Fallot tetralogy

2009-2010 Department of Pediatrics

Prof. Mona El-Samahy unit Under supervision of: Prof. Mahmoud Tarek Dr. Ahmed Samir Prepared by the fifth year medical students: Karim Mohammed Karim Nagy Karim Yousry Kawthar Sayed Kyrillos Girgis Kyrillos Raafat Kyrillos Samir Lara Ashraf Lobna Abd El-Fatah Lobna Ez El-Din

TETRALOGY OF FALLOT

In The name of The Holy GOD

Presentation

After we finished we realized how great we enrich our experience!!! .The experience of achieving an

interesting research in a well managed cooperative teamwork. We tried as much as we can to put this research in semi-arranged notes. We know! …….this research isn’t perfect, but it is our first little step in a very long way….and what we are proud of is

that we have done our best and we were interested……

Now..!! It’s time for the show…So let’s go…Thanks...!!!

The teamwork,

Cairo, Dec, 2009

December 6, 2009 [TETRALOGY OF FALLOT]

[Department of pediatrics] | Prof. Mona El-Samahy unit 1

Index Introduction ………………………………………………………………………….... 2

Historical origin& Definition ………………………………………..................................... 3

Epidemiology& Etiology& Embryological background…………………………..…..4

Pathophysiology ……………………………………………………………………... 5-6

Clinical picture ………………………………………………………………………... 7-9

Investigations ………………………………………………………………………... 9-11

Complications ………………………………………………………….……………. 11-12

Medical treatment of fallot tetralogy ………………………………...…………. 12

Surgical treatment of TOF ………………………………………………………….. 13-16

References …………………………………………………………………………….. 17



Fallot Tetralogy

Introduction : *Congenital cardiac defects can be divided into two major groups based on the

presence or absence of cyanosis into:

Congenital acyanotic heart disease

Normal Pulmonary BF(no shunt) Pulmonary Plethora (Lt Rt shunt)

Rt ventricular enlargement

PS

MS


ASD

PAPVR

Lt ventricular enlargement

AS

Coarcotation of Aorta


PDA

A-P window

--------------- Biventricular enlargement

VSD

Congenital cyanotic heart disease

Pulmonary oligaemia Pulmonary plethora


Fallot tetralogy

VSD + PS

VSD + P.atresia (extreme F4)

DORV + PS

TGA + PS


Hypoplastic left heart syndrome

TGA

TAPVR


Pulmonary atresia

Tricuspid atresia

Rt/Lt ventricular enlargement or both

Truncus arteriosus

Single ventricle

Huge Rt arium

Ebstein anomaly

---------------

Classification:

**the fallot tetralogy is one of cyanotic congenital heart lesions with decreased

pulmonary blood flow.



Historical origin: (6)

Tetralogy of Fallot (TOF) is a congenital heart defect which is classically

understood to involve four anatomical abnormalities (although only three of

them are always present). It is the most common cyanotic heart defect,

representing 55-70%, and the most common cause of blue baby syndrome. It

was described in 1672 by Niels Stensen, in 1773 by Edward Sandifort, and in

1888 by the French physician Etienne-Louis Arthur Fallot, for whom it is

named.

Definition:(6)

Tetralogy of Fallot (TOF) is a congenital cyanotic heart disease, which

is classically understood to involve four anatomical abnormalities

Its four signs are :

1) Ventricular septal defect (figure 1)

2) Pulmonary stenosis , Sometimes the pulmonary valve isn’t just

narrowed but is completely obstructed (pulmonary atresia).

3) Overriding aorta , the aorta lies directly over the ventricular septal

defect .

4) Right ventricle develops hypertrophy .

*In addition, tetralogy of Fallot may present with other anatomical anomalies, including:

- stenosis of the left pulmonary artery, in 40% of patients

- a bicuspid pulmonary valve, in 40% of patients

- right-sided aortic arch, in 25% of patients

- coronary artery anomalies, in 10% of patients

- a foramen ovale or atrial septal defect, in which case the syndrome is sometimes called

a pentalogy of Fallot,

- an atrioventricular septal defect

partially or totally anomalous pulmonary venous return

forked ribs and scoliosis

- triology of fallot

Figure 1 : ventricular septal defect

Dr. Fallot



Epidemiology:(6)

Tetralogy of Fallot occurs in approximately 400 per million live births

Tetralogy of Fallot accounts for 10-15% of all congenital (newborn) heart defects

It is the most common cyanotic heart defect, representing 55-70%,

It occurs slightly more often in males than in females.

Etiology:(6)(7)

*Its cause is thought to be due to environmental as carbon monoxide or genetic factors

or a combination.

*It is associated with chromosome 22 deletions.

*mothers who experience rubella or other viral illnesses during pregnancy have a higher

risk of having a baby with tetralogy of fallot, in addition maternal alcoholism

and diabetes.

*There is higher risk for tetralogy of fallot among white babies than babies of other races

*it may be seen more commonly in patients with Down syndrome (in association with AV

canal defects) , DiGeorge syndrome , Alagille syndrome , charge syndrome ,vacteral

syndrome , fetal alcohol syndrome .

Embryological background :(1)(figue 2)

Tetralogy of Fallot, the most frequently occurring abnormality of the

conotruncal region (Figure. 3), is due to an unequal division of the conus resulting from

anterior displacement of the conotruncal septum.

Displacement of the septum produces the four cardiovascular abnormalities mentioned

before .

Figure 3 : unequal division of the conus Figure 2 :Embryology of TOF



Trilogy of Fallot: (6)

presented by:

Pulmonary valve stenosis

Right ventricular hypertrophy

Atrial septal defect

Pentalogy of fallot: (8) Presented by:

The four characteristics of Fallot's tetralogy syndrome, plus a patent foramen

Pathophysiology:

The combination of congenital defects in TOF results

in right to left shunt across the large VSD from the

hypertrophied right ventricle to the overriding aorta

due to obstructed right ventricle outflow tract mixing

of oxygenated and deoxygenated blood in left

ventricle causing persistent arterial desaturation and

cyanosis(5)(figure 4) . The degree of right ventricular

outflow obstruction determines the timing of the

onset of symptoms, the severity of cyanosis, and the

degree of right ventricular hypertrophy(2). So Fallot is

described in three types depending on the severity or

extent of the anatomical defects(5):

1. Extreme Fallot: F4 + sever pulmonary (atresia

or absent).

2. Classic Fallot: F4 + pulmonary stenosis.

3. Pink (acyanotic) Fallot: F4 + mild pulmonary stenosis.

Figure 4: Pathophysiology of TOF



Figure 5 : Blood flow in normal heart and

heart with tetralogy of Fallot



Clinical picture:

A. Symptoms:

1. Cyanosis:(5)

Onset of cyanosis usually observed weeks after delivery when the ductus

begins to close as PDA in the early postnatal life redirect a large portion of

partially oxygenated blood leaving the heart for the body to the lungs

increasing flow through the pulmonary circulation with relatively better

oxygenation.

Or sever cyanosis at birth in infant with TOF associated with pulmonary

atresia.

2. Paroxysmal hypercyanotic attacks (hypoxic, “blue,” or “tet” spells)(2)(3)(figure 6):

are particular problems during the 1st 2 yr of life, with a peak

incidence between 2 and 4 months of age. Hypoxic spells

are characterized by a paroxysm of hyperpnoea (i.e., rapid

and deep respiration), irritability and prolonged crying, chest

infection, increasing cyanosis, and decreasing intensity of

the heart murmur as flow across the right ventricular outflow

tract diminishes. These spells usually occur in the morning

after crying, feeding, or defecation. The onset is usually

spontaneous and unpredictable. The spells may last from a

few minutes to a few hours but are rarely fatal. A severe spell

may lead to limpness, convulsion, cerebrovascular accident,

and may progress to unconsciousness and, occasionally, to

hemiparesis. Infants who are only mildly cyanotic at rest are often more prone to

the development of hypoxic spells because they have not acquired the

homeostatic mechanisms to tolerate rapid lowering of arterial oxygen saturation,

such as polycythemia.

3. Dyspnea occurs on exertion(2). Characteristically, children assume a squatting

position for the relief of dyspnea caused by physical effort; the child is usually able

to resume physical activity within a few minutes. These findings occur most often in

patients with significant cyanosis at rest.

4. Low birth weight.(5)

5. Poor feeding, breathlessness and agitation.(5)

6. Growth and development may be delayed in patients with severe untreated

tetralogy of Fallot, particularly when oxygen saturation is chronically <70%. Puberty

may also be delayed in patients who do not undergo surgery.(2)

7. TB infection due to decrease pulmonary blood flow.

Figure 6 : hypoxic spells



B. Signs:

-Delayed central cyanosis.

It is most prominent in the mucous membranes of the lips

and mouth and in the fingernails and toenails. neonatal

cyanosis is noted immediately in severe degrees of

pulmonary stenosis.

older children with long standing cyanosis who have not

undergone surgery may have dusky blue skin, grey sclera

with engorged blood vessels and marked clubbing of

fingers and toes.(2)(figure 7)

Infants with acyanotic Tetralogy of Fallot may be asymptomatic or may show signs of

CHF from a large right-to-left ventricular shunt.(3)

-Children assume a squatting position for the relief of dyspnea caused by physical effort;

the child is usually able to resume physical activity within a few minutes.(2)

Squatting increases the pressure transiently in the aorta and left ventricle, causing less

blood to move into the left ventricle, more out the pulmonary artery to the lungs.(9)

-The pulse is usually normal, as is venous and arterial pressure.

-By inspection:

The apex is shifted outwards and diffuse in extent.

The left anterior hemithorax may bulge anteriorly because of right

ventricular hypertrophy.

There are parasternal pulsations.

- Palpation reveals:

Right ventricular predominance.

In about half the cases, a systolic thrill is felt along the left sternal border in

the 3rd and 4th parasternal spaces.

A left parasternal heave can be detected.

A thrill may be felt in the pulmonary area.

No special character and no thrills are felt on the apex.

-On percussion: Increased area of cardiac dullness on both sides of the chest.

-On auscultation:

The first heart sound (S1) is normal.

The second heart sound (S2) is single.

Figure 7 : cyanotic signs



A systolic murmur is usually loud (grade 3 to 5/6) and harsh; it may be

transmitted widely, especially to the lungs, but is most intense at the left

sternal border. The murmur is generally ejection in quality. It may be

preceded by a click. It is caused by turbulence through the right

ventricular outflow tract. (2)

The more severe the obstruction of the right ventricular outflow tract, the

shorter and softer the systolic murmur. In a deeply cyanotic neonate with

Tetralogy of fallot with pulmonary atresia, heart murmur is either absent or

very soft, although a continuous murmur representing PDA may be

occasionally audible.(3)

Investigations:

Chest Radiography: (figure 8)

There is a normal-sized boot-shaped heart (coeur en sabot) with prominence of the right

ventricle, elevation of the apex and a concavity in the region of the underdeveloped

right ventricular outflow tract and main pulmonary artery. The pulmonary vascular

markings are typically diminished.(4)

Figure 8: coeur en sabot



Electrocardiogram (ECG):

Figure 9 : ECG of right ventricular hypertrophy

ECG demonstrates right axis deviation and evidence of right ventricular hypertrophy.

Note the tall R waves in the right precordium and deep S waves in V6.The positive T

waves in V4R and V1are also characteristic of right ventricular hypertrophy.(figure 9)

P wave is tall and peaked or sometimes bifid .(figure 10)

Echocardiography: (figure 11)

- echocardiography establishes the diagnosis and

provides information about the extent of aortic

override of the septum, the location and degree of

the right ventricular outflow tract obstruction, the

associated ventricular septal defect, the size of the

proximaI branch pulmonary arteries, and the side of

the aortic arch. The Echocardiogram is also useful in

determining whether a PDA is supplying a portion of

the pulmonary blood flow. (2)

Cardiac catheterization:

a catheter is inserted through the skin into a blood vessel (usually in the groin)

and advanced up the inferior vena cava into the heart. An x-ray image is taken while a

small amount of dye is infused. The dye helps highlight the ventricular septal defect,

pulmonary stenosis, overriding aorta, and the size of the pulmonary arteries.(9)

Figure 10 : tall-peaked-bifid

P wave

peaked

bifid

Figure 11: TOF echo

http://www.emedicinehealth.com/script/main/art.asp?articlekey=2646







Lab tests:

Polycythemia as the body attempts to compensate for the lack of oxygen to the

tissues.

MRI:

The goals of MRI after tetralogy of Fallot repair include the quantitative assessment of left

and particularly right ventricular volumes, stroke volumes and ejection fraction; imaging

of the anatomy of the right ventricular outflow tract, the pulmonary arteries, the aorta

and aortopulmonary collaterals; and quantifying pulmonary, aortic, and tricuspid

regurgitation. (4)

Complications:(2)(9)

Bacterial endocarditis may occur in the right ventricular infundibulum or on

the pulmonic, aortic, or, rarely, tricuspid valves. Endocarditis may complicate

palliative shunts or, in patients with corrective surgery, any residual pulmonic

stenosis or VSD.

Arrythmia: junctional tachycardia

Heart block:postoperative due to right bundle branch block after right

venriculotomy Pulmonary valve regurge with right ventricular

enlargement[postoperative]

Cerebral thrombosis, usually occurring in the cerebral veins or dural sinuses

and occasionally in the cerebral arteries, are common in the presence of

extreme polycythemia and dehydration. Thromboses occur most often in

patients younger than 2 yr. These patients may have iron deficiency anemia,

frequently with hemoglobin and hematocrit levels in the normal range (but

too low for cyanotic heart disease).

Brain abscess is less common than cerebral vascular events and extremely

rare when most patients are repaired at young ages. Patients with a brain

abscess are usually older than 2 yr. The onset of the illness is often insidious

and consists of low-grade fever or a gradual change in behavior, or both.

Some patients have an acute onset of symptoms that may develop after a

recent history of headache, nausea, and vomiting. Seizures may occur;

localized neurologic signs depend on the site and size of the abscess and the

presence of increased intracranial pressure.

Heart failure is not a usual feature in patients with the tetralogy of Fallot. It

may occur in a young infant with “pink” or acyanotic tetralogy of Fallot. As

the degree of pulmonary obstruction worsens with age, the symptoms of

heart failure resolve and eventually the patient experiences cyanosis, often

by 6–12 mo of age.



Delayed growth and development

Death due to:

1. Prolonged, severe hypoxia which may lead to shock,respiratory failure

and acidosis

2. Arrythmia

3. Heart failure

Medical treatment of fallot tetralogy: (2)(10)(11)(12)

Once tetralogy of Fallot is diagnosed, the immediate management focuses on

determining whether the child's oxygen levels are in a safe range.

1. prostaglandin E1:

dose: (0.01–0.20 μg/kg/min]

route:iv infusion

mechanism :

(a potent and specific relaxant of ductal smooth muscle

is usually initiated to keep the ductus arteriosus open which will provide additional

pulmonary blood flow and increase the child's oxygen level.

This is continued through the preoperative period and during cardiac

catheterization.

2. Treatment of arrythemia[junctional tachycardia] by temporary pacemaker and ,

prophylactic antiarrhythmic therapy

3. Heart block treated by placement of a permanently implanted pacemaker

4. Treatment of cyanotic spells:

Put the patient in squatting position

Oxygen for correction of anoxia

NAHCO3(1-2meq/kg)

Inderal iv [0.1-0.2mg /kg]to relax infandibualr spasm

Morphione[0.2mg/kg]in resistant cases

. Oral propranolol (0.5–1 mg/kg every 6 hr)

5. iron therapy : decrease frequency of Paroxysmal dyspneic attacks

and increases RBCs count so it improve exercise tolerance and general well-being

6. prophylaxis against bacterial endocarditis:

Antibiotic prophylaxis is essential before and after dental and certain surgical

procedures associated with a high incidence of bacteremia. .

7. Prevention or treatment of dehydration is important to avoid hemoconcentration

and possible thrombotic episodes.

8. Treatment of heart failure : digoxin and diuretics

9. Lifestyle and home remedies:(13)

give baby smaller more frequent meals

Remain calm if your baby has a cyanotic spell. This will reduce your child's

anxiety

Good oral hygiene



Exercising and play:after surgery patient may participate in normal

activities and avoid competitive sports

Surgical treatment of TOF:(2)(14)(15)

Treatment of the tetralogy of fallot depends on the severity of the right ventricular

outflow tract obstruction. Infants with sever tetralogy requiremedical treatment and

surgical intervention in the neonatal period. Therapy is aimed at providing an immediate

increase in pulmonary blood flow to prevent the sequalae of severe hypoxia. Prolonged,

sever hypoxia may lead to shock, respiratory failure and acidosis and will significantly

reduce the chance of survival, even when surgically amenable lesions are present. Cold

increases oxygen consumption, which places additional stress on a cyanotic infant,

whose oxygen delivery is already limited. Blood glocuse level should be monitored

because hypoglycemia is more likely to develop in infants with cyanotic heart diseases.

Infants with symptoms and sever cyanosis in the 1st month of life have marked obstruction

of the right ventricular outflow tract or pulmonary atresia.

Two options are available: 1- Palliative systemic to pulmonary artery shunt:

Aim: to augment pulmonary artery blood flow, to:

A) decease the amount of hypoxia

B) improve linear growth

C) Augment growth of the branch pulmonary arteries . Indications

Shunt procedures are performed to increase PBF. Indications for shunt procedures vary

from institution to institution. Many institutions, however, prefer primary repair without a

shunt operation regardless of the patient's age. However, when the following situations

are present, a shunt operation may usually be chosen rather than primary repair.

1. Neonates with TOF and pulmonary atresia

2. Infants with hypoplastic pulmonary annulus, which requires a transannular patch

for complete repair

3. Children with hypoplastic PAs

4. Unfavorable coronary artery anatomy

5. Infants younger than 3 to 4 months old who have medically unmanageable

hypoxic spells

6. Infants weighing less than 2.5 kg



Technique:

Although several other procedures were performed in the past (see Fig. 14-22 ), a

modified Blalock-Taussig (Gore-Tex interposition) shunt is the only popular procedure

performed at this time. Occasionally, a classic Blalock-Taussig shunt is performed.

1. Classic Blalock-Taussig shunt, anastomosed between the subclavian artery and

the ipsilateral PA, is usually performed for infants older than 3 months (see Fig. 14-

22 ) because the shunt is often thrombosed in younger infants with smaller

arteries. A right-sided shunt is performed in patients with left aortic arch; a left-

sided shunt is performed for right aortic arch.

2. Modified Blalock-Taussig (BT) shunt. A Gore-Tex interposition shunt is placed

between the subclavian artery and the ipsilateral PA. This is the most popular

procedure for any age, especially for small infants younger than 3 months of age

(see Fig. 14-22 ). A left-sided shunt is preferred for patients with a left aortic arch,

whereas a right-sided shunt is preferred for patients with a right aortic arch. The

surgical mortality rate is 1% or less.

3. The Waterston shunt, anastomosed between the ascending aorta and the right

PA, is no longer performed because of a high incidence of surgical complications

(see Fig. 14-22 ). Complications resulting from this procedure included too large a

shunt leading to CHF or pulmonary hypertension, of both, and narrowing and

kinking of the right PA at the site of the anastomosis. This created difficult

problems in closing the shunt and reconstructing the right PA at the time of

corrective surgery.

4. The Potts operation, anastomosed between the descending aorta and the left

PA, is no longer performed either (see Fig. 14-22 ). It may result in heart failure or

pulmonary hypertension, as in the Waterston operation. A separate incision (i.e.,

left thoracotomy) is required to close the shunt during corrective surgery, which is

performed through a midsternal incision.



Complications:

1) Chylothorax: treated by repeated thoracocentesis or reoperation the ligate the

thoracic duct.

2) Diaphragmatic paralysis: requires prolonged ventilator support and vigorous

physical therapy, until the function of the phrenic nerve returns in 1 to 2 months(

unless it's completely devided )

3) Horner syndrome: usually temporary and doesn't require treatment.

Successful shunt procedure will result in disappearance of the cyanosis. The

development of a continuous murmur over the lung fields after

the operation indicates a functioning anastomosis. A good continuous

shunt murmur may not be heard until several days after

surgery.

The duration of symptomatic relief is variable. As the child

grows, more pulmonary blood flow is needed and the shunt

eventually becomes inadequate.

When increasing cyanosis develops, a corrective operation

should be performed if the anatomy is favorable. If not

possible (because of hypoplastic branch pulmonary

arteries) or if the 1st shunt lasts only a brief period in a small

infant, a second aortopulmonary anastomosis may be

required on the opposite side.

2- Corrective surgical therapy ( complete intracardiac repair) :

a) Ventricular hypertrophy: Removing obstructive muscle bunbles in the right

ventricle to relief the right ventricular outflow tract obstruction.

b) Patch closure of the VSD

c) Pulmonary stenosis: Vulvotomy if the pulmonary

valve is stenotic.

Vulvectomy if the pulmonary valve annulus is

extremely thickened.

(figure 12: Complete surgical correction for tetralogy of

Fallot. Sketch of corrective surgery for tetralogy of Fallot.

Diagram shows closing of ventricular septal defect and

widening of right ventricular outflow tract with patching of

infundibular tract (gray).)

NB: Any previously established shunt MUST be ligated and

divided before full repair.

Figure 12



Prognosis:

After successful total correction, patients are generally asymptomatic and are able to

lead unrestricted lives.

Immediate post operative complications:

1) right ventricular failure: treated by diuretics and positive inoropic agent

2) transient heart block

3) residual VSD with left to right shunting

4) myocardial infarction from interruptionof an aberrant coronary artery.

5) Pulmonary incompetence: if severe, it requires reoperation.



References

Textbook:

1) Medical Embryology 9th

edition page 250

2) Nelson Textbook of Pediatrics,18 ed, chapter 430 ( Cyanotic congenital heart lesions: Lesions Associated with decreased pulmonary blood flow, tetralogy of fallot)

3) Tetralogy of Fallot.Park textbook: Pediatric Cardiology for Practitioners, Elsevier ,5th ed.

4) Zipes:Tetralogy of Fallot. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine, Elsevier,7th ed.

5) Fundamentals of pediatrics, Third edition 2008 ,Faculty of medicine, Ain Shams university.

6) www.wikipedia.com

7) www.nlm.nih.gov/medlineplus/ency/article/001567.htm

8) www.whonamedit.com/synd.cfm/2280.html

9) www.emedicine.com

10) www.pubmed.gov.com

11) www.mayoclinic.com

12) www.medlineplus.com

13) www.american heart .com

14) www.ajronline.org/cgi/content-nw/full/189/6/1353/FIG24

15) www.pediatriconcall.com/FORDOCTOR/Diseasesand

mk:@MSITStore:D:\Fallot\Cardiology\Park%205th.chm::/HTML/about/book/mosby.html

http://www.wikipedia.com/

http://www.nlm.nih.gov/medlineplus/ency/article/001567.htm

http://www.whonamedit.com/synd.cfm/2280.html

http://www.emedicine.com/

http://www.pubmed.gov.com/

http://www.mayoclinic.com/

http://www.american/

http://www.ajronline.org/cgi/content-nw/full/189/6/1353/FIG24



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Fallot tetralogy