricle)
from the main blood vessel leading to the lungs
(pulmonary artery).
 Narrowing (constriction) of the pulmonary valve
reduces blood flow to the lungs. The narrowing
might also affect the muscle beneath the
pulmonary valve. In some severe cases, the
pulmonary valve doesn't form properly
(pulmonary atresia) and causes reduced blood
flow to the lungs. An obstruction from the heart to the lungs

22. 2. Right Ventricular Hypertrophy
22
When the heart's pumping action is
overworked due to Pulmonary
Stenosis, it causes the muscular wall of
the right ventricle to thicken. Over
time this might cause the heart to
stiffen, become weak and eventually
fail.
The muscle surrounding the lower right chamber
becomes overly thickened.

23. 3. Overriding Aorta
23
 Normally the aorta — the
main artery leading out to
the body — branches off the
left ventricle.
 In tetralogy of Fallot, the
aorta is shifted slightly to the
right and lies directly above
the ventricular septal defect.
The aorta (blood vessel) lies over the hole in
the lower chambers

24. 4. Ventricular Septal Defect (VSD)
24
 Ventricular septal defect. A ventricular
septal defect is a hole (defect) in the
wall (septum) that separates the two
lower chambers of the heart — the left
and right ventricles.
 The hole allows deoxygenated blood in
the right ventricle — blood that has
circulated through the body and is
returning to the lungs to replenish its
oxygen supply — to flow into the left
ventricle and mix with oxygenated
blood fresh from the lungs.

25. 25
Signs & Symptoms
Signs and symptoms of tetralogy of Fallot vary,
depending on the extent of obstruction of blood
flow out of the right ventricle and into the lungs.

26. 1. Activity Intolerance/Lack of Endurance
26
 Sometimes, babies who have tetralogy of Fallot
will suddenly develop deep blue skin
(cyanosis), nails and lips after crying or feeding,
or when agitated. When playing or doing light
activities, they experience SOB and rapid
breathing because O2 in their blood is
inadequate to sustain activities like feeding or
playing.
 These episodes are called Tet spells and are
caused by a rapid drop in the amount of
oxygen in the blood (HYPOXEMIA). Tet spells are
most common in young infants, around 2 to 4
months old.
 Tet spells or hypercyanotic spells are due to
cerebral anoxia – It consists of irritability,
dyspnea, cyanosis, flaccidity with or without
unconsciousness. It is found in the morning after
awakening, during or after feeding and painful
procedures.

27. 27
Cause of spell: Due to "spasm" or
contraction of a band of muscle in the
right ventricle just under the
pulmonary valve. When this muscle
contracts, it further narrows the
channel for blood flow into the lungs.
As a result, oxygen delivery becomes
further reduced.
*Squatting (a compensatory
mechanism) is uniquely characteristic
of a right- to-left shunt that presents in
the exercising child. Squatting
increases the peripheral vascular
resistance, which diminishes the right-
to- left shunt and increases pulmonary
blood flow. Lowering your baby's anxiety or stress can help prevent
Tet spells; and save the baby's energy.

28. 2. Clubbing of fingers and toes
28
*Clubbing of fingers and toes, or
abnormal rounded shape of nail
beds.
- caused by low oxygen levels in
the blood. The vascularization under
the nail beds widens (dilates) due to
low levels of oxygen.

29. Signs and symptoms
29
5. Cardiac Murmurs – due to RVOTO or Pulmonary Stenosis, an audible
murmur is usually noted & presence of Residual blood from the VSD, and will
reveal a loud pansystolic murmur (mayoclinic.org).
*According to NCLEXRN.com, a systolic murmur is present because the blood
is not pumped efficiently to pulmonary circulation due to pulmonary valve
stenosis.
4. Loss of Consciousness/ sudden death – if the oxygen levels rapidly drop
and brain is deprived with sufficient oxygen.
3. Cyanosis – bluish discoloration of the skin due to low oxygen levels in the
blood, as a result of ventricular left-right shunting that causes mixing of non-
oxygenated and oxygenated blood that enters the circulation.

30. Diagnosis
30
3. Chest X-ray – shows the structure of the heart and lungs, a “boot shaped”
heart (it means apex is lifted up & there is a concavity in the region of
pulmonary artery).
2. ECG – records heart’s electrical activity each time it contracts. This test
determine if right ventricle is enlarged or RVH, and if the rhythm is regular.
1. Echocardiography – use of a high pitched sound waves to produce an
image of the heart. Sound waves bounce to the heart and produce moving
images that can be viewed on a video screen. It is use to determine if heart
structure is altered.
4. Pulse Oximetry – measure amounts of oxygen levels in the blood.
Normal Value: 95-100% (mayoclinic.org)
5. Arterial Blood Gas (ABG) – an accurate but invasive procedure to measure
arterial blood gas. Getting a sample of blood from an artery to measure its
oxygen saturation.

31. 31
3. Chest X-ray – shows the structure of the heart and lungs, a “boot shaped”
heart (it means apex is lifted up & there is a concavity in the region of
pulmonary artery).

32. Diagnosis
32
*As TOF progresses in adults, exertional dyspnea, syncope, palpitations, and
evidence of right heart failure such as elevated Jugular Venous Pressure
(JVP), ascites, Peripheral edema, and hepatomegaly (Medscape.org).
7. Physical Assessment – auscultation of the pulmonary valve
insufficiency on the chest will reveal a low-pitched short diastolic
murmur. If RVOTO is present, an audible murmur is usually noted. The
presence of residual VSD will reveal a loud pansystolic murmur.
6. Cardiac catheterization – insertion of a thin, flexible tube (catheter)
into an artery or vein and thread up into the heart.
-when the tube is in the heart, the doctor will inject a dye via the tube
to make the heart structures visible on x-ray pictures.

33. Treatment for Tet Spells
33
Treatment for spells: Knee chest
position to increase systemic vascular
resistance and aortic resistance
(because BV’s on lower extremities are
squeezed). The increased aortic and
left ventricular pressure reduces the
rush of blood through the septal hole
from the right ventricle and improves
blood circulation to the lungs

34. Medical Management
34
Oxygenation – to compensate for blood O2
desaturation.
IV Fluids – to increase intravascular volume and
decrease pulmonary resistance.

35. Treatment
35
Surgery is the only effective treatment for Tetralogy of Fallot.
1. Intracardiac Repair – an open heart surgery within the first year after birth.
-Placement of a patch over the VSD to close the hole between the ventricles.
-Repair or replacement of pulmonary valve and widening the pulmonary arteries to
increase pulmonary circulation. After the procedure, the Right ventricle workload
was lessened, so later RV will go back to it’s normal thickness and signs and
symptoms will be lessened.
2. Temporary Repair – babies need to undergo a temporary or palliative surgery
before having intracardiac repair to improve blood flow to the lungs.
-This procedure is done if baby has premature lungs or born with hypoplastic
pulmonary arteries.
-When baby is ready for Intracardiac repair, the surgeon removes the shunt during
the procedure for intracardiac repair.

36. Treatment
36
3. Blalock Taussig Shunting – connection between the right
subclavian artery, and the right pulmonary artery, which
increases the amount of oxygenated blood reaching the
lungs, relieving cyanosis.
4.Pott`s shunt - descending aorta is anastomosed to the
pulmonary artery.
5.Waterstont`s shunt - ascending aorta right pulmonary
artery anastomosis .
6.Prostaglandin (Alprostadil) Therapy - for keeping the
Ductus Arteriosus open, to increase pulmonary circulation.

37. Living with Tetralogy of Fallot
37
 Small, frequent meals may be easier for your baby to
handle.
 Supplement for an extra feeding that can give the baby
more calories, vitamins, or iron.
 Lowering your baby's anxiety or stress can help prevent Tet
Spells and save the baby's energy.
 Bring the baby's or child's knees up tight against his or her
chest (this is called the knee–chest position) or have your
child squat down. This will increase blood flow to the lungs.
*Some children with tetralogy of Fallot may need to limit
certain types of exercise/activities

38. Complications after Surgery
38
1. Chronic Pulmonary Regurgitation
2. Valvular Problems
3. VSD Development/ Enlargement
4. RVH or LVH that is not working properly
5. Arrhythmias
6. Coronary Artery Disease
7. Enlargement of Ascending Aorta
8. Sudden Cardiac Death or Heart Failure.

39. Complications if LEFT UNTREATED
39
1. Brain abscess
2. Bacterial endocarditis
3. Ventricular arrhythmias

40. 40
Reference: Mayoclinic.org
MSDManuals
NCLEXRN.com
American Heart Association Journals (ahajournals.org)
NCBI
Salamat sa pagtitiwala.
-Jerardu