Tetralogy of FallotNina Dwi Putri

History• First described in 1673 by the Danish monk, Nicholas Steno, in

an ectopic heart from a fetus

• Arthur Louis Etienne Fallot (1888): all cases have an interventricular communication, biventricular origin of aorta, muscular obstruction of right ventricular outflow tract, and right ventricular hypertrophy

• Fallot deserves his eponym, first observed that combination of lesions accounted for the majority of cases of cyanosis

• Abbott (Classic Atlas of Congenital Cardiac Disease), emphasized the observations of Fallot

Incidence, Prevalence, Etiology• Approximately 3.5% of infants born with congenital heart

disease, or 0.28 per 1,000, or 1 in 3,600 live births, males and females equally affected

• Precise etiology unknown, majority of cases are sporadic, some cases linked with:• Rubela in the first trimester of pregnancy• Abnormal migration of cells from the neural crest• Microdeletions of the q11 region of chromosome 22

• Polygenic model of inheritance genes act additively to produce the spectrum of maldevelopment

Phenotypic Features• Primary defect: anterior and cephalad deviation of the

infundibular septum producing annular obstruction at the mouth of the infundibulum

• The consequences are• Obstruction to right ventricular outflow (pulmonary stenosis)• Ventricular septal defect (VSD)• Dextroposition of aorta with override of ventricular septum• Right ventricular hypertrophy

• Degree of pulmonary outflow obstruction varies severity of obstruction determining the degree of patient's cyanosis

Phenotypic Features

Physiology• Atrial (mixed venous)

oxygen saturation is decreased because of systemic hypoxemia

• Pulmonary blood flow is two thirds normal (Qp : Qs [pulmonary-to-systemic blood flow ratio] of 0.7 : 1)

• Aortic saturation is decreased, and cardiac output is normal

Signs: Severe Obstruction• When obstruction of the right ventricular outflow tract is

severe at birth, presentation is in the neonatal period

• Persistent cyanosis becomes apparent within first few hours or days of life, increases with crying, feeding, or other activities

• Severe arterial desaturation metabolic acidosis compensated by increased respiratory rate fall in arterial carbon dioxide compensatory respiratory alkalosis

• Intercostal or subcostal recession unusual – initially, the baby does not appear unduly distressed

Signs: Moderate Obstruction• Majority of children are acyanotic at birth

• Often present because a systolic murmur is detected during routine examination

• Development of cyanosis is dependent on increasing infundibular stenosis, not on the degree of aortic override Usually noted within the first few weeks of life, but development of cyanosis rarely be delayed to late childhood

• Later, hypercyanotic spells or squatting on exercise may all occur

Signs: Minimal Obstruction• Some infants with tetralogy may uncommonly present at the

age of 4 to 6 weeks with features indistinguishable from those of a large ventricular septal defect

• These babies are breathless, feed poorly, gain weight poorly, and are not cyanosed

• Increasing right ventricular hypertrophy subpulmonary obstruction becomes more marked shunt is reversed signs and progression as described for the group with moderate obstruction

Absent Pulmonary Valve• Absence of the leaflets of the pulmonary valve different

characteristic presentation from previous

• Present in infancy with respiratory symptoms of inspiratory and expiratory stridor, dyspnoea caused by lobar collapse or lobar emphysema

• Symptoms directly related to abnormal haemodynamics are unusual

Physical Examination• Essential abnormal cardiac findings in severe tetralogy of

Fallot: cyanosis and systolic ejection murmur with a single second heart sound

• Overt clubbing of fingers and toes typically not detected until 2-3 months of age

• The baby may be normally grown, although a higher proportion weighs less than would be expected by chance

• Some degree of facial dysmorphism is quite common, and typical features of associated syndromes may be obvious(DiGeorge, Goldenhauer, Down syndromes)

Chest Radiograph• Typical features• Trachea slightly

compressed by aorta arching to its right side• Concavity or

pulmonary arterial bay

Electrocardiography• Sinus rhythm, a normal or rightward QRS axis and overt right

ventricular hypertrophy

• After surgery, right bundle branch block with prolongation of the QRS duration is frequent

Echocardiography• Transthoracic cross sectional echocardiography usually allows

clear demonstration of all the intracardiac anatomy• Subcostal paracoronal view: narrowed subpulmonary outflow

tract, with malalignment of anteriorly displaced muscular outlet septum

• Parasternal long-axis views: aortic override• Anteriorly tilted four-chamber view: Biventricular connection is

seen (less reliable at defining the degree of override), also straddling or overriding tricuspid valve

• Parasternal short-axis view: identify margins of ventricular septal defect

Echocardiography• classical subcostal

right anterior oblique view • marked trabeculations

of right ventricle (RV)• antero-cephalad

deviation of outlet septum• narrowing of right

ventricular outflow tract

Echocardiography• modified right

anterior oblique view• outlet septum

(arrows) is elongated with lengthening of the subpulmonary infundibulum

Echocardiography• parasternal

long-axis view • aortic valve (ao)

overriding the crest of the muscular ventricular septum

• marked hypertrophy of the right ventricular myocardium

Echocardiography• short-axis view in a

patient with absent pulmonary valve• rudimentary nature of

the leaflets of the pulmonary valve

• narrowing of the pulmonary trunk (arrow)

• markedly dilated left and right pulmonary arteries

Therapeutic Options• Primary complete correction is now the treatment of choice,

almost no matter what the age or size of the patient• Precise timing may depend on the experience of the particular

unit; there is a role for interventional catheterization in some • Medical management of a symptomatic child is devoted

principally to preparation for surgery

Medical Management• Hypercyanotic crisis• Place the child in knee-chest position• Administer oxygen by face mask• If extremely restless, insert IV line, administer small dose of

morphine sulphate (0.1 mg per kg)• β-blocking agent such as propranolol will reduce tachycardia and

increase systemic resistance; half given rapidly, and the remaining half more slowly over the next few minutes

• Arterial blood gases should be assessed• Accompanying metabolic acidosis should be corrected• Intubation and ventilation required in extreme cases, and iv

vasoconstrictor, such as phenylephrine, often effective

Surgical Management

• Palliative procedures: Blalock-Taussig shunt and modifications

• CBTS: classic Blalock-Taussig shunt• MBTS: modified

Blalock-Taussig shunt

Surgical Management• Definitive repair:• Reconstituting the ventricular septum: rarely performed via a

large ventriculotomy, usually transatrial closure of the septal defect

• Relieving subpulmonary obstruction: the hypertrophied outlet septum, together with its parietal and septal extensions, is excised as indicated

• Ideal result:• Normal right ventricular pressures• Absence of pressure gradient

between RV and PA• Competent pulmonary valve

Early Post-op Complications• Usual complications of cardiac surgery: bleeding, low cardiac

output may occur because of inadequate relief of subpulmonary obstruction, or an obstructed or restrictive pulmonary vascular bed

• Management: • maintenance of sinus rhythm and right ventricular preload,

keeping the central venous pressure at 12 to 15 mm hg, early drainage of resulting effusions, and early extubation

• Careful use of inotropic or inodilator support is required, as these may make things worse and are rarely required, as systolic function is usually preserved

Late Outcomes• Actuarial survival 86% among patients surviving 30 days after

complete repair, compared with 96% in control population

• Rates of survival after 30 years of 90%, 93%, and 91%, in patients undergoing surgery <5 years, 5-7 years, 8-11 years

• Patients who were >12 years the time of operation, only 76% were alive, compared with 93% in controls

• Late mortality after definitive repair will far exceed the early post-operative risk

Response to Correction• Following successful repair, almost all children rapidly catch up

their height and weight, reaching normal 5 years after repair

• Murmurs frequently persist, usually related to• Mild residual subpulmonary obstruction• Acquired pulmonary incompetence

• Typical auscultatory findings are single second sound, an ejection systolic murmur in the second or third left intercostal space, and a slightly delayed diastolic decrescendo murmur

Long-Term Follow-Up• Regular follow-up by an appropriately trained cardiologist at

least once per year

• Investigations include:• Thorough clinical assessment• Electrocardiogram• Echo-doppler examination to detect and quantify residual

pulmonary stenosis and regurgitation, any residual ventricular septal defect, right and left ventricular size and function, aortic regurgitation, and size of aortic root

• Magnetic resonance imaging at least every two or three years to document and detect acute changes in right ventricular size and function, as well as pulmonary regurgitant fraction